[fontloader] sync with Context as of 2015-12-21

12 files changed, 5352 insertions, 44 deletions

diff --git a/src/fontloader/misc/fontloader-basics-nod.lua b/src/fontloader/misc/fontloader-basics-nod.lua
index 39400a3..78f1b17 100644
--- a/src/fontloader/misc/fontloader-basics-nod.lua
+++ b/src/fontloader/misc/fontloader-basics-nod.lua
@@ -51,17 +51,23 @@ nodes              = { }
 nodes.pool         = { }
 nodes.handlers     = { }
 
-local nodecodes    = { } for k,v in next, node.types   () do nodecodes[string.gsub(v,"_","")] = k end
-local whatcodes    = { } for k,v in next, node.whatsits() do whatcodes[string.gsub(v,"_","")] = k end
-local glyphcodes   = { [0] = "character", "glyph", "ligature", "ghost", "left", "right" }
-local disccodes    = { [0] = "discretionary", "explicit", "automatic", "regular", "first", "second" }
-
-for i=0,#glyphcodes do glyphcodes[glyphcodes[i]] = i end
-for i=0,#disccodes  do disccodes [disccodes [i]] = i end
+local nodecodes    = { }
+local glyphcodes   = node.subtypes("glyph")
+local disccodes    = node.subtypes("disc")
+
+for k, v in next, node.types() do
+    v = string.gsub(v,"_","")
+    nodecodes[k] = v
+    nodecodes[v] = k
+end
+for i=0,#glyphcodes do
+    glyphcodes[glyphcodes[i]] = i
+end
+for i=0,#disccodes do
+    disccodes[disccodes[i]] = i
+end
 
 nodes.nodecodes    = nodecodes
-nodes.whatcodes    = whatcodes
-nodes.whatsitcodes = whatcodes
 nodes.glyphcodes   = glyphcodes
 nodes.disccodes    = disccodes
 
@@ -140,7 +146,6 @@ nodes.slide                = node.slide
 nodes.vpack                = node.vpack
 
 nodes.first_glyph          = node.first_glyph
-nodes.first_character      = node.first_character
 nodes.has_glyph            = node.has_glyph or node.first_glyph
 
 nodes.current_attr         = node.current_attr
@@ -178,20 +183,33 @@ nodes.tonut              = tonut
 nuts.tonode              = tonode
 nuts.tonut               = tonut
 
-
 local getfield           = direct.getfield
 local setfield           = direct.setfield
 
 nuts.getfield            = getfield
 nuts.setfield            = setfield
 nuts.getnext             = direct.getnext
+nuts.setnext             = direct.setnext
 nuts.getprev             = direct.getprev
+nuts.setprev             = direct.setprev
+nuts.getboth             = direct.getboth
+nuts.setboth             = direct.setboth
 nuts.getid               = direct.getid
-nuts.getattr             = getfield
+nuts.getattr             = direct.get_attribute or direct.has_attribute or getfield
 nuts.setattr             = setfield
 nuts.getfont             = direct.getfont
+nuts.setfont             = direct.setfont
 nuts.getsubtype          = direct.getsubtype
+nuts.setsubtype          = direct.setsubtype or function(n,s) setfield(n,"subtype",s) end
 nuts.getchar             = direct.getchar
+nuts.setchar             = direct.setchar
+nuts.getdisc             = direct.getdisc
+nuts.setdisc             = direct.setdisc
+nuts.setlink             = direct.setlink
+nuts.getlist             = direct.getlist
+nuts.setlist             = direct.setlist    or function(n,l) setfield(n,"list",l) end
+nuts.getleader           = direct.getleader
+nuts.setleader           = direct.setleader  or function(n,l) setfield(n,"leader",l) end
 
 nuts.insert_before       = direct.insert_before
 nuts.insert_after        = direct.insert_after
@@ -206,6 +224,9 @@ nuts.is_node             = direct.is_node
 nuts.end_of_math         = direct.end_of_math
 nuts.traverse            = direct.traverse
 nuts.traverse_id         = direct.traverse_id
+nuts.traverse_char       = direct.traverse_char
+nuts.ligaturing          = direct.ligaturing
+nuts.kerning             = direct.kerning
 
 nuts.getprop             = nuts.getattr
 nuts.setprop             = nuts.setattr
diff --git a/src/fontloader/misc/fontloader-font-con.lua b/src/fontloader/misc/fontloader-font-con.lua
index 55d7793..e5bf9e9 100644
--- a/src/fontloader/misc/fontloader-font-con.lua
+++ b/src/fontloader/misc/fontloader-font-con.lua
@@ -682,6 +682,8 @@ function constructors.scale(tfmdata,specification)
         if isunicode then
             chr.unicode   = isunicode
             chr.tounicode = tounicode(isunicode)
+            -- in luatex > 0.85 we can do this:
+         -- chr.tounicode = isunicode
         end
         if hasquality then
             -- we could move these calculations elsewhere (saves calculations)
diff --git a/src/fontloader/misc/fontloader-font-inj.lua b/src/fontloader/misc/fontloader-font-inj.lua
new file mode 100644
index 0000000..8937021
--- /dev/null
+++ b/src/fontloader/misc/fontloader-font-inj.lua
@@ -0,0 +1,1196 @@
+if not modules then modules = { } end modules ['font-inj'] = {
+    version   = 1.001,
+    comment   = "companion to font-lib.mkiv",
+    author    = "Hans Hagen, PRAGMA-ADE, Hasselt NL",
+    copyright = "PRAGMA ADE / ConTeXt Development Team",
+    license   = "see context related readme files",
+}
+
+-- This property based variant is not faster but looks nicer than the attribute one. We
+-- need to use rawget (which is apbout 4 times slower than a direct access but we cannot
+-- get/set that one for our purpose! This version does a bit more with discretionaries
+-- (and Kai has tested it with his collection of weird fonts.)
+
+-- There is some duplicate code here (especially in the the pre/post/replace branches) but
+-- we go for speed. We could store a list of glyph and mark nodes when registering but it's
+-- cleaner to have an identification pass here. Also, I need to keep tracing in mind so
+-- being too clever here is dangerous.
+
+-- The subtype test is not needed as there will be no (new) properties set, given that we
+-- reset the properties.
+
+if not nodes.properties then return end
+
+local next, rawget = next, rawget
+local utfchar = utf.char
+local fastcopy = table.fastcopy
+
+local trace_injections = false  trackers.register("fonts.injections", function(v) trace_injections = v end)
+
+local report_injections = logs.reporter("fonts","injections")
+
+local attributes, nodes, node = attributes, nodes, node
+
+fonts                    = fonts
+local fontdata           = fonts.hashes.identifiers
+
+nodes.injections         = nodes.injections or { }
+local injections         = nodes.injections
+
+local nodecodes          = nodes.nodecodes
+local glyph_code         = nodecodes.glyph
+local disc_code          = nodecodes.disc
+local kern_code          = nodecodes.kern
+
+local nuts               = nodes.nuts
+local nodepool           = nuts.pool
+
+local newkern            = nodepool.kern
+
+local tonode             = nuts.tonode
+local tonut              = nuts.tonut
+
+local getfield           = nuts.getfield
+local setfield           = nuts.setfield
+local getnext            = nuts.getnext
+local getprev            = nuts.getprev
+local getid              = nuts.getid
+local getfont            = nuts.getfont
+local getsubtype         = nuts.getsubtype
+local getchar            = nuts.getchar
+
+local traverse_id        = nuts.traverse_id
+local insert_node_before = nuts.insert_before
+local insert_node_after  = nuts.insert_after
+local find_tail          = nuts.tail
+
+local properties         = nodes.properties.data
+
+function injections.installnewkern(nk)
+    newkern = nk or newkern
+end
+
+local nofregisteredkerns    = 0
+local nofregisteredpairs    = 0
+local nofregisteredmarks    = 0
+local nofregisteredcursives = 0
+local keepregisteredcounts  = false
+
+function injections.keepcounts()
+    keepregisteredcounts = true
+end
+
+function injections.resetcounts()
+    nofregisteredkerns    = 0
+    nofregisteredpairs    = 0
+    nofregisteredmarks    = 0
+    nofregisteredcursives = 0
+    keepregisteredcounts  = false
+end
+
+-- We need to make sure that a possible metatable will not kick in unexpectedly.
+
+-- function injections.reset(n)
+--     local p = rawget(properties,n)
+--     if p and rawget(p,"injections") then
+--         p.injections = nil
+--     end
+-- end
+
+-- function injections.copy(target,source)
+--     local sp = rawget(properties,source)
+--     if sp then
+--         local tp = rawget(properties,target)
+--         local si = rawget(sp,"injections")
+--         if si then
+--             si = fastcopy(si)
+--             if tp then
+--                 tp.injections = si
+--             else
+--                 propertydata[target] = {
+--                     injections = si,
+--                 }
+--             end
+--         else
+--             if tp then
+--                 tp.injections = nil
+--             end
+--         end
+--     end
+-- end
+
+function injections.reset(n)
+    local p = rawget(properties,n)
+    if p then
+        p.injections = false -- { }
+    else
+        properties[n] = false -- { injections = { } }
+    end
+end
+
+function injections.copy(target,source)
+    local sp = rawget(properties,source)
+    if sp then
+        local tp = rawget(properties,target)
+        local si = rawget(sp,"injections")
+        if si then
+            si = fastcopy(si)
+            if tp then
+                tp.injections = si
+            else
+                propertydata[target] = {
+                    injections = si,
+                }
+            end
+        elseif tp then
+            tp.injections = false -- { }
+        else
+            properties[target] = { injections = { } }
+        end
+    else
+        local tp = rawget(properties,target)
+        if tp then
+            tp.injections = false -- { }
+        else
+            properties[target] = false -- { injections = { } }
+        end
+    end
+end
+
+function injections.setligaindex(n,index)
+    local p = rawget(properties,n)
+    if p then
+        local i = rawget(p,"injections")
+        if i then
+            i.ligaindex = index
+        else
+            p.injections = {
+                ligaindex = index
+            }
+        end
+    else
+        properties[n] = {
+            injections = {
+                ligaindex = index
+            }
+        }
+    end
+end
+
+function injections.getligaindex(n,default)
+    local p = rawget(properties,n)
+    if p then
+        local i = rawget(p,"injections")
+        if i then
+            return i.ligaindex or default
+        end
+    end
+    return default
+end
+
+function injections.setcursive(start,nxt,factor,rlmode,exit,entry,tfmstart,tfmnext) -- hm: nuts or nodes
+    local dx =  factor*(exit[1]-entry[1])
+    local dy = -factor*(exit[2]-entry[2])
+    local ws = tfmstart.width
+    local wn = tfmnext.width
+    nofregisteredcursives = nofregisteredcursives + 1
+    if rlmode < 0 then
+        dx = -(dx + wn)
+    else
+        dx = dx - ws
+    end
+    --
+    local p = rawget(properties,start)
+    if p then
+        local i = rawget(p,"injections")
+        if i then
+            i.cursiveanchor = true
+        else
+            p.injections = {
+                cursiveanchor = true,
+            }
+        end
+    else
+        properties[start] = {
+            injections = {
+                cursiveanchor = true,
+            },
+        }
+    end
+    local p = rawget(properties,nxt)
+    if p then
+        local i = rawget(p,"injections")
+        if i then
+            i.cursivex = dx
+            i.cursivey = dy
+        else
+            p.injections = {
+                cursivex = dx,
+                cursivey = dy,
+            }
+        end
+    else
+        properties[nxt] = {
+            injections = {
+                cursivex = dx,
+                cursivey = dy,
+            },
+        }
+    end
+    return dx, dy, nofregisteredcursives
+end
+
+function injections.setpair(current,factor,rlmode,r2lflag,spec,injection) -- r2lflag & tfmchr not used
+    local x = factor*spec[1]
+    local y = factor*spec[2]
+    local w = factor*spec[3]
+    local h = factor*spec[4]
+    if x ~= 0 or w ~= 0 or y ~= 0 or h ~= 0 then -- okay?
+        local yoffset   = y - h
+        local leftkern  = x      -- both kerns are set in a pair kern compared
+        local rightkern = w - x  -- to normal kerns where we set only leftkern
+        if leftkern ~= 0 or rightkern ~= 0 or yoffset ~= 0 then
+            nofregisteredpairs = nofregisteredpairs + 1
+            if rlmode and rlmode < 0 then
+                leftkern, rightkern = rightkern, leftkern
+            end
+            if not injection then
+                injection = "injections"
+            end
+            local p = rawget(properties,current)
+            if p then
+                local i = rawget(p,injection)
+                if i then
+                    if leftkern ~= 0 then
+                        i.leftkern  = (i.leftkern  or 0) + leftkern
+                    end
+                    if rightkern ~= 0 then
+                        i.rightkern = (i.rightkern or 0) + rightkern
+                    end
+                    if yoffset ~= 0 then
+                        i.yoffset = (i.yoffset or 0) + yoffset
+                    end
+                elseif leftkern ~= 0 or rightkern ~= 0 then
+                    p[injection] = {
+                        leftkern  = leftkern,
+                        rightkern = rightkern,
+                        yoffset   = yoffset,
+                    }
+                else
+                    p[injection] = {
+                        yoffset = yoffset,
+                    }
+                end
+            elseif leftkern ~= 0 or rightkern ~= 0 then
+                properties[current] = {
+                    [injection] = {
+                        leftkern  = leftkern,
+                        rightkern = rightkern,
+                        yoffset   = yoffset,
+                    },
+                }
+            else
+                properties[current] = {
+                    [injection] = {
+                        yoffset = yoffset,
+                    },
+                }
+            end
+            return x, y, w, h, nofregisteredpairs
+         end
+    end
+    return x, y, w, h -- no bound
+end
+
+-- This needs checking for rl < 0 but it is unlikely that a r2l script uses kernclasses between
+-- glyphs so we're probably safe (KE has a problematic font where marks interfere with rl < 0 in
+-- the previous case)
+
+function injections.setkern(current,factor,rlmode,x,injection)
+    local dx = factor * x
+    if dx ~= 0 then
+        nofregisteredkerns = nofregisteredkerns + 1
+        local p = rawget(properties,current)
+        if not injection then
+            injection = "injections"
+        end
+        if p then
+            local i = rawget(p,injection)
+            if i then
+                i.leftkern = dx + (i.leftkern or 0)
+            else
+                p[injection] = {
+                    leftkern = dx,
+                }
+            end
+        else
+            properties[current] = {
+                [injection] = {
+                    leftkern = dx,
+                },
+            }
+        end
+        return dx, nofregisteredkerns
+    else
+        return 0, 0
+    end
+end
+
+function injections.setmark(start,base,factor,rlmode,ba,ma,tfmbase,mkmk) -- ba=baseanchor, ma=markanchor
+    local dx, dy = factor*(ba[1]-ma[1]), factor*(ba[2]-ma[2])
+    nofregisteredmarks = nofregisteredmarks + 1
+ -- markanchors[nofregisteredmarks] = base
+    if rlmode >= 0 then
+        dx = tfmbase.width - dx -- see later commented ox
+    end
+    local p = rawget(properties,start)
+    -- hm, dejavu serif does a sloppy mark2mark before mark2base
+    if p then
+        local i = rawget(p,"injections")
+        if i then
+            if i.markmark then
+                -- out of order mkmk: yes or no or option
+            else
+                i.markx        = dx
+                i.marky        = dy
+                i.markdir      = rlmode or 0
+                i.markbase     = nofregisteredmarks
+                i.markbasenode = base
+                i.markmark     = mkmk
+            end
+        else
+            p.injections = {
+                markx        = dx,
+                marky        = dy,
+                markdir      = rlmode or 0,
+                markbase     = nofregisteredmarks,
+                markbasenode = base,
+                markmark     = mkmk,
+            }
+        end
+    else
+        properties[start] = {
+            injections = {
+                markx        = dx,
+                marky        = dy,
+                markdir      = rlmode or 0,
+                markbase     = nofregisteredmarks,
+                markbasenode = base,
+                markmark     = mkmk,
+            },
+        }
+    end
+    return dx, dy, nofregisteredmarks
+end
+
+local function dir(n)
+    return (n and n<0 and "r-to-l") or (n and n>0 and "l-to-r") or "unset"
+end
+
+local function showchar(n,nested)
+    local char = getchar(n)
+    report_injections("%wfont %s, char %U, glyph %c",nested and 2 or 0,getfont(n),char,char)
+end
+
+local function show(n,what,nested,symbol)
+    if n then
+        local p = rawget(properties,n)
+        if p then
+            local i = rawget(p,what)
+            if i then
+                local leftkern  = i.leftkern  or 0
+                local rightkern = i.rightkern or 0
+                local yoffset   = i.yoffset   or 0
+                local markx     = i.markx     or 0
+                local marky     = i.marky     or 0
+                local markdir   = i.markdir   or 0
+                local markbase  = i.markbase  or 0
+                local cursivex  = i.cursivex  or 0
+                local cursivey  = i.cursivey  or 0
+                local ligaindex = i.ligaindex or 0
+                local cursbase  = i.cursiveanchor
+                local margin    = nested and 4 or 2
+                --
+                if rightkern ~= 0 or yoffset ~= 0 then
+                    report_injections("%w%s pair: lx %p, rx %p, dy %p",margin,symbol,leftkern,rightkern,yoffset)
+                elseif leftkern ~= 0 then
+                    report_injections("%w%s kern: dx %p",margin,symbol,leftkern)
+                end
+                if markx ~= 0 or marky ~= 0 or markbase ~= 0 then
+                    report_injections("%w%s mark: dx %p, dy %p, dir %s, base %s",margin,symbol,markx,marky,markdir,markbase ~= 0 and "yes" or "no")
+                end
+                if cursivex ~= 0 or cursivey ~= 0 then
+                    if cursbase then
+                        report_injections("%w%s curs: base dx %p, dy %p",margin,symbol,cursivex,cursivey)
+                    else
+                        report_injections("%w%s curs: dx %p, dy %p",margin,symbol,cursivex,cursivey)
+                    end
+                elseif cursbase then
+                    report_injections("%w%s curs: base",margin,symbol)
+                end
+                if ligaindex ~= 0 then
+                    report_injections("%w%s liga: index %i",margin,symbol,ligaindex)
+                end
+            end
+        end
+    end
+end
+
+local function showsub(n,what,where)
+    report_injections("begin subrun: %s",where)
+    for n in traverse_id(glyph_code,n) do
+        showchar(n,where)
+        show(n,what,where," ")
+    end
+    report_injections("end subrun")
+end
+
+local function trace(head,where)
+    report_injections("begin run %s: %s kerns, %s pairs, %s marks and %s cursives registered",
+        where or "",nofregisteredkerns,nofregisteredpairs,nofregisteredmarks,nofregisteredcursives)
+    local n = head
+    while n do
+        local id = getid(n)
+        if id == glyph_code then
+            showchar(n)
+            show(n,"injections",false," ")
+            show(n,"preinjections",false,"<")
+            show(n,"postinjections",false,">")
+            show(n,"replaceinjections",false,"=")
+        elseif id == disc_code then
+            local pre     = getfield(n,"pre")
+            local post    = getfield(n,"post")
+            local replace = getfield(n,"replace")
+            if pre then
+                showsub(pre,"preinjections","pre")
+            end
+            if post then
+                showsub(post,"postinjections","post")
+            end
+            if replace then
+                showsub(replace,"replaceinjections","replace")
+            end
+        end
+        n = getnext(n)
+    end
+    report_injections("end run")
+end
+
+local function show_result(head)
+    local current  = head
+    local skipping = false
+    while current do
+        local id = getid(current)
+        if id == glyph_code then
+            report_injections("char: %C, width %p, xoffset %p, yoffset %p",
+                getchar(current),getfield(current,"width"),getfield(current,"xoffset"),getfield(current,"yoffset"))
+            skipping = false
+        elseif id == kern_code then
+            report_injections("kern: %p",getfield(current,"kern"))
+            skipping = false
+        elseif not skipping then
+            report_injections()
+            skipping = true
+        end
+        current = getnext(current)
+    end
+end
+
+local function collect_glyphs(head,offsets)
+    local glyphs, glyphi, nofglyphs = { }, { }, 0
+    local marks, marki, nofmarks = { }, { }, 0
+    local nf, tm = nil, nil
+    local n = head
+
+    local function identify(n,what)
+        local f = getfont(n)
+        if f ~= nf then
+            nf = f
+            -- other hash in ctx:
+            tm = fontdata[nf].resources
+            if tm then
+                tm = tm.marks
+            end
+        end
+        if tm and tm[getchar(n)] then
+            nofmarks = nofmarks + 1
+            marks[nofmarks] = n
+            marki[nofmarks] = "injections"
+        else
+            nofglyphs = nofglyphs + 1
+            glyphs[nofglyphs] = n
+            glyphi[nofglyphs] = what
+        end
+        if offsets then
+            -- yoffsets can influence curs steps
+            local p = rawget(properties,n)
+            if p then
+                local i = rawget(p,what)
+                if i then
+                    local yoffset = i.yoffset
+                    if yoffset and yoffset ~= 0 then
+                        setfield(n,"yoffset",yoffset)
+                    end
+                end
+            end
+        end
+    end
+
+    while n do -- only needed for relevant fonts
+        local id = getid(n)
+        if id == glyph_code then
+            identify(n,"injections")
+        elseif id == disc_code then
+            local d = getfield(n,"pre")
+            if d then
+                for n in traverse_id(glyph_code,d) do
+                    if getsubtype(n) < 256 then
+                        identify(n,"preinjections")
+                    end
+                end
+			end
+            local d = getfield(n,"post")
+            if d then
+                for n in traverse_id(glyph_code,d) do
+                    if getsubtype(n) < 256 then
+                        identify(n,"postinjections")
+                    end
+                end
+			end
+            local d = getfield(n,"replace")
+            if d then
+                for n in traverse_id(glyph_code,d) do
+                    if getsubtype(n) < 256 then
+                        identify(n,"replaceinjections")
+                    end
+                end
+			end
+        end
+		n = getnext(n)
+    end
+
+    return glyphs, glyphi, nofglyphs, marks, marki, nofmarks
+end
+
+local function inject_marks(marks,marki,nofmarks)
+    for i=1,nofmarks do
+        local n  = marks[i]
+        local pn = rawget(properties,n)
+        if pn then
+            local ni = marki[i]
+            local pn = rawget(pn,ni)
+            if pn then
+                local p = pn.markbasenode
+                if p then
+                    local px = getfield(p,"xoffset")
+                    local ox = 0
+                    local rightkern = nil
+                    local pp = rawget(properties,p)
+                    if pp then
+                        pp = rawget(pp,ni)
+                        if pp then
+                            rightkern = pp.rightkern
+                        end
+                    end
+                    if rightkern then -- x and w ~= 0
+                        if pn.markdir < 0 then
+                            -- kern(w-x) glyph(p) kern(x) mark(n)
+                            ox = px - pn.markx - rightkern
+                         -- report_injections("r2l case 1: %p",ox)
+                        else
+                            -- kern(x) glyph(p) kern(w-x) mark(n)
+                         -- ox = px - getfield(p,"width") + pn.markx - pp.leftkern
+                            --
+							-- According to Kai we don't need to handle leftkern here but I'm
+                            -- pretty sure I've run into a case where it was needed so maybe
+	                        -- some day we need something more clever here.
+                            --
+							if false then
+                                -- a mark with kerning
+                                local leftkern = pp.leftkern
+                                if leftkern then
+                                    ox = px - pn.markx - leftkern
+                                else
+                                    ox = px - pn.markx
+                                end
+                            else
+                                ox = px - pn.markx
+                            end
+                        end
+                    else
+                        -- we need to deal with fonts that have marks with width
+                     -- if pn.markdir < 0 then
+                     --     ox = px - pn.markx
+                     --  -- report_injections("r2l case 3: %p",ox)
+                     -- else
+                     --  -- ox = px - getfield(p,"width") + pn.markx
+                            ox = px - pn.markx
+                         -- report_injections("l2r case 3: %p",ox)
+                     -- end
+                        local wn = getfield(n,"width") -- in arial marks have widths
+                        if wn ~= 0 then
+                            -- bad: we should center
+                         -- insert_node_before(head,n,newkern(-wn/2))
+                         -- insert_node_after(head,n,newkern(-wn/2))
+                            pn.leftkern  = -wn/2
+                            pn.rightkern = -wn/2
+                         -- wx[n] = { 0, -wn/2, 0, -wn }
+                        end
+                        -- so far
+                    end
+                    setfield(n,"xoffset",ox)
+                    --
+                    local py = getfield(p,"yoffset")
+--                     local oy = 0
+--                     if marks[p] then
+--                         oy = py + pn.marky
+--                     else
+--                         oy = getfield(n,"yoffset") + py + pn.marky
+--                     end
+                    local oy = getfield(n,"yoffset") + py + pn.marky
+                    setfield(n,"yoffset",oy)
+                else
+                    -- normally this can't happen (only when in trace mode which is a special case anyway)
+                 -- report_injections("missing mark anchor %i",pn.markbase or 0)
+                end
+            end
+        end
+    end
+end
+
+local function inject_cursives(glyphs,glyphi,nofglyphs)
+    local cursiveanchor, lastanchor = nil, nil
+    local minc, maxc, last = 0, 0, nil
+    for i=1,nofglyphs do
+        local n  = glyphs[i]
+        local pn = rawget(properties,n)
+        if pn then
+            pn = rawget(pn,glyphi[i])
+        end
+        if pn then
+            local cursivex = pn.cursivex
+            if cursivex then
+                if cursiveanchor then
+                    if cursivex ~= 0 then
+                        pn.leftkern = (pn.leftkern or 0) + cursivex
+                    end
+                    if lastanchor then
+                        if maxc == 0 then
+                            minc = lastanchor
+                        end
+                        maxc = lastanchor
+                        properties[cursiveanchor].cursivedy = pn.cursivey
+                    end
+                    last = n
+                else
+                    maxc = 0
+                end
+            elseif maxc > 0 then
+                local ny = getfield(n,"yoffset")
+                for i=maxc,minc,-1 do
+                    local ti = glyphs[i]
+                    ny = ny + properties[ti].cursivedy
+                    setfield(ti,"yoffset",ny) -- why not add ?
+                end
+                maxc = 0
+            end
+            if pn.cursiveanchor then
+                cursiveanchor = n
+                lastanchor = i
+            else
+                cursiveanchor = nil
+                lastanchor = nil
+                if maxc > 0 then
+                    local ny = getfield(n,"yoffset")
+                    for i=maxc,minc,-1 do
+                        local ti = glyphs[i]
+                        ny = ny + properties[ti].cursivedy
+                        setfield(ti,"yoffset",ny) -- why not add ?
+                    end
+                    maxc = 0
+                end
+            end
+        elseif maxc > 0 then
+            local ny = getfield(n,"yoffset")
+            for i=maxc,minc,-1 do
+                local ti = glyphs[i]
+                ny = ny + properties[ti].cursivedy
+                setfield(ti,"yoffset",getfield(ti,"yoffset") + ny) -- ?
+            end
+            maxc = 0
+            cursiveanchor = nil
+            lastanchor = nil
+        end
+     -- if maxc > 0 and not cursiveanchor then
+     --     local ny = getfield(n,"yoffset")
+     --     for i=maxc,minc,-1 do
+     --         local ti = glyphs[i][1]
+     --         ny = ny + properties[ti].cursivedy
+     --         setfield(ti,"yoffset",ny) -- why not add ?
+     --     end
+     --     maxc = 0
+     -- end
+    end
+    if last and maxc > 0 then
+        local ny = getfield(last,"yoffset")
+        for i=maxc,minc,-1 do
+            local ti = glyphs[i]
+            ny = ny + properties[ti].cursivedy
+            setfield(ti,"yoffset",ny) -- why not add ?
+        end
+    end
+end
+
+-- G  +D-pre        G
+--     D-post+
+--    +D-replace+
+--
+-- G  +D-pre       +D-pre
+--     D-post      +D-post
+--    +D-replace   +D-replace
+
+local function inject_kerns(head,glist,ilist,length) -- not complete ! compare with inject_kerns_only (but unlikely disc here)
+    for i=1,length do
+        local n  = glist[i]
+        local pn = rawget(properties,n)
+        if pn then
+			local dp = nil
+			local dr = nil
+            local ni = ilist[i]
+            local p  = nil
+			if ni == "injections" then
+				p = getprev(n)
+				if p then
+					local id = getid(p)
+					if id == disc_code then
+						dp = getfield(p,"post")
+						dr = getfield(p,"replace")
+					end
+				end
+			end
+			if dp then
+				local i = rawget(pn,"postinjections")
+				if i then
+					local leftkern = i.leftkern
+					if leftkern and leftkern ~= 0 then
+						local t = find_tail(dp)
+						insert_node_after(dp,t,newkern(leftkern))
+                        setfield(p,"post",dp) -- currently we need to force a tail refresh
+					end
+				end
+			end
+			if dr then
+				local i = rawget(pn,"replaceinjections")
+				if i then
+					local leftkern = i.leftkern
+					if leftkern and leftkern ~= 0 then
+						local t = find_tail(dr)
+						insert_node_after(dr,t,newkern(leftkern))
+                        setfield(p,"replace",dr) -- currently we need to force a tail refresh
+					end
+				end
+			else
+				local i = rawget(pn,ni)
+				if i then
+					local leftkern = i.leftkern
+					if leftkern and leftkern ~= 0 then
+						insert_node_before(head,n,newkern(leftkern)) -- type 0/2
+					end
+					local rightkern = i.rightkern
+					if rightkern and rightkern ~= 0 then
+						insert_node_after(head,n,newkern(rightkern)) -- type 0/2
+					end
+				end
+			end
+        end
+    end
+end
+
+local function inject_everything(head,where)
+    head = tonut(head)
+    if trace_injections then
+        trace(head,"everything")
+    end
+    local glyphs, glyphi, nofglyphs, marks, marki, nofmarks = collect_glyphs(head,nofregisteredpairs > 0)
+    if nofglyphs > 0 then
+        if nofregisteredcursives > 0 then
+            inject_cursives(glyphs,glyphi,nofglyphs)
+        end
+        if nofregisteredmarks > 0 then -- and nofmarks > 0
+            inject_marks(marks,marki,nofmarks)
+        end
+        inject_kerns(head,glyphs,glyphi,nofglyphs)
+    end
+    if nofmarks > 0 then
+        inject_kerns(head,marks,marki,nofmarks)
+	end
+    if keepregisteredcounts then
+        keepregisteredcounts  = false
+    else
+        nofregisteredkerns    = 0
+        nofregisteredpairs    = 0
+        nofregisteredmarks    = 0
+        nofregisteredcursives = 0
+    end
+    return tonode(head), true
+end
+
+-- G  +D-pre        G
+--     D-post+
+--    +D-replace+
+--
+-- G  +D-pre       +D-pre
+--     D-post      +D-post
+--    +D-replace   +D-replace
+
+local function inject_kerns_only(head,where)
+    head = tonut(head)
+    if trace_injections then
+        trace(head,"kerns")
+    end
+    local n = head
+    local p = nil -- disc node when non-nil
+    while n do
+        local id = getid(n)
+        if id == glyph_code then
+            if getsubtype(n) < 256 then
+                local pn = rawget(properties,n)
+                if pn then
+                    if p then
+                        local d = getfield(p,"post")
+                        if d then
+                            local i = rawget(pn,"postinjections")
+                            if i then
+                                local leftkern = i.leftkern
+                                if leftkern and leftkern ~= 0 then
+                                    local t = find_tail(d)
+                                    insert_node_after(d,t,newkern(leftkern))
+                                    setfield(p,"post",d) -- currently we need to force a tail refresh
+                                end
+                            end
+                        end
+                        local d = getfield(p,"replace")
+                        if d then
+                            local i = rawget(pn,"replaceinjections")
+                            if i then
+                                local leftkern = i.leftkern
+                                if leftkern and leftkern ~= 0 then
+                                    local t = find_tail(d)
+                                    insert_node_after(d,t,newkern(leftkern))
+                                    setfield(p,"replace",d) -- currently we need to force a tail refresh
+                                end
+                            end
+                        else
+                            local i = rawget(pn,"injections")
+                            if i then
+                                local leftkern = i.leftkern
+                                if leftkern and leftkern ~= 0 then
+                                    setfield(p,"replace",newkern(leftkern))
+                                end
+                            end
+                        end
+                    else
+                        -- this is the most common case
+                        local i = rawget(pn,"injections")
+                        if i then
+                            local leftkern = i.leftkern
+                            if leftkern and leftkern ~= 0 then
+                                head = insert_node_before(head,n,newkern(leftkern))
+                            end
+                        end
+                    end
+                end
+            end
+            p = nil
+        elseif id == disc_code then
+            local d = getfield(n,"pre")
+            if d then
+                local h = d
+                for n in traverse_id(glyph_code,d) do
+                    if getsubtype(n) < 256 then
+                        local pn = rawget(properties,n)
+                        if pn then
+                            local i = rawget(pn,"preinjections")
+                            if i then
+                                local leftkern = i.leftkern
+                                if leftkern and leftkern ~= 0 then
+                                    h = insert_node_before(h,n,newkern(leftkern))
+                                end
+                            end
+                        end
+                    else
+                        break
+                    end
+                end
+                if h ~= d then
+                    setfield(n,"pre",h)
+                end
+            end
+            local d = getfield(n,"post")
+            if d then
+                local h = d
+                for n in traverse_id(glyph_code,d) do
+                    if getsubtype(n) < 256 then
+                        local pn = rawget(properties,n)
+                        if pn then
+                            local i = rawget(pn,"postinjections")
+                            if i then
+                                local leftkern = i.leftkern
+                                if leftkern and leftkern ~= 0 then
+                                    h = insert_node_before(h,n,newkern(leftkern))
+                                end
+                            end
+                        end
+                    else
+                        break
+                    end
+                end
+                if h ~= d then
+                    setfield(n,"post",h)
+                end
+            end
+            local d = getfield(n,"replace")
+            if d then
+                local h = d
+                for n in traverse_id(glyph_code,d) do
+                    if getsubtype(n) < 256 then
+                        local pn = rawget(properties,n)
+                        if pn then
+                            local i = rawget(pn,"replaceinjections")
+                            if i then
+                                local leftkern = i.leftkern
+                                if leftkern and leftkern ~= 0 then
+                                    h = insert_node_before(h,n,newkern(leftkern))
+                                end
+                            end
+                        end
+                    else
+                        break
+                    end
+                end
+                if h ~= d then
+                    setfield(n,"replace",h)
+                end
+            end
+            p = n
+        else
+            p = nil
+        end
+        n = getnext(n)
+    end
+    --
+    if keepregisteredcounts then
+        keepregisteredcounts = false
+    else
+        nofregisteredkerns   = 0
+    end
+    return tonode(head), true
+end
+
+local function inject_pairs_only(head,where)
+    head = tonut(head)
+    if trace_injections then
+        trace(head,"pairs")
+    end
+    local n = head
+    local p = nil -- disc node when non-nil
+    while n do
+        local id = getid(n)
+        if id == glyph_code then
+            if getsubtype(n) < 256 then
+                local pn = rawget(properties,n)
+                if pn then
+                    if p then
+                        local d = getfield(p,"post")
+                        if d then
+                            local i = rawget(pn,"postinjections")
+                            if i then
+                                local leftkern = i.leftkern
+                                if leftkern and leftkern ~= 0 then
+                                    local t = find_tail(d)
+                                    insert_node_after(d,t,newkern(leftkern))
+                                    setfield(p,"post",d) -- currently we need to force a tail refresh
+                                end
+                             -- local rightkern = i.rightkern
+                             -- if rightkern and rightkern ~= 0 then
+                             --     insert_node_after(head,n,newkern(rightkern))
+                             --     n = getnext(n) -- to be checked
+                             -- end
+                            end
+                        end
+                        local d = getfield(p,"replace")
+                        if d then
+                            local i = rawget(pn,"replaceinjections")
+                            if i then
+                                local leftkern = i.leftkern
+                                if leftkern and leftkern ~= 0 then
+                                    local t = find_tail(d)
+                                    insert_node_after(d,t,newkern(leftkern))
+                                    setfield(p,"replace",d) -- currently we need to force a tail refresh
+                                end
+                             -- local rightkern = i.rightkern
+                             -- if rightkern and rightkern ~= 0 then
+                             --     insert_node_after(head,n,newkern(rightkern))
+                             --     n = getnext(n) -- to be checked
+                             -- end
+                            end
+                        else
+                            local i = rawget(pn,"injections")
+                            if i then
+                                local leftkern = i.leftkern
+                                if leftkern and leftkern ~= 0 then
+                                    setfield(p,"replace",newkern(leftkern))
+                                end
+                             -- local rightkern = i.rightkern
+                             -- if rightkern and rightkern ~= 0 then
+                             --     insert_node_after(head,n,newkern(rightkern))
+                             --     n = getnext(n) -- to be checked
+                             -- end
+                            end
+                        end
+                    else
+                        -- this is the most common case
+                        local i = rawget(pn,"injections")
+                        if i then
+                            local leftkern = i.leftkern
+                            if leftkern and leftkern ~= 0 then
+                                head = insert_node_before(head,n,newkern(leftkern))
+                            end
+                            local rightkern = i.rightkern
+                            if rightkern and rightkern ~= 0 then
+                                insert_node_after(head,n,newkern(rightkern))
+                                n = getnext(n) -- to be checked
+                            end
+                            local yoffset = i.yoffset
+                            if yoffset and yoffset ~= 0 then
+                                setfield(n,"yoffset",yoffset)
+                            end
+                        end
+                    end
+                end
+            end
+            p = nil
+        elseif id == disc_code then
+            local d = getfield(n,"pre")
+            if d then
+                local h = d
+                for n in traverse_id(glyph_code,d) do
+                    if getsubtype(n) < 256 then
+                        local pn = rawget(properties,n)
+                        if pn then
+                            local i = rawget(pn,"preinjections")
+                            if i then
+                                local leftkern = i.leftkern
+                                if leftkern and leftkern ~= 0 then
+                                    h = insert_node_before(h,n,newkern(leftkern))
+                                end
+                                local rightkern = i.rightkern
+                                if rightkern and rightkern ~= 0 then
+                                    insert_node_after(head,n,newkern(rightkern))
+                                    n = getnext(n) -- to be checked
+                                end
+                                local yoffset = i.yoffset
+                                if yoffset and yoffset ~= 0 then
+                                    setfield(n,"yoffset",yoffset)
+                                end
+                            end
+                        end
+                    else
+                        break
+                    end
+                end
+                if h ~= d then
+                    setfield(n,"pre",h)
+                end
+            end
+            local d = getfield(n,"post")
+            if d then
+                local h = d
+                for n in traverse_id(glyph_code,d) do
+                    if getsubtype(n) < 256 then
+                        local pn = rawget(properties,n)
+                        if pn then
+                            local i = rawget(pn,"postinjections")
+                            if i then
+                                local leftkern = i.leftkern
+                                if leftkern and leftkern ~= 0 then
+                                    h = insert_node_before(h,n,newkern(leftkern))
+                                end
+                                local rightkern = i.rightkern
+                                if rightkern and rightkern ~= 0 then
+                                    insert_node_after(head,n,newkern(rightkern))
+                                    n = getnext(n) -- to be checked
+                                end
+                                local yoffset = i.yoffset
+                                if yoffset and yoffset ~= 0 then
+                                    setfield(n,"yoffset",yoffset)
+                                end
+                            end
+                        end
+                    else
+                        break
+                    end
+                end
+                if h ~= d then
+                    setfield(n,"post",h)
+                end
+            end
+            local d = getfield(n,"replace")
+            if d then
+                local h = d
+                for n in traverse_id(glyph_code,d) do
+                    if getsubtype(n) < 256 then
+                        local pn = rawget(properties,n)
+                        if pn then
+                            local i = rawget(pn,"replaceinjections")
+                            if i then
+                                local leftkern = i.leftkern
+                                if leftkern and leftkern ~= 0 then
+                                    h = insert_node_before(h,n,newkern(leftkern))
+                                end
+                                local rightkern = i.rightkern
+                                if rightkern and rightkern ~= 0 then
+                                    insert_node_after(head,n,newkern(rightkern))
+                                    n = getnext(n) -- to be checked
+                                end
+                                local yoffset = i.yoffset
+                                if yoffset and yoffset ~= 0 then
+                                    setfield(n,"yoffset",yoffset)
+                                end
+                            end
+                        end
+                    else
+                        break
+                    end
+                end
+                if h ~= d then
+                    setfield(n,"replace",h)
+                end
+            end
+            p = n
+        else
+            p = nil
+        end
+        n = getnext(n)
+    end
+    --
+    if keepregisteredcounts then
+        keepregisteredcounts = false
+    else
+        nofregisteredpairs = 0
+        nofregisteredkerns = 0
+    end
+    return tonode(head), true
+end
+
+function injections.handler(head,where)
+    if nofregisteredmarks > 0 or nofregisteredcursives > 0 then
+        return inject_everything(head,where)
+    elseif nofregisteredpairs > 0 then
+        return inject_pairs_only(head,where)
+    elseif nofregisteredkerns > 0 then
+        return inject_kerns_only(head,where)
+    else
+        return head, false
+    end
+end
diff --git a/src/fontloader/misc/fontloader-font-map.lua b/src/fontloader/misc/fontloader-font-map.lua
index b645d9a..dc3f499 100644
--- a/src/fontloader/misc/fontloader-font-map.lua
+++ b/src/fontloader/misc/fontloader-font-map.lua
@@ -74,6 +74,71 @@ end
 local f_single = formatters["%04X"]
 local f_double = formatters["%04X%04X"]
 
+-- 0.684 0.661 0,672 0.650 : cache at lua end (more mem)
+-- 0.682 0,672 0.698 0.657 : no cache (moderate mem i.e. lua strings)
+-- 0.644 0.647 0.655 0.645 : convert in c (less mem in theory)
+
+-- local tounicodes = table.setmetatableindex(function(t,unicode)
+--     local s
+--     if unicode < 0x10000 then
+--         s = f_single(unicode)
+--     elseif unicode < 0x1FFFFFFFFF then
+--         s = f_double(floor(unicode/1024),unicode%1024+0xDC00)
+--     else
+--         s = false
+--     end
+--     t[unicode] = s
+--     return s
+-- end)
+--
+-- local function tounicode16(unicode,name)
+--     local s = tounicodes[unicode]
+--     if s then
+--         return s
+--     else
+--         report_fonts("can't convert %a in %a into tounicode",unicode,name)
+--     end
+-- end
+--
+-- local function tounicode16sequence(unicodes,name)
+--     local t = { }
+--     for l=1,#unicodes do
+--         local u = unicodes[l]
+--         local s = tounicodes[u]
+--         if s then
+--             t[l] = s
+--         else
+--             report_fonts ("can't convert %a in %a into tounicode",u,name)
+--             return
+--         end
+--     end
+--     return concat(t)
+-- end
+--
+-- local function tounicode(unicode,name)
+--     if type(unicode) == "table" then
+--         local t = { }
+--         for l=1,#unicode do
+--             local u = unicode[l]
+--             local s = tounicodes[u]
+--             if s then
+--                 t[l] = s
+--             else
+--                 report_fonts ("can't convert %a in %a into tounicode",u,name)
+--                 return
+--             end
+--         end
+--         return concat(t)
+--     else
+--         local s = tounicodes[unicode]
+--         if s then
+--             return s
+--         else
+--             report_fonts("can't convert %a in %a into tounicode",unicode,name)
+--         end
+--     end
+-- end
+
 local function tounicode16(unicode,name)
     if unicode < 0x10000 then
         return f_single(unicode)
@@ -126,7 +191,6 @@ local function tounicode(unicode,name)
     end
 end
 
-
 local function fromunicode16(str)
     if #str == 4 then
         return tonumber(str,16)
diff --git a/src/fontloader/misc/fontloader-font-otf.lua b/src/fontloader/misc/fontloader-font-otf.lua
index f709e70..86b1313 100644
--- a/src/fontloader/misc/fontloader-font-otf.lua
+++ b/src/fontloader/misc/fontloader-font-otf.lua
@@ -58,7 +58,7 @@ local otf                = fonts.handlers.otf
 
 otf.glists               = { "gsub", "gpos" }
 
-otf.version              = 2.819 -- beware: also sync font-mis.lua and in mtx-fonts
+otf.version              = 2.820 -- beware: also sync font-mis.lua and in mtx-fonts
 otf.cache                = containers.define("fonts", "otf", otf.version, true)
 
 local hashes             = fonts.hashes
@@ -2959,7 +2959,7 @@ otf.coverup = {
         kern         = justset,
     },
     register = function(coverage,lookuptype,format,feature,n,descriptions,resources)
-        local name = formatters["ctx_%s_%s"](feature,n)
+        local name = formatters["ctx_%s_%s_%s"](feature,lookuptype,n) -- we can have a mix of types
         if lookuptype == "kern" then
             resources.lookuptypes[name] = "position"
         else
@@ -2973,7 +2973,6 @@ otf.coverup = {
             else
                 description.slookups = { [name] = c }
             end
--- inspect(feature,description)
         end
         return name
     end
diff --git a/src/fontloader/misc/fontloader-font-oti.lua b/src/fontloader/misc/fontloader-font-oti.lua
index 06c2a42..bacd001 100644
--- a/src/fontloader/misc/fontloader-font-oti.lua
+++ b/src/fontloader/misc/fontloader-font-oti.lua
@@ -13,9 +13,11 @@ local constructors       = fonts.constructors
 
 local otf                = constructors.newhandler("otf")
 local otffeatures        = constructors.newfeatures("otf")
-local otftables          = otf.tables
 local registerotffeature = otffeatures.register
 
+local otftables          = otf.tables or { }
+otf.tables               = otftables
+
 local allocate           = utilities.storage.allocate
 
 registerotffeature {
@@ -89,3 +91,68 @@ registerotffeature {
     }
 }
 
+-- here (as also in generic
+
+otftables.featuretypes = allocate {
+    gpos_single              = "position",
+    gpos_pair                = "position",
+    gpos_cursive             = "position",
+    gpos_mark2base           = "position",
+    gpos_mark2ligature       = "position",
+    gpos_mark2mark           = "position",
+    gpos_context             = "position",
+    gpos_contextchain        = "position",
+    gsub_single              = "substitution",
+    gsub_multiple            = "substitution",
+    gsub_alternate           = "substitution",
+    gsub_ligature            = "substitution",
+    gsub_context             = "substitution",
+    gsub_contextchain        = "substitution",
+    gsub_reversecontextchain = "substitution",
+    gsub_reversesub          = "substitution",
+}
+
+function otffeatures.checkeddefaultscript(featuretype,autoscript,scripts)
+    if featuretype == "position" then
+        local default = scripts.dflt
+        if default then
+            if autoscript == "position" or autoscript == true then
+                return default
+            else
+                report_otf("script feature %s not applied, enable default positioning")
+            end
+        else
+            -- no positioning at all
+        end
+    elseif featuretype == "substitution" then
+        local default = scripts.dflt
+        if default then
+            if autoscript == "substitution" or autoscript == true then
+                return default
+            end
+        end
+    end
+end
+
+function otffeatures.checkeddefaultlanguage(featuretype,autolanguage,languages)
+    if featuretype == "position" then
+        local default = languages.dflt
+        if default then
+            if autolanguage == "position" or autolanguage == true then
+                return default
+            else
+                report_otf("language feature %s not applied, enable default positioning")
+            end
+        else
+            -- no positioning at all
+        end
+    elseif featuretype == "substitution" then
+        local default = languages.dflt
+        if default then
+            if autolanguage == "substitution" or autolanguage == true then
+                return default
+            end
+        end
+    end
+end
+
diff --git a/src/fontloader/misc/fontloader-font-otn.lua b/src/fontloader/misc/fontloader-font-otn.lua
new file mode 100644
index 0000000..8df01bd
--- /dev/null
+++ b/src/fontloader/misc/fontloader-font-otn.lua
@@ -0,0 +1,3958 @@
+if not modules then modules = { } end modules ['font-otn'] = {
+    version   = 1.001,
+    comment   = "companion to font-ini.mkiv",
+    author    = "Hans Hagen, PRAGMA-ADE, Hasselt NL",
+    copyright = "PRAGMA ADE / ConTeXt Development Team",
+    license   = "see context related readme files",
+}
+
+-- this is a context version which can contain experimental code, but when we
+-- have serious patches we also need to change the other two font-otn files
+
+-- at some point i might decide to convert the whole list into a table and then
+-- run over that instead (but it has some drawbacks as we also need to deal with
+-- attributes and such so we need to keep a lot of track - which is why i rejected
+-- that method - although it has become a bit easier in the meantime so it might
+-- become an alternative (by that time i probably have gone completely lua) .. the
+-- usual chicken-egg issues ... maybe mkix as it's no real tex any more then
+
+-- preprocessors = { "nodes" }
+
+-- anchor class : mark, mkmk, curs, mklg (todo)
+-- anchor type  : mark, basechar, baselig, basemark, centry, cexit, max (todo)
+
+-- this is still somewhat preliminary and it will get better in due time;
+-- much functionality could only be implemented thanks to the husayni font
+-- of Idris Samawi Hamid to who we dedicate this module.
+
+-- in retrospect it always looks easy but believe it or not, it took a lot
+-- of work to get proper open type support done: buggy fonts, fuzzy specs,
+-- special made testfonts, many skype sessions between taco, idris and me,
+-- torture tests etc etc ... unfortunately the code does not show how much
+-- time it took ...
+
+-- todo:
+--
+-- extension infrastructure (for usage out of context)
+-- sorting features according to vendors/renderers
+-- alternative loop quitters
+-- check cursive and r2l
+-- find out where ignore-mark-classes went
+-- default features (per language, script)
+-- handle positions (we need example fonts)
+-- handle gpos_single (we might want an extra width field in glyph nodes because adding kerns might interfere)
+-- mark (to mark) code is still not what it should be (too messy but we need some more extreem husayni tests)
+-- remove some optimizations (when I have a faster machine)
+--
+-- beware:
+--
+-- we do some disc jugling where we need to keep in mind that the
+-- pre, post and replace fields can have prev pointers to a nesting
+-- node ... i wonder if that is still needed
+--
+-- not possible:
+--
+-- \discretionary {alpha-} {betagammadelta}
+--   {\discretionary {alphabeta-} {gammadelta}
+--      {\discretionary {alphabetagamma-} {delta}
+--         {alphabetagammadelta}}}
+
+--[[ldx--
+<p>This module is a bit more split up that I'd like but since we also want to test
+with plain <l n='tex'/> it has to be so. This module is part of <l n='context'/>
+and discussion about improvements and functionality mostly happens on the
+<l n='context'/> mailing list.</p>
+
+<p>The specification of OpenType is kind of vague. Apart from a lack of a proper
+free specifications there's also the problem that Microsoft and Adobe
+may have their own interpretation of how and in what order to apply features.
+In general the Microsoft website has more detailed specifications and is a
+better reference. There is also some information in the FontForge help files.</p>
+
+<p>Because there is so much possible, fonts might contain bugs and/or be made to
+work with certain rederers. These may evolve over time which may have the side
+effect that suddenly fonts behave differently.</p>
+
+<p>After a lot of experiments (mostly by Taco, me and Idris) we're now at yet another
+implementation. Of course all errors are mine and of course the code can be
+improved. There are quite some optimizations going on here and processing speed
+is currently acceptable. Not all functions are implemented yet, often because I
+lack the fonts for testing. Many scripts are not yet supported either, but I will
+look into them as soon as <l n='context'/> users ask for it.</p>
+
+<p>The specification leaves room for interpretation. In case of doubt the microsoft
+implementation is the reference as it is the most complete one. As they deal with
+lots of scripts and fonts, Kai and Ivo did a lot of testing of the generic code and
+their suggestions help improve the code. I'm aware that not all border cases can be
+taken care of, unless we accept excessive runtime, and even then the interference
+with other mechanisms (like hyphenation) are not trivial.</p>
+
+<p>Glyphs are indexed not by unicode but in their own way. This is because there is no
+relationship with unicode at all, apart from the fact that a font might cover certain
+ranges of characters. One character can have multiple shapes. However, at the
+<l n='tex'/> end we use unicode so and all extra glyphs are mapped into a private
+space. This is needed because we need to access them and <l n='tex'/> has to include
+then in the output eventually.</p>
+
+<p>The raw table as it coms from <l n='fontforge'/> gets reorganized in to fit out needs.
+In <l n='context'/> that table is packed (similar tables are shared) and cached on disk
+so that successive runs can use the optimized table (after loading the table is
+unpacked). The flattening code used later is a prelude to an even more compact table
+format (and as such it keeps evolving).</p>
+
+<p>This module is sparsely documented because it is a moving target. The table format
+of the reader changes and we experiment a lot with different methods for supporting
+features.</p>
+
+<p>As with the <l n='afm'/> code, we may decide to store more information in the
+<l n='otf'/> table.</p>
+
+<p>Incrementing the version number will force a re-cache. We jump the number by one
+when there's a fix in the <l n='fontforge'/> library or <l n='lua'/> code that
+results in different tables.</p>
+--ldx]]--
+
+-- action                    handler     chainproc
+--
+-- gsub_single               ok          ok
+-- gsub_multiple             ok          ok
+-- gsub_alternate            ok          ok
+-- gsub_ligature             ok          ok
+-- gsub_context              ok          --
+-- gsub_contextchain         ok          --
+-- gsub_reversecontextchain  ok          --
+-- chainsub                  --          ok
+-- reversesub                --          ok
+-- gpos_mark2base            ok          ok
+-- gpos_mark2ligature        ok          ok
+-- gpos_mark2mark            ok          ok
+-- gpos_cursive              ok          untested
+-- gpos_single               ok          ok
+-- gpos_pair                 ok          ok
+-- gpos_context              ok          --
+-- gpos_contextchain         ok          --
+--
+-- todo: contextpos
+--
+-- actions:
+--
+-- handler   : actions triggered by lookup
+-- chainproc : actions triggered by contextual lookup
+-- chainmore : multiple substitutions triggered by contextual lookup (e.g. fij -> f + ij)
+--
+-- remark: the 'not implemented yet' variants will be done when we have fonts that use them
+
+-- We used to have independent hashes for lookups but as the tags are unique
+-- we now use only one hash. If needed we can have multiple again but in that
+-- case I will probably prefix (i.e. rename) the lookups in the cached font file.
+
+-- Todo: make plugin feature that operates on char/glyphnode arrays
+
+local type, next, tonumber = type, next, tonumber
+local random = math.random
+local formatters = string.formatters
+
+local logs, trackers, nodes, attributes = logs, trackers, nodes, attributes
+
+local registertracker   = trackers.register
+local registerdirective = directives.register
+
+local fonts = fonts
+local otf   = fonts.handlers.otf
+
+local trace_lookups      = false  registertracker("otf.lookups",      function(v) trace_lookups      = v end)
+local trace_singles      = false  registertracker("otf.singles",      function(v) trace_singles      = v end)
+local trace_multiples    = false  registertracker("otf.multiples",    function(v) trace_multiples    = v end)
+local trace_alternatives = false  registertracker("otf.alternatives", function(v) trace_alternatives = v end)
+local trace_ligatures    = false  registertracker("otf.ligatures",    function(v) trace_ligatures    = v end)
+local trace_contexts     = false  registertracker("otf.contexts",     function(v) trace_contexts     = v end)
+local trace_marks        = false  registertracker("otf.marks",        function(v) trace_marks        = v end)
+local trace_kerns        = false  registertracker("otf.kerns",        function(v) trace_kerns        = v end)
+local trace_cursive      = false  registertracker("otf.cursive",      function(v) trace_cursive      = v end)
+local trace_preparing    = false  registertracker("otf.preparing",    function(v) trace_preparing    = v end)
+local trace_bugs         = false  registertracker("otf.bugs",         function(v) trace_bugs         = v end)
+local trace_details      = false  registertracker("otf.details",      function(v) trace_details      = v end)
+local trace_applied      = false  registertracker("otf.applied",      function(v) trace_applied      = v end)
+local trace_steps        = false  registertracker("otf.steps",        function(v) trace_steps        = v end)
+local trace_skips        = false  registertracker("otf.skips",        function(v) trace_skips        = v end)
+local trace_directions   = false  registertracker("otf.directions",   function(v) trace_directions   = v end)
+
+local trace_kernruns     = false  registertracker("otf.kernruns",     function(v) trace_kernruns     = v end)
+local trace_discruns     = false  registertracker("otf.discruns",     function(v) trace_discruns     = v end)
+local trace_compruns     = false  registertracker("otf.compruns",     function(v) trace_compruns     = v end)
+
+local quit_on_no_replacement = true  -- maybe per font
+local zwnjruns               = true
+
+registerdirective("otf.zwnjruns",                 function(v) zwnjruns = v end)
+registerdirective("otf.chain.quitonnoreplacement",function(value) quit_on_no_replacement = value end)
+
+local report_direct   = logs.reporter("fonts","otf direct")
+local report_subchain = logs.reporter("fonts","otf subchain")
+local report_chain    = logs.reporter("fonts","otf chain")
+local report_process  = logs.reporter("fonts","otf process")
+local report_prepare  = logs.reporter("fonts","otf prepare")
+local report_warning  = logs.reporter("fonts","otf warning")
+local report_run      = logs.reporter("fonts","otf run")
+
+registertracker("otf.verbose_chain", function(v) otf.setcontextchain(v and "verbose") end)
+registertracker("otf.normal_chain",  function(v) otf.setcontextchain(v and "normal")  end)
+
+registertracker("otf.replacements", "otf.singles,otf.multiples,otf.alternatives,otf.ligatures")
+registertracker("otf.positions","otf.marks,otf.kerns,otf.cursive")
+registertracker("otf.actions","otf.replacements,otf.positions")
+registertracker("otf.injections","nodes.injections")
+
+registertracker("*otf.sample","otf.steps,otf.actions,otf.analyzing")
+
+local nuts               = nodes.nuts
+local tonode             = nuts.tonode
+local tonut              = nuts.tonut
+
+local getfield           = nuts.getfield
+local setfield           = nuts.setfield
+local getnext            = nuts.getnext
+local setnext            = nuts.setnext
+local getprev            = nuts.getprev
+local setprev            = nuts.setprev
+local getid              = nuts.getid
+local getattr            = nuts.getattr
+local setattr            = nuts.setattr
+local getprop            = nuts.getprop
+local setprop            = nuts.setprop
+local getfont            = nuts.getfont
+local getsubtype         = nuts.getsubtype
+local setsubtype         = nuts.setsubtype
+local getchar            = nuts.getchar
+local setchar            = nuts.setchar
+
+local insert_node_before = nuts.insert_before
+local insert_node_after  = nuts.insert_after
+local delete_node        = nuts.delete
+local remove_node        = nuts.remove
+local copy_node          = nuts.copy
+local copy_node_list     = nuts.copy_list
+local find_node_tail     = nuts.tail
+local flush_node_list    = nuts.flush_list
+local free_node          = nuts.free
+local end_of_math        = nuts.end_of_math
+local traverse_nodes     = nuts.traverse
+local traverse_id        = nuts.traverse_id
+
+local setmetatableindex  = table.setmetatableindex
+
+local zwnj               = 0x200C
+local zwj                = 0x200D
+local wildcard           = "*"
+local default            = "dflt"
+
+local nodecodes          = nodes.nodecodes
+local glyphcodes         = nodes.glyphcodes
+local disccodes          = nodes.disccodes
+
+local glyph_code         = nodecodes.glyph
+local glue_code          = nodecodes.glue
+local disc_code          = nodecodes.disc
+local math_code          = nodecodes.math
+local dir_code           = nodecodes.dir
+local localpar_code      = nodecodes.localpar
+
+local discretionary_code = disccodes.discretionary
+local ligature_code      = glyphcodes.ligature
+
+local privateattribute   = attributes.private
+
+-- Something is messed up: we have two mark / ligature indices, one at the injection
+-- end and one here ... this is based on KE's patches but there is something fishy
+-- there as I'm pretty sure that for husayni we need some connection (as it's much
+-- more complex than an average font) but I need proper examples of all cases, not
+-- of only some.
+
+local a_state            = privateattribute('state')
+local a_cursbase         = privateattribute('cursbase') -- to be checked, probably can go
+
+local injections         = nodes.injections
+local setmark            = injections.setmark
+local setcursive         = injections.setcursive
+local setkern            = injections.setkern
+local setpair            = injections.setpair
+local resetinjection     = injections.reset
+local copyinjection      = injections.copy
+local setligaindex       = injections.setligaindex
+local getligaindex       = injections.getligaindex
+
+local cursonce           = true
+
+local fonthashes         = fonts.hashes
+local fontdata           = fonthashes.identifiers
+
+local otffeatures        = fonts.constructors.newfeatures("otf")
+local registerotffeature = otffeatures.register
+
+local onetimemessage     = fonts.loggers.onetimemessage or function() end
+
+otf.defaultnodealternate = "none" -- first last
+
+-- we share some vars here, after all, we have no nested lookups and less code
+
+local tfmdata             = false
+local characters          = false
+local descriptions        = false
+local resources           = false
+local marks               = false
+local currentfont         = false
+local lookuptable         = false
+local anchorlookups       = false
+local lookuptypes         = false
+local lookuptags          = false
+local handlers            = { }
+local rlmode              = 0
+local featurevalue        = false
+
+local sweephead           = { }
+local sweepnode           = nil
+local sweepprev           = nil
+local sweepnext           = nil
+
+local notmatchpre         = { }
+local notmatchpost        = { }
+local notmatchreplace     = { }
+
+-- we use this for special testing and documentation
+
+local checkstep       = (nodes and nodes.tracers and nodes.tracers.steppers.check)    or function() end
+local registerstep    = (nodes and nodes.tracers and nodes.tracers.steppers.register) or function() end
+local registermessage = (nodes and nodes.tracers and nodes.tracers.steppers.message)  or function() end
+
+local function logprocess(...)
+    if trace_steps then
+        registermessage(...)
+    end
+    report_direct(...)
+end
+
+local function logwarning(...)
+    report_direct(...)
+end
+
+local f_unicode = formatters["%U"]
+local f_uniname = formatters["%U (%s)"]
+local f_unilist = formatters["% t (% t)"]
+
+local function gref(n) -- currently the same as in font-otb
+    if type(n) == "number" then
+        local description = descriptions[n]
+        local name = description and description.name
+        if name then
+            return f_uniname(n,name)
+        else
+            return f_unicode(n)
+        end
+    elseif n then
+        local num, nam = { }, { }
+        for i=1,#n do
+            local ni = n[i]
+            if tonumber(ni) then -- later we will start at 2
+                local di = descriptions[ni]
+                num[i] = f_unicode(ni)
+                nam[i] = di and di.name or "-"
+            end
+        end
+        return f_unilist(num,nam)
+    else
+        return "<error in node mode tracing>"
+    end
+end
+
+local function cref(kind,chainname,chainlookupname,lookupname,index) -- not in the mood to alias f_
+    if index then
+        return formatters["feature %a, chain %a, sub %a, lookup %a, index %a"](kind,chainname,chainlookupname,lookuptags[lookupname],index)
+    elseif lookupname then
+        return formatters["feature %a, chain %a, sub %a, lookup %a"](kind,chainname,chainlookupname,lookuptags[lookupname])
+    elseif chainlookupname then
+        return formatters["feature %a, chain %a, sub %a"](kind,lookuptags[chainname],lookuptags[chainlookupname])
+    elseif chainname then
+        return formatters["feature %a, chain %a"](kind,lookuptags[chainname])
+    else
+        return formatters["feature %a"](kind)
+    end
+end
+
+local function pref(kind,lookupname)
+    return formatters["feature %a, lookup %a"](kind,lookuptags[lookupname])
+end
+
+-- We can assume that languages that use marks are not hyphenated. We can also assume
+-- that at most one discretionary is present.
+
+-- We do need components in funny kerning mode but maybe I can better reconstruct then
+-- as we do have the font components info available; removing components makes the
+-- previous code much simpler. Also, later on copying and freeing becomes easier.
+-- However, for arabic we need to keep them around for the sake of mark placement
+-- and indices.
+
+local function copy_glyph(g) -- next and prev are untouched !
+    local components = getfield(g,"components")
+    if components then
+        setfield(g,"components",nil)
+        local n = copy_node(g)
+        copyinjection(n,g) -- we need to preserve the lig indices
+        setfield(g,"components",components)
+        return n
+    else
+        local n = copy_node(g)
+        copyinjection(n,g) -- we need to preserve the lig indices
+        return n
+    end
+end
+
+local function flattendisk(head,disc)
+    local replace = getfield(disc,"replace")
+    setfield(disc,"replace",nil)
+    free_node(disc)
+    if head == disc then
+        local next = getnext(disc)
+        if replace then
+            if next then
+                local tail = find_node_tail(replace)
+                setnext(tail,next)
+                setprev(next,tail)
+            end
+            return replace, replace
+        elseif next then
+            return next, next
+        else
+            return -- maybe warning
+        end
+    else
+        local next = getnext(disc)
+        local prev = getprev(disc)
+        if replace then
+            local tail = find_node_tail(replace)
+            if next then
+                setnext(tail,next)
+                setprev(next,tail)
+            end
+            setnext(prev,replace)
+            setprev(replace,prev)
+            return head, replace
+        else
+            if next then
+                setprev(next,prev)
+            end
+            setnext(prev,next)
+            return head, next
+        end
+    end
+end
+
+local function appenddisc(disc,list)
+    local post    = getfield(disc,"post")
+    local replace = getfield(disc,"replace")
+    local phead   = list
+    local rhead   = copy_node_list(list)
+    local ptail   = find_node_tail(post)
+    local rtail   = find_node_tail(replace)
+    if post then
+        setnext(ptail,phead)
+        setprev(phead,ptail)
+    else
+        setfield(disc,"post",phead)
+    end
+    if replace then
+        setnext(rtail,rhead)
+        setprev(rhead,rtail)
+    else
+        setfield(disc,"replace",rhead)
+    end
+end
+
+-- start is a mark and we need to keep that one
+
+local function markstoligature(kind,lookupname,head,start,stop,char)
+    if start == stop and getchar(start) == char then
+        return head, start
+    else
+        local prev = getprev(start)
+        local next = getnext(stop)
+        setprev(start,nil)
+        setnext(stop,nil)
+        local base = copy_glyph(start)
+        if head == start then
+            head = base
+        end
+        resetinjection(base)
+        setchar(base,char)
+        setsubtype(base,ligature_code)
+        setfield(base,"components",start)
+        if prev then
+            setnext(prev,base)
+        end
+        if next then
+            setprev(next,base)
+        end
+        setnext(base,next)
+        setprev(base,prev)
+        return head, base
+    end
+end
+
+-- The next code is somewhat complicated by the fact that some fonts can have ligatures made
+-- from ligatures that themselves have marks. This was identified by Kai in for instance
+-- arabtype:  KAF LAM SHADDA ALEF FATHA (0x0643 0x0644 0x0651 0x0627 0x064E). This becomes
+-- KAF LAM-ALEF with a SHADDA on the first and a FATHA op de second component. In a next
+-- iteration this becomes a KAF-LAM-ALEF with a SHADDA on the second and a FATHA on the
+-- third component.
+
+local function getcomponentindex(start) -- we could store this offset in the glyph (nofcomponents)
+    if getid(start) ~= glyph_code then  -- and then get rid of all components
+        return 0
+    elseif getsubtype(start) == ligature_code then
+        local i = 0
+        local components = getfield(start,"components")
+        while components do
+            i = i + getcomponentindex(components)
+            components = getnext(components)
+        end
+        return i
+    elseif not marks[getchar(start)] then
+        return 1
+    else
+        return 0
+    end
+end
+
+local a_noligature = attributes.private("noligature")
+
+local function toligature(kind,lookupname,head,start,stop,char,markflag,discfound) -- brr head
+    if getattr(start,a_noligature) == 1 then
+        -- so we can do: e\noligature{ff}e e\noligature{f}fie (we only look at the first)
+        return head, start
+    end
+    if start == stop and getchar(start) == char then
+        resetinjection(start)
+        setchar(start,char)
+        return head, start
+    end
+    -- needs testing (side effects):
+    local components = getfield(start,"components")
+    if components then
+     -- we get a double free .. needs checking
+     -- flush_node_list(components)
+    end
+    --
+    local prev = getprev(start)
+    local next = getnext(stop)
+    local comp = start
+    setprev(start,nil)
+    setnext(stop,nil)
+    local base = copy_glyph(start)
+    if start == head then
+        head = base
+    end
+    resetinjection(base)
+    setchar(base,char)
+    setsubtype(base,ligature_code)
+    setfield(base,"components",comp) -- start can have components ... do we need to flush?
+    if prev then
+        setnext(prev,base)
+    end
+    if next then
+        setprev(next,base)
+    end
+    setprev(base,prev)
+    setnext(base,next)
+    if not discfound then
+        local deletemarks = markflag ~= "mark"
+        local components = start
+        local baseindex = 0
+        local componentindex = 0
+        local head = base
+        local current = base
+        -- first we loop over the glyphs in start .. stop
+        while start do
+            local char = getchar(start)
+            if not marks[char] then
+                baseindex = baseindex + componentindex
+                componentindex = getcomponentindex(start)
+            elseif not deletemarks then -- quite fishy
+                setligaindex(start,baseindex + getligaindex(start,componentindex))
+                if trace_marks then
+                    logwarning("%s: keep mark %s, gets index %s",pref(kind,lookupname),gref(char),getligaindex(start))
+                end
+                local n = copy_node(start)
+                copyinjection(n,start)
+                head, current = insert_node_after(head,current,n) -- unlikely that mark has components
+            elseif trace_marks then
+                logwarning("%s: delete mark %s",pref(kind,lookupname),gref(char))
+            end
+            start = getnext(start)
+        end
+        -- we can have one accent as part of a lookup and another following
+     -- local start = components -- was wrong (component scanning was introduced when more complex ligs in devanagari was added)
+        local start = getnext(current)
+        while start and getid(start) == glyph_code do
+            local char = getchar(start)
+            if marks[char] then
+                setligaindex(start,baseindex + getligaindex(start,componentindex))
+                if trace_marks then
+                    logwarning("%s: set mark %s, gets index %s",pref(kind,lookupname),gref(char),getligaindex(start))
+                end
+            else
+                break
+            end
+            start = getnext(start)
+        end
+    else
+        -- discfound ... forget about marks .. probably no scripts that hyphenate and have marks
+        local discprev = getprev(discfound)
+        local discnext = getnext(discfound)
+        if discprev and discnext then
+            -- we assume normalization in context, and don't care about generic ... especially
+            -- \- can give problems as there we can have a negative char but that won't match
+            -- anyway
+            local pre     = getfield(discfound,"pre")
+            local post    = getfield(discfound,"post")
+            local replace = getfield(discfound,"replace")
+            if not replace then -- todo: signal simple hyphen
+                local prev = getprev(base)
+                local copied = copy_node_list(comp)
+                setprev(discnext,nil) -- also blocks funny assignments
+                setnext(discprev,nil) -- also blocks funny assignments
+                if pre then
+                    setnext(discprev,pre)
+                    setprev(pre,discprev)
+                end
+                pre = comp
+                if post then
+                    local tail = find_node_tail(post)
+                    setnext(tail,discnext)
+                    setprev(discnext,tail)
+                    setprev(post,nil)
+                else
+                    post = discnext
+                end
+                setnext(prev,discfound)
+                setprev(discfound,prev)
+                setnext(discfound,next)
+                setprev(next,discfound)
+                setnext(base,nil)
+                setprev(base,nil)
+                setfield(base,"components",copied)
+                setfield(discfound,"pre",pre)
+                setfield(discfound,"post",post)
+                setfield(discfound,"replace",base)
+                setsubtype(discfound,discretionary_code)
+                base = prev -- restart
+            end
+        end
+    end
+    return head, base
+end
+
+local function multiple_glyphs(head,start,multiple,ignoremarks)
+    local nofmultiples = #multiple
+    if nofmultiples > 0 then
+        resetinjection(start)
+        setchar(start,multiple[1])
+        if nofmultiples > 1 then
+            local sn = getnext(start)
+            for k=2,nofmultiples do -- todo: use insert_node
+-- untested:
+--
+-- while ignoremarks and marks[getchar(sn)] then
+--     local sn = getnext(sn)
+-- end
+                local n = copy_node(start) -- ignore components
+                resetinjection(n)
+                setchar(n,multiple[k])
+                setprev(n,start)
+                setnext(n,sn)
+                if sn then
+                    setprev(sn,n)
+                end
+                setnext(start,n)
+                start = n
+            end
+        end
+        return head, start, true
+    else
+        if trace_multiples then
+            logprocess("no multiple for %s",gref(getchar(start)))
+        end
+        return head, start, false
+    end
+end
+
+local function get_alternative_glyph(start,alternatives,value,trace_alternatives)
+    local n = #alternatives
+    if value == "random" then
+        local r = random(1,n)
+        return alternatives[r], trace_alternatives and formatters["value %a, taking %a"](value,r)
+    elseif value == "first" then
+        return alternatives[1], trace_alternatives and formatters["value %a, taking %a"](value,1)
+    elseif value == "last" then
+        return alternatives[n], trace_alternatives and formatters["value %a, taking %a"](value,n)
+    else
+        value = tonumber(value)
+        if type(value) ~= "number" then
+            return alternatives[1], trace_alternatives and formatters["invalid value %s, taking %a"](value,1)
+        elseif value > n then
+            local defaultalt = otf.defaultnodealternate
+            if defaultalt == "first" then
+                return alternatives[n], trace_alternatives and formatters["invalid value %s, taking %a"](value,1)
+            elseif defaultalt == "last" then
+                return alternatives[1], trace_alternatives and formatters["invalid value %s, taking %a"](value,n)
+            else
+                return false, trace_alternatives and formatters["invalid value %a, %s"](value,"out of range")
+            end
+        elseif value == 0 then
+            return getchar(start), trace_alternatives and formatters["invalid value %a, %s"](value,"no change")
+        elseif value < 1 then
+            return alternatives[1], trace_alternatives and formatters["invalid value %a, taking %a"](value,1)
+        else
+            return alternatives[value], trace_alternatives and formatters["value %a, taking %a"](value,value)
+        end
+    end
+end
+
+-- handlers
+
+function handlers.gsub_single(head,start,kind,lookupname,replacement)
+    if trace_singles then
+        logprocess("%s: replacing %s by single %s",pref(kind,lookupname),gref(getchar(start)),gref(replacement))
+    end
+    resetinjection(start)
+    setchar(start,replacement)
+    return head, start, true
+end
+
+function handlers.gsub_alternate(head,start,kind,lookupname,alternative,sequence)
+    local value = featurevalue == true and tfmdata.shared.features[kind] or featurevalue
+    local choice, comment = get_alternative_glyph(start,alternative,value,trace_alternatives)
+    if choice then
+        if trace_alternatives then
+            logprocess("%s: replacing %s by alternative %a to %s, %s",pref(kind,lookupname),gref(getchar(start)),choice,gref(choice),comment)
+        end
+        resetinjection(start)
+        setchar(start,choice)
+    else
+        if trace_alternatives then
+            logwarning("%s: no variant %a for %s, %s",pref(kind,lookupname),value,gref(getchar(start)),comment)
+        end
+    end
+    return head, start, true
+end
+
+function handlers.gsub_multiple(head,start,kind,lookupname,multiple,sequence)
+    if trace_multiples then
+        logprocess("%s: replacing %s by multiple %s",pref(kind,lookupname),gref(getchar(start)),gref(multiple))
+    end
+    return multiple_glyphs(head,start,multiple,sequence.flags[1])
+end
+
+function handlers.gsub_ligature(head,start,kind,lookupname,ligature,sequence)
+    local s, stop = getnext(start), nil
+    local startchar = getchar(start)
+    if marks[startchar] then
+        while s do
+            local id = getid(s)
+            if id == glyph_code and getfont(s) == currentfont and getsubtype(s)<256 then
+                local lg = ligature[getchar(s)]
+                if lg then
+                    stop = s
+                    ligature = lg
+                    s = getnext(s)
+                else
+                    break
+                end
+            else
+                break
+            end
+        end
+        if stop then
+            local lig = ligature.ligature
+            if lig then
+                if trace_ligatures then
+                    local stopchar = getchar(stop)
+                    head, start = markstoligature(kind,lookupname,head,start,stop,lig)
+                    logprocess("%s: replacing %s upto %s by ligature %s case 1",pref(kind,lookupname),gref(startchar),gref(stopchar),gref(getchar(start)))
+                else
+                    head, start = markstoligature(kind,lookupname,head,start,stop,lig)
+                end
+                return head, start, true, false
+            else
+                -- ok, goto next lookup
+            end
+        end
+    else
+        local skipmark  = sequence.flags[1]
+        local discfound = false
+        local lastdisc  = nil
+        while s do
+            local id = getid(s)
+            if id == glyph_code and getsubtype(s)<256 then -- not needed
+                if getfont(s) == currentfont then          -- also not needed only when mark
+                    local char = getchar(s)
+                    if skipmark and marks[char] then
+                        s = getnext(s)
+                    else -- ligature is a tree
+                        local lg = ligature[char] -- can there be multiple in a row? maybe in a bad font
+                        if lg then
+                            if not discfound and lastdisc then
+                                discfound = lastdisc
+                                lastdisc  = nil
+                            end
+                            stop = s -- needed for fake so outside then
+                            ligature = lg
+                            s = getnext(s)
+                        else
+                            break
+                        end
+                    end
+                else
+                    break
+                end
+            elseif id == disc_code then
+                lastdisc = s
+                s = getnext(s)
+            else
+                break
+            end
+        end
+        local lig = ligature.ligature -- can't we get rid of this .ligature?
+        if lig then
+            if stop then
+                if trace_ligatures then
+                    local stopchar = getchar(stop)
+                    head, start = toligature(kind,lookupname,head,start,stop,lig,skipmark,discfound)
+                    logprocess("%s: replacing %s upto %s by ligature %s case 2",pref(kind,lookupname),gref(startchar),gref(stopchar),gref(getchar(start)))
+                else
+                    head, start = toligature(kind,lookupname,head,start,stop,lig,skipmark,discfound)
+                end
+            else
+                -- weird but happens (in some arabic font)
+                resetinjection(start)
+                setchar(start,lig)
+                if trace_ligatures then
+                    logprocess("%s: replacing %s by (no real) ligature %s case 3",pref(kind,lookupname),gref(startchar),gref(lig))
+                end
+            end
+            return head, start, true, discfound
+        else
+            -- weird but happens, pseudo ligatures ... just the components
+        end
+    end
+    return head, start, false, discfound
+end
+
+function handlers.gpos_single(head,start,kind,lookupname,kerns,sequence,injection)
+    local startchar = getchar(start)
+    local dx, dy, w, h = setpair(start,tfmdata.parameters.factor,rlmode,sequence.flags[4],kerns,injection) -- ,characters[startchar])
+    if trace_kerns then
+        logprocess("%s: shifting single %s by (%p,%p) and correction (%p,%p)",pref(kind,lookupname),gref(startchar),dx,dy,w,h)
+    end
+    return head, start, false
+end
+
+function handlers.gpos_pair(head,start,kind,lookupname,kerns,sequence,lookuphash,i,injection)
+    -- todo: kerns in disc nodes: pre, post, replace -> loop over disc too
+    -- todo: kerns in components of ligatures
+    local snext = getnext(start)
+    if not snext then
+        return head, start, false
+    else
+        local prev   = start
+        local done   = false
+        local factor = tfmdata.parameters.factor
+        local lookuptype = lookuptypes[lookupname]
+        while snext and getid(snext) == glyph_code and getfont(snext) == currentfont and getsubtype(snext)<256 do
+            local nextchar = getchar(snext)
+            local krn = kerns[nextchar]
+            if not krn and marks[nextchar] then
+                prev = snext
+                snext = getnext(snext)
+            else
+                if not krn then
+                    -- skip
+                elseif type(krn) == "table" then
+                    if lookuptype == "pair" then -- probably not needed
+                        local a, b = krn[2], krn[3]
+                        if a and #a > 0 then
+                            local x, y, w, h = setpair(start,factor,rlmode,sequence.flags[4],a,injection) -- characters[startchar])
+                            if trace_kerns then
+                                local startchar = getchar(start)
+                                logprocess("%s: shifting first of pair %s and %s by (%p,%p) and correction (%p,%p)",pref(kind,lookupname),gref(startchar),gref(nextchar),x,y,w,h)
+                            end
+                        end
+                        if b and #b > 0 then
+                            local x, y, w, h = setpair(snext,factor,rlmode,sequence.flags[4],b,injection) -- characters[nextchar])
+                            if trace_kerns then
+                                local startchar = getchar(start)
+                                logprocess("%s: shifting second of pair %s and %s by (%p,%p) and correction (%p,%p)",pref(kind,lookupname),gref(startchar),gref(nextchar),x,y,w,h)
+                            end
+                        end
+                    else -- wrong ... position has different entries
+                        report_process("%s: check this out (old kern stuff)",pref(kind,lookupname))
+                     -- local a, b = krn[2], krn[6]
+                     -- if a and a ~= 0 then
+                     --     local k = setkern(snext,factor,rlmode,a)
+                     --     if trace_kerns then
+                     --         logprocess("%s: inserting first kern %s between %s and %s",pref(kind,lookupname),k,gref(getchar(prev)),gref(nextchar))
+                     --     end
+                     -- end
+                     -- if b and b ~= 0 then
+                     --     logwarning("%s: ignoring second kern xoff %s",pref(kind,lookupname),b*factor)
+                     -- end
+                    end
+                    done = true
+                elseif krn ~= 0 then
+                    local k = setkern(snext,factor,rlmode,krn,injection)
+                    if trace_kerns then
+                        logprocess("%s: inserting kern %s between %s and %s",pref(kind,lookupname),k,gref(getchar(prev)),gref(nextchar)) -- prev?
+                    end
+                    done = true
+                end
+                break
+            end
+        end
+        return head, start, done
+    end
+end
+
+--[[ldx--
+<p>We get hits on a mark, but we're not sure if the it has to be applied so
+we need to explicitly test for basechar, baselig and basemark entries.</p>
+--ldx]]--
+
+function handlers.gpos_mark2base(head,start,kind,lookupname,markanchors,sequence)
+    local markchar = getchar(start)
+    if marks[markchar] then
+        local base = getprev(start) -- [glyph] [start=mark]
+        if base and getid(base) == glyph_code and getfont(base) == currentfont and getsubtype(base)<256 then
+            local basechar = getchar(base)
+            if marks[basechar] then
+                while true do
+                    base = getprev(base)
+                    if base and getid(base) == glyph_code and getfont(base) == currentfont and getsubtype(base)<256 then
+                        basechar = getchar(base)
+                        if not marks[basechar] then
+                            break
+                        end
+                    else
+                        if trace_bugs then
+                            logwarning("%s: no base for mark %s",pref(kind,lookupname),gref(markchar))
+                        end
+                        return head, start, false
+                    end
+                end
+            end
+            local baseanchors = descriptions[basechar]
+            if baseanchors then
+                baseanchors = baseanchors.anchors
+            end
+            if baseanchors then
+                local baseanchors = baseanchors['basechar']
+                if baseanchors then
+                    local al = anchorlookups[lookupname]
+                    for anchor,ba in next, baseanchors do
+                        if al[anchor] then
+                            local ma = markanchors[anchor]
+                            if ma then
+                                local dx, dy, bound = setmark(start,base,tfmdata.parameters.factor,rlmode,ba,ma,characters[basechar])
+                                if trace_marks then
+                                    logprocess("%s, anchor %s, bound %s: anchoring mark %s to basechar %s => (%p,%p)",
+                                        pref(kind,lookupname),anchor,bound,gref(markchar),gref(basechar),dx,dy)
+                                end
+                                return head, start, true
+                            end
+                        end
+                    end
+                    if trace_bugs then
+                        logwarning("%s, no matching anchors for mark %s and base %s",pref(kind,lookupname),gref(markchar),gref(basechar))
+                    end
+                end
+            elseif trace_bugs then
+            --  logwarning("%s: char %s is missing in font",pref(kind,lookupname),gref(basechar))
+                onetimemessage(currentfont,basechar,"no base anchors",report_fonts)
+            end
+        elseif trace_bugs then
+            logwarning("%s: prev node is no char",pref(kind,lookupname))
+        end
+    elseif trace_bugs then
+        logwarning("%s: mark %s is no mark",pref(kind,lookupname),gref(markchar))
+    end
+    return head, start, false
+end
+
+function handlers.gpos_mark2ligature(head,start,kind,lookupname,markanchors,sequence)
+    -- check chainpos variant
+    local markchar = getchar(start)
+    if marks[markchar] then
+        local base = getprev(start) -- [glyph] [optional marks] [start=mark]
+        if base and getid(base) == glyph_code and getfont(base) == currentfont and getsubtype(base)<256 then
+            local basechar = getchar(base)
+            if marks[basechar] then
+                while true do
+                    base = getprev(base)
+                    if base and getid(base) == glyph_code and getfont(base) == currentfont and getsubtype(base)<256 then
+                        basechar = getchar(base)
+                        if not marks[basechar] then
+                            break
+                        end
+                    else
+                        if trace_bugs then
+                            logwarning("%s: no base for mark %s",pref(kind,lookupname),gref(markchar))
+                        end
+                        return head, start, false
+                    end
+                end
+            end
+            local index = getligaindex(start)
+            local baseanchors = descriptions[basechar]
+            if baseanchors then
+                baseanchors = baseanchors.anchors
+                if baseanchors then
+                   local baseanchors = baseanchors['baselig']
+                   if baseanchors then
+                        local al = anchorlookups[lookupname]
+                        for anchor, ba in next, baseanchors do
+                            if al[anchor] then
+                                local ma = markanchors[anchor]
+                                if ma then
+                                    ba = ba[index]
+                                    if ba then
+                                        local dx, dy, bound = setmark(start,base,tfmdata.parameters.factor,rlmode,ba,ma,characters[basechar]) -- index
+                                        if trace_marks then
+                                            logprocess("%s, anchor %s, index %s, bound %s: anchoring mark %s to baselig %s at index %s => (%p,%p)",
+                                                pref(kind,lookupname),anchor,index,bound,gref(markchar),gref(basechar),index,dx,dy)
+                                        end
+                                        return head, start, true
+                                    else
+                                        if trace_bugs then
+                                            logwarning("%s: no matching anchors for mark %s and baselig %s with index %a",pref(kind,lookupname),gref(markchar),gref(basechar),index)
+                                        end
+                                    end
+                                end
+                            end
+                        end
+                        if trace_bugs then
+                            logwarning("%s: no matching anchors for mark %s and baselig %s",pref(kind,lookupname),gref(markchar),gref(basechar))
+                        end
+                    end
+                end
+            elseif trace_bugs then
+            --  logwarning("%s: char %s is missing in font",pref(kind,lookupname),gref(basechar))
+                onetimemessage(currentfont,basechar,"no base anchors",report_fonts)
+            end
+        elseif trace_bugs then
+            logwarning("%s: prev node is no char",pref(kind,lookupname))
+        end
+    elseif trace_bugs then
+        logwarning("%s: mark %s is no mark",pref(kind,lookupname),gref(markchar))
+    end
+    return head, start, false
+end
+
+function handlers.gpos_mark2mark(head,start,kind,lookupname,markanchors,sequence)
+    local markchar = getchar(start)
+    if marks[markchar] then
+        local base = getprev(start) -- [glyph] [basemark] [start=mark]
+        local slc = getligaindex(start)
+        if slc then -- a rather messy loop ... needs checking with husayni
+            while base do
+                local blc = getligaindex(base)
+                if blc and blc ~= slc then
+                    base = getprev(base)
+                else
+                    break
+                end
+            end
+        end
+        if base and getid(base) == glyph_code and getfont(base) == currentfont and getsubtype(base)<256 then -- subtype test can go
+            local basechar = getchar(base)
+            local baseanchors = descriptions[basechar]
+            if baseanchors then
+                baseanchors = baseanchors.anchors
+                if baseanchors then
+                    baseanchors = baseanchors['basemark']
+                    if baseanchors then
+                        local al = anchorlookups[lookupname]
+                        for anchor,ba in next, baseanchors do
+                            if al[anchor] then
+                                local ma = markanchors[anchor]
+                                if ma then
+                                    local dx, dy, bound = setmark(start,base,tfmdata.parameters.factor,rlmode,ba,ma,characters[basechar],true)
+                                    if trace_marks then
+                                        logprocess("%s, anchor %s, bound %s: anchoring mark %s to basemark %s => (%p,%p)",
+                                            pref(kind,lookupname),anchor,bound,gref(markchar),gref(basechar),dx,dy)
+                                    end
+                                    return head, start, true
+                                end
+                            end
+                        end
+                        if trace_bugs then
+                            logwarning("%s: no matching anchors for mark %s and basemark %s",pref(kind,lookupname),gref(markchar),gref(basechar))
+                        end
+                    end
+                end
+            elseif trace_bugs then
+            --  logwarning("%s: char %s is missing in font",pref(kind,lookupname),gref(basechar))
+                onetimemessage(currentfont,basechar,"no base anchors",report_fonts)
+            end
+        elseif trace_bugs then
+            logwarning("%s: prev node is no mark",pref(kind,lookupname))
+        end
+    elseif trace_bugs then
+        logwarning("%s: mark %s is no mark",pref(kind,lookupname),gref(markchar))
+    end
+    return head, start, false
+end
+
+function handlers.gpos_cursive(head,start,kind,lookupname,exitanchors,sequence) -- to be checked
+    local alreadydone = cursonce and getprop(start,a_cursbase)
+    if not alreadydone then
+        local done = false
+        local startchar = getchar(start)
+        if marks[startchar] then
+            if trace_cursive then
+                logprocess("%s: ignoring cursive for mark %s",pref(kind,lookupname),gref(startchar))
+            end
+        else
+            local nxt = getnext(start)
+            while not done and nxt and getid(nxt) == glyph_code and getfont(nxt) == currentfont and getsubtype(nxt)<256 do
+                local nextchar = getchar(nxt)
+                if marks[nextchar] then
+                    -- should not happen (maybe warning)
+                    nxt = getnext(nxt)
+                else
+                    local entryanchors = descriptions[nextchar]
+                    if entryanchors then
+                        entryanchors = entryanchors.anchors
+                        if entryanchors then
+                            entryanchors = entryanchors['centry']
+                            if entryanchors then
+                                local al = anchorlookups[lookupname]
+                                for anchor, entry in next, entryanchors do
+                                    if al[anchor] then
+                                        local exit = exitanchors[anchor]
+                                        if exit then
+                                            local dx, dy, bound = setcursive(start,nxt,tfmdata.parameters.factor,rlmode,exit,entry,characters[startchar],characters[nextchar])
+                                            if trace_cursive then
+                                                logprocess("%s: moving %s to %s cursive (%p,%p) using anchor %s and bound %s in rlmode %s",pref(kind,lookupname),gref(startchar),gref(nextchar),dx,dy,anchor,bound,rlmode)
+                                            end
+                                            done = true
+                                            break
+                                        end
+                                    end
+                                end
+                            end
+                        end
+                    elseif trace_bugs then
+                    --  logwarning("%s: char %s is missing in font",pref(kind,lookupname),gref(startchar))
+                        onetimemessage(currentfont,startchar,"no entry anchors",report_fonts)
+                    end
+                    break
+                end
+            end
+        end
+        return head, start, done
+    else
+        if trace_cursive and trace_details then
+            logprocess("%s, cursive %s is already done",pref(kind,lookupname),gref(getchar(start)),alreadydone)
+        end
+        return head, start, false
+    end
+end
+
+--[[ldx--
+<p>I will implement multiple chain replacements once I run into a font that uses
+it. It's not that complex to handle.</p>
+--ldx]]--
+
+local chainprocs = { }
+
+local function logprocess(...)
+    if trace_steps then
+        registermessage(...)
+    end
+    report_subchain(...)
+end
+
+local logwarning = report_subchain
+
+local function logprocess(...)
+    if trace_steps then
+        registermessage(...)
+    end
+    report_chain(...)
+end
+
+local logwarning = report_chain
+
+-- We could share functions but that would lead to extra function calls with many
+-- arguments, redundant tests and confusing messages.
+
+function chainprocs.chainsub(head,start,stop,kind,chainname,currentcontext,lookuphash,lookuplist,chainlookupname)
+    logwarning("%s: a direct call to chainsub cannot happen",cref(kind,chainname,chainlookupname))
+    return head, start, false
+end
+
+-- The reversesub is a special case, which is why we need to store the replacements
+-- in a bit weird way. There is no lookup and the replacement comes from the lookup
+-- itself. It is meant mostly for dealing with Urdu.
+
+function chainprocs.reversesub(head,start,stop,kind,chainname,currentcontext,lookuphash,replacements)
+    local char = getchar(start)
+    local replacement = replacements[char]
+    if replacement then
+        if trace_singles then
+            logprocess("%s: single reverse replacement of %s by %s",cref(kind,chainname),gref(char),gref(replacement))
+        end
+        resetinjection(start)
+        setchar(start,replacement)
+        return head, start, true
+    else
+        return head, start, false
+    end
+end
+
+--[[ldx--
+<p>This chain stuff is somewhat tricky since we can have a sequence of actions to be
+applied: single, alternate, multiple or ligature where ligature can be an invalid
+one in the sense that it will replace multiple by one but not neccessary one that
+looks like the combination (i.e. it is the counterpart of multiple then). For
+example, the following is valid:</p>
+
+<typing>
+<line>xxxabcdexxx [single a->A][multiple b->BCD][ligature cde->E] xxxABCDExxx</line>
+</typing>
+
+<p>Therefore we we don't really do the replacement here already unless we have the
+single lookup case. The efficiency of the replacements can be improved by deleting
+as less as needed but that would also make the code even more messy.</p>
+--ldx]]--
+
+-- local function delete_till_stop(head,start,stop,ignoremarks) -- keeps start
+--     local n = 1
+--     if start == stop then
+--         -- done
+--     elseif ignoremarks then
+--         repeat -- start x x m x x stop => start m
+--             local next = getnext(start)
+--             if not marks[getchar(next)] then
+--                 local components = getnext(next,"components")
+--                 if components then -- probably not needed
+--                     flush_node_list(components)
+--                 end
+--                 head = delete_node(head,next)
+--             end
+--             n = n + 1
+--         until next == stop
+--     else -- start x x x stop => start
+--         repeat
+--             local next = getnext(start)
+--             local components = getfield(next,"components")
+--             if components then -- probably not needed
+--                 flush_node_list(components)
+--             end
+--             head = delete_node(head,next)
+--             n = n + 1
+--         until next == stop
+--     end
+--     return head, n
+-- end
+
+--[[ldx--
+<p>Here we replace start by a single variant.</p>
+--ldx]]--
+
+function chainprocs.gsub_single(head,start,stop,kind,chainname,currentcontext,lookuphash,currentlookup,chainlookupname,chainindex)
+    -- todo: marks ?
+    local current = start
+    local subtables = currentlookup.subtables
+    if #subtables > 1 then
+        logwarning("todo: check if we need to loop over the replacements: % t",subtables)
+    end
+    while current do
+        if getid(current) == glyph_code then
+            local currentchar = getchar(current)
+            local lookupname = subtables[1] -- only 1
+            local replacement = lookuphash[lookupname]
+            if not replacement then
+                if trace_bugs then
+                    logwarning("%s: no single hits",cref(kind,chainname,chainlookupname,lookupname,chainindex))
+                end
+            else
+                replacement = replacement[currentchar]
+                if not replacement or replacement == "" then
+                    if trace_bugs then
+                        logwarning("%s: no single for %s",cref(kind,chainname,chainlookupname,lookupname,chainindex),gref(currentchar))
+                    end
+                else
+                    if trace_singles then
+                        logprocess("%s: replacing single %s by %s",cref(kind,chainname,chainlookupname,lookupname,chainindex),gref(currentchar),gref(replacement))
+                    end
+                    resetinjection(current)
+                    setchar(current,replacement)
+                end
+            end
+            return head, start, true
+        elseif current == stop then
+            break
+        else
+            current = getnext(current)
+        end
+    end
+    return head, start, false
+end
+
+--[[ldx--
+<p>Here we replace start by a sequence of new glyphs.</p>
+--ldx]]--
+
+function chainprocs.gsub_multiple(head,start,stop,kind,chainname,currentcontext,lookuphash,currentlookup,chainlookupname)
+ -- local head, n = delete_till_stop(head,start,stop)
+    local startchar = getchar(start)
+    local subtables = currentlookup.subtables
+    local lookupname = subtables[1]
+    local replacements = lookuphash[lookupname]
+    if not replacements then
+        if trace_bugs then
+            logwarning("%s: no multiple hits",cref(kind,chainname,chainlookupname,lookupname))
+        end
+    else
+        replacements = replacements[startchar]
+        if not replacements or replacement == "" then
+            if trace_bugs then
+                logwarning("%s: no multiple for %s",cref(kind,chainname,chainlookupname,lookupname),gref(startchar))
+            end
+        else
+            if trace_multiples then
+                logprocess("%s: replacing %s by multiple characters %s",cref(kind,chainname,chainlookupname,lookupname),gref(startchar),gref(replacements))
+            end
+            return multiple_glyphs(head,start,replacements,currentlookup.flags[1])
+        end
+    end
+    return head, start, false
+end
+
+--[[ldx--
+<p>Here we replace start by new glyph. First we delete the rest of the match.</p>
+--ldx]]--
+
+-- char_1 mark_1 -> char_x mark_1 (ignore marks)
+-- char_1 mark_1 -> char_x
+
+-- to be checked: do we always have just one glyph?
+-- we can also have alternates for marks
+-- marks come last anyway
+-- are there cases where we need to delete the mark
+
+function chainprocs.gsub_alternate(head,start,stop,kind,chainname,currentcontext,lookuphash,currentlookup,chainlookupname)
+    local current = start
+    local subtables = currentlookup.subtables
+    local value  = featurevalue == true and tfmdata.shared.features[kind] or featurevalue
+    while current do
+        if getid(current) == glyph_code then -- is this check needed?
+            local currentchar = getchar(current)
+            local lookupname = subtables[1]
+            local alternatives = lookuphash[lookupname]
+            if not alternatives then
+                if trace_bugs then
+                    logwarning("%s: no alternative hit",cref(kind,chainname,chainlookupname,lookupname))
+                end
+            else
+                alternatives = alternatives[currentchar]
+                if alternatives then
+                    local choice, comment = get_alternative_glyph(current,alternatives,value,trace_alternatives)
+                    if choice then
+                        if trace_alternatives then
+                            logprocess("%s: replacing %s by alternative %a to %s, %s",cref(kind,chainname,chainlookupname,lookupname),gref(char),choice,gref(choice),comment)
+                        end
+                        resetinjection(start)
+                        setchar(start,choice)
+                    else
+                        if trace_alternatives then
+                            logwarning("%s: no variant %a for %s, %s",cref(kind,chainname,chainlookupname,lookupname),value,gref(char),comment)
+                        end
+                    end
+                elseif trace_bugs then
+                    logwarning("%s: no alternative for %s, %s",cref(kind,chainname,chainlookupname,lookupname),gref(currentchar),comment)
+                end
+            end
+            return head, start, true
+        elseif current == stop then
+            break
+        else
+            current = getnext(current)
+        end
+    end
+    return head, start, false
+end
+
+--[[ldx--
+<p>When we replace ligatures we use a helper that handles the marks. I might change
+this function (move code inline and handle the marks by a separate function). We
+assume rather stupid ligatures (no complex disc nodes).</p>
+--ldx]]--
+
+function chainprocs.gsub_ligature(head,start,stop,kind,chainname,currentcontext,lookuphash,currentlookup,chainlookupname,chainindex)
+    local startchar = getchar(start)
+    local subtables = currentlookup.subtables
+    local lookupname = subtables[1]
+    local ligatures = lookuphash[lookupname]
+    if not ligatures then
+        if trace_bugs then
+            logwarning("%s: no ligature hits",cref(kind,chainname,chainlookupname,lookupname,chainindex))
+        end
+    else
+        ligatures = ligatures[startchar]
+        if not ligatures then
+            if trace_bugs then
+                logwarning("%s: no ligatures starting with %s",cref(kind,chainname,chainlookupname,lookupname,chainindex),gref(startchar))
+            end
+        else
+            local s = getnext(start)
+            local discfound = false
+            local last = stop
+            local nofreplacements = 1
+            local skipmark = currentlookup.flags[1]
+            while s do
+                local id = getid(s)
+                if id == disc_code then
+                    if not discfound then
+                        discfound = s
+                    end
+                    if s == stop then
+                        break -- okay? or before the disc
+                    else
+                        s = getnext(s)
+                    end
+                else
+                    local schar = getchar(s)
+                    if skipmark and marks[schar] then -- marks
+                        s = getnext(s)
+                    else
+                        local lg = ligatures[schar]
+                        if lg then
+                            ligatures, last, nofreplacements = lg, s, nofreplacements + 1
+                            if s == stop then
+                                break
+                            else
+                                s = getnext(s)
+                            end
+                        else
+                            break
+                        end
+                    end
+                end
+            end
+            local l2 = ligatures.ligature
+            if l2 then
+                if chainindex then
+                    stop = last
+                end
+                if trace_ligatures then
+                    if start == stop then
+                        logprocess("%s: replacing character %s by ligature %s case 3",cref(kind,chainname,chainlookupname,lookupname,chainindex),gref(startchar),gref(l2))
+                    else
+                        logprocess("%s: replacing character %s upto %s by ligature %s case 4",cref(kind,chainname,chainlookupname,lookupname,chainindex),gref(startchar),gref(getchar(stop)),gref(l2))
+                    end
+                end
+                head, start = toligature(kind,lookupname,head,start,stop,l2,currentlookup.flags[1],discfound)
+                return head, start, true, nofreplacements, discfound
+            elseif trace_bugs then
+                if start == stop then
+                    logwarning("%s: replacing character %s by ligature fails",cref(kind,chainname,chainlookupname,lookupname,chainindex),gref(startchar))
+                else
+                    logwarning("%s: replacing character %s upto %s by ligature fails",cref(kind,chainname,chainlookupname,lookupname,chainindex),gref(startchar),gref(getchar(stop)))
+                end
+            end
+        end
+    end
+    return head, start, false, 0, false
+end
+
+function chainprocs.gpos_single(head,start,stop,kind,chainname,currentcontext,lookuphash,currentlookup,chainlookupname,chainindex,sequence)
+    -- untested .. needs checking for the new model
+    local startchar = getchar(start)
+    local subtables = currentlookup.subtables
+    local lookupname = subtables[1]
+    local kerns = lookuphash[lookupname]
+    if kerns then
+        kerns = kerns[startchar] -- needed ?
+        if kerns then
+            local dx, dy, w, h = setpair(start,tfmdata.parameters.factor,rlmode,sequence.flags[4],kerns) -- ,characters[startchar])
+            if trace_kerns then
+                logprocess("%s: shifting single %s by (%p,%p) and correction (%p,%p)",cref(kind,chainname,chainlookupname),gref(startchar),dx,dy,w,h)
+            end
+        end
+    end
+    return head, start, false
+end
+
+function chainprocs.gpos_pair(head,start,stop,kind,chainname,currentcontext,lookuphash,currentlookup,chainlookupname,chainindex,sequence)
+    local snext = getnext(start)
+    if snext then
+        local startchar = getchar(start)
+        local subtables = currentlookup.subtables
+        local lookupname = subtables[1]
+        local kerns = lookuphash[lookupname]
+        if kerns then
+            kerns = kerns[startchar]
+            if kerns then
+                local lookuptype = lookuptypes[lookupname]
+                local prev, done = start, false
+                local factor = tfmdata.parameters.factor
+                while snext and getid(snext) == glyph_code and getfont(snext) == currentfont and getsubtype(snext)<256 do
+                    local nextchar = getchar(snext)
+                    local krn = kerns[nextchar]
+                    if not krn and marks[nextchar] then
+                        prev = snext
+                        snext = getnext(snext)
+                    else
+                        if not krn then
+                            -- skip
+                        elseif type(krn) == "table" then
+                            if lookuptype == "pair" then
+                                local a, b = krn[2], krn[3]
+                                if a and #a > 0 then
+                                    local startchar = getchar(start)
+                                    local x, y, w, h = setpair(start,factor,rlmode,sequence.flags[4],a) -- ,characters[startchar])
+                                    if trace_kerns then
+                                        logprocess("%s: shifting first of pair %s and %s by (%p,%p) and correction (%p,%p)",cref(kind,chainname,chainlookupname),gref(startchar),gref(nextchar),x,y,w,h)
+                                    end
+                                end
+                                if b and #b > 0 then
+                                    local startchar = getchar(start)
+                                    local x, y, w, h = setpair(snext,factor,rlmode,sequence.flags[4],b) -- ,characters[nextchar])
+                                    if trace_kerns then
+                                        logprocess("%s: shifting second of pair %s and %s by (%p,%p) and correction (%p,%p)",cref(kind,chainname,chainlookupname),gref(startchar),gref(nextchar),x,y,w,h)
+                                    end
+                                end
+                            else
+                                report_process("%s: check this out (old kern stuff)",cref(kind,chainname,chainlookupname))
+                             -- local a, b = krn[2], krn[6]
+                             -- if a and a ~= 0 then
+                             --     local k = setkern(snext,factor,rlmode,a)
+                             --     if trace_kerns then
+                             --         logprocess("%s: inserting first kern %s between %s and %s",cref(kind,chainname,chainlookupname),k,gref(getchar(prev)),gref(nextchar))
+                             --     end
+                             -- end
+                             -- if b and b ~= 0 then
+                             --     logwarning("%s: ignoring second kern xoff %s",cref(kind,chainname,chainlookupname),b*factor)
+                             -- end
+                            end
+                            done = true
+                        elseif krn ~= 0 then
+                            local k = setkern(snext,factor,rlmode,krn)
+                            if trace_kerns then
+                                logprocess("%s: inserting kern %s between %s and %s",cref(kind,chainname,chainlookupname),k,gref(getchar(prev)),gref(nextchar))
+                            end
+                            done = true
+                        end
+                        break
+                    end
+                end
+                return head, start, done
+            end
+        end
+    end
+    return head, start, false
+end
+
+function chainprocs.gpos_mark2base(head,start,stop,kind,chainname,currentcontext,lookuphash,currentlookup,chainlookupname)
+    local markchar = getchar(start)
+    if marks[markchar] then
+        local subtables = currentlookup.subtables
+        local lookupname = subtables[1]
+        local markanchors = lookuphash[lookupname]
+        if markanchors then
+            markanchors = markanchors[markchar]
+        end
+        if markanchors then
+            local base = getprev(start) -- [glyph] [start=mark]
+            if base and getid(base) == glyph_code and getfont(base) == currentfont and getsubtype(base)<256 then
+                local basechar = getchar(base)
+                if marks[basechar] then
+                    while true do
+                        base = getprev(base)
+                        if base and getid(base) == glyph_code and getfont(base) == currentfont and getsubtype(base)<256 then
+                            basechar = getchar(base)
+                            if not marks[basechar] then
+                                break
+                            end
+                        else
+                            if trace_bugs then
+                                logwarning("%s: no base for mark %s",pref(kind,lookupname),gref(markchar))
+                            end
+                            return head, start, false
+                        end
+                    end
+                end
+                local baseanchors = descriptions[basechar].anchors
+                if baseanchors then
+                    local baseanchors = baseanchors['basechar']
+                    if baseanchors then
+                        local al = anchorlookups[lookupname]
+                        for anchor,ba in next, baseanchors do
+                            if al[anchor] then
+                                local ma = markanchors[anchor]
+                                if ma then
+                                    local dx, dy, bound = setmark(start,base,tfmdata.parameters.factor,rlmode,ba,ma,characters[basechar])
+                                    if trace_marks then
+                                        logprocess("%s, anchor %s, bound %s: anchoring mark %s to basechar %s => (%p,%p)",
+                                            cref(kind,chainname,chainlookupname,lookupname),anchor,bound,gref(markchar),gref(basechar),dx,dy)
+                                    end
+                                    return head, start, true
+                                end
+                            end
+                        end
+                        if trace_bugs then
+                            logwarning("%s, no matching anchors for mark %s and base %s",cref(kind,chainname,chainlookupname,lookupname),gref(markchar),gref(basechar))
+                        end
+                    end
+                end
+            elseif trace_bugs then
+                logwarning("%s: prev node is no char",cref(kind,chainname,chainlookupname,lookupname))
+            end
+        elseif trace_bugs then
+            logwarning("%s: mark %s has no anchors",cref(kind,chainname,chainlookupname,lookupname),gref(markchar))
+        end
+    elseif trace_bugs then
+        logwarning("%s: mark %s is no mark",cref(kind,chainname,chainlookupname),gref(markchar))
+    end
+    return head, start, false
+end
+
+function chainprocs.gpos_mark2ligature(head,start,stop,kind,chainname,currentcontext,lookuphash,currentlookup,chainlookupname)
+    local markchar = getchar(start)
+    if marks[markchar] then
+        local subtables = currentlookup.subtables
+        local lookupname = subtables[1]
+        local markanchors = lookuphash[lookupname]
+        if markanchors then
+            markanchors = markanchors[markchar]
+        end
+        if markanchors then
+            local base = getprev(start) -- [glyph] [optional marks] [start=mark]
+            if base and getid(base) == glyph_code and getfont(base) == currentfont and getsubtype(base)<256 then
+                local basechar = getchar(base)
+                if marks[basechar] then
+                    while true do
+                        base = getprev(base)
+                        if base and getid(base) == glyph_code and getfont(base) == currentfont and getsubtype(base)<256 then
+                            basechar = getchar(base)
+                            if not marks[basechar] then
+                                break
+                            end
+                        else
+                            if trace_bugs then
+                                logwarning("%s: no base for mark %s",cref(kind,chainname,chainlookupname,lookupname),markchar)
+                            end
+                            return head, start, false
+                        end
+                    end
+                end
+                -- todo: like marks a ligatures hash
+                local index = getligaindex(start)
+                local baseanchors = descriptions[basechar].anchors
+                if baseanchors then
+                   local baseanchors = baseanchors['baselig']
+                   if baseanchors then
+                        local al = anchorlookups[lookupname]
+                        for anchor,ba in next, baseanchors do
+                            if al[anchor] then
+                                local ma = markanchors[anchor]
+                                if ma then
+                                    ba = ba[index]
+                                    if ba then
+                                        local dx, dy, bound = setmark(start,base,tfmdata.parameters.factor,rlmode,ba,ma,characters[basechar])
+                                        if trace_marks then
+                                            logprocess("%s, anchor %s, bound %s: anchoring mark %s to baselig %s at index %s => (%p,%p)",
+                                                cref(kind,chainname,chainlookupname,lookupname),anchor,a or bound,gref(markchar),gref(basechar),index,dx,dy)
+                                        end
+                                        return head, start, true
+                                    end
+                                end
+                            end
+                        end
+                        if trace_bugs then
+                            logwarning("%s: no matching anchors for mark %s and baselig %s",cref(kind,chainname,chainlookupname,lookupname),gref(markchar),gref(basechar))
+                        end
+                    end
+                end
+            elseif trace_bugs then
+                logwarning("feature %s, lookup %s: prev node is no char",kind,lookupname)
+            end
+        elseif trace_bugs then
+            logwarning("%s: mark %s has no anchors",cref(kind,chainname,chainlookupname,lookupname),gref(markchar))
+        end
+    elseif trace_bugs then
+        logwarning("%s: mark %s is no mark",cref(kind,chainname,chainlookupname),gref(markchar))
+    end
+    return head, start, false
+end
+
+function chainprocs.gpos_mark2mark(head,start,stop,kind,chainname,currentcontext,lookuphash,currentlookup,chainlookupname)
+    local markchar = getchar(start)
+    if marks[markchar] then
+    --  local markanchors = descriptions[markchar].anchors markanchors = markanchors and markanchors.mark
+        local subtables = currentlookup.subtables
+        local lookupname = subtables[1]
+        local markanchors = lookuphash[lookupname]
+        if markanchors then
+            markanchors = markanchors[markchar]
+        end
+        if markanchors then
+            local base = getprev(start) -- [glyph] [basemark] [start=mark]
+            local slc = getligaindex(start)
+            if slc then -- a rather messy loop ... needs checking with husayni
+                while base do
+                    local blc = getligaindex(base)
+                    if blc and blc ~= slc then
+                        base = getprev(base)
+                    else
+                        break
+                    end
+                end
+            end
+            if base and getid(base) == glyph_code and getfont(base) == currentfont and getsubtype(base)<256 then -- subtype test can go
+                local basechar = getchar(base)
+                local baseanchors = descriptions[basechar].anchors
+                if baseanchors then
+                    baseanchors = baseanchors['basemark']
+                    if baseanchors then
+                        local al = anchorlookups[lookupname]
+                        for anchor,ba in next, baseanchors do
+                            if al[anchor] then
+                                local ma = markanchors[anchor]
+                                if ma then
+                                    local dx, dy, bound = setmark(start,base,tfmdata.parameters.factor,rlmode,ba,ma,characters[basechar],true)
+                                    if trace_marks then
+                                        logprocess("%s, anchor %s, bound %s: anchoring mark %s to basemark %s => (%p,%p)",
+                                            cref(kind,chainname,chainlookupname,lookupname),anchor,bound,gref(markchar),gref(basechar),dx,dy)
+                                    end
+                                    return head, start, true
+                                end
+                            end
+                        end
+                        if trace_bugs then
+                            logwarning("%s: no matching anchors for mark %s and basemark %s",gref(kind,chainname,chainlookupname,lookupname),gref(markchar),gref(basechar))
+                        end
+                    end
+                end
+            elseif trace_bugs then
+                logwarning("%s: prev node is no mark",cref(kind,chainname,chainlookupname,lookupname))
+            end
+        elseif trace_bugs then
+            logwarning("%s: mark %s has no anchors",cref(kind,chainname,chainlookupname,lookupname),gref(markchar))
+        end
+    elseif trace_bugs then
+        logwarning("%s: mark %s is no mark",cref(kind,chainname,chainlookupname),gref(markchar))
+    end
+    return head, start, false
+end
+
+function chainprocs.gpos_cursive(head,start,stop,kind,chainname,currentcontext,lookuphash,currentlookup,chainlookupname)
+    local alreadydone = cursonce and getprop(start,a_cursbase)
+    if not alreadydone then
+        local startchar = getchar(start)
+        local subtables = currentlookup.subtables
+        local lookupname = subtables[1]
+        local exitanchors = lookuphash[lookupname]
+        if exitanchors then
+            exitanchors = exitanchors[startchar]
+        end
+        if exitanchors then
+            local done = false
+            if marks[startchar] then
+                if trace_cursive then
+                    logprocess("%s: ignoring cursive for mark %s",pref(kind,lookupname),gref(startchar))
+                end
+            else
+                local nxt = getnext(start)
+                while not done and nxt and getid(nxt) == glyph_code and getfont(nxt) == currentfont and getsubtype(nxt)<256 do
+                    local nextchar = getchar(nxt)
+                    if marks[nextchar] then
+                        -- should not happen (maybe warning)
+                        nxt = getnext(nxt)
+                    else
+                        local entryanchors = descriptions[nextchar]
+                        if entryanchors then
+                            entryanchors = entryanchors.anchors
+                            if entryanchors then
+                                entryanchors = entryanchors['centry']
+                                if entryanchors then
+                                    local al = anchorlookups[lookupname]
+                                    for anchor, entry in next, entryanchors do
+                                        if al[anchor] then
+                                            local exit = exitanchors[anchor]
+                                            if exit then
+                                                local dx, dy, bound = setcursive(start,nxt,tfmdata.parameters.factor,rlmode,exit,entry,characters[startchar],characters[nextchar])
+                                                if trace_cursive then
+                                                    logprocess("%s: moving %s to %s cursive (%p,%p) using anchor %s and bound %s in rlmode %s",pref(kind,lookupname),gref(startchar),gref(nextchar),dx,dy,anchor,bound,rlmode)
+                                                end
+                                                done = true
+                                                break
+                                            end
+                                        end
+                                    end
+                                end
+                            end
+                        elseif trace_bugs then
+                        --  logwarning("%s: char %s is missing in font",pref(kind,lookupname),gref(startchar))
+                            onetimemessage(currentfont,startchar,"no entry anchors",report_fonts)
+                        end
+                        break
+                    end
+                end
+            end
+            return head, start, done
+        else
+            if trace_cursive and trace_details then
+                logprocess("%s, cursive %s is already done",pref(kind,lookupname),gref(getchar(start)),alreadydone)
+            end
+            return head, start, false
+        end
+    end
+    return head, start, false
+end
+
+-- what pointer to return, spec says stop
+-- to be discussed ... is bidi changer a space?
+-- elseif char == zwnj and sequence[n][32] then -- brrr
+
+-- somehow l or f is global
+-- we don't need to pass the currentcontext, saves a bit
+-- make a slow variant then can be activated but with more tracing
+
+local function show_skip(kind,chainname,char,ck,class)
+    if ck[9] then
+        logwarning("%s: skipping char %s, class %a, rule %a, lookuptype %a, %a => %a",cref(kind,chainname),gref(char),class,ck[1],ck[2],ck[9],ck[10])
+    else
+        logwarning("%s: skipping char %s, class %a, rule %a, lookuptype %a",cref(kind,chainname),gref(char),class,ck[1],ck[2])
+    end
+end
+
+-- A previous version had disc collapsing code in the (single sub) handler plus some
+-- checking in the main loop, but that left the pre/post sequences undone. The best
+-- solution is to add some checking there and backtrack when a replace/post matches
+-- but it takes a bit of work to figure out an efficient way (this is what the sweep*
+-- names refer to). I might look into that variant one day again as it can replace
+-- some other code too. In that approach we can have a special version for gub and pos
+-- which gains some speed. This method does the test and passes info to the handlers
+-- (sweepnode, sweepmode, sweepprev, sweepnext, etc). Here collapsing is handled in the
+-- main loop which also makes code elsewhere simpler (i.e. no need for the other special
+-- runners and disc code in ligature building). I also experimented with pushing preceding
+-- glyphs sequences in the replace/pre fields beforehand which saves checking afterwards
+-- but at the cost of duplicate glyphs (memory) but it's too much overhead (runtime).
+--
+-- In the meantime Kai had moved the code from the single chain into a more general handler
+-- and this one (renamed to chaindisk) is used now. I optimized the code a bit and brought
+-- it in sycn with the other code. Hopefully I didn't introduce errors. Note: this somewhat
+-- complex approach is meant for fonts that implement (for instance) ligatures by character
+-- replacement which to some extend is not that suitable for hyphenation. I also use some
+-- helpers. This method passes some states but reparses the list. There is room for a bit of
+-- speed up but that will be done in the context version. (In fact a partial rewrite of all
+-- code can bring some more efficientry.)
+--
+-- I didn't test it with extremes but successive disc nodes still can give issues but in
+-- order to handle that we need more complex code which also slows down even more. The main
+-- loop variant could deal with that: test, collapse, backtrack.
+
+local function chaindisk(head,start,last,kind,chainname,ck,lookuphash,chainlookup,chainlookupname,chainindex,sequence,chainproc)
+
+    if not start then
+        return head, start, false
+    end
+
+    local startishead   = start == head
+    local seq           = ck[3]
+    local f             = ck[4]
+    local l             = ck[5]
+    local s             = #seq
+    local done          = false
+    local sweepnode     = sweepnode
+    local sweeptype     = sweeptype
+    local sweepoverflow = false
+    local checkdisc     = getprev(head) -- hm bad name head
+    local keepdisc      = not sweepnode
+    local lookaheaddisc = nil
+    local backtrackdisc = nil
+    local current       = start
+    local last          = start
+    local prev          = getprev(start)
+
+    -- fishy: so we can overflow and then go on in the sweep?
+
+    local i = f
+    while i <= l do
+        local id = getid(current)
+        if id == glyph_code then
+            i       = i + 1
+            last    = current
+            current = getnext(current)
+        elseif id == disc_code then
+            if keepdisc then
+                keepdisc = false
+                if notmatchpre[current] ~= notmatchreplace[current] then
+                    lookaheaddisc = current
+                end
+                local replace = getfield(current,"replace")
+                while replace and i <= l do
+                    if getid(replace) == glyph_code then
+                        i = i + 1
+                    end
+                    replace = getnext(replace)
+                end
+                last    = current
+                current = getnext(c)
+            else
+                head, current = flattendisk(head,current)
+            end
+        else
+            last    = current
+            current = getnext(current)
+        end
+        if current then
+            -- go on
+        elseif sweepoverflow then
+            -- we already are folling up on sweepnode
+            break
+        elseif sweeptype == "post" or sweeptype == "replace" then
+            current = getnext(sweepnode)
+            if current then
+                sweeptype     = nil
+                sweepoverflow = true
+            else
+                break
+            end
+        end
+    end
+
+    if sweepoverflow then
+        local prev = current and getprev(current)
+        if not current or prev ~= sweepnode then
+            local head = getnext(sweepnode)
+            local tail = nil
+            if prev then
+                tail = prev
+                setprev(current,sweepnode)
+            else
+                tail = find_node_tail(head)
+            end
+            setnext(sweepnode,current)
+            setprev(head,nil)
+            setnext(tail,nil)
+            appenddisc(sweepnode,head)
+        end
+    end
+
+    if l < s then
+        local i = l
+        local t = sweeptype == "post" or sweeptype == "replace"
+        while current and i < s do
+            local id = getid(current)
+            if id == glyph_code then
+                i       = i + 1
+                current = getnext(current)
+            elseif id == disc_code then
+                if keepdisc then
+                    keepdisc = false
+                    if notmatchpre[current] ~= notmatchreplace[current] then
+                        lookaheaddisc = current
+                    end
+                    local replace = getfield(c,"replace")
+                    while replace and i < s do
+                        if getid(replace) == glyph_code then
+                            i = i + 1
+                        end
+                        replace = getnext(replace)
+                    end
+                    current = getnext(current)
+                elseif notmatchpre[current] ~= notmatchreplace[current] then
+                    head, current = flattendisk(head,current)
+                else
+                    current = getnext(current) -- HH
+                end
+            else
+                current = getnext(current)
+            end
+            if not current and t then
+                current = getnext(sweepnode)
+                if current then
+                    sweeptype = nil
+                end
+            end
+        end
+    end
+
+    if f > 1 then
+        local current = prev
+        local i       = f
+        local t       = sweeptype == "pre" or sweeptype == "replace"
+        if not current and t and current == checkdisk then
+            current = getprev(sweepnode)
+        end
+        while current and i > 1 do -- missing getprev added / moved outside
+            local id = getid(current)
+            if id == glyph_code then
+                i = i - 1
+            elseif id == disc_code then
+                if keepdisc then
+                    keepdisc = false
+                    if notmatchpost[current] ~= notmatchreplace[current] then
+                        backtrackdisc = current
+                    end
+                    local replace = getfield(current,"replace")
+                    while replace and i > 1 do
+                        if getid(replace) == glyph_code then
+                            i = i - 1
+                        end
+                        replace = getnext(replace)
+                    end
+                elseif notmatchpost[current] ~= notmatchreplace[current] then
+                    head, current = flattendisk(head,current)
+                end
+            end
+            current = getprev(current)
+            if t and current == checkdisk then
+                current = getprev(sweepnode)
+            end
+        end
+    end
+
+    local ok = false
+    if lookaheaddisc then
+
+        local cf            = start
+        local cl            = getprev(lookaheaddisc)
+        local cprev         = getprev(start)
+        local insertedmarks = 0
+
+        while cprev and getid(cf) == glyph_code and getfont(cf) == currentfont and getsubtype(cf) < 256 and marks[getchar(cf)] do
+            insertedmarks = insertedmarks + 1
+            cf            = cprev
+            startishead   = cf == head
+            cprev         = getprev(cprev)
+        end
+
+        setprev(lookaheaddisc,cprev)
+        if cprev then
+            setnext(cprev,lookaheaddisc)
+        end
+        setprev(cf,nil)
+        setnext(cl,nil)
+        if startishead then
+            head = lookaheaddisc
+        end
+
+        local replace = getfield(lookaheaddisc,"replace")
+        local pre     = getfield(lookaheaddisc,"pre")
+        local new     = copy_node_list(cf)
+        local cnew = new
+        for i=1,insertedmarks do
+            cnew = getnext(cnew)
+        end
+        local clast = cnew
+        for i=f,l do
+            clast = getnext(clast)
+        end
+        if not notmatchpre[lookaheaddisc] then
+            cf, start, ok = chainproc(cf,start,last,kind,chainname,ck,lookuphash,chainlookup,chainlookupname,nil,sequence)
+        end
+        if not notmatchreplace[lookaheaddisc] then
+            new, cnew, ok = chainproc(new,cnew,clast,kind,chainname,ck,lookuphash,chainlookup,chainlookupname,nil,sequence)
+        end
+        if pre then
+            setnext(cl,pre)
+            setprev(pre,cl)
+        end
+        if replace then
+            local tail = find_node_tail(new)
+            setnext(tail,replace)
+            setprev(replace,tail)
+        end
+        setfield(lookaheaddisc,"pre",cf)      -- also updates tail
+        setfield(lookaheaddisc,"replace",new) -- also updates tail
+
+        start          = getprev(lookaheaddisc)
+        sweephead[cf]  = getnext(clast)
+        sweephead[new] = getnext(last)
+
+    elseif backtrackdisc then
+
+        local cf            = getnext(backtrackdisc)
+        local cl            = start
+        local cnext         = getnext(start)
+        local insertedmarks = 0
+
+        while cnext and getid(cnext) == glyph_code and getfont(cnext) == currentfont and getsubtype(cnext) < 256 and marks[getchar(cnext)] do
+            insertedmarks = insertedmarks + 1
+            cl            = cnext
+            cnext         = getnext(cnext)
+        end
+        if cnext then
+            setprev(cnext,backtrackdisc)
+        end
+        setnext(backtrackdisc,cnext)
+        setprev(cf,nil)
+        setnext(cl,nil)
+        local replace = getfield(backtrackdisc,"replace")
+        local post    = getfield(backtrackdisc,"post")
+        local new     = copy_node_list(cf)
+        local cnew    = find_node_tail(new)
+        for i=1,insertedmarks do
+            cnew = getprev(cnew)
+        end
+        local clast = cnew
+        for i=f,l do
+            clast = getnext(clast)
+        end
+        if not notmatchpost[backtrackdisc] then
+            cf, start, ok = chainproc(cf,start,last,kind,chainname,ck,lookuphash,chainlookup,chainlookupname,nil,sequence)
+        end
+        if not notmatchreplace[backtrackdisc] then
+            new, cnew, ok = chainproc(new,cnew,clast,kind,chainname,ck,lookuphash,chainlookup,chainlookupname,nil,sequence)
+        end
+        if post then
+            local tail = find_node_tail(post)
+            setnext(tail,cf)
+            setprev(cf,tail)
+        else
+            post = cf
+        end
+        if replace then
+            local tail = find_node_tail(replace)
+            setnext(tail,new)
+            setprev(new,tail)
+        else
+            replace = new
+        end
+        setfield(backtrackdisc,"post",post)       -- also updates tail
+        setfield(backtrackdisc,"replace",replace) -- also updates tail
+        start              = getprev(backtrackdisc)
+        sweephead[post]    = getnext(clast)
+        sweephead[replace] = getnext(last)
+
+    else
+
+        head, start, ok = chainproc(head,start,last,kind,chainname,ck,lookuphash,chainlookup,chainlookupname,nil,sequence)
+
+    end
+
+    return head, start, ok
+end
+
+local function normal_handle_contextchain(head,start,kind,chainname,contexts,sequence,lookuphash)
+    local sweepnode    = sweepnode
+    local sweeptype    = sweeptype
+    local diskseen     = false
+    local checkdisc    = getprev(head)
+    local flags        = sequence.flags
+    local done         = false
+    local skipmark     = flags[1]
+    local skipligature = flags[2]
+    local skipbase     = flags[3]
+    local markclass    = sequence.markclass
+    local skipped      = false
+
+    for k=1,#contexts do -- i've only seen ccmp having > 1 (e.g. dejavu)
+        local match   = true
+        local current = start
+        local last    = start
+        local ck      = contexts[k]
+        local seq     = ck[3]
+        local s       = #seq
+        -- f..l = mid string
+        if s == 1 then
+            -- never happens
+            match = getid(current) == glyph_code and getfont(current) == currentfont and getsubtype(current)<256 and seq[1][getchar(current)]
+        else
+            -- maybe we need a better space check (maybe check for glue or category or combination)
+            -- we cannot optimize for n=2 because there can be disc nodes
+            local f = ck[4]
+            local l = ck[5]
+            -- current match
+            if f == 1 and f == l then -- current only
+                -- already a hit
+             -- match = true
+            else -- before/current/after | before/current | current/after
+                -- no need to test first hit (to be optimized)
+                if f == l then -- new, else last out of sync (f is > 1)
+                 -- match = true
+                else
+                    local discfound = nil
+                    local n = f + 1
+                    last = getnext(last)
+                    while n <= l do
+                        if not last and (sweeptype == "post" or sweeptype == "replace") then
+                            last      = getnext(sweepnode)
+                            sweeptype = nil
+                        end
+                        if last then
+                            local id = getid(last)
+                            if id == glyph_code then
+                                if getfont(last) == currentfont and getsubtype(last)<256 then
+                                    local char = getchar(last)
+                                    local ccd = descriptions[char]
+                                    if ccd then
+                                        local class = ccd.class or "base"
+                                        if class == skipmark or class == skipligature or class == skipbase or (markclass and class == "mark" and not markclass[char]) then
+                                            skipped = true
+                                            if trace_skips then
+                                                show_skip(kind,chainname,char,ck,class)
+                                            end
+                                            last = getnext(last)
+                                        elseif seq[n][char] then
+                                            if n < l then
+                                                last = getnext(last)
+                                            end
+                                            n = n + 1
+                                        else
+                                            if discfound then
+                                                notmatchreplace[discfound] = true
+                                                match = not notmatchpre[discfound]
+                                            else
+                                                match = false
+                                            end
+                                            break
+                                        end
+                                    else
+                                        if discfound then
+                                            notmatchreplace[discfound] = true
+                                            match = not notmatchpre[discfound]
+                                        else
+                                            match = false
+                                        end
+                                        break
+                                    end
+                                else
+                                    if discfound then
+                                        notmatchreplace[discfound] = true
+                                        match = not notmatchpre[discfound]
+                                    else
+                                        match = false
+                                    end
+                                    break
+                                end
+                            elseif id == disc_code then
+                                diskseen              = true
+                                discfound             = last
+                                notmatchpre[last]     = nil
+                                notmatchpost[last]    = true
+                                notmatchreplace[last] = nil
+                                local pre     = getfield(last,"pre")
+                                local replace = getfield(last,"replace")
+                                if pre then
+                                    local n = n
+                                    while pre do
+                                        if seq[n][getchar(pre)] then
+                                            n = n + 1
+                                            pre = getnext(pre)
+                                            if n > l then
+                                                break
+                                            end
+                                        else
+                                            notmatchpre[last] = true
+                                            break
+                                        end
+                                    end
+                                    if n <= l then
+                                        notmatchpre[last] = true
+                                    end
+                                else
+                                    notmatchpre[last] = true
+                                end
+                                if replace then
+                                    -- so far we never entered this branch
+                                    while replace do
+                                        if seq[n][getchar(replace)] then
+                                            n = n + 1
+                                            replace = getnext(replace)
+                                            if n > l then
+                                                break
+                                            end
+                                        else
+                                            notmatchreplace[last] = true
+                                            match = not notmatchpre[last]
+                                            break
+                                        end
+                                    end
+                                    match = not notmatchpre[last]
+                                end
+                                last = getnext(last)
+                            else
+                                match = false
+                                break
+                            end
+                        else
+                            match = false
+                            break
+                        end
+                    end
+                end
+            end
+            -- before
+            if match and f > 1 then
+                local prev = getprev(start)
+                if prev then
+                    if prev == checkdisc and (sweeptype == "pre" or sweeptype == "replace") then
+                        prev      = getprev(sweepnode)
+                     -- sweeptype = nil
+                    end
+                    if prev then
+                        local discfound = nil
+                        local n = f - 1
+                        while n >= 1 do
+                            if prev then
+                                local id = getid(prev)
+                                if id == glyph_code then
+                                    if getfont(prev) == currentfont and getsubtype(prev)<256 then -- normal char
+                                        local char = getchar(prev)
+                                        local ccd = descriptions[char]
+                                        if ccd then
+                                            local class = ccd.class
+                                            if class == skipmark or class == skipligature or class == skipbase or (markclass and class == "mark" and not markclass[char]) then
+                                                skipped = true
+                                                if trace_skips then
+                                                    show_skip(kind,chainname,char,ck,class)
+                                                end
+                                            elseif seq[n][char] then
+                                                n = n -1
+                                            else
+                                                if discfound then
+                                                    notmatchreplace[discfound] = true
+                                                    match = not notmatchpost[discfound]
+                                                else
+                                                    match = false
+                                                end
+                                                break
+                                            end
+                                        else
+                                            if discfound then
+                                                notmatchreplace[discfound] = true
+                                                match = not notmatchpost[discfound]
+                                            else
+                                                match = false
+                                            end
+                                            break
+                                        end
+                                    else
+                                        if discfound then
+                                            notmatchreplace[discfound] = true
+                                            match = not notmatchpost[discfound]
+                                        else
+                                            match = false
+                                        end
+                                        break
+                                    end
+                                elseif id == disc_code then
+                                    -- the special case: f i where i becomes dottless i ..
+                                    diskseen              = true
+                                    discfound             = prev
+                                    notmatchpre[prev]     = true
+                                    notmatchpost[prev]    = nil
+                                    notmatchreplace[prev] = nil
+                                    local pre     = getfield(prev,"pre")
+                                    local post    = getfield(prev,"post")
+                                    local replace = getfield(prev,"replace")
+                                    if pre ~= start and post ~= start and replace ~= start then
+                                        if post then
+                                            local n = n
+                                            local posttail = find_node_tail(post)
+                                            while posttail do
+                                                if seq[n][getchar(posttail)] then
+                                                    n = n - 1
+                                                    if posttail == post then
+                                                        break
+                                                    else
+                                                        posttail = getprev(posttail)
+                                                        if n < 1 then
+                                                            break
+                                                        end
+                                                    end
+                                                else
+                                                    notmatchpost[prev] = true
+                                                    break
+                                                end
+                                            end
+                                            if n >= 1 then
+                                                notmatchpost[prev] = true
+                                            end
+                                        else
+                                            notmatchpost[prev] = true
+                                        end
+                                        if replace then
+                                            -- we seldom enter this branch (e.g. on brill efficient)
+                                            local replacetail = find_node_tail(replace)
+                                            while replacetail do
+                                                if seq[n][getchar(replacetail)] then
+                                                    n = n - 1
+                                                    if replacetail == replace then
+                                                        break
+                                                    else
+                                                        replacetail = getprev(replacetail)
+                                                        if n < 1 then
+                                                            break
+                                                        end
+                                                    end
+                                                else
+                                                    notmatchreplace[prev] = true
+                                                    match = not notmatchpost[prev]
+                                                    break
+                                                end
+                                            end
+                                            if not match then
+                                                break
+                                            end
+                                        else
+                                            -- skip 'm
+                                        end
+                                    else
+                                        -- skip 'm
+                                    end
+                                elseif seq[n][32] then
+                                    n = n -1
+                                else
+                                    match = false
+                                    break
+                                end
+                                prev = getprev(prev)
+                            elseif seq[n][32] then -- somewhat special, as zapfino can have many preceding spaces
+                                n = n - 1
+                            else
+                                match = false
+                                break
+                            end
+                        end
+                    else
+                        match = false
+                    end
+                else
+                    match = false
+                end
+            end
+            -- after
+            if match and s > l then
+                local current = last and getnext(last)
+                if not current then
+                    if sweeptype == "post" or sweeptype == "replace" then
+                        current   = getnext(sweepnode)
+                     -- sweeptype = nil
+                    end
+                end
+                if current then
+                    local discfound = nil
+                    -- removed optimization for s-l == 1, we have to deal with marks anyway
+                    local n = l + 1
+                    while n <= s do
+                        if current then
+                            local id = getid(current)
+                            if id == glyph_code then
+                                if getfont(current) == currentfont and getsubtype(current)<256 then -- normal char
+                                    local char = getchar(current)
+                                    local ccd = descriptions[char]
+                                    if ccd then
+                                        local class = ccd.class
+                                        if class == skipmark or class == skipligature or class == skipbase or (markclass and class == "mark" and not markclass[char]) then
+                                            skipped = true
+                                            if trace_skips then
+                                                show_skip(kind,chainname,char,ck,class)
+                                            end
+                                        elseif seq[n][char] then
+                                            n = n + 1
+                                        else
+                                            if discfound then
+                                                notmatchreplace[discfound] = true
+                                                match = not notmatchpre[discfound]
+                                            else
+                                                match = false
+                                            end
+                                            break
+                                        end
+                                    else
+                                        if discfound then
+                                            notmatchreplace[discfound] = true
+                                            match = not notmatchpre[discfound]
+                                        else
+                                            match = false
+                                        end
+                                        break
+                                    end
+                                else
+                                    if discfound then
+                                        notmatchreplace[discfound] = true
+                                        match = not notmatchpre[discfound]
+                                    else
+                                        match = false
+                                    end
+                                    break
+                                end
+                            elseif id == disc_code then
+                                diskseen                 = true
+                                discfound                = current
+                                notmatchpre[current]     = nil
+                                notmatchpost[current]    = true
+                                notmatchreplace[current] = nil
+                                local pre     = getfield(current,"pre")
+                                local replace = getfield(current,"replace")
+                                if pre then
+                                    local n = n
+                                    while pre do
+                                        if seq[n][getchar(pre)] then
+                                            n = n + 1
+                                            pre = getnext(pre)
+                                            if n > s then
+                                                break
+                                            end
+                                        else
+                                            notmatchpre[current] = true
+                                            break
+                                        end
+                                    end
+                                    if n <= s then
+                                        notmatchpre[current] = true
+                                    end
+                                else
+                                    notmatchpre[current] = true
+                                end
+                                if replace then
+                                    -- so far we never entered this branch
+                                    while replace do
+                                        if seq[n][getchar(replace)] then
+                                            n = n + 1
+                                            replace = getnext(replace)
+                                            if n > s then
+                                                break
+                                            end
+                                        else
+                                            notmatchreplace[current] = true
+                                            match = notmatchpre[current]
+                                            break
+                                        end
+                                    end
+                                    if not match then
+                                        break
+                                    end
+                                else
+                                    -- skip 'm
+                                end
+                            elseif seq[n][32] then -- brrr
+                                n = n + 1
+                            else
+                                match = false
+                                break
+                            end
+                            current = getnext(current)
+                        elseif seq[n][32] then
+                            n = n + 1
+                        else
+                            match = false
+                            break
+                        end
+                    end
+                else
+                    match = false
+                end
+            end
+        end
+        if match then
+            -- can lookups be of a different type ?
+            local diskchain = diskseen or sweepnode
+            if trace_contexts then
+                local rule, lookuptype, f, l = ck[1], ck[2], ck[4], ck[5]
+                local char = getchar(start)
+                if ck[9] then
+                    logwarning("%s: rule %s matches at char %s for (%s,%s,%s) chars, lookuptype %a, %a => %a",
+                        cref(kind,chainname),rule,gref(char),f-1,l-f+1,s-l,lookuptype,ck[9],ck[10])
+                else
+                    logwarning("%s: rule %s matches at char %s for (%s,%s,%s) chars, lookuptype %a",
+                        cref(kind,chainname),rule,gref(char),f-1,l-f+1,s-l,lookuptype)
+                end
+            end
+            local chainlookups = ck[6]
+            if chainlookups then
+                local nofchainlookups = #chainlookups
+                -- we can speed this up if needed
+                if nofchainlookups == 1 then
+                    local chainlookupname = chainlookups[1]
+                    local chainlookup = lookuptable[chainlookupname]
+                    if chainlookup then
+                        local chainproc = chainprocs[chainlookup.type]
+                        if chainproc then
+                            local ok
+                            if diskchain then
+                                head, start, ok = chaindisk(head,start,last,kind,chainname,ck,lookuphash,chainlookup,chainlookupname,nil,sequence,chainproc)
+                            else
+                                head, start, ok = chainproc(head,start,last,kind,chainname,ck,lookuphash,chainlookup,chainlookupname,nil,sequence)
+                            end
+                            if ok then
+                                done = true
+                            end
+                        else
+                            logprocess("%s: %s is not yet supported",cref(kind,chainname,chainlookupname),chainlookup.type)
+                        end
+                    else -- shouldn't happen
+                        logprocess("%s is not yet supported",cref(kind,chainname,chainlookupname))
+                    end
+                 else
+                    local i = 1
+                    while start and true do
+                        if skipped then
+                            while true do -- todo: use properties
+                                local char = getchar(start)
+                                local ccd = descriptions[char]
+                                if ccd then
+                                    local class = ccd.class or "base"
+                                    if class == skipmark or class == skipligature or class == skipbase or (markclass and class == "mark" and not markclass[char]) then
+                                        start = getnext(start)
+                                    else
+                                        break
+                                    end
+                                else
+                                    break
+                                end
+                            end
+                        end
+                        -- see remark in ms standard under : LookupType 5: Contextual Substitution Subtable
+                        local chainlookupname = chainlookups[i]
+                        local chainlookup = lookuptable[chainlookupname]
+                        if not chainlookup then
+                            -- we just advance
+                            i = i + 1
+                        else
+                            local chainproc = chainprocs[chainlookup.type]
+                            if not chainproc then
+                                -- actually an error
+                                logprocess("%s: %s is not yet supported",cref(kind,chainname,chainlookupname),chainlookup.type)
+                                i = i + 1
+                            else
+                                local ok, n
+                                if diskchain then
+                                    head, start, ok    = chaindisk(head,start,last,kind,chainname,ck,lookuphash,chainlookup,chainlookupname,nil,sequence,chainproc)
+                                else
+                                    head, start, ok, n = chainproc(head,start,last,kind,chainname,ck,lookuphash,chainlookup,chainlookupname,i,sequence)
+                                end
+                                -- messy since last can be changed !
+                                if ok then
+                                    done = true
+                                    if n and n > 1 then
+                                        -- we have a ligature (cf the spec we advance one but we really need to test it
+                                        -- as there are fonts out there that are fuzzy and have too many lookups:
+                                        --
+                                        -- U+1105 U+119E U+1105 U+119E : sourcehansansklight: script=hang ccmp=yes
+                                        --
+                                        if i + n > nofchainlookups then
+                                         -- if trace_contexts then
+                                         --     logprocess("%s: quitting lookups",cref(kind,chainname))
+                                         -- end
+                                            break
+                                        else
+                                            -- we need to carry one
+                                        end
+                                    end
+                                end
+                                i = i + 1
+                            end
+                        end
+                        if i > nofchainlookups or not start then
+                            break
+                        elseif start then
+                            start = getnext(start)
+                        end
+                    end
+                end
+            else
+                local replacements = ck[7]
+                if replacements then
+                    head, start, done = chainprocs.reversesub(head,start,last,kind,chainname,ck,lookuphash,replacements) -- sequence
+                else
+                    done = quit_on_no_replacement -- can be meant to be skipped / quite inconsistent in fonts
+                    if trace_contexts then
+                        logprocess("%s: skipping match",cref(kind,chainname))
+                    end
+                end
+            end
+            if done then
+                break -- out of contexts (new, needs checking)
+            end
+        end
+    end
+    if diskseen then -- maybe move up so that we can turn checking on/off
+        notmatchpre     = { }
+        notmatchpost    = { }
+        notmatchreplace = { }
+    end
+    return head, start, done
+end
+
+-- Because we want to keep this elsewhere (an because speed is less an issue) we
+-- pass the font id so that the verbose variant can access the relevant helper tables.
+
+local verbose_handle_contextchain = function(font,...)
+    logwarning("no verbose handler installed, reverting to 'normal'")
+    otf.setcontextchain()
+    return normal_handle_contextchain(...)
+end
+
+otf.chainhandlers = {
+    normal  = normal_handle_contextchain,
+    verbose = verbose_handle_contextchain,
+}
+
+local handle_contextchain = nil
+
+-- normal_handle_contextchain(head,start,kind,chainname,contexts,sequence,lookuphash)
+
+function chained_contextchain(head,start,stop,...)
+    local steps    = currentlookup.steps
+    local nofsteps = currentlookup.nofsteps
+    if nofsteps > 1 then
+        reportmoresteps(dataset,sequence)
+    end
+    return handle_contextchain(head,start,...)
+end
+
+function otf.setcontextchain(method)
+    if not method or method == "normal" or not otf.chainhandlers[method] then
+        if handle_contextchain then -- no need for a message while making the format
+            logwarning("installing normal contextchain handler")
+        end
+        handle_contextchain = normal_handle_contextchain
+    else
+        logwarning("installing contextchain handler %a",method)
+        local handler = otf.chainhandlers[method]
+        handle_contextchain = function(...)
+            return handler(currentfont,...) -- hm, get rid of ...
+        end
+    end
+
+    handlers.gsub_context             = handle_contextchain
+    handlers.gsub_contextchain        = handle_contextchain
+    handlers.gsub_reversecontextchain = handle_contextchain
+    handlers.gpos_contextchain        = handle_contextchain
+    handlers.gpos_context             = handle_contextchain
+
+    handlers.contextchain = handle_contextchain
+
+end
+
+chainprocs.gsub_context             = chained_contextchain
+chainprocs.gsub_contextchain        = chained_contextchain
+chainprocs.gsub_reversecontextchain = chained_contextchain
+chainprocs.gpos_contextchain        = chained_contextchain
+chainprocs.gpos_context             = chained_contextchain
+
+otf.setcontextchain()
+
+local missing = { } -- we only report once
+
+local function logprocess(...)
+    if trace_steps then
+        registermessage(...)
+    end
+    report_process(...)
+end
+
+local logwarning = report_process
+
+local function report_missing_cache(typ,lookup)
+    local f = missing[currentfont] if not f then f = { } missing[currentfont] = f end
+    local t = f[typ]               if not t then t = { } f[typ]               = t end
+    if not t[lookup] then
+        t[lookup] = true
+        logwarning("missing cache for lookup %a, type %a, font %a, name %a",lookup,typ,currentfont,tfmdata.properties.fullname)
+    end
+end
+
+local resolved = { } -- we only resolve a font,script,language pair once
+
+-- todo: pass all these 'locals' in a table
+
+local lookuphashes = { }
+
+setmetatableindex(lookuphashes, function(t,font)
+    local lookuphash = fontdata[font].resources.lookuphash
+    if not lookuphash or not next(lookuphash) then
+        lookuphash = false
+    end
+    t[font] = lookuphash
+    return lookuphash
+end)
+
+-- fonts.hashes.lookups = lookuphashes
+
+local autofeatures    = fonts.analyzers.features
+local featuretypes    = otf.tables.featuretypes
+local defaultscript   = otf.features.checkeddefaultscript
+local defaultlanguage = otf.features.checkeddefaultlanguage
+
+local function initialize(sequence,script,language,enabled,autoscript,autolanguage)
+    local features = sequence.features
+    if features then
+        local order = sequence.order
+        if order then
+            local featuretype = featuretypes[sequence.type or "unknown"]
+            for i=1,#order do
+                local kind  = order[i]
+                local valid = enabled[kind]
+                if valid then
+                    local scripts   = features[kind]
+                    local languages = scripts and (
+                        scripts[script] or
+                        scripts[wildcard] or
+                        (autoscript and defaultscript(featuretype,autoscript,scripts))
+                    )
+                    local enabled = languages and (
+                        languages[language] or
+                        languages[wildcard] or
+                        (autolanguage and defaultlanguage(featuretype,autolanguage,languages))
+                    )
+                    if enabled then
+                        return { valid, autofeatures[kind] or false, sequence, kind }
+                    end
+                end
+            end
+        else
+            -- can't happen
+        end
+    end
+    return false
+end
+
+function otf.dataset(tfmdata,font) -- generic variant, overloaded in context
+    local shared       = tfmdata.shared
+    local properties   = tfmdata.properties
+    local language     = properties.language or "dflt"
+    local script       = properties.script   or "dflt"
+    local enabled      = shared.features
+    local autoscript   = enabled and enabled.autoscript
+    local autolanguage = enabled and enabled.autolanguage
+    local res = resolved[font]
+    if not res then
+        res = { }
+        resolved[font] = res
+    end
+    local rs = res[script]
+    if not rs then
+        rs = { }
+        res[script] = rs
+    end
+    local rl = rs[language]
+    if not rl then
+        rl = {
+            -- indexed but we can also add specific data by key
+        }
+        rs[language] = rl
+        local sequences = tfmdata.resources.sequences
+        for s=1,#sequences do
+            local v = enabled and initialize(sequences[s],script,language,enabled,autoscript,autolanguage)
+            if v then
+                rl[#rl+1] = v
+            end
+        end
+    end
+    return rl
+end
+
+-- assumptions:
+--
+-- * languages that use complex disc nodes
+
+local function kernrun(disc,run)
+    --
+    -- we catch <font 1><disc font 2>
+    --
+    if trace_kernruns then
+        report_run("kern") -- will be more detailed
+    end
+    --
+    local prev      = getprev(disc) -- todo, keep these in the main loop
+    local next      = getnext(disc) -- todo, keep these in the main loop
+    --
+    local pre       = getfield(disc,"pre")
+    local post      = getfield(disc,"post")
+    local replace   = getfield(disc,"replace")
+    --
+    local prevmarks = prev
+    --
+    -- can be optional, because why on earth do we get a disc after a mark (okay, maybe when a ccmp
+    -- has happened but then it should be in the disc so basically this test indicates an error)
+    --
+    while prevmarks and getid(prevmarks) == glyph_code and marks[getchar(prevmarks)] and getfont(prevmarks) == currentfont and getsubtype(prevmarks) < 256 do
+        prevmarks = getprev(prevmarks)
+    end
+    --
+    if prev and (pre or replace) and not (getid(prev) == glyph_code and getfont(prev) == currentfont and getsubtype(prev)<256) then
+        prev = false
+    end
+    if next and (post or replace) and not (getid(next) == glyph_code and getfont(next) == currentfont and getsubtype(next)<256) then
+        next = false
+    end
+    --
+    if not pre then
+        -- go on
+    elseif prev then
+        local nest = getprev(pre)
+        setprev(pre,prev)
+        setnext(prev,pre)
+        run(prevmarks,"preinjections")
+        setprev(pre,nest)
+        setnext(prev,disc)
+    else
+        run(pre,"preinjections")
+    end
+    --
+    if not post then
+        -- go on
+    elseif next then
+        local tail = find_node_tail(post)
+        setnext(tail,next)
+        setprev(next,tail)
+        run(post,"postinjections",next)
+        setnext(tail,nil)
+        setprev(next,disc)
+    else
+        run(post,"postinjections")
+    end
+    --
+    if not replace and prev and next then
+        -- this should be already done by discfound
+        setnext(prev,next)
+        setprev(next,prev)
+        run(prevmarks,"injections",next)
+        setnext(prev,disc)
+        setprev(next,disc)
+    elseif prev and next then
+        local tail = find_node_tail(replace)
+        local nest = getprev(replace)
+        setprev(replace,prev)
+        setnext(prev,replace)
+        setnext(tail,next)
+        setprev(next,tail)
+        run(prevmarks,"replaceinjections",next)
+        setprev(replace,nest)
+        setnext(prev,disc)
+        setnext(tail,nil)
+        setprev(next,disc)
+    elseif prev then
+        local nest = getprev(replace)
+        setprev(replace,prev)
+        setnext(prev,replace)
+        run(prevmarks,"replaceinjections")
+        setprev(replace,nest)
+        setnext(prev,disc)
+    elseif next then
+        local tail = find_node_tail(replace)
+        setnext(tail,next)
+        setprev(next,tail)
+        run(replace,"replaceinjections",next)
+        setnext(tail,nil)
+        setprev(next,disc)
+    else
+        run(replace,"replaceinjections")
+    end
+end
+
+-- the if new test might be dangerous as luatex will check / set some tail stuff
+-- in a temp node
+
+local function comprun(disc,run)
+    if trace_compruns then
+        report_run("comp: %s",languages.serializediscretionary(disc))
+    end
+    --
+    local pre = getfield(disc,"pre")
+    if pre then
+        sweepnode = disc
+        sweeptype = "pre" -- in alternative code preinjections is used (also used then for proeprties, saves a variable)
+        local new, done = run(pre)
+        if done then
+            setfield(disc,"pre",new)
+        end
+    end
+    --
+    local post = getfield(disc,"post")
+    if post then
+        sweepnode = disc
+        sweeptype = "post"
+        local new, done = run(post)
+        if done then
+            setfield(disc,"post",new)
+        end
+    end
+    --
+    local replace = getfield(disc,"replace")
+    if replace then
+        sweepnode = disc
+        sweeptype = "replace"
+        local new, done = run(replace)
+        if done then
+            setfield(disc,"replace",new)
+        end
+    end
+    sweepnode = nil
+    sweeptype = nil
+end
+
+local function testrun(disc,trun,crun) -- use helper
+    local next = getnext(disc)
+    if next then
+        local replace = getfield(disc,"replace")
+        if replace then
+            local prev = getprev(disc)
+            if prev then
+                -- only look ahead
+                local tail = find_node_tail(replace)
+             -- local nest = getprev(replace)
+                setnext(tail,next)
+                setprev(next,tail)
+                if trun(replace,next) then
+                    setfield(disc,"replace",nil) -- beware, side effects of nest so first
+                    setnext(prev,replace)
+                    setprev(replace,prev)
+                    setprev(next,tail)
+                    setnext(tail,next)
+                    setprev(disc,nil)
+                    setnext(disc,nil)
+                    flush_node_list(disc)
+                    return replace -- restart
+                else
+                    setnext(tail,nil)
+                    setprev(next,disc)
+                end
+            else
+                -- weird case
+            end
+        else
+            -- no need
+        end
+    else
+        -- weird case
+    end
+    comprun(disc,crun)
+    return next
+end
+
+local function discrun(disc,drun,krun)
+    local next = getnext(disc)
+    local prev = getprev(disc)
+    if trace_discruns then
+        report_run("disc") -- will be more detailed
+    end
+    if next and prev then
+        setnext(prev,next)
+     -- setprev(next,prev)
+        drun(prev)
+        setnext(prev,disc)
+     -- setprev(next,disc)
+    end
+    --
+    local pre = getfield(disc,"pre")
+    if not pre then
+        -- go on
+    elseif prev then
+        local nest = getprev(pre)
+        setprev(pre,prev)
+        setnext(prev,pre)
+        krun(prev,"preinjections")
+        setprev(pre,nest)
+        setnext(prev,disc)
+    else
+        krun(pre,"preinjections")
+    end
+    return next
+end
+
+-- todo: maybe run lr and rl stretches
+
+local function featuresprocessor(head,font,attr)
+
+    local lookuphash = lookuphashes[font] -- we can also check sequences here
+
+    if not lookuphash then
+        return head, false
+    end
+
+    head = tonut(head)
+
+    if trace_steps then
+        checkstep(head)
+    end
+
+    tfmdata         = fontdata[font]
+    descriptions    = tfmdata.descriptions
+    characters      = tfmdata.characters
+    resources       = tfmdata.resources
+
+    marks           = resources.marks
+    anchorlookups   = resources.lookup_to_anchor
+    lookuptable     = resources.lookups
+    lookuptypes     = resources.lookuptypes
+    lookuptags      = resources.lookuptags
+
+    currentfont     = font
+    rlmode          = 0
+    sweephead       = { }
+
+    local sequences = resources.sequences
+    local done      = false
+    local datasets  = otf.dataset(tfmdata,font,attr)
+
+    local dirstack  = { } -- could move outside function
+
+    -- We could work on sub start-stop ranges instead but I wonder if there is that
+    -- much speed gain (experiments showed that it made not much sense) and we need
+    -- to keep track of directions anyway. Also at some point I want to play with
+    -- font interactions and then we do need the full sweeps.
+
+    -- Keeping track of the headnode is needed for devanagari (I generalized it a bit
+    -- so that multiple cases are also covered.)
+
+    -- We don't goto the next node of a disc node is created so that we can then treat
+    -- the pre, post and replace. It's abit of a hack but works out ok for most cases.
+
+    -- there can be less subtype and attr checking in the comprun etc helpers
+
+    for s=1,#datasets do
+        local dataset      = datasets[s]
+              featurevalue = dataset[1] -- todo: pass to function instead of using a global
+        local attribute    = dataset[2]
+        local sequence     = dataset[3] -- sequences[s] -- also dataset[5]
+        local kind         = dataset[4]
+        ----- chain        = dataset[5] -- sequence.chain or 0
+        local rlparmode    = 0
+        local topstack     = 0
+        local success      = false
+        local typ          = sequence.type
+        local gpossing     = typ == "gpos_single" or typ == "gpos_pair" -- maybe all of them
+        local subtables    = sequence.subtables
+        local handler      = handlers[typ]
+        if typ == "gsub_reversecontextchain" then -- chain < 0
+            -- this is a limited case, no special treatments like 'init' etc
+            -- we need to get rid of this slide! probably no longer needed in latest luatex
+            local start = find_node_tail(head) -- slow (we can store tail because there's always a skip at the end): todo
+            while start do
+                local id = getid(start)
+                if id == glyph_code then
+                    if getfont(start) == font and getsubtype(start) < 256 then
+                        local a = getattr(start,0)
+                        if a then
+                            a = a == attr
+                        else
+                            a = true
+                        end
+                        if a then
+                            local char = getchar(start)
+                            for i=1,#subtables do
+                                local lookupname = subtables[i]
+                                local lookupcache = lookuphash[lookupname]
+                                if lookupcache then
+                                    local lookupmatch = lookupcache[char]
+                                    if lookupmatch then
+                                        -- todo: disc?
+                                        head, start, success = handler(head,start,kind,lookupname,lookupmatch,sequence,lookuphash,i)
+                                        if success then
+                                            break
+                                        end
+                                    end
+                                else
+                                    report_missing_cache(typ,lookupname)
+                                end
+                            end
+                            if start then start = getprev(start) end
+                        else
+                            start = getprev(start)
+                        end
+                    else
+                        start = getprev(start)
+                    end
+                else
+                    start = getprev(start)
+                end
+            end
+        else
+            local ns = #subtables
+            local start = head -- local ?
+            rlmode = 0 -- to be checked ?
+            if ns == 1 then -- happens often
+                local lookupname  = subtables[1]
+                local lookupcache = lookuphash[lookupname]
+                if not lookupcache then -- also check for empty cache
+                    report_missing_cache(typ,lookupname)
+                else
+
+                    local function c_run(head) -- no need to check for 256 and attr probably also the same
+                        local done  = false
+                        local start = sweephead[head]
+                        if start then
+                            sweephead[head] = nil
+                        else
+                            start = head
+                        end
+                        while start do
+                            local id = getid(start)
+                            if id ~= glyph_code then
+                                -- very unlikely
+                                start = getnext(start)
+                            elseif getfont(start) == font and getsubtype(start) < 256 then
+                                local a = getattr(start,0)
+                                if a then
+                                    a = (a == attr) and (not attribute or getprop(start,a_state) == attribute)
+                                else
+                                    a = not attribute or getprop(start,a_state) == attribute
+                                end
+                                if a then
+                                    local lookupmatch = lookupcache[getchar(start)]
+                                    if lookupmatch then
+                                        -- sequence kan weg
+                                        local ok
+                                        head, start, ok = handler(head,start,kind,lookupname,lookupmatch,sequence,lookuphash,1)
+                                        if ok then
+                                            done = true
+                                        end
+                                    end
+                                    if start then start = getnext(start) end
+                                else
+                                    start = getnext(start)
+                                end
+                            else
+                                return head, false
+                            end
+                        end
+                        if done then
+                            success = true -- needed in this subrun?
+                        end
+                        return head, done
+                    end
+
+                    local function t_run(start,stop)
+                        while start ~= stop do
+                            local id = getid(start)
+                            if id == glyph_code and getfont(start) == font and getsubtype(start) < 256 then
+                                local a = getattr(start,0)
+                                if a then
+                                    a = (a == attr) and (not attribute or getprop(start,a_state) == attribute)
+                                else
+                                    a = not attribute or getprop(start,a_state) == attribute
+                                end
+                                if a then
+                                    local lookupmatch = lookupcache[getchar(start)]
+                                    if lookupmatch then -- hm, hyphens can match (tlig) so we need to really check
+                                        -- if we need more than ligatures we can outline the code and use functions
+                                        local s = getnext(start)
+                                        local l = nil
+                                        while s do
+                                            local lg = lookupmatch[getchar(s)]
+                                            if lg then
+                                                l = lg
+                                                s = getnext(s)
+                                            else
+                                                break
+                                            end
+                                        end
+                                        if l and l.ligature then
+                                            return true
+                                        end
+                                    end
+                                end
+                                start = getnext(start)
+                            else
+                                break
+                            end
+                        end
+                    end
+
+                    local function d_run(prev) -- we can assume that prev and next are glyphs
+                        local a = getattr(prev,0)
+                        if a then
+                            a = (a == attr) and (not attribute or getprop(prev,a_state) == attribute)
+                        else
+                            a = not attribute or getprop(prev,a_state) == attribute
+                        end
+                        if a then
+                            local lookupmatch = lookupcache[getchar(prev)]
+                            if lookupmatch then
+                                -- sequence kan weg
+                                local h, d, ok = handler(head,prev,kind,lookupname,lookupmatch,sequence,lookuphash,1)
+                                if ok then
+                                    done    = true
+                                    success = true
+                                end
+                            end
+                        end
+                    end
+
+                    local function k_run(sub,injection,last)
+                        local a = getattr(sub,0)
+                        if a then
+                            a = (a == attr) and (not attribute or getprop(sub,a_state) == attribute)
+                        else
+                            a = not attribute or getprop(sub,a_state) == attribute
+                        end
+                        if a then
+                            -- sequence kan weg
+                            for n in traverse_nodes(sub) do -- only gpos
+                                if n == last then
+                                    break
+                                end
+                                local id = getid(n)
+                                if id == glyph_code then
+                                    local lookupmatch = lookupcache[getchar(n)]
+                                    if lookupmatch then
+                                        local h, d, ok = handler(sub,n,kind,lookupname,lookupmatch,sequence,lookuphash,1,injection)
+                                        if ok then
+                                            done    = true
+                                            success = true
+                                        end
+                                    end
+                                else
+                                    -- message
+                                end
+                            end
+                        end
+                    end
+
+                    while start do
+                        local id = getid(start)
+                        if id == glyph_code then
+                            if getfont(start) == font and getsubtype(start) < 256 then -- why a 256 test ...
+                                local a = getattr(start,0)
+                                if a then
+                                    a = (a == attr) and (not attribute or getprop(start,a_state) == attribute)
+                                else
+                                    a = not attribute or getprop(start,a_state) == attribute
+                                end
+                                if a then
+                                    local char        = getchar(start)
+                                    local lookupmatch = lookupcache[char]
+                                    if lookupmatch then
+                                        -- sequence kan weg
+                                        local ok
+                                        head, start, ok = handler(head,start,kind,lookupname,lookupmatch,sequence,lookuphash,1)
+                                        if ok then
+                                            success = true
+                                        elseif gpossing and zwnjruns and char == zwnj then
+                                            discrun(start,d_run)
+                                        end
+                                    elseif gpossing and zwnjruns and char == zwnj then
+                                        discrun(start,d_run)
+                                    end
+                                    if start then start = getnext(start) end
+                                else
+                                   start = getnext(start)
+                                end
+                            else
+                                start = getnext(start)
+                            end
+                        elseif id == disc_code then
+                            if gpossing then
+                                kernrun(start,k_run)
+                                start = getnext(start)
+                            elseif typ == "gsub_ligature" then
+                                start = testrun(start,t_run,c_run)
+                            else
+                                comprun(start,c_run)
+                                start = getnext(start)
+                            end
+                        elseif id == math_code then
+                            start = getnext(end_of_math(start))
+                        elseif id == dir_code then
+                            local dir = getfield(start,"dir")
+                            if dir == "+TLT" then
+                                topstack = topstack + 1
+                                dirstack[topstack] = dir
+                                rlmode = 1
+                            elseif dir == "+TRT" then
+                                topstack = topstack + 1
+                                dirstack[topstack] = dir
+                                rlmode = -1
+                            elseif dir == "-TLT" or dir == "-TRT" then
+                                topstack = topstack - 1
+                                rlmode = dirstack[topstack] == "+TRT" and -1 or 1
+                            else
+                                rlmode = rlparmode
+                            end
+                            if trace_directions then
+                                report_process("directions after txtdir %a: parmode %a, txtmode %a, # stack %a, new dir %a",dir,rlparmode,rlmode,topstack,newdir)
+                            end
+                            start = getnext(start)
+                        elseif id == localpar_code then
+                            local dir = getfield(start,"dir")
+                            if dir == "TRT" then
+                                rlparmode = -1
+                            elseif dir == "TLT" then
+                                rlparmode = 1
+                            else
+                                rlparmode = 0
+                            end
+                            -- one might wonder if the par dir should be looked at, so we might as well drop the next line
+                            rlmode = rlparmode
+                            if trace_directions then
+                                report_process("directions after pardir %a: parmode %a, txtmode %a",dir,rlparmode,rlmode)
+                            end
+                            start = getnext(start)
+                        else
+                            start = getnext(start)
+                        end
+                    end
+                end
+
+            else
+
+                local function c_run(head)
+                    local done  = false
+                    local start = sweephead[head]
+                    if start then
+                        sweephead[head] = nil
+                    else
+                        start = head
+                    end
+                    while start do
+                        local id = getid(start)
+                        if id ~= glyph_code then
+                            -- very unlikely
+                            start = getnext(start)
+                        elseif getfont(start) == font and getsubtype(start) < 256 then
+                            local a = getattr(start,0)
+                            if a then
+                                a = (a == attr) and (not attribute or getprop(start,a_state) == attribute)
+                            else
+                                a = not attribute or getprop(start,a_state) == attribute
+                            end
+                            if a then
+                                local char = getchar(start)
+                                for i=1,ns do
+                                    local lookupname = subtables[i]
+                                    local lookupcache = lookuphash[lookupname]
+                                    if lookupcache then
+                                        local lookupmatch = lookupcache[char]
+                                        if lookupmatch then
+                                            -- we could move all code inline but that makes things even more unreadable
+                                            local ok
+                                            head, start, ok = handler(head,start,kind,lookupname,lookupmatch,sequence,lookuphash,i)
+                                            if ok then
+                                                done = true
+                                                break
+                                            elseif not start then
+                                                -- don't ask why ... shouldn't happen
+                                                break
+                                            end
+                                        end
+                                    else
+                                        report_missing_cache(typ,lookupname)
+                                    end
+                                end
+                                if start then start = getnext(start) end
+                            else
+                                start = getnext(start)
+                            end
+                        else
+                            return head, false
+                        end
+                    end
+                    if done then
+                        success = true
+                    end
+                    return head, done
+                end
+
+                local function d_run(prev)
+                    local a = getattr(prev,0)
+                    if a then
+                        a = (a == attr) and (not attribute or getprop(prev,a_state) == attribute)
+                    else
+                        a = not attribute or getprop(prev,a_state) == attribute
+                    end
+                    if a then
+                        -- brr prev can be disc
+                        local char = getchar(prev)
+                        for i=1,ns do
+                            local lookupname  = subtables[i]
+                            local lookupcache = lookuphash[lookupname]
+                            if lookupcache then
+                                local lookupmatch = lookupcache[char]
+                                if lookupmatch then
+                                    -- we could move all code inline but that makes things even more unreadable
+                                    local h, d, ok = handler(head,prev,kind,lookupname,lookupmatch,sequence,lookuphash,i)
+                                    if ok then
+                                        done = true
+                                        break
+                                    end
+                                end
+                            else
+                                report_missing_cache(typ,lookupname)
+                            end
+                        end
+                    end
+                end
+
+               local function k_run(sub,injection,last)
+                    local a = getattr(sub,0)
+                    if a then
+                        a = (a == attr) and (not attribute or getprop(sub,a_state) == attribute)
+                    else
+                        a = not attribute or getprop(sub,a_state) == attribute
+                    end
+                    if a then
+                        for n in traverse_nodes(sub) do -- only gpos
+                            if n == last then
+                                break
+                            end
+                            local id = getid(n)
+                            if id == glyph_code then
+                                local char = getchar(n)
+                                for i=1,ns do
+                                    local lookupname  = subtables[i]
+                                    local lookupcache = lookuphash[lookupname]
+                                    if lookupcache then
+                                        local lookupmatch = lookupcache[char]
+                                        if lookupmatch then
+                                            local h, d, ok = handler(head,n,kind,lookupname,lookupmatch,sequence,lookuphash,i,injection)
+                                            if ok then
+                                                done = true
+                                                break
+                                            end
+                                        end
+                                    else
+                                        report_missing_cache(typ,lookupname)
+                                    end
+                                end
+                            else
+                                -- message
+                            end
+                        end
+                    end
+                end
+
+                local function t_run(start,stop)
+                    while start ~= stop do
+                        local id = getid(start)
+                        if id == glyph_code and getfont(start) == font and getsubtype(start) < 256 then
+                            local a = getattr(start,0)
+                            if a then
+                                a = (a == attr) and (not attribute or getprop(start,a_state) == attribute)
+                            else
+                                a = not attribute or getprop(start,a_state) == attribute
+                            end
+                            if a then
+                                local char = getchar(start)
+                                for i=1,ns do
+                                    local lookupname  = subtables[i]
+                                    local lookupcache = lookuphash[lookupname]
+                                    if lookupcache then
+                                        local lookupmatch = lookupcache[char]
+                                        if lookupmatch then
+                                            -- if we need more than ligatures we can outline the code and use functions
+                                            local s = getnext(start)
+                                            local l = nil
+                                            while s do
+                                                local lg = lookupmatch[getchar(s)]
+                                                if lg then
+                                                    l = lg
+                                                    s = getnext(s)
+                                                else
+                                                    break
+                                                end
+                                            end
+                                            if l and l.ligature then
+                                                return true
+                                            end
+                                        end
+                                    else
+                                        report_missing_cache(typ,lookupname)
+                                    end
+                                end
+                            end
+                            start = getnext(start)
+                        else
+                            break
+                        end
+                    end
+                end
+
+                while start do
+                    local id = getid(start)
+                    if id == glyph_code then
+                        if getfont(start) == font and getsubtype(start) < 256 then
+                            local a = getattr(start,0)
+                            if a then
+                                a = (a == attr) and (not attribute or getprop(start,a_state) == attribute)
+                            else
+                                a = not attribute or getprop(start,a_state) == attribute
+                            end
+                            if a then
+                                for i=1,ns do
+                                    local lookupname  = subtables[i]
+                                    local lookupcache = lookuphash[lookupname]
+                                    if lookupcache then
+                                        local char = getchar(start)
+                                        local lookupmatch = lookupcache[char]
+                                        if lookupmatch then
+                                            -- we could move all code inline but that makes things even more unreadable
+                                            local ok
+                                            head, start, ok = handler(head,start,kind,lookupname,lookupmatch,sequence,lookuphash,i)
+                                            if ok then
+                                                success = true
+                                                break
+                                            elseif not start then
+                                                -- don't ask why ... shouldn't happen
+                                                break
+                                            elseif gpossing and zwnjruns and char == zwnj then
+                                                discrun(start,d_run)
+                                            end
+                                        elseif gpossing and zwnjruns and char == zwnj then
+                                            discrun(start,d_run)
+                                        end
+                                    else
+                                        report_missing_cache(typ,lookupname)
+                                    end
+                                end
+                                if start then start = getnext(start) end
+                            else
+                                start = getnext(start)
+                            end
+                        else
+                            start = getnext(start)
+                        end
+                    elseif id == disc_code then
+                        if gpossing then
+                            kernrun(start,k_run)
+                            start = getnext(start)
+                        elseif typ == "gsub_ligature" then
+                            start = testrun(start,t_run,c_run)
+                        else
+                            comprun(start,c_run)
+                            start = getnext(start)
+                        end
+                    elseif id == math_code then
+                        start = getnext(end_of_math(start))
+                    elseif id == dir_code then
+                        local dir = getfield(start,"dir")
+                        if dir == "+TLT" then
+                            topstack = topstack + 1
+                            dirstack[topstack] = dir
+                            rlmode = 1
+                        elseif dir == "+TRT" then
+                            topstack = topstack + 1
+                            dirstack[topstack] = dir
+                            rlmode = -1
+                        elseif dir == "-TLT" or dir == "-TRT" then
+                            topstack = topstack - 1
+                            rlmode = dirstack[topstack] == "+TRT" and -1 or 1
+                        else
+                            rlmode = rlparmode
+                        end
+                        if trace_directions then
+                            report_process("directions after txtdir %a: parmode %a, txtmode %a, # stack %a, new dir %a",dir,rlparmode,rlmode,topstack,newdir)
+                        end
+                        start = getnext(start)
+                    elseif id == localpar_code then
+                        local dir = getfield(start,"dir")
+                        if dir == "TRT" then
+                            rlparmode = -1
+                        elseif dir == "TLT" then
+                            rlparmode = 1
+                        else
+                            rlparmode = 0
+                        end
+                        rlmode = rlparmode
+                        if trace_directions then
+                            report_process("directions after pardir %a: parmode %a, txtmode %a",dir,rlparmode,rlmode)
+                        end
+                        start = getnext(start)
+                    else
+                        start = getnext(start)
+                    end
+                end
+            end
+        end
+        if success then
+            done = true
+        end
+        if trace_steps then -- ?
+            registerstep(head)
+        end
+
+    end
+
+    head = tonode(head)
+
+    return head, done
+end
+
+-- this might move to the loader
+
+local function generic(lookupdata,lookupname,unicode,lookuphash)
+    local target = lookuphash[lookupname]
+    if target then
+        target[unicode] = lookupdata
+    else
+        lookuphash[lookupname] = { [unicode] = lookupdata }
+    end
+end
+
+local function ligature(lookupdata,lookupname,unicode,lookuphash)
+    local target = lookuphash[lookupname]
+    if not target then
+        target = { }
+        lookuphash[lookupname] = target
+    end
+    for i=1,#lookupdata do
+        local li = lookupdata[i]
+        local tu = target[li]
+        if not tu then
+            tu = { }
+            target[li] = tu
+        end
+        target = tu
+    end
+    target.ligature = unicode
+end
+
+local function pair(lookupdata,lookupname,unicode,lookuphash)
+    local target = lookuphash[lookupname]
+    if not target then
+        target = { }
+        lookuphash[lookupname] = target
+    end
+    local others = target[unicode]
+    local paired = lookupdata[1]
+    if others then
+        others[paired] = lookupdata
+    else
+        others = { [paired] = lookupdata }
+        target[unicode] = others
+    end
+end
+
+local action = {
+    substitution = generic,
+    multiple     = generic,
+    alternate    = generic,
+    position     = generic,
+    ligature     = ligature,
+    pair         = pair,
+    kern         = pair,
+}
+
+local function prepare_lookups(tfmdata)
+
+    local rawdata          = tfmdata.shared.rawdata
+    local resources        = rawdata.resources
+    local lookuphash       = resources.lookuphash
+    local anchor_to_lookup = resources.anchor_to_lookup
+    local lookup_to_anchor = resources.lookup_to_anchor
+    local lookuptypes      = resources.lookuptypes
+    local characters       = tfmdata.characters
+    local descriptions     = tfmdata.descriptions
+    local duplicates       = resources.duplicates
+
+    -- we cannot free the entries in the descriptions as sometimes we access
+    -- then directly (for instance anchors) ... selectively freeing does save
+    -- much memory as it's only a reference to a table and the slot in the
+    -- description hash is not freed anyway
+
+    -- we can delay this using metatables so that we don't make the hashes for
+    -- features we don't use but then we need to loop over the characters
+    -- many times so we gain nothing
+
+    for unicode, character in next, characters do -- we cannot loop over descriptions !
+
+        local description = descriptions[unicode]
+
+        if description then
+
+            local lookups = description.slookups
+            if lookups then
+                for lookupname, lookupdata in next, lookups do
+                    action[lookuptypes[lookupname]](lookupdata,lookupname,unicode,lookuphash,duplicates)
+                end
+            end
+
+            local lookups = description.mlookups
+            if lookups then
+                for lookupname, lookuplist in next, lookups do
+                    local lookuptype = lookuptypes[lookupname]
+                    for l=1,#lookuplist do
+                        local lookupdata = lookuplist[l]
+                        action[lookuptype](lookupdata,lookupname,unicode,lookuphash,duplicates)
+                    end
+                end
+            end
+
+            local list = description.kerns
+            if list then
+                for lookup, krn in next, list do  -- ref to glyph, saves lookup
+                    local target = lookuphash[lookup]
+                    if target then
+                        target[unicode] = krn
+                    else
+                        lookuphash[lookup] = { [unicode] = krn }
+                    end
+                end
+            end
+
+            local list = description.anchors
+            if list then
+                for typ, anchors in next, list do -- types
+                    if typ == "mark" or typ == "cexit" then -- or entry?
+                        for name, anchor in next, anchors do
+                            local lookups = anchor_to_lookup[name]
+                            if lookups then
+                                for lookup in next, lookups do
+                                    local target = lookuphash[lookup]
+                                    if target then
+                                        target[unicode] = anchors
+                                    else
+                                        lookuphash[lookup] = { [unicode] = anchors }
+                                    end
+                                end
+                            end
+                        end
+                    end
+                end
+            end
+
+        end
+
+    end
+
+end
+
+-- so far
+
+local function split(replacement,original)
+    local result = { }
+    for i=1,#replacement do
+        result[original[i]] = replacement[i]
+    end
+    return result
+end
+
+local valid = { -- does contextpos work?
+    coverage        = { chainsub = true, chainpos = true, contextsub = true, contextpos = true },
+    reversecoverage = { reversesub = true },
+    glyphs          = { chainsub = true, chainpos = true, contextsub = true, contextpos = true },
+}
+
+local function prepare_contextchains(tfmdata)
+    local rawdata    = tfmdata.shared.rawdata
+    local resources  = rawdata.resources
+    local lookuphash = resources.lookuphash
+    local lookuptags = resources.lookuptags
+    local lookups    = rawdata.lookups
+    if lookups then
+        for lookupname, lookupdata in next, rawdata.lookups do
+            local lookuptype = lookupdata.type
+            if lookuptype then
+                local rules = lookupdata.rules
+                if rules then
+                    local format = lookupdata.format
+                    local validformat = valid[format]
+                    if not validformat then
+                        report_prepare("unsupported format %a",format)
+                    elseif not validformat[lookuptype] then
+                        -- todo: dejavu-serif has one (but i need to see what use it has)
+                        report_prepare("unsupported format %a, lookuptype %a, lookupname %a",format,lookuptype,lookuptags[lookupname])
+                    else
+                        local contexts = lookuphash[lookupname]
+                        if not contexts then
+                            contexts = { }
+                            lookuphash[lookupname] = contexts
+                        end
+                        local t, nt = { }, 0
+                        for nofrules=1,#rules do
+                            local rule         = rules[nofrules]
+                            local current      = rule.current
+                            local before       = rule.before
+                            local after        = rule.after
+                            local replacements = rule.replacements
+                            local sequence     = { }
+                            local nofsequences = 0
+                            -- Eventually we can store start, stop and sequence in the cached file
+                            -- but then less sharing takes place so best not do that without a lot
+                            -- of profiling so let's forget about it.
+                            if before then
+                                for n=1,#before do
+                                    nofsequences = nofsequences + 1
+                                    sequence[nofsequences] = before[n]
+                                end
+                            end
+                            local start = nofsequences + 1
+                            for n=1,#current do
+                                nofsequences = nofsequences + 1
+                                sequence[nofsequences] = current[n]
+                            end
+                            local stop = nofsequences
+                            if after then
+                                for n=1,#after do
+                                    nofsequences = nofsequences + 1
+                                    sequence[nofsequences] = after[n]
+                                end
+                            end
+                            if sequence[1] then
+                                -- Replacements only happen with reverse lookups as they are single only. We
+                                -- could pack them into current (replacement value instead of true) and then
+                                -- use sequence[start] instead but it's somewhat ugly.
+                                nt = nt + 1
+                                t[nt] = { nofrules, lookuptype, sequence, start, stop, rule.lookups, replacements }
+                                for unic in next, sequence[start] do
+                                    local cu = contexts[unic]
+                                    if not cu then
+                                        contexts[unic] = t
+                                    end
+                                end
+                            end
+                        end
+                    end
+                else
+                    -- no rules
+                end
+            else
+                report_prepare("missing lookuptype for lookupname %a",lookuptags[lookupname])
+            end
+        end
+    end
+end
+
+-- we can consider lookuphash == false (initialized but empty) vs lookuphash == table
+
+local function featuresinitializer(tfmdata,value)
+    if true then -- value then
+        -- beware we need to use the topmost properties table
+        local rawdata    = tfmdata.shared.rawdata
+        local properties = rawdata.properties
+        if not properties.initialized then
+            local starttime = trace_preparing and os.clock()
+            local resources = rawdata.resources
+            resources.lookuphash = resources.lookuphash or { }
+            prepare_contextchains(tfmdata)
+            prepare_lookups(tfmdata)
+            properties.initialized = true
+            if trace_preparing then
+                report_prepare("preparation time is %0.3f seconds for %a",os.clock()-starttime,tfmdata.properties.fullname)
+            end
+        end
+    end
+end
+
+registerotffeature {
+    name         = "features",
+    description  = "features",
+    default      = true,
+    initializers = {
+        position = 1,
+        node     = featuresinitializer,
+    },
+    processors   = {
+        node     = featuresprocessor,
+    }
+}
+
+-- This can be used for extra handlers, but should be used with care!
+
+otf.handlers = handlers
diff --git a/src/fontloader/misc/fontloader-fonts-def.lua b/src/fontloader/misc/fontloader-fonts-def.lua
index 0c2f0db..f0941ec 100644
--- a/src/fontloader/misc/fontloader-fonts-def.lua
+++ b/src/fontloader/misc/fontloader-fonts-def.lua
@@ -1,4 +1,4 @@
-if not modules then modules = { } end modules ['luatex-font-def'] = {
+if not modules then modules = { } end modules ['luatex-fonts-def'] = {
     version   = 1.001,
     comment   = "companion to luatex-*.tex",
     author    = "Hans Hagen, PRAGMA-ADE, Hasselt NL",
diff --git a/src/fontloader/misc/fontloader-fonts-ota.lua b/src/fontloader/misc/fontloader-fonts-ota.lua
index f083fe0..256ead5 100644
--- a/src/fontloader/misc/fontloader-fonts-ota.lua
+++ b/src/fontloader/misc/fontloader-fonts-ota.lua
@@ -1,4 +1,4 @@
-if not modules then modules = { } end modules ['font-otx'] = {
+if not modules then modules = { } end modules ['luatex-fonts-ota'] = {
     version   = 1.001,
     comment   = "companion to font-otf.lua (analysing)",
     author    = "Hans Hagen, PRAGMA-ADE, Hasselt NL",
@@ -24,7 +24,6 @@ local methods             = allocate()
 
 analyzers.initializers    = initializers
 analyzers.methods         = methods
-analyzers.useunicodemarks = false
 
 local a_state             = attributes.private('state')
 
@@ -98,8 +97,9 @@ local features = {
     pstf = s_pstf,
 }
 
-analyzers.states   = states
-analyzers.features = features
+analyzers.states          = states
+analyzers.features        = features
+analyzers.useunicodemarks = false
 
 -- todo: analyzers per script/lang, cross font, so we need an font id hash -> script
 -- e.g. latin -> hyphenate, arab -> 1/2/3 analyze -- its own namespace
@@ -117,7 +117,10 @@ function analyzers.setstate(head,font)
             local char = getchar(current)
             local d = descriptions[char]
             if d then
-                if d.class == "mark" or (useunicodemarks and categories[char] == "mn") then
+                if d.class == "mark" then
+                    done = true
+                    setprop(current,a_state,s_mark)
+                elseif useunicodemarks and categories[char] == "mn" then
                     done = true
                     setprop(current,a_state,s_mark)
                 elseif n == 0 then
@@ -136,7 +139,9 @@ function analyzers.setstate(head,font)
                 first, last, n = nil, nil, 0
             end
         elseif id == disc_code then
-            -- always in the middle
+            -- always in the middle .. it doesn't make much sense to assign a property
+            -- here ... we might at some point decide to flag the components when present
+            -- but even then it's kind of bogus
             setprop(current,a_state,s_medi)
             last = current
         else -- finish
@@ -213,17 +218,6 @@ registerotffeature {
 
 methods.latn = analyzers.setstate
 
--- This info eventually can go into char-def and we will have a state
--- table for generic then (unicode recognized all states but in practice
--- only has only
---
--- isolated : isol
--- final    : isol_fina
--- medial   : isol_fina_medi_init
---
--- so in practice, without analyzer it's rather useless info which is
--- why having it in char-def makes only sense for special purposes (like)
--- like tracing cq. visualizing.
 
 local tatweel = 0x0640
 local zwnj    = 0x200C
@@ -344,8 +338,6 @@ local medial = { -- isol_fina_medi_init
 
 local arab_warned = { }
 
--- todo: gref
-
 local function warning(current,what)
     local char = getchar(current)
     if not arab_warned[char] then
diff --git a/src/fontloader/misc/fontloader-fonts.lua b/src/fontloader/misc/fontloader-fonts.lua
index f18ba35..2e34fb8 100644
--- a/src/fontloader/misc/fontloader-fonts.lua
+++ b/src/fontloader/misc/fontloader-fonts.lua
@@ -215,9 +215,11 @@ if non_generic_context.luatex_fonts.skip_loading ~= true then
         loadmodule('font-oti.lua')
         loadmodule('font-otf.lua')
         loadmodule('font-otb.lua')
-        loadmodule('luatex-fonts-inj.lua') -- normally the same as font-inj.lua
+        ----------('luatex-fonts-inj.lua') -- normally the same as font-inj.lua / beware loadmodule is parsed
+        loadmodule('font-inj.lua')
         loadmodule('luatex-fonts-ota.lua')
-        loadmodule('luatex-fonts-otn.lua') -- normally the same as font-otn.lua
+        ----------('luatex-fonts-otn.lua') -- normally the same as font-otn.lua / beware loadmodule is parsed
+        loadmodule('font-otn.lua')
         loadmodule('font-otp.lua')
         loadmodule('luatex-fonts-lua.lua')
         loadmodule('font-def.lua')         -- this code (stripped) might end up in luatex-fonts-def.lua
diff --git a/src/fontloader/misc/fontloader-languages.lua b/src/fontloader/misc/fontloader-languages.lua
index 1ea8c1f..cecd60c 100644
--- a/src/fontloader/misc/fontloader-languages.lua
+++ b/src/fontloader/misc/fontloader-languages.lua
@@ -16,28 +16,33 @@ function languages.loadpatterns(tag)
     if not loaded[tag] then
         loaded[tag] = 0
         local filename = kpse.find_file("lang-" .. tag .. ".lua")
-        if filename and filename == "" then
-            print("<unknown language file for: " .. tag .. ">")
+        if not filename or filename == "" then
+            texio.write("<unknown language file for: " .. tag .. ">")
         else
             local whatever = loadfile(filename)
             if type(whatever) == "function" then
                 whatever = whatever()
                 if type(whatever) == "table" then
+                    texio.write("<language file: " .. tag .. ">")
                     local characters = whatever.patterns.characters or ""
                     local patterns = whatever.patterns.data or ""
                     local exceptions = whatever.exceptions.data or ""
-                    local language = lang.new()
                     for b in string.utfvalues(characters) do
+                        -- what about uppercase
+-- lang.sethjcode(b,b)
                         tex.setlccode(b,b)
                     end
+                    local language = lang.new()
                     lang.patterns(language, patterns)
                     lang.hyphenation(language, exceptions)
                     loaded[tag] = lang.id(language)
                 else
-                    print("<invalid language table: " .. tag .. ">")
+                    texio.write("<invalid language table: " .. tag .. ">")
+                    os.exit()
                 end
             else
-                print("<invalid language file: " .. tag .. ">")
+                texio.write("<invalid language file: " .. tag .. ">")
+                os.exit()
             end
         end
     end
diff --git a/src/fontloader/misc/fontloader-languages.tex b/src/fontloader/misc/fontloader-languages.tex
index 9778da3..a087b30 100644
--- a/src/fontloader/misc/fontloader-languages.tex
+++ b/src/fontloader/misc/fontloader-languages.tex
@@ -8,6 +8,8 @@
 
 %D Cf. discussion on \CONTEXT\ list:
 
+% \savinghyphcodes1
+
 \directlua {
     dofile(kpse.find_file("luatex-languages.lua","tex"))
 }