Merge pull request #366 from phi-gamma/master

[fontloader] sync with Context as of 2016-06-16

5 files changed, 253 insertions, 244 deletions

diff --git a/src/fontloader/misc/fontloader-font-dsp.lua b/src/fontloader/misc/fontloader-font-dsp.lua
index a1ae17f..1e8b3bd 100644
--- a/src/fontloader/misc/fontloader-font-dsp.lua
+++ b/src/fontloader/misc/fontloader-font-dsp.lua
@@ -365,6 +365,26 @@ end
 -- We generalize the chained lookups so that we can do with only one handler
 -- when processing them.
 
+local function readlookuparray(f,noflookups)
+    local lookups = { }
+    if noflookups > 0 then
+        local length = 0
+        for i=1,noflookups do
+            local index = readushort(f) + 1
+            if index > length then
+                length = index
+            end
+            lookups[index] = readushort(f) + 1
+        end
+        for index=1,length do
+            if not lookups[index] then
+                lookups[index] = false
+            end
+        end
+    end
+    return lookups
+end
+
 local function unchainedcontext(f,fontdata,lookupid,lookupoffset,offset,glyphs,nofglyphs,what)
     local tableoffset = lookupoffset + offset
     setposition(f,tableoffset)
@@ -389,10 +409,7 @@ local function unchainedcontext(f,fontdata,lookupid,lookupoffset,offset,glyphs,n
                         for i=2,nofcurrent do
                             current[i] = { readushort(f) }
                         end
-                        local lookups = { }
-                        for i=1,noflookups do
-                            lookups[readushort(f)+1] = readushort(f) + 1
-                        end
+                        local lookups = readlookuparray(f,noflookups)
                         rules[#rules+1] = {
                             current = current,
                             lookups = lookups
@@ -435,10 +452,7 @@ local function unchainedcontext(f,fontdata,lookupid,lookupoffset,offset,glyphs,n
                                 for i=2,nofcurrent do
                                     current[i] = currentclasses[readushort(f) + 1]
                                 end
-                                local lookups = { }
-                                for i=1,noflookups do
-                                    lookups[readushort(f)+1] = readushort(f) + 1
-                                end
+                                local lookups = readlookuparray(f,noflookups)
                                 rules[#rules+1] = {
                                     current = current,
                                     lookups = lookups
@@ -462,10 +476,7 @@ local function unchainedcontext(f,fontdata,lookupid,lookupoffset,offset,glyphs,n
     elseif subtype == 3 then
         local current    = readarray(f)
         local noflookups = readushort(f)
-        local lookups    = { }
-        for i=1,noflookups do
-            lookups[readushort(f)+1] = readushort(f) + 1
-        end
+        local lookups    = readlookuparray(f,noflookups)
         current = readcoveragearray(f,tableoffset,current,true)
         return {
             format = "coverage",
@@ -525,10 +536,7 @@ local function chainedcontext(f,fontdata,lookupid,lookupoffset,offset,glyphs,nof
                             end
                         end
                         local noflookups = readushort(f)
-                        local lookups    = { }
-                        for i=1,noflookups do
-                            lookups[readushort(f)+1] = readushort(f) + 1
-                        end
+                        local lookups    = readlookuparray(f,noflookups)
                         rules[#rules+1] = {
                             before  = before,
                             current = current,
@@ -596,10 +604,7 @@ local function chainedcontext(f,fontdata,lookupid,lookupoffset,offset,glyphs,nof
                                 end
                                 -- no sequence index here (so why in context as it saves nothing)
                                 local noflookups = readushort(f)
-                                local lookups    = { }
-                                for i=1,noflookups do
-                                    lookups[readushort(f)+1] = readushort(f) + 1
-                                end
+                                local lookups    = readlookuparray(f,noflookups)
                                 rules[#rules+1] = {
                                     before  = before,
                                     current = current,
@@ -627,10 +632,7 @@ local function chainedcontext(f,fontdata,lookupid,lookupoffset,offset,glyphs,nof
         local current    = readarray(f)
         local after      = readarray(f)
         local noflookups = readushort(f)
-        local lookups    = { }
-        for i=1,noflookups do
-            lookups[readushort(f)+1] = readushort(f) + 1
-        end
+        local lookups    = readlookuparray(f,noflookups)
         before  = readcoveragearray(f,tableoffset,before,true)
         current = readcoveragearray(f,tableoffset,current,true)
         after   = readcoveragearray(f,tableoffset,after,true)
@@ -1626,45 +1628,58 @@ do
                             report_issue(i,what,sequence,"empty")
                             rule.lookups = nil
                         else
-                            for index, lookupid in sortedhash(rlookups) do -- nicer
-                                local h = sublookuphash[lookupid]
-                                if not h then
-                                    -- here we have a lookup that is used independent as well
-                                    -- as in another one
-                                    local lookup = lookups[lookupid]
-                                    if lookup then
-                                        local d = lookup.done
-                                        if d then
-                                            nofsublookups = nofsublookups + 1
-                                         -- report("registering %i as sublookup %i",lookupid,nofsublookups)
-                                            h = {
-                                                index     = nofsublookups, -- handy for tracing
-                                                name      = f_lookupname(lookupprefix,"d",lookupid+lookupidoffset),
-                                                derived   = true,          -- handy for tracing
-                                                steps     = d.steps,
-                                                nofsteps  = d.nofsteps,
-                                                type      = d.lookuptype,
-                                                markclass = d.markclass or nil,
-                                                flags     = d.flags,
-                                             -- chain     = d.chain,
-                                            }
-                                            sublookuplist[nofsublookups] = h
-                                            sublookuphash[lookupid] = nofsublookups
-                                            sublookupcheck[lookupid] = 1
+                            -- we can have holes in rlookups
+                         -- for index, lookupid in sortedhash(rlookups) do
+                            local length = #rlookups
+--                             for index in next, rlookups do
+--                                 if index > length then
+--                                     length = index
+--                                 end
+--                             end
+                            for index=1,length do
+                                local lookupid = rlookups[index]
+                                if lookupid then
+                                    local h = sublookuphash[lookupid]
+                                    if not h then
+                                        -- here we have a lookup that is used independent as well
+                                        -- as in another one
+                                        local lookup = lookups[lookupid]
+                                        if lookup then
+                                            local d = lookup.done
+                                            if d then
+                                                nofsublookups = nofsublookups + 1
+                                             -- report("registering %i as sublookup %i",lookupid,nofsublookups)
+                                                h = {
+                                                    index     = nofsublookups, -- handy for tracing
+                                                    name      = f_lookupname(lookupprefix,"d",lookupid+lookupidoffset),
+                                                    derived   = true,          -- handy for tracing
+                                                    steps     = d.steps,
+                                                    nofsteps  = d.nofsteps,
+                                                    type      = d.lookuptype,
+                                                    markclass = d.markclass or nil,
+                                                    flags     = d.flags,
+                                                 -- chain     = d.chain,
+                                                }
+                                                sublookuplist[nofsublookups] = h
+                                                sublookuphash[lookupid] = nofsublookups
+                                                sublookupcheck[lookupid] = 1
+                                            else
+                                                report_issue(i,what,sequence,"missing")
+                                                rule.lookups = nil
+                                                break
+                                            end
                                         else
-                                            report_issue(i,what,sequence,"missing")
+                                            report_issue(i,what,sequence,"bad")
                                             rule.lookups = nil
                                             break
                                         end
                                     else
-                                        report_issue(i,what,sequence,"bad")
-                                        rule.lookups = nil
-                                        break
+                                        sublookupcheck[lookupid] = sublookupcheck[lookupid] + 1
                                     end
+                                    rlookups[index] = h or false
                                 else
-                                    sublookupcheck[lookupid] = sublookupcheck[lookupid] + 1
+                                    rlookups[index] = false
                                 end
-                                rlookups[index] = h
                             end
                         end
                     end
diff --git a/src/fontloader/misc/fontloader-font-ocl.lua b/src/fontloader/misc/fontloader-font-ocl.lua
index 9661083..b2aba7a 100644
--- a/src/fontloader/misc/fontloader-font-ocl.lua
+++ b/src/fontloader/misc/fontloader-font-ocl.lua
@@ -8,6 +8,8 @@ if not modules then modules = { } end modules ['font-ocl'] = {
 
 -- todo : user list of colors
 
+local tostring, next = tostring, next
+
 local formatters = string.formatters
 
 local otf = fonts.handlers.otf
@@ -168,31 +170,81 @@ if context and xml.convert then
 
     local report_svg = logs.reporter("fonts","svg conversion")
 
+    local xmlconvert = xml.convert
+    local xmlfirst   = xml.first
+    local loaddata   = io.loaddata
+    local savedata   = io.savedata
+    local remove     = os.remove
+
+ -- function otfsvg.topdf(svgshapes)
+ --     local svgfile   = "temp-otf-svg-shape.svg"
+ --     local pdffile   = "temp-otf-svg-shape.pdf"
+ --     local command   = "inkscape " .. svgfile .. " --export-pdf=" .. pdffile
+ --     local testrun   = false
+ --     local pdfshapes = { }
+ --     local nofshapes = #svgshapes
+ --     report_svg("processing %i svg containers",nofshapes)
+ --     statistics.starttiming()
+ --     for i=1,nofshapes do
+ --         local entry = svgshapes[i]
+ --         for j=entry.first,entry.last do
+ --             local svg  = xmlconvert(entry.data)
+ --             local data = xmlfirst(svg,"/svg[@id='glyph"..j.."']")
+ --             savedata(svgfile,tostring(data))
+ --             report_svg("processing svg shape of glyph %i in container %i",j,i)
+ --             os.execute(command)
+ --             pdfshapes[j] = loaddata(pdffile)
+ --         end
+ --         if testrun and i > testrun then
+ --             report_svg("quiting test run")
+ --             break
+ --         end
+ --     end
+ --     remove(svgfile)
+ --     statistics.stoptiming()
+ --     report_svg("conversion time: %0.3f",statistics.elapsedtime())
+ --     return pdfshapes
+ -- end
+
     function otfsvg.topdf(svgshapes)
-        local svgfile   = "temp-otf-svg-shape.svg"
-        local pdffile   = "temp-otf-svg-shape.pdf"
-        local command   = "inkscape " .. svgfile .. " --export-pdf=" .. pdffile
-     -- local command   = [[python "c:\Users\Hans Hagen\AppData\Roaming\Python\Scripts\cairosvg" -f pdf ]] .. svgfile .. " -o " .. pdffile
-        local testrun   = false
+        local inkscape  = io.popen("inkscape --shell 2>&1","w")
         local pdfshapes = { }
         local nofshapes = #svgshapes
+        local f_svgfile = formatters["temp-otf-svg-shape-%i.svg"]
+        local f_pdffile = formatters["temp-otf-svg-shape-%i.pdf"]
+        local f_convert = formatters["%s --export-pdf=%s\n"]
         report_svg("processing %i svg containers",nofshapes)
+        statistics.starttiming()
         for i=1,nofshapes do
             local entry = svgshapes[i]
             for j=entry.first,entry.last do
-                local svg  = xml.convert(entry.data)
-                local data = xml.first(svg,"/svg[@id='glyph"..j.."']")
-                io.savedata(svgfile,tostring(data))
-                report_svg("processing svg shape of glyph %i in container %i",j,i)
-                os.execute(command)
-                pdfshapes[j] = io.loaddata(pdffile)
-            end
-            if testrun and i > testrun then
-                report_svg("quiting test run")
-                break
+                local svg  = xmlconvert(entry.data)
+                local root = svg and xmlfirst(svg,"/svg[@id='glyph"..j.."']")
+                local data = root and tostring(root)
+                if data and data ~= "" then
+                    local svgfile = f_svgfile(j)
+                    local pdffile = f_pdffile(j)
+                    savedata(svgfile,data)
+                    inkscape:write(f_convert(svgfile,pdffile))
+                    pdfshapes[j] = true
+                end
             end
         end
-        os.remove(svgfile)
+        inkscape:write("quit\n")
+     -- while inkscape:read("*a") do
+     --     os.sleep(0.1)
+     -- end
+        inkscape:close()
+        report_svg("processing %i pdf results",nofshapes)
+        for i in next, pdfshapes do
+            local svgfile = f_svgfile(i)
+            local pdffile = f_pdffile(i)
+            pdfshapes[i] = loaddata(pdffile)
+            remove(svgfile)
+            remove(pdffile)
+        end
+        statistics.stoptiming()
+        report_svg("conversion time: %0.3f",statistics.elapsedtime())
         return pdfshapes
     end
 
diff --git a/src/fontloader/misc/fontloader-font-otl.lua b/src/fontloader/misc/fontloader-font-otl.lua
index c7c278a..59d868b 100644
--- a/src/fontloader/misc/fontloader-font-otl.lua
+++ b/src/fontloader/misc/fontloader-font-otl.lua
@@ -53,7 +53,7 @@ local report_otf         = logs.reporter("fonts","otf loading")
 local fonts              = fonts
 local otf                = fonts.handlers.otf
 
-otf.version              = 3.022 -- beware: also sync font-mis.lua and in mtx-fonts
+otf.version              = 3.023 -- beware: also sync font-mis.lua and in mtx-fonts
 otf.cache                = containers.define("fonts", "otl", otf.version, true)
 otf.svgcache             = containers.define("fonts", "svg", otf.version, true)
 otf.pdfcache             = containers.define("fonts", "pdf", otf.version, true)
@@ -747,7 +747,7 @@ end
 otf.getgsub = getgsub -- returns value, gsub_kind
 
 function otf.getsubstitution(tfmdata,k,kind,value)
-    local found, kind = getgsub(tfmdata,k,kind)
+    local found, kind = getgsub(tfmdata,k,kind,value)
     if not found then
         --
     elseif kind == "gsub_single" then
diff --git a/src/fontloader/misc/fontloader-font-ots.lua b/src/fontloader/misc/fontloader-font-ots.lua
index 51704bf..d63d524 100644
--- a/src/fontloader/misc/fontloader-font-ots.lua
+++ b/src/fontloader/misc/fontloader-font-ots.lua
@@ -192,6 +192,7 @@ 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 remove_node        = nuts.remove
 
 local setmetatableindex  = table.setmetatableindex
 
@@ -1236,7 +1237,7 @@ function chainprocs.gsub_multiple(head,start,stop,dataset,sequence,currentlookup
         if trace_multiples then
             logprocess("%s: replacing %s by multiple characters %s",cref(dataset,sequence),gref(startchar),gref(replacement))
         end
-        return multiple_glyphs(head,start,replacement,currentlookup.flags[1]) -- not sequence.flags?
+        return multiple_glyphs(head,start,replacement,sequence.flags[1])
     end
     return head, start, false
 end
@@ -2033,67 +2034,6 @@ local function chaindisk(head,start,last,dataset,sequence,chainlookup,rlmode,k,c
     return head, start, ok
 end
 
--- helpers from elsewhere
-
--- local function currentmatch(current,n,l)
---     while current do
---         if getid(current) ~= glyph_code then
---             return false
---         elseif seq[n][getchar(current)] then
---             n = n + 1
---             current = getnext(current)
---             if not current then
---                 return true, n, current
---             elseif n > l then
---              -- match = false
---                 return true, n, current
---             end
---         else
---             return false
---         end
---     end
--- end
---
--- local function aftermatch(current,n,l)
---     while current do
---         if getid(current) ~= glyph_code then
---             return false
---         elseif seq[n][getchar(current)] then
---             n = n + 1
---             current = getnext(current)
---             if not current then
---                 return true, n, current
---             elseif n > l then
---              -- match = false
---                 return true, n, current
---             end
---         else
---             return false
---         end
---     end
--- end
---
--- local function beforematch(current,n)
---     local finish  = getprev(current)
---     local current = find_node_tail(current)
---     while current do
---         if getid(current) ~= glyph_code then
---             return false
---         elseif seq[n][getchar(current)] then
---             n = n - 1
---             current = getprev(current)
---             if not current or current == finish then
---                 return true, n, current
---             elseif n < 1 then
---              -- match = false
---                 return true, n, current
---             end
---         else
---             return false
---         end
---     end
--- end
-
 local noflags = { false, false, false, false }
 
 local function handle_contextchain(head,start,dataset,sequence,contexts,rlmode)
@@ -2116,9 +2056,10 @@ local function handle_contextchain(head,start,dataset,sequence,contexts,rlmode)
         local ck      = contexts[k]
         local seq     = ck[3]
         local s       = #seq
+        local size    = 1
         -- f..l = mid string
         if s == 1 then
-            -- never happens
+            -- this seldom happens as it makes no sense (bril, ebgaramond, husayni, minion)
             local char = ischar(current,currentfont)
             if char then
                 match = seq[1][char]
@@ -2129,48 +2070,34 @@ local function handle_contextchain(head,start,dataset,sequence,contexts,rlmode)
             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) -- the second in current (first already matched)
-                    while n <= l do
-                        if not last and (sweeptype == "post" or sweeptype == "replace") then
-                            last      = getnext(sweepnode)
-                            sweeptype = nil
-                        end
-                        if last then
-                            local char, id = ischar(last,currentfont)
-                            if char then
-                                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(dataset,sequence,char,ck,class)
-                                        end
+            size = l - f + 1
+            if size > 1 then
+                -- before/current/after | before/current | current/after
+                local discfound = nil
+                local n = f + 1
+                last = getnext(last) -- the second in current (first already matched)
+                while n <= l do
+                    if not last and (sweeptype == "post" or sweeptype == "replace") then
+                        last      = getnext(sweepnode)
+                        sweeptype = nil
+                    end
+                    if last then
+                        local char, id = ischar(last,currentfont)
+                        if char then
+                            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(dataset,sequence,char,ck,class)
+                                    end
+                                    last = getnext(last)
+                                elseif seq[n][char] then
+                                    if n < l then
                                         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
+                                    n = n + 1
                                 else
                                     if discfound then
                                         notmatchreplace[discfound] = true
@@ -2180,7 +2107,7 @@ local function handle_contextchain(head,start,dataset,sequence,contexts,rlmode)
                                     end
                                     break
                                 end
-                            elseif char == false then
+                            else
                                 if discfound then
                                     notmatchreplace[discfound] = true
                                     match = not notmatchpre[discfound]
@@ -2188,60 +2115,68 @@ local function handle_contextchain(head,start,dataset,sequence,contexts,rlmode)
                                     match = false
                                 end
                                 break
-                            elseif id == disc_code then
-                                diskseen              = true
-                                discfound             = last
-                                notmatchpre[last]     = nil
-                                notmatchpost[last]    = true
-                                notmatchreplace[last] = nil
-                                local pre, post, replace = getdisc(last)
-                                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
+                            end
+                        elseif char == false then
+                            if discfound then
+                                notmatchreplace[discfound] = true
+                                match = not notmatchpre[discfound]
+                            else
+                                match = false
+                            end
+                            break
+                        elseif id == disc_code then
+                            diskseen              = true
+                            discfound             = last
+                            notmatchpre[last]     = nil
+                            notmatchpost[last]    = true
+                            notmatchreplace[last] = nil
+                            local pre, post, replace = getdisc(last)
+                            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
-                                    end
-                                    if n <= l then
+                                    else
                                         notmatchpre[last] = true
+                                        break
                                     end
-                                else
+                                end
+                                if n <= l then
                                     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]
+                            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
-                                    match = not notmatchpre[last]
                                 end
-                                -- maybe only if match
-                                last = getnext(last)
-                            else
-                                match = false
-                                break
+                                match = not notmatchpre[last]
                             end
+                            -- maybe only if match
+                            last = getnext(last)
                         else
                             match = false
                             break
                         end
+                    else
+                        match = false
+                        break
                     end
                 end
             end
@@ -2509,7 +2444,7 @@ local function handle_contextchain(head,start,dataset,sequence,contexts,rlmode)
             end
         end
         if match then
-            -- can lookups be of a different type ?
+            -- Can lookups be of a different type?
             local diskchain = diskseen or sweepnode
             if trace_contexts then
                 local rule       = ck[1]
@@ -2523,8 +2458,12 @@ local function handle_contextchain(head,start,dataset,sequence,contexts,rlmode)
             local chainlookups = ck[6]
             if chainlookups then
                 local nofchainlookups = #chainlookups
-                -- we can speed this up if needed
-                if nofchainlookups == 1 then
+                -- Lookups can be like { 1, false, 3 } or { false, 2 } or basically anything and
+                -- #lookups can be less than #current
+                if size == 1 then
+                 -- if nofchainlookups > size then
+                 --     -- bad rules
+                 -- end
                     local chainlookup = chainlookups[1]
                     local chainkind   = chainlookup.type
                     local chainproc   = chainprocs[chainkind]
@@ -2542,8 +2481,16 @@ local function handle_contextchain(head,start,dataset,sequence,contexts,rlmode)
                         logprocess("%s: %s is not yet supported (1)",cref(dataset,sequence),chainkind)
                     end
                  else
+                    -- See LookupType 5: Contextual Substitution Subtable. Now it becomes messy. The
+                    -- easiest case is where #current maps on #lookups i.e. one-to-one. But what if
+                    -- we have a ligature. Cf the spec we then need to advance one character 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
+                    --
                     local i = 1
-                    while start and true do
+                    while start do
                         if skipped then
                             while start do -- todo: use properties
                                 local char = getchar(start)
@@ -2560,12 +2507,8 @@ local function handle_contextchain(head,start,dataset,sequence,contexts,rlmode)
                                 end
                             end
                         end
-                        -- see remark in ms standard under : LookupType 5: Contextual Substitution Subtable
-                        local chainlookup = chainlookups[1] -- should be i when they can be different
-                        if not chainlookup then
-                            -- we just advance
-                            i = i + 1 -- shouldn't that be #current
-                        else
+                        local chainlookup = chainlookups[i]
+                        if chainlookup then
                             local chainkind = chainlookup.type
                             local chainproc = chainprocs[chainkind]
                             if chainproc then
@@ -2578,29 +2521,18 @@ local function handle_contextchain(head,start,dataset,sequence,contexts,rlmode)
                                 -- 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(dataset,sequence))
-                                         -- end
-                                            break
-                                        else
-                                            -- we need to carry one
-                                        end
+                                    if n and n > 1 and i + n > nofchainlookups then
+                                        -- this is a safeguard, we just ignore the rest of the lookups
+                                        break
                                     end
                                 end
                             else
                                 -- actually an error
                                 logprocess("%s: %s is not yet supported (2)",cref(dataset,sequence),chainkind)
                             end
-                            i = i + 1
                         end
-                        if i > nofchainlookups or not start then
+                        i = i + 1
+                        if i > size or not start then
                             break
                         elseif start then
                             start = getnext(start)
@@ -2608,6 +2540,7 @@ local function handle_contextchain(head,start,dataset,sequence,contexts,rlmode)
                     end
                 end
             else
+                -- todo: needs checking for holes in the replacements
                 local replacements = ck[7]
                 if replacements then
                     head, start, done = reversesub(head,start,last,dataset,sequence,replacements,rlmode)
diff --git a/src/fontloader/misc/fontloader-font-oup.lua b/src/fontloader/misc/fontloader-font-oup.lua
index e2d209a..571c69f 100644
--- a/src/fontloader/misc/fontloader-font-oup.lua
+++ b/src/fontloader/misc/fontloader-font-oup.lua
@@ -1302,7 +1302,8 @@ function readers.pack(data)
                                     local r = rule.before       if r then for i=1,#r do r[i] = pack_boolean(r[i]) end end
                                     local r = rule.after        if r then for i=1,#r do r[i] = pack_boolean(r[i]) end end
                                     local r = rule.current      if r then for i=1,#r do r[i] = pack_boolean(r[i]) end end
-                                    local r = rule.replacements if r then rule.replacements  = pack_flat   (r)    end -- can have holes
+                                    local r = rule.lookups      if r then rule.lookups       = pack_mixed  (r)    end
+                                    local r = rule.replacements if r then rule.replacements  = pack_flat   (r)    end
                                 end
                             end
                         end
@@ -1703,9 +1704,16 @@ function readers.unpack(data)
                                             end
                                         end
                                     end
+                                    local lookups = rule.lookups
+                                    if lookups then
+                                        local tv = tables[lookups]
+                                        if tv then
+                                            rule.lookups = tv
+                                        end
+                                    end
                                     local replacements = rule.replacements
                                     if replacements then
-                                        local tv = tables[replace]
+                                        local tv = tables[replacements]
                                         if tv then
                                             rule.replacements = tv
                                         end
@@ -2171,6 +2179,7 @@ function readers.expand(data)
                                 local lookups = rule.lookups or false
                                 local subtype = nil
                                 if lookups then
+                                    -- is now indexed
                                     for k, v in next, lookups do
                                         local lookup = sublookups[v]
                                         if lookup then