if not modules then modules = { } end modules ['node-acc'] = {
    version   = 1.001,
    comment   = "companion to node-ini.mkiv",
    author    = "Hans Hagen, PRAGMA-ADE, Hasselt NL",
    copyright = "PRAGMA ADE / ConTeXt Development Team",
    license   = "see context related readme files"
}

local nodes, node = nodes, node

local nodecodes      = nodes.nodecodes
local tasks          = nodes.tasks

local nuts           = nodes.nuts
local tonut          = nodes.tonut
local tonode         = nodes.tonode

local getid          = nuts.getid
local getfield       = nuts.getfield
local getattr        = nuts.getattr
local getlist        = nuts.getlist
local getchar        = nuts.getchar
local getnext        = nuts.getnext

local setfield       = nuts.setfield
local setattr        = nuts.setattr

local traverse_nodes = nuts.traverse
local traverse_id    = nuts.traverse_id
local copy_node      = nuts.copy
local free_nodelist  = nuts.flush_list
local insert_after   = nuts.insert_after

local new_gluespec   = nuts.pool.gluespec -- temp hack

local glue_code      = nodecodes.glue
local kern_code      = nodecodes.kern
local glyph_code     = nodecodes.glyph
local hlist_code     = nodecodes.hlist
local vlist_code     = nodecodes.vlist

local a_characters   = attributes.private("characters")

local threshold      = 65536 -- not used
local nofreplaced    = 0

-- todo: nbsp etc
-- todo: collapse kerns

-- p_id

local function injectspaces(head)
    local p, p_id
    local n = head
    while n do
        local id = getid(n)
        if id == glue_code then -- todo: check for subtype related to spacing (13/14 but most seems to be 0)
       -- if getfield(getfield(n,"spec"),"width") > 0 then -- threshold
--          if p and p_id == glyph_code then
            if p and getid(p) == glyph_code then
                local g = copy_node(p)
                local c = getfield(g,"components")
                if c then -- it happens that we copied a ligature
                    free_nodelist(c)
                    setfield(g,"components",nil)
                    setfield(g,"subtype",256)
                end
                local a = getattr(n,a_characters)
                -- local s = copy_node(getfield(n,"spec"))
                -- this will be fixed in luatex but for now a temp hack (zero test)
                local s = getfield(n,"spec")
                s = s == 0 and new_gluespec(0) or copy_node(s)
                --
                setfield(g,"char",32)
                setfield(n,"spec",s)
             -- insert_after(p,p,g)
                setfield(p,"next",g)
                setfield(g,"prev",p)
                setfield(g,"next",n)
                setfield(n,"prev",g)
                setfield(s,"width",getfield(s,"width") - getfield(g,"width"))
                if a then
                    setattr(g,a_characters,a)
                end
                setattr(s,a_characters,0)
                setattr(n,a_characters,0)
                nofreplaced = nofreplaced + 1
            end
       -- end
        elseif id == hlist_code or id == vlist_code then
            injectspaces(getlist(n),attribute)
     -- elseif id == kern_code then -- the backend already collapses
     --     local first = n
     --     while true do
     --         local nn = getnext(n)
     --         if nn and getid(nn) == kern_code then
     --          -- maybe we should delete kerns but who cares at this stage
     --             setfield(first,"kern",getfield(first,"kern") + getfield(nn,"kern")
     --             setfield(nn,"kern",0)
     --             n = nn
     --         else
     --             break
     --         end
     --     end
        end
        p_id = id
        p = n
        n = getnext(n)
    end
    return head, true -- always done anyway
end

nodes.handlers.accessibility = function(head)
    local head, done = injectspaces(tonut(head))
    return tonode(head), done
end

statistics.register("inserted spaces in output",function()
    if nofreplaced > 0 then
        return nofreplaced
    end
end)

-- todo:

-- local a_hyphenated = attributes.private('hyphenated')
--
-- local hyphenated, codes = { }, { }
--
-- local function compact(n)
--     local t = { }
--     for n in traverse_id(glyph_code,n) do
--         t[#t+1] = utfchar(getchar(n)) -- check for unicode
--     end
--     return concat(t,"")
-- end
--
-- local function injectspans(head)
--     local done = false
--     for n in traverse_nodes(tonuts(head)) do
--         local id = getid(n)
--         if id == disc then
--             local r = getfield(n,"replace")
--             local p = getfield(n,"pre")
--             if r and p then
--                 local str = compact(r)
--                 local hsh = hyphenated[str]
--                 if not hsh then
--                     hsh = #codes + 1
--                     hyphenated[str] = hsh
--                     codes[hsh] = str
--                 end
--                 setattr(n,a_hyphenated,hsh)
--                 done = true
--             end
--         elseif id == hlist_code or id == vlist_code then
--             injectspans(getlist(n))
--         end
--     end
--     return tonodes(head), done
-- end
--
-- nodes.injectspans = injectspans
--
-- tasks.appendaction("processors", "words", "nodes.injectspans")
--
-- local function injectspans(head)
--     local done = false
--     for n in traverse_nodes(tonut(head)) do
--         local id = getid(n)
--         if id == disc then
--             local a = getattr(n,a_hyphenated)
--             if a then
--                 local str = codes[a]
--                 local b = new_pdfliteral(format("/Span << /ActualText %s >> BDC", lpdf.tosixteen(str)))
--                 local e = new_pdfliteral("EMC")
--                 insert_before(head,n,b)
--                 insert_after(head,n,e)
--                 done = true
--             end
--         elseif id == hlist_code or id == vlist_code then
--             injectspans(getlist(n))
--         end
--     end
--     return tonodes(head), done
-- end