if not modules then modules = { } end modules ['font-con'] = {
    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"
}

-- some names of table entries will be changed (no _)

local next, tostring, rawget = next, tostring, rawget
local format, match, lower, gsub = string.format, string.match, string.lower, string.gsub
local utfbyte = utf.byte
local sort, insert, concat, sortedkeys, serialize, fastcopy = table.sort, table.insert, table.concat, table.sortedkeys, table.serialize, table.fastcopy
local derivetable = table.derive

local trace_defining = false  trackers.register("fonts.defining", function(v) trace_defining = v end)
local trace_scaling  = false  trackers.register("fonts.scaling" , function(v) trace_scaling  = v end)

local report_defining = logs.reporter("fonts","defining")

-- watch out: no negative depths and negative eights permitted in regular fonts

--[[ldx--
<p>Here we only implement a few helper functions.</p>
--ldx]]--

local fonts                  = fonts
local constructors           = fonts.constructors or { }
fonts.constructors           = constructors
local handlers               = fonts.handlers or { } -- can have preloaded tables
fonts.handlers               = handlers

local allocate               = utilities.storage.allocate
local setmetatableindex      = table.setmetatableindex

-- will be directives

constructors.dontembed       = allocate()
constructors.autocleanup     = true
constructors.namemode        = "fullpath" -- will be a function

constructors.version         = 1.01
constructors.cache           = containers.define("fonts", "constructors", constructors.version, false)

constructors.privateoffset   = 0xF0000 -- 0x10FFFF

-- Some experimental helpers (handy for tracing):
--
-- todo: extra:
--
-- extra_space       => space.extra
-- space             => space.width
-- space_stretch     => space.stretch
-- space_shrink      => space.shrink

-- We do keep the x-height, extra_space, space_shrink and space_stretch
-- around as these are low level official names.

constructors.keys = {
    properties = {
        encodingbytes          = "number",
        embedding              = "number",
        cidinfo                = {
                                 },
        format                 = "string",
        fontname               = "string",
        fullname               = "string",
        filename               = "filename",
        psname                 = "string",
        name                   = "string",
        virtualized            = "boolean",
        hasitalics             = "boolean",
        autoitalicamount       = "basepoints",
        nostackmath            = "boolean",
        noglyphnames           = "boolean",
        mode                   = "string",
        hasmath                = "boolean",
        mathitalics            = "boolean",
        textitalics            = "boolean",
        finalized              = "boolean",
    },
    parameters = {
        mathsize               = "number",
        scriptpercentage       = "float",
        scriptscriptpercentage = "float",
        units                  = "cardinal",
        designsize             = "scaledpoints",
        expansion              = {
                                    stretch = "integerscale", -- might become float
                                    shrink  = "integerscale", -- might become float
                                    step    = "integerscale", -- might become float
                                    auto    = "boolean",
                                 },
        protrusion             = {
                                    auto    = "boolean",
                                 },
        slantfactor            = "float",
        extendfactor           = "float",
        factor                 = "float",
        hfactor                = "float",
        vfactor                = "float",
        size                   = "scaledpoints",
        units                  = "scaledpoints",
        scaledpoints           = "scaledpoints",
        slantperpoint          = "scaledpoints",
        spacing                = {
                                    width   = "scaledpoints",
                                    stretch = "scaledpoints",
                                    shrink  = "scaledpoints",
                                    extra   = "scaledpoints",
                                 },
        xheight                = "scaledpoints",
        quad                   = "scaledpoints",
        ascender               = "scaledpoints",
        descender              = "scaledpoints",
        synonyms               = {
                                    space         = "spacing.width",
                                    spacestretch  = "spacing.stretch",
                                    spaceshrink   = "spacing.shrink",
                                    extraspace    = "spacing.extra",
                                    x_height      = "xheight",
                                    space_stretch = "spacing.stretch",
                                    space_shrink  = "spacing.shrink",
                                    extra_space   = "spacing.extra",
                                    em            = "quad",
                                    ex            = "xheight",
                                    slant         = "slantperpoint",
                                  },
    },
    description = {
        width                  = "basepoints",
        height                 = "basepoints",
        depth                  = "basepoints",
        boundingbox            = { },
    },
    character = {
        width                  = "scaledpoints",
        height                 = "scaledpoints",
        depth                  = "scaledpoints",
        italic                 = "scaledpoints",
    },
}

-- This might become an interface:

local designsizes           = allocate()
constructors.designsizes    = designsizes
local loadedfonts           = allocate()
constructors.loadedfonts    = loadedfonts

--[[ldx--
<p>We need to normalize the scale factor (in scaled points). This has to
do with the fact that <l n='tex'/> uses a negative multiple of 1000 as
a signal for a font scaled based on the design size.</p>
--ldx]]--

local factors = {
    pt = 65536.0,
    bp = 65781.8,
}

function constructors.setfactor(f)
    constructors.factor = factors[f or 'pt'] or factors.pt
end

constructors.setfactor()

function constructors.scaled(scaledpoints, designsize) -- handles designsize in sp as well
    if scaledpoints < 0 then
        if designsize then
            local factor = constructors.factor
            if designsize > factor then -- or just 1000 / when? mp?
                return (- scaledpoints/1000) * designsize -- sp's
            else
                return (- scaledpoints/1000) * designsize * factor
            end
        else
            return (- scaledpoints/1000) * 10 * factor
        end
    else
        return scaledpoints
    end
end

--[[ldx--
<p>Beware, the boundingbox is passed as reference so we may not overwrite it
in the process; numbers are of course copies. Here 65536 equals 1pt. (Due to
excessive memory usage in CJK fonts, we no longer pass the boundingbox.)</p>
--ldx]]--

-- The scaler is only used for otf and afm and virtual fonts. If
-- a virtual font has italic correction make sure to set the
-- hasitalics flag. Some more flags will be added in
-- the future.

--[[ldx--
<p>The reason why the scaler was originally split, is that for a while we experimented
with a helper function. However, in practice the <l n='api'/> calls are too slow to
make this profitable and the <l n='lua'/> based variant was just faster. A days
wasted day but an experience richer.</p>
--ldx]]--

-- we can get rid of the tfm instance when we have fast access to the
-- scaled character dimensions at the tex end, e.g. a fontobject.width
-- actually we already have some of that now as virtual keys in glyphs
--
-- flushing the kern and ligature tables from memory saves a lot (only
-- base mode) but it complicates vf building where the new characters
-- demand this data .. solution: functions that access them

function constructors.cleanuptable(tfmdata)
    if constructors.autocleanup and tfmdata.properties.virtualized then
        for k, v in next, tfmdata.characters do
            if v.commands then v.commands = nil end
        --  if v.kerns    then v.kerns    = nil end
        end
    end
end

-- experimental, sharing kerns (unscaled and scaled) saves memory
-- local sharedkerns, basekerns = constructors.check_base_kerns(tfmdata)
-- loop over descriptions (afm and otf have descriptions, tfm not)
-- there is no need (yet) to assign a value to chr.tonunicode

-- constructors.prepare_base_kerns(tfmdata) -- optimalization

-- we have target.name=metricfile and target.fullname=RealName and target.filename=diskfilename
-- when collapsing fonts, luatex looks as both target.name and target.fullname as ttc files
-- can have multiple subfonts

function constructors.calculatescale(tfmdata,scaledpoints)
    local parameters = tfmdata.parameters
    if scaledpoints < 0 then
        scaledpoints = (- scaledpoints/1000) * (tfmdata.designsize or parameters.designsize) -- already in sp
    end
    return scaledpoints, scaledpoints / (parameters.units or 1000) -- delta
end

local unscaled = {
    ScriptPercentScaleDown          = true,
    ScriptScriptPercentScaleDown    = true,
    RadicalDegreeBottomRaisePercent = true
}

function constructors.assignmathparameters(target,original) -- simple variant, not used in context
    -- when a tfm file is loaded, it has already been scaled
    -- and it never enters the scaled so this is otf only and
    -- even then we do some extra in the context math plugins
    local mathparameters = original.mathparameters
    if mathparameters and next(mathparameters) then
        local targetparameters     = target.parameters
        local targetproperties     = target.properties
        local targetmathparameters = { }
        local factor               = targetproperties.math_is_scaled and 1 or targetparameters.factor
        for name, value in next, mathparameters do
            if unscaled[name] then
                targetmathparameters[name] = value
            else
                targetmathparameters[name] = value * factor
            end
        end
        if not targetmathparameters.FractionDelimiterSize then
            targetmathparameters.FractionDelimiterSize = 1.01 * targetparameters.size
        end
        if not mathparameters.FractionDelimiterDisplayStyleSize then
            targetmathparameters.FractionDelimiterDisplayStyleSize = 2.40 * targetparameters.size
        end
        target.mathparameters = targetmathparameters
    end
end

function constructors.beforecopyingcharacters(target,original)
    -- can be used for additional tweaking
end

function constructors.aftercopyingcharacters(target,original)
    -- can be used for additional tweaking
end

function constructors.enhanceparameters(parameters)
    local xheight = parameters.x_height
    local quad    = parameters.quad
    local space   = parameters.space
    local stretch = parameters.space_stretch
    local shrink  = parameters.space_shrink
    local extra   = parameters.extra_space
    local slant   = parameters.slant
    parameters.xheight       = xheight
    parameters.spacestretch  = stretch
    parameters.spaceshrink   = shrink
    parameters.extraspace    = extra
    parameters.em            = quad
    parameters.ex            = xheight
    parameters.slantperpoint = slant
    parameters.spacing = {
        width   = space,
        stretch = stretch,
        shrink  = shrink,
        extra   = extra,
    }
end

function constructors.scale(tfmdata,specification)
    local target         = { } -- the new table
    --
    if tonumber(specification) then
        specification    = { size = specification }
    end
    --
    local scaledpoints   = specification.size
    local relativeid     = specification.relativeid
    --
    local properties     = tfmdata.properties     or { }
    local goodies        = tfmdata.goodies        or { }
    local resources      = tfmdata.resources      or { }
    local descriptions   = tfmdata.descriptions   or { } -- bad news if empty
    local characters     = tfmdata.characters     or { } -- bad news if empty
    local changed        = tfmdata.changed        or { } -- for base mode
    local shared         = tfmdata.shared         or { }
    local parameters     = tfmdata.parameters     or { }
    local mathparameters = tfmdata.mathparameters or { }
    --
    local targetcharacters     = { }
    local targetdescriptions   = derivetable(descriptions)
    local targetparameters     = derivetable(parameters)
    local targetproperties     = derivetable(properties)
    local targetgoodies        = goodies                        -- we need to loop so no metatable
    target.characters          = targetcharacters
    target.descriptions        = targetdescriptions
    target.parameters          = targetparameters
 -- target.mathparameters      = targetmathparameters           -- happens elsewhere
    target.properties          = targetproperties
    target.goodies             = targetgoodies
    target.shared              = shared
    target.resources           = resources
    target.unscaled            = tfmdata                        -- the original unscaled one
    --
    -- specification.mathsize : 1=text 2=script 3=scriptscript
    -- specification.textsize : natural (text)size
    -- parameters.mathsize    : 1=text 2=script 3=scriptscript >1000 enforced size (feature value other than yes)
    --
    local mathsize    = tonumber(specification.mathsize) or 0
    local textsize    = tonumber(specification.textsize) or scaledpoints
    local forcedsize  = tonumber(parameters.mathsize   ) or 0
    local extrafactor = tonumber(specification.factor  ) or 1
    if (mathsize == 2 or forcedsize == 2) and parameters.scriptpercentage then
        scaledpoints = parameters.scriptpercentage * textsize / 100
    elseif (mathsize == 3 or forcedsize == 3) and parameters.scriptscriptpercentage then
        scaledpoints = parameters.scriptscriptpercentage * textsize / 100
    elseif forcedsize > 1000 then -- safeguard
        scaledpoints = forcedsize
    end
    targetparameters.mathsize    = mathsize    -- context specific
    targetparameters.textsize    = textsize    -- context specific
    targetparameters.forcedsize  = forcedsize  -- context specific
    targetparameters.extrafactor = extrafactor -- context specific
    --
    local tounicode     = resources.tounicode
    local defaultwidth  = resources.defaultwidth  or 0
    local defaultheight = resources.defaultheight or 0
    local defaultdepth  = resources.defaultdepth or 0
    local units         = parameters.units or 1000
    --
    if target.fonts then
        target.fonts = fastcopy(target.fonts) -- maybe we virtualize more afterwards
    end
    --
    -- boundary keys are no longer needed as we now have a string 'right_boundary'
    -- that can be used in relevant tables (kerns and ligatures) ... not that I ever
    -- used them
    --
 -- boundarychar_label = 0,     -- not needed
 -- boundarychar       = 65536, -- there is now a string 'right_boundary'
 -- false_boundarychar = 65536, -- produces invalid tfm in luatex
    --
    targetproperties.language = properties.language or "dflt" -- inherited
    targetproperties.script   = properties.script   or "dflt" -- inherited
    targetproperties.mode     = properties.mode     or "base" -- inherited
    --
    local askedscaledpoints   = scaledpoints
    local scaledpoints, delta = constructors.calculatescale(tfmdata,scaledpoints) -- no shortcut, dan be redefined
    --
    local hdelta         = delta
    local vdelta         = delta
    --
    target.designsize    = parameters.designsize -- not really needed so it muight become obsolete
    target.units_per_em  = units                 -- just a trigger for the backend (does luatex use this? if not it will go)
    --
    local direction      = properties.direction or tfmdata.direction or 0 -- pointless, as we don't use omf fonts at all
    target.direction     = direction
    properties.direction = direction
    --
    target.size          = scaledpoints
    --
    target.encodingbytes = properties.encodingbytes or 1
    target.embedding     = properties.embedding or "subset"
    target.tounicode     = 1
    target.cidinfo       = properties.cidinfo
    target.format        = properties.format
    --
    local fontname = properties.fontname or tfmdata.fontname -- for the moment we fall back on
    local fullname = properties.fullname or tfmdata.fullname -- names in the tfmdata although
    local filename = properties.filename or tfmdata.filename -- that is not the right place to
    local psname   = properties.psname   or tfmdata.psname   -- pass them
    local name     = properties.name     or tfmdata.name
    --
    if not psname or psname == "" then
     -- name used in pdf file as well as for selecting subfont in ttc/dfont
        psname = fontname or (fullname and fonts.names.cleanname(fullname))
    end
    target.fontname = fontname
    target.fullname = fullname
    target.filename = filename
    target.psname   = psname
    target.name     = name
    --
 -- inspect(properties)
    --
    properties.fontname = fontname
    properties.fullname = fullname
    properties.filename = filename
    properties.psname   = psname
    properties.name     = name
    -- expansion (hz)
    local expansion = parameters.expansion
    if expansion then
        target.stretch     = expansion.stretch
        target.shrink      = expansion.shrink
        target.step        = expansion.step
        target.auto_expand = expansion.auto
    end
    -- protrusion
    local protrusion = parameters.protrusion
    if protrusion then
        target.auto_protrude = protrusion.auto
    end
    -- widening
    local extendfactor = parameters.extendfactor or 0
    if extendfactor ~= 0 and extendfactor ~= 1 then
        hdelta = hdelta * extendfactor
        target.extend = extendfactor * 1000 -- extent ?
    else
        target.extend = 1000 -- extent ?
    end
    -- slanting
    local slantfactor = parameters.slantfactor or 0
    if slantfactor ~= 0 then
        target.slant = slantfactor * 1000
    else
        target.slant = 0
    end
    --
    targetparameters.factor       = delta
    targetparameters.hfactor      = hdelta
    targetparameters.vfactor      = vdelta
    targetparameters.size         = scaledpoints
    targetparameters.units        = units
    targetparameters.scaledpoints = askedscaledpoints
    --
    local isvirtual        = properties.virtualized or tfmdata.type == "virtual"
    local hasquality       = target.auto_expand or target.auto_protrude
    local hasitalics       = properties.hasitalics
    local autoitalicamount = properties.autoitalicamount
    local stackmath        = not properties.nostackmath
    local nonames          = properties.noglyphnames
    local nodemode         = properties.mode == "node"
    --
    if changed and not next(changed) then
        changed = false
    end
    --
    target.type = isvirtual and "virtual" or "real"
    --
    target.postprocessors = tfmdata.postprocessors
    --
    local targetslant         = (parameters.slant         or parameters[1] or 0)
    local targetspace         = (parameters.space         or parameters[2] or 0)*hdelta
    local targetspace_stretch = (parameters.space_stretch or parameters[3] or 0)*hdelta
    local targetspace_shrink  = (parameters.space_shrink  or parameters[4] or 0)*hdelta
    local targetx_height      = (parameters.x_height      or parameters[5] or 0)*vdelta
    local targetquad          = (parameters.quad          or parameters[6] or 0)*hdelta
    local targetextra_space   = (parameters.extra_space   or parameters[7] or 0)*hdelta
    --
    targetparameters.slant         = targetslant -- slantperpoint
    targetparameters.space         = targetspace
    targetparameters.space_stretch = targetspace_stretch
    targetparameters.space_shrink  = targetspace_shrink
    targetparameters.x_height      = targetx_height
    targetparameters.quad          = targetquad
    targetparameters.extra_space   = targetextra_space
    --
    local ascender = parameters.ascender
    if ascender then
        targetparameters.ascender  = delta * ascender
    end
    local descender = parameters.descender
    if descender then
        targetparameters.descender = delta * descender
    end
    --
    constructors.enhanceparameters(targetparameters) -- official copies for us
    --
    local protrusionfactor = (targetquad ~= 0 and 1000/targetquad) or 0
    local scaledwidth      = defaultwidth  * hdelta
    local scaledheight     = defaultheight * vdelta
    local scaleddepth      = defaultdepth  * vdelta
    --
    local hasmath = (properties.hasmath or next(mathparameters)) and true
    --
    if hasmath then
        constructors.assignmathparameters(target,tfmdata) -- does scaling and whatever is needed
        properties.hasmath    = true
        target.nomath         = false
        target.MathConstants  = target.mathparameters
    else
        properties.hasmath    = false
        target.nomath         = true
        target.mathparameters = nil -- nop
    end
    --
    local italickey  = "italic"
    local useitalics = true -- something context
    --
    -- some context specific trickery (this will move to a plugin)
    --
    if hasmath then
     -- the latest luatex can deal with it itself so we now disable this
     -- mechanism here
     --
     -- if properties.mathitalics then
     --     italickey = "italic_correction"
     --     if trace_defining then
     --         report_defining("math italics disabled for font %a, fullname %a, filename %a",name,fullname,filename)
     --     end
     -- end
        autoitalicamount = false -- new
    elseif properties.textitalics then
        italickey = "italic_correction"
        useitalics = false
        if properties.delaytextitalics then
            autoitalicamount = false
        end
    end
    --
    -- end of context specific trickery
    --
    if trace_defining then
        report_defining("defining tfm, name %a, fullname %a, filename %a, hscale %a, vscale %a, math %a, italics %a",
            name,fullname,filename,hdelta,vdelta,
            hasmath and "enabled" or "disabled",useitalics and "enabled" or "disabled")
    end
    --
    constructors.beforecopyingcharacters(target,tfmdata)
    --
    local sharedkerns = { }
    --
    -- we can have a dumb mode (basemode without math etc) that skips most
    --
    for unicode, character in next, characters do
        local chr, description, index, touni
        if changed then
            -- basemode hack (we try to catch missing tounicodes, e.g. needed for ssty in math cambria)
            local c = changed[unicode]
            if c then
                description = descriptions[c] or descriptions[unicode] or character
                character = characters[c] or character
                index = description.index or c
                if tounicode then
                    touni = tounicode[index] -- nb: index!
                    if not touni then -- goodie
                        local d = descriptions[unicode] or characters[unicode]
                        local i = d.index or unicode
                        touni = tounicode[i] -- nb: index!
                    end
                end
            else
                description = descriptions[unicode] or character
                index = description.index or unicode
                if tounicode then
                    touni = tounicode[index] -- nb: index!
                end
            end
        else
            description = descriptions[unicode] or character
            index = description.index or unicode
            if tounicode then
                touni = tounicode[index] -- nb: index!
            end
        end
        local width  = description.width
        local height = description.height
        local depth  = description.depth
        if width  then width  = hdelta*width  else width  = scaledwidth  end
        if height then height = vdelta*height else height = scaledheight end
    --  if depth  then depth  = vdelta*depth  else depth  = scaleddepth  end
        if depth and depth ~= 0 then
            depth = delta*depth
            if nonames then
                chr = {
                    index  = index,
                    height = height,
                    depth  = depth,
                    width  = width,
                }
            else
                chr = {
                    name   = description.name,
                    index  = index,
                    height = height,
                    depth  = depth,
                    width  = width,
                }
            end
        else
            -- this saves a little bit of memory time and memory, esp for big cjk fonts
            if nonames then
                chr = {
                    index  = index,
                    height = height,
                    width  = width,
                }
            else
                chr = {
                    name   = description.name,
                    index  = index,
                    height = height,
                    width  = width,
                }
            end
        end
        if touni then
            chr.tounicode = touni
        end
        if hasquality then
            -- we could move these calculations elsewhere (saves calculations)
            local ve = character.expansion_factor
            if ve then
                chr.expansion_factor = ve*1000 -- expansionfactor, hm, can happen elsewhere
            end
            local vl = character.left_protruding
            if vl then
                chr.left_protruding  = protrusionfactor*width*vl
            end
            local vr = character.right_protruding
            if vr then
                chr.right_protruding  = protrusionfactor*width*vr
            end
        end
        --
        if autoitalicamount then
            local vi = description.italic
            if not vi then
                local vi = description.boundingbox[3] - description.width + autoitalicamount
                if vi > 0 then -- < 0 indicates no overshoot or a very small auto italic
                    chr[italickey] = vi*hdelta
                end
            elseif vi ~= 0 then
                chr[italickey] = vi*hdelta
            end
        elseif hasitalics then
            local vi = description.italic
            if vi and vi ~= 0 then
                chr[italickey] = vi*hdelta
            end
        end
        -- to be tested
        if hasmath then
            -- todo, just operate on descriptions.math
            local vn = character.next
            if vn then
                chr.next = vn
            else
                local vv = character.vert_variants
                if vv then
                    local t = { }
                    for i=1,#vv do
                        local vvi = vv[i]
                        t[i] = {
                            ["start"]    = (vvi["start"]   or 0)*vdelta,
                            ["end"]      = (vvi["end"]     or 0)*vdelta,
                            ["advance"]  = (vvi["advance"] or 0)*vdelta,
                            ["extender"] =  vvi["extender"],
                            ["glyph"]    =  vvi["glyph"],
                        }
                    end
                    chr.vert_variants = t
                else
                    local hv = character.horiz_variants
                    if hv then
                        local t = { }
                        for i=1,#hv do
                            local hvi = hv[i]
                            t[i] = {
                                ["start"]    = (hvi["start"]   or 0)*hdelta,
                                ["end"]      = (hvi["end"]     or 0)*hdelta,
                                ["advance"]  = (hvi["advance"] or 0)*hdelta,
                                ["extender"] =  hvi["extender"],
                                ["glyph"]    =  hvi["glyph"],
                            }
                        end
                        chr.horiz_variants = t
                    end
                end
            end
            local va = character.top_accent
            if va then
                chr.top_accent = vdelta*va
            end
            if stackmath then
                local mk = character.mathkerns -- not in math ?
                if mk then
                    local kerns = { }
                    local v = mk.top_right    if v then local k = { } for i=1,#v do local vi = v[i]
                        k[i] = { height = vdelta*vi.height, kern = vdelta*vi.kern }
                    end     kerns.top_right    = k end
                    local v = mk.top_left     if v then local k = { } for i=1,#v do local vi = v[i]
                        k[i] = { height = vdelta*vi.height, kern = vdelta*vi.kern }
                    end     kerns.top_left     = k end
                    local v = mk.bottom_left  if v then local k = { } for i=1,#v do local vi = v[i]
                        k[i] = { height = vdelta*vi.height, kern = vdelta*vi.kern }
                    end     kerns.bottom_left  = k end
                    local v = mk.bottom_right if v then local k = { } for i=1,#v do local vi = v[i]
                        k[i] = { height = vdelta*vi.height, kern = vdelta*vi.kern }
                    end     kerns.bottom_right = k end
                    chr.mathkern = kerns -- singular -> should be patched in luatex !
                end
            end
        end
        if not nodemode then
            local vk = character.kerns
            if vk then
                local s = sharedkerns[vk]
                if not s then
                    s = { }
                    for k,v in next, vk do s[k] = v*hdelta end
                    sharedkerns[vk] = s
                end
                chr.kerns = s
            end
            local vl = character.ligatures
            if vl then
                if true then
                    chr.ligatures = vl -- shared
                else
                    local tt = { }
                    for i,l in next, vl do
                        tt[i] = l
                    end
                    chr.ligatures = tt
                end
            end
        end
        if isvirtual then
            local vc = character.commands
            if vc then
                -- we assume non scaled commands here
                -- tricky .. we need to scale pseudo math glyphs too
                -- which is why we deal with rules too
                local ok = false
                for i=1,#vc do
                    local key = vc[i][1]
                    if key == "right" or key == "down" then
                        ok = true
                        break
                    end
                end
                if ok then
                    local tt = { }
                    for i=1,#vc do
                        local ivc = vc[i]
                        local key = ivc[1]
                        if key == "right" then
                            tt[i] = { key, ivc[2]*hdelta }
                        elseif key == "down" then
                            tt[i] = { key, ivc[2]*vdelta }
                        elseif key == "rule" then
                            tt[i] = { key, ivc[2]*vdelta, ivc[3]*hdelta }
                        else -- not comment
                            tt[i] = ivc -- shared since in cache and untouched
                        end
                    end
                    chr.commands = tt
                else
                    chr.commands = vc
                end
                chr.index = nil
            end
        end
        targetcharacters[unicode] = chr
    end
    --
    constructors.aftercopyingcharacters(target,tfmdata)
    --
    return target
end

function constructors.finalize(tfmdata)
    if tfmdata.properties and tfmdata.properties.finalized then
        return
    end
    --
    if not tfmdata.characters then
        return nil
    end
    --
    if not tfmdata.goodies then
        tfmdata.goodies = { } -- context specific
    end
    --
    local parameters = tfmdata.parameters
    if not parameters then
        return nil
    end
    --
    if not parameters.expansion then
        parameters.expansion = {
            stretch = tfmdata.stretch     or 0,
            shrink  = tfmdata.shrink      or 0,
            step    = tfmdata.step        or 0,
            auto    = tfmdata.auto_expand or false,
        }
    end
    --
    if not parameters.protrusion then
        parameters.protrusion = {
            auto = auto_protrude
        }
    end
    --
    if not parameters.size then
        parameters.size = tfmdata.size
    end
    --
    if not parameters.extendfactor then
        parameters.extendfactor = tfmdata.extend or 0
    end
    --
    if not parameters.slantfactor then
        parameters.slantfactor = tfmdata.slant or 0
    end
    --
    if not parameters.designsize then
        parameters.designsize = tfmdata.designsize or 655360
    end
    --
    if not parameters.units then
        parameters.units = tfmdata.units_per_em or 1000
    end
    --
    if not tfmdata.descriptions then
        local descriptions = { } -- yes or no
        setmetatableindex(descriptions, function(t,k) local v = { } t[k] = v return v end)
        tfmdata.descriptions = descriptions
    end
    --
    local properties = tfmdata.properties
    if not properties then
        properties = { }
        tfmdata.properties = properties
    end
    --
    if not properties.virtualized then
        properties.virtualized = tfmdata.type == "virtual"
    end
    --
    if not tfmdata.properties then
        tfmdata.properties = {
            fontname      = tfmdata.fontname,
            filename      = tfmdata.filename,
            fullname      = tfmdata.fullname,
            name          = tfmdata.name,
            psname        = tfmdata.psname,
            --
            encodingbytes = tfmdata.encodingbytes or 1,
            embedding     = tfmdata.embedding     or "subset",
            tounicode     = tfmdata.tounicode     or 1,
            cidinfo       = tfmdata.cidinfo       or nil,
            format        = tfmdata.format        or "type1",
            direction     = tfmdata.direction     or 0,
        }
    end
    if not tfmdata.resources then
        tfmdata.resources = { }
    end
    if not tfmdata.shared then
        tfmdata.shared = { }
    end
    --
    -- tfmdata.fonts
    -- tfmdata.unscaled
    --
    if not properties.hasmath then
        properties.hasmath  = not tfmdata.nomath
    end
    --
    tfmdata.MathConstants  = nil
    tfmdata.postprocessors = nil
    --
    tfmdata.fontname       = nil
    tfmdata.filename       = nil
    tfmdata.fullname       = nil
    tfmdata.name           = nil -- most tricky part
    tfmdata.psname         = nil
    --
    tfmdata.encodingbytes  = nil
    tfmdata.embedding      = nil
    tfmdata.tounicode      = nil
    tfmdata.cidinfo        = nil
    tfmdata.format         = nil
    tfmdata.direction      = nil
    tfmdata.type           = nil
    tfmdata.nomath         = nil
    tfmdata.designsize     = nil
    --
    tfmdata.size           = nil
    tfmdata.stretch        = nil
    tfmdata.shrink         = nil
    tfmdata.step           = nil
    tfmdata.auto_expand    = nil
    tfmdata.auto_protrude  = nil
    tfmdata.extend         = nil
    tfmdata.slant          = nil
    tfmdata.units_per_em   = nil
    --
    properties.finalized   = true
    --
    return tfmdata
end

--[[ldx--
<p>A unique hash value is generated by:</p>
--ldx]]--

local hashmethods        = { }
constructors.hashmethods = hashmethods

function constructors.hashfeatures(specification) -- will be overloaded
    local features = specification.features
    if features then
        local t, tn = { }, 0
        for category, list in next, features do
            if next(list) then
                local hasher = hashmethods[category]
                if hasher then
                    local hash = hasher(list)
                    if hash then
                        tn = tn + 1
                        t[tn] = category .. ":" .. hash
                    end
                end
            end
        end
        if tn > 0 then
            return concat(t," & ")
        end
    end
    return "unknown"
end

hashmethods.normal = function(list)
    local s = { }
    local n = 0
    for k, v in next, list do
        if not k then
            -- no need to add to hash
        elseif k == "number" or k == "features" then
            -- no need to add to hash (maybe we need a skip list)
        else
            n = n + 1
            s[n] = k
        end
    end
    if n > 0 then
        sort(s)
        for i=1,n do
            local k = s[i]
            s[i] = k .. '=' .. tostring(list[k])
        end
        return concat(s,"+")
    end
end

--[[ldx--
<p>In principle we can share tfm tables when we are in node for a font, but then
we need to define a font switch as an id/attr switch which is no fun, so in that
case users can best use dynamic features ... so, we will not use that speedup. Okay,
when we get rid of base mode we can optimize even further by sharing, but then we
loose our testcases for <l n='luatex'/>.</p>
--ldx]]--

function constructors.hashinstance(specification,force)
    local hash, size, fallbacks = specification.hash, specification.size, specification.fallbacks
    if force or not hash then
        hash = constructors.hashfeatures(specification)
        specification.hash = hash
    end
    if size < 1000 and designsizes[hash] then
        size = math.round(constructors.scaled(size,designsizes[hash]))
        specification.size = size
    end
 -- local mathsize = specification.mathsize or 0
 -- if mathsize > 0 then
 --     local textsize = specification.textsize
 --     if fallbacks then
 --         return hash .. ' @ ' .. tostring(size) .. ' [ ' .. tostring(mathsize) .. ' : ' .. tostring(textsize) .. ' ] @ ' .. fallbacks
 --     else
 --         return hash .. ' @ ' .. tostring(size) .. ' [ ' .. tostring(mathsize) .. ' : ' .. tostring(textsize) .. ' ]'
 --     end
 -- else
        if fallbacks then
            return hash .. ' @ ' .. tostring(size) .. ' @ ' .. fallbacks
        else
            return hash .. ' @ ' .. tostring(size)
        end
 -- end
end

function constructors.setname(tfmdata,specification) -- todo: get specification from tfmdata
    if constructors.namemode == "specification" then
        -- not to be used in context !
        local specname = specification.specification
        if specname then
            tfmdata.properties.name = specname
            if trace_defining then
                report_otf("overloaded fontname %a",specname)
            end
        end
    end
end

function constructors.checkedfilename(data)
    local foundfilename = data.foundfilename
    if not foundfilename then
        local askedfilename = data.filename or ""
        if askedfilename ~= "" then
            askedfilename = resolvers.resolve(askedfilename) -- no shortcut
            foundfilename = resolvers.findbinfile(askedfilename,"") or ""
            if foundfilename == "" then
                report_defining("source file %a is not found",askedfilename)
                foundfilename = resolvers.findbinfile(file.basename(askedfilename),"") or ""
                if foundfilename ~= "" then
                    report_defining("using source file %a due to cache mismatch",foundfilename)
                end
            end
        end
        data.foundfilename = foundfilename
    end
    return foundfilename
end

local formats = allocate()
fonts.formats = formats

setmetatableindex(formats, function(t,k)
    local l = lower(k)
    if rawget(t,k) then
        t[k] = l
        return l
    end
    return rawget(t,file.suffix(l))
end)

local locations = { }

local function setindeed(mode,target,group,name,action,position)
    local t = target[mode]
    if not t then
        report_defining("fatal error in setting feature %a, group %a, mode %a",name,group,mode)
        os.exit()
    elseif position then
        -- todo: remove existing
        insert(t, position, { name = name, action = action })
    else
        for i=1,#t do
            local ti = t[i]
            if ti.name == name then
                ti.action = action
                return
            end
        end
        insert(t, { name = name, action = action })
    end
end

local function set(group,name,target,source)
    target = target[group]
    if not target then
        report_defining("fatal target error in setting feature %a, group %a",name,group)
        os.exit()
    end
    local source = source[group]
    if not source then
        report_defining("fatal source error in setting feature %a, group %a",name,group)
        os.exit()
    end
    local node     = source.node
    local base     = source.base
    local position = source.position
    if node then
        setindeed("node",target,group,name,node,position)
    end
    if base then
        setindeed("base",target,group,name,base,position)
    end
end

local function register(where,specification)
    local name = specification.name
    if name and name ~= "" then
        local default      = specification.default
        local description  = specification.description
        local initializers = specification.initializers
        local processors   = specification.processors
        local manipulators = specification.manipulators
        local modechecker  = specification.modechecker
        if default then
            where.defaults[name] = default
        end
        if description and description ~= "" then
            where.descriptions[name] = description
        end
        if initializers then
            set('initializers',name,where,specification)
        end
        if processors then
            set('processors',  name,where,specification)
        end
        if manipulators then
            set('manipulators',name,where,specification)
        end
        if modechecker then
           where.modechecker = modechecker
        end
    end
end

constructors.registerfeature = register

function constructors.getfeatureaction(what,where,mode,name)
    what = handlers[what].features
    if what then
        where = what[where]
        if where then
            mode = where[mode]
            if mode then
                for i=1,#mode do
                    local m = mode[i]
                    if m.name == name then
                        return m.action
                    end
                end
            end
        end
    end
end

function constructors.newhandler(what) -- could be a metatable newindex
    local handler = handlers[what]
    if not handler then
        handler = { }
        handlers[what] = handler
    end
    return handler
end

function constructors.newfeatures(what) -- could be a metatable newindex
    local handler = handlers[what]
    local features = handler.features
    if not features then
        local tables     = handler.tables     -- can be preloaded
        local statistics = handler.statistics -- can be preloaded
        features = allocate {
            defaults     = { },
            descriptions = tables and tables.features or { },
            used         = statistics and statistics.usedfeatures or { },
            initializers = { base = { }, node = { } },
            processors   = { base = { }, node = { } },
            manipulators = { base = { }, node = { } },
        }
        features.register = function(specification) return register(features,specification) end
        handler.features = features -- will also become hidden
    end
    return features
end

--[[ldx--
<p>We need to check for default features. For this we provide
a helper function.</p>
--ldx]]--

function constructors.checkedfeatures(what,features)
    local defaults = handlers[what].features.defaults
    if features and next(features) then
        features = fastcopy(features) -- can be inherited (mt) but then no loops possible
        for key, value in next, defaults do
            if features[key] == nil then
                features[key] = value
            end
        end
        return features
    else
        return fastcopy(defaults) -- we can change features in place
    end
end

-- before scaling

function constructors.initializefeatures(what,tfmdata,features,trace,report)
    if features and next(features) then
        local properties       = tfmdata.properties or { } -- brrr
        local whathandler      = handlers[what]
        local whatfeatures     = whathandler.features
        local whatinitializers = whatfeatures.initializers
        local whatmodechecker  = whatfeatures.modechecker
        -- properties.mode can be enforces (for instance in font-otd)
        local mode             = properties.mode or (whatmodechecker and whatmodechecker(tfmdata,features,features.mode)) or features.mode or "base"
        properties.mode        = mode -- also status
        features.mode          = mode -- both properties.mode or features.mode can be changed
        --
        local done             = { }
        while true do
            local redo = false
            local initializers = whatfeatures.initializers[mode]
            if initializers then
                for i=1,#initializers do
                    local step = initializers[i]
                    local feature = step.name
-- we could intercept mode here .. needs a rewrite of this whole loop then but it's cleaner that way
                    local value = features[feature]
                    if not value then
                        -- disabled
                    elseif done[feature] then
                        -- already done
                    else
                        local action = step.action
                        if trace then
                            report("initializing feature %a to %a for mode %a for font %a",feature,
                                value,mode,tfmdata.properties.fullname)
                        end
                        action(tfmdata,value,features) -- can set mode (e.g. goodies) so it can trigger a restart
                        if mode ~= properties.mode or mode ~= features.mode then
                            if whatmodechecker then
                                properties.mode = whatmodechecker(tfmdata,features,properties.mode) -- force checking
                                features.mode   = properties.mode
                            end
                            if mode ~= properties.mode then
                                mode = properties.mode
                                redo = true
                            end
                        end
                        done[feature] = true
                    end
                    if redo then
                        break
                    end
                end
                if not redo then
                    break
                end
            else
                break
            end
        end
        properties.mode = mode -- to be sure
        return true
    else
        return false
    end
end

-- while typesetting

function constructors.collectprocessors(what,tfmdata,features,trace,report)
    local processes, nofprocesses = { }, 0
    if features and next(features) then
        local properties     = tfmdata.properties
        local whathandler    = handlers[what]
        local whatfeatures   = whathandler.features
        local whatprocessors = whatfeatures.processors
        local processors     = whatprocessors[properties.mode]
        if processors then
            for i=1,#processors do
                local step = processors[i]
                local feature = step.name
                if features[feature] then
                    local action = step.action
                    if trace then
                        report("installing feature processor %a for mode %a for font %a",feature,mode,tfmdata.properties.fullname)
                    end
                    if action then
                        nofprocesses = nofprocesses + 1
                        processes[nofprocesses] = action
                    end
                end
            end
        elseif trace then
            report("no feature processors for mode %a for font %a",mode,tfmdata.properties.fullname)
        end
    end
    return processes
end

-- after scaling

function constructors.applymanipulators(what,tfmdata,features,trace,report)
    if features and next(features) then
        local properties       = tfmdata.properties
        local whathandler      = handlers[what]
        local whatfeatures     = whathandler.features
        local whatmanipulators = whatfeatures.manipulators
        local manipulators     = whatmanipulators[properties.mode]
        if manipulators then
            for i=1,#manipulators do
                local step = manipulators[i]
                local feature = step.name
                local value = features[feature]
                if value then
                    local action = step.action
                    if trace then
                        report("applying feature manipulator %a for mode %a for font %a",feature,mode,tfmdata.properties.fullname)
                    end
                    if action then
                        action(tfmdata,feature,value)
                    end
                end
            end
        end
    end
end
