summaryrefslogtreecommitdiff
path: root/Master/texmf-dist/tex/context/base/mkiv/font-otb.lua
blob: a310792250d9ff95778df318b9234ac6154693ad (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
if not modules then modules = { } end modules ['font-otb'] = {
    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"
}
local concat = table.concat
local format, gmatch, gsub, find, match, lower, strip = string.format, string.gmatch, string.gsub, string.find, string.match, string.lower, string.strip
local type, next, tonumber, tostring, rawget = type, next, tonumber, tostring, rawget

local trace_baseinit         = false  trackers.register("otf.baseinit",         function(v) trace_baseinit         = v end)
local trace_singles          = false  trackers.register("otf.singles",          function(v) trace_singles          = v end)
local trace_multiples        = false  trackers.register("otf.multiples",        function(v) trace_multiples        = v end)
local trace_alternatives     = false  trackers.register("otf.alternatives",     function(v) trace_alternatives     = v end)
local trace_ligatures        = false  trackers.register("otf.ligatures",        function(v) trace_ligatures        = v end)
local trace_ligatures_detail = false  trackers.register("otf.ligatures.detail", function(v) trace_ligatures_detail = v end)
local trace_kerns            = false  trackers.register("otf.kerns",            function(v) trace_kerns            = v end)
local trace_preparing        = false  trackers.register("otf.preparing",        function(v) trace_preparing        = v end)

local report_prepare         = logs.reporter("fonts","otf prepare")

local fonts                  = fonts
local otf                    = fonts.handlers.otf

local otffeatures            = otf.features
local registerotffeature     = otffeatures.register

otf.defaultbasealternate     = "none" -- first last

local wildcard               = "*"
local default                = "dflt"

local formatters             = string.formatters
local f_unicode              = formatters["%U"]
local f_uniname              = formatters["%U (%s)"]
local f_unilist              = formatters["% t (% t)"]

local function gref(descriptions,n)
    if type(n) == "number" then
        local name = descriptions[n].name
        if name then
            return f_uniname(n,name)
        else
            return f_unicode(n)
        end
    elseif n then
        local num, nam, j = { }, { }, 0
        for i=1,#n do
            local ni = n[i]
            if tonumber(ni) then -- first is likely a key
                j = j + 1
                local di = descriptions[ni]
                num[j] = f_unicode(ni)
                nam[j] = di and di.name or "-"
            end
        end
        return f_unilist(num,nam)
    else
        return "<error in base mode tracing>"
    end
end

local function cref(feature,lookuptags,lookupname)
    if lookupname then
        return formatters["feature %a, lookup %a"](feature,lookuptags[lookupname])
    else
        return formatters["feature %a"](feature)
    end
end

local function report_alternate(feature,lookuptags,lookupname,descriptions,unicode,replacement,value,comment)
    report_prepare("%s: base alternate %s => %s (%S => %S)",
        cref(feature,lookuptags,lookupname),
        gref(descriptions,unicode),
        replacement and gref(descriptions,replacement),
        value,
        comment)
end

local function report_substitution(feature,lookuptags,lookupname,descriptions,unicode,substitution)
    report_prepare("%s: base substitution %s => %S",
        cref(feature,lookuptags,lookupname),
        gref(descriptions,unicode),
        gref(descriptions,substitution))
end

local function report_ligature(feature,lookuptags,lookupname,descriptions,unicode,ligature)
    report_prepare("%s: base ligature %s => %S",
        cref(feature,lookuptags,lookupname),
        gref(descriptions,ligature),
        gref(descriptions,unicode))
end

local function report_kern(feature,lookuptags,lookupname,descriptions,unicode,otherunicode,value)
    report_prepare("%s: base kern %s + %s => %S",
        cref(feature,lookuptags,lookupname),
        gref(descriptions,unicode),
        gref(descriptions,otherunicode),
        value)
end

local basemethods = { }
local basemethod  = "<unset>"

local function applybasemethod(what,...)
    local m = basemethods[basemethod][what]
    if m then
        return m(...)
    end
end

-- We need to make sure that luatex sees the difference between
-- base fonts that have different glyphs in the same slots in fonts
-- that have the same fullname (or filename). LuaTeX will merge fonts
-- eventually (and subset later on). If needed we can use a more
-- verbose name as long as we don't use <()<>[]{}/%> and the length
-- is < 128.

local basehash, basehashes, applied = { }, 1, { }

local function registerbasehash(tfmdata)
    local properties = tfmdata.properties
    local hash = concat(applied," ")
    local base = basehash[hash]
    if not base then
        basehashes     = basehashes + 1
        base           = basehashes
        basehash[hash] = base
    end
    properties.basehash = base
    properties.fullname = properties.fullname .. "-" .. base
 -- report_prepare("fullname base hash '%a, featureset %a",tfmdata.properties.fullname,hash)
    applied = { }
end

local function registerbasefeature(feature,value)
    applied[#applied+1] = feature  .. "=" .. tostring(value)
end

-- The original basemode ligature builder used the names of components
-- and did some expression juggling to get the chain right. The current
-- variant starts with unicodes but still uses names to make the chain.
-- This is needed because we have to create intermediates when needed
-- but use predefined snippets when available. To some extend the
-- current builder is more stupid but I don't worry that much about it
-- as ligatures are rather predicatable.
--
-- Personally I think that an ff + i == ffi rule as used in for instance
-- latin modern is pretty weird as no sane person will key that in and
-- expect a glyph for that ligature plus the following character. Anyhow,
-- as we need to deal with this, we do, but no guarantes are given.
--
--         latin modern       dejavu
--
-- f+f       102 102             102 102
-- f+i       102 105             102 105
-- f+l       102 108             102 108
-- f+f+i                         102 102 105
-- f+f+l     102 102 108         102 102 108
-- ff+i    64256 105           64256 105
-- ff+l                        64256 108
--
-- As you can see here, latin modern is less complete than dejavu but
-- in practice one will not notice it.
--
-- The while loop is needed because we need to resolve for instance
-- pseudo names like hyphen_hyphen to endash so in practice we end
-- up with a bit too many definitions but the overhead is neglectable.
--
-- We can have changed[first] or changed[second] but it quickly becomes
-- messy if we need to take that into account.

local trace = false

local function finalize_ligatures(tfmdata,ligatures)
    local nofligatures = #ligatures
    if nofligatures > 0 then
        local characters   = tfmdata.characters
        local descriptions = tfmdata.descriptions
        local resources    = tfmdata.resources
        local unicodes     = resources.unicodes -- we use rawget in order to avoid bulding the table
        local private      = resources.private
        local alldone      = false
        while not alldone do
            local done = 0
            for i=1,nofligatures do
                local ligature = ligatures[i]
                if ligature then
                    local unicode, lookupdata = ligature[1], ligature[2]
                    if trace_ligatures_detail then
                        report_prepare("building % a into %a",lookupdata,unicode)
                    end
                    local size = #lookupdata
                    local firstcode = lookupdata[1] -- [2]
                    local firstdata = characters[firstcode]
                    local okay = false
                    if firstdata then
                        local firstname = "ctx_" .. firstcode
                        for i=1,size-1 do -- for i=2,size-1 do
                            local firstdata = characters[firstcode]
                            if not firstdata then
                                firstcode = private
                                if trace_ligatures_detail then
                                    report_prepare("defining %a as %a",firstname,firstcode)
                                end
                                unicodes[firstname] = firstcode
                                firstdata = { intermediate = true, ligatures = { } }
                                characters[firstcode] = firstdata
                                descriptions[firstcode] = { name = firstname }
                                private = private + 1
                            end
                            local target
                            local secondcode = lookupdata[i+1]
                            local secondname = firstname .. "_" .. secondcode
                            if i == size - 1 then
                                target = unicode
                                if not rawget(unicodes,secondname) then
                                    unicodes[secondname] = unicode -- map final ligature onto intermediates
                                end
                                okay = true
                            else
                                target = rawget(unicodes,secondname)
                                if not target then
                                    break
                                end
                            end
                            if trace_ligatures_detail then
                                report_prepare("codes (%a,%a) + (%a,%a) -> %a",firstname,firstcode,secondname,secondcode,target)
                            end
                            local firstligs = firstdata.ligatures
                            if firstligs then
                                firstligs[secondcode] = { char = target }
                            else
                                firstdata.ligatures = { [secondcode] = { char = target } }
                            end
                            firstcode = target
                            firstname = secondname
                        end
                    elseif trace_ligatures_detail then
                        report_prepare("no glyph (%a,%a) for building %a",firstname,firstcode,target)
                    end
                    if okay then
                        ligatures[i] = false
                        done = done + 1
                    end
                end
            end
            alldone = done == 0
        end
        if trace_ligatures_detail then
            for k, v in table.sortedhash(characters) do
                if v.ligatures then
                    table.print(v,k)
                end
            end
        end
        resources.private = private
        return true
    end
end

local function preparesubstitutions(tfmdata,feature,value,validlookups,lookuplist)
    local characters   = tfmdata.characters
    local descriptions = tfmdata.descriptions
    local resources    = tfmdata.resources
    local properties   = tfmdata.properties
    local changed      = tfmdata.changed
    local lookuphash   = resources.lookuphash
    local lookuptypes  = resources.lookuptypes
    local lookuptags   = resources.lookuptags

    local ligatures    = { }
    local alternate    = tonumber(value) or true and 1
    local defaultalt   = otf.defaultbasealternate

    local trace_singles      = trace_baseinit and trace_singles
    local trace_alternatives = trace_baseinit and trace_alternatives
    local trace_ligatures    = trace_baseinit and trace_ligatures

    local actions      = {
        substitution = function(lookupdata,lookuptags,lookupname,description,unicode)
            if trace_singles then
                report_substitution(feature,lookuptags,lookupname,descriptions,unicode,lookupdata)
            end
            changed[unicode] = lookupdata
        end,
        alternate = function(lookupdata,lookuptags,lookupname,description,unicode)
            local replacement = lookupdata[alternate]
            if replacement then
                changed[unicode] = replacement
                if trace_alternatives then
                    report_alternate(feature,lookuptags,lookupname,descriptions,unicode,replacement,value,"normal")
                end
            elseif defaultalt == "first" then
                replacement = lookupdata[1]
                changed[unicode] = replacement
                if trace_alternatives then
                    report_alternate(feature,lookuptags,lookupname,descriptions,unicode,replacement,value,defaultalt)
                end
            elseif defaultalt == "last" then
                replacement = lookupdata[#data]
                if trace_alternatives then
                    report_alternate(feature,lookuptags,lookupname,descriptions,unicode,replacement,value,defaultalt)
                end
            else
                if trace_alternatives then
                    report_alternate(feature,lookuptags,lookupname,descriptions,unicode,replacement,value,"unknown")
                end
            end
        end,
        ligature = function(lookupdata,lookuptags,lookupname,description,unicode)
            if trace_ligatures then
                report_ligature(feature,lookuptags,lookupname,descriptions,unicode,lookupdata)
            end
            ligatures[#ligatures+1] = { unicode, lookupdata }
        end,
    }

    for unicode, character in next, characters do
        local description = descriptions[unicode]
        local lookups     = description.slookups
        if lookups then
            for l=1,#lookuplist do
                local lookupname = lookuplist[l]
                local lookupdata = lookups[lookupname]
                if lookupdata then
                    local lookuptype = lookuptypes[lookupname]
                    local action     = actions[lookuptype]
                    if action then
                        action(lookupdata,lookuptags,lookupname,description,unicode)
                    end
                end
            end
        end
        local lookups = description.mlookups
        if lookups then
            for l=1,#lookuplist do
                local lookupname = lookuplist[l]
                local lookuplist = lookups[lookupname]
                if lookuplist then
                    local lookuptype = lookuptypes[lookupname]
                    local action     = actions[lookuptype]
                    if action then
                        for i=1,#lookuplist do
                            action(lookuplist[i],lookuptags,lookupname,description,unicode)
                        end
                    end
                end
            end
        end
    end
    properties.hasligatures = finalize_ligatures(tfmdata,ligatures)
end

local function preparepositionings(tfmdata,feature,value,validlookups,lookuplist) -- todo what kind of kerns, currently all
    local characters   = tfmdata.characters
    local descriptions = tfmdata.descriptions
    local resources    = tfmdata.resources
    local properties   = tfmdata.properties
    local lookuptags   = resources.lookuptags
    local sharedkerns  = { }
    local traceindeed  = trace_baseinit and trace_kerns
    local haskerns     = false
    for unicode, character in next, characters do
        local description = descriptions[unicode]
        local rawkerns = description.kerns -- shared
        if rawkerns then
            local s = sharedkerns[rawkerns]
            if s == false then
                -- skip
            elseif s then
                character.kerns = s
            else
                local newkerns = character.kerns
                local done     = false
                for l=1,#lookuplist do
                    local lookup = lookuplist[l]
                    local kerns  = rawkerns[lookup]
                    if kerns then
                        for otherunicode, value in next, kerns do
                            if value == 0 then
                                -- maybe no 0 test here
                            elseif not newkerns then
                                newkerns = { [otherunicode] = value }
                                done = true
                                if traceindeed then
                                    report_kern(feature,lookuptags,lookup,descriptions,unicode,otherunicode,value)
                                end
                            elseif not newkerns[otherunicode] then -- first wins
                                newkerns[otherunicode] = value
                                done = true
                                if traceindeed then
                                    report_kern(feature,lookuptags,lookup,descriptions,unicode,otherunicode,value)
                                end
                            end
                        end
                    end
                end
                if done then
                    sharedkerns[rawkerns] = newkerns
                    character.kerns       = newkerns -- no empty assignments
                    haskerns              = true
                else
                    sharedkerns[rawkerns] = false
                end
            end
        end
    end
    properties.haskerns = haskerns
end

basemethods.independent = {
    preparesubstitutions = preparesubstitutions,
    preparepositionings  = preparepositionings,
}

local function makefake(tfmdata,name,present)
    local resources = tfmdata.resources
    local private   = resources.private
    local character = { intermediate = true, ligatures = { } }
    resources.unicodes[name] = private
    tfmdata.characters[private] = character
    tfmdata.descriptions[private] = { name = name }
    resources.private = private + 1
    present[name] = private
    return character
end

local function make_1(present,tree,name)
    for k, v in next, tree do
        if k == "ligature" then
            present[name] = v
        else
            make_1(present,v,name .. "_" .. k)
        end
    end
end

local function make_2(present,tfmdata,characters,tree,name,preceding,unicode,done,lookuptags,lookupname)
    for k, v in next, tree do
        if k == "ligature" then
            local character = characters[preceding]
            if not character then
                if trace_baseinit then
                    report_prepare("weird ligature in lookup %a, current %C, preceding %C",lookuptags[lookupname],v,preceding)
                end
                character = makefake(tfmdata,name,present)
            end
            local ligatures = character.ligatures
            if ligatures then
                ligatures[unicode] = { char = v }
            else
                character.ligatures = { [unicode] = { char = v } }
            end
            if done then
                local d = done[lookupname]
                if not d then
                    done[lookupname] = { "dummy", v }
                else
                    d[#d+1] = v
                end
            end
        else
            local code = present[name] or unicode
            local name = name .. "_" .. k
            make_2(present,tfmdata,characters,v,name,code,k,done,lookuptags,lookupname)
        end
    end
end

local function preparesubstitutions(tfmdata,feature,value,validlookups,lookuplist)
    local characters   = tfmdata.characters
    local descriptions = tfmdata.descriptions
    local resources    = tfmdata.resources
    local changed      = tfmdata.changed
    local lookuphash   = resources.lookuphash
    local lookuptypes  = resources.lookuptypes
    local lookuptags   = resources.lookuptags

    local ligatures    = { }
    local alternate    = tonumber(value) or true and 1
    local defaultalt   = otf.defaultbasealternate

    local trace_singles      = trace_baseinit and trace_singles
    local trace_alternatives = trace_baseinit and trace_alternatives
    local trace_ligatures    = trace_baseinit and trace_ligatures

    for l=1,#lookuplist do
        local lookupname = lookuplist[l]
        local lookupdata = lookuphash[lookupname]
        local lookuptype = lookuptypes[lookupname]
        for unicode, data in next, lookupdata do
            if lookuptype == "substitution" then
                if trace_singles then
                    report_substitution(feature,lookuptags,lookupname,descriptions,unicode,data)
                end
                changed[unicode] = data
            elseif lookuptype == "alternate" then
                local replacement = data[alternate]
                if replacement then
                    changed[unicode] = replacement
                    if trace_alternatives then
                        report_alternate(feature,lookuptags,lookupname,descriptions,unicode,replacement,value,"normal")
                    end
                elseif defaultalt == "first" then
                    replacement = data[1]
                    changed[unicode] = replacement
                    if trace_alternatives then
                        report_alternate(feature,lookuptags,lookupname,descriptions,unicode,replacement,value,defaultalt)
                    end
                elseif defaultalt == "last" then
                    replacement = data[#data]
                    if trace_alternatives then
                        report_alternate(feature,lookuptags,lookupname,descriptions,unicode,replacement,value,defaultalt)
                    end
                else
                    if trace_alternatives then
                        report_alternate(feature,lookuptags,lookupname,descriptions,unicode,replacement,value,"unknown")
                    end
                end
            elseif lookuptype == "ligature" then
                ligatures[#ligatures+1] = { unicode, data, lookupname }
                if trace_ligatures then
                    report_ligature(feature,lookuptags,lookupname,descriptions,unicode,data)
                end
            end
        end
    end

    local nofligatures = #ligatures

    if nofligatures > 0 then

        local characters = tfmdata.characters
        local present    = { }
        local done       = trace_baseinit and trace_ligatures and { }

        for i=1,nofligatures do
            local ligature = ligatures[i]
            local unicode, tree = ligature[1], ligature[2]
            make_1(present,tree,"ctx_"..unicode)
        end

        for i=1,nofligatures do
            local ligature = ligatures[i]
            local unicode, tree, lookupname = ligature[1], ligature[2], ligature[3]
            make_2(present,tfmdata,characters,tree,"ctx_"..unicode,unicode,unicode,done,lookuptags,lookupname)
        end

    end

end

local function preparepositionings(tfmdata,feature,value,validlookups,lookuplist)
    local characters   = tfmdata.characters
    local descriptions = tfmdata.descriptions
    local resources    = tfmdata.resources
    local properties   = tfmdata.properties
    local lookuphash   = resources.lookuphash
    local lookuptags   = resources.lookuptags
    local traceindeed  = trace_baseinit and trace_kerns
    -- check out this sharedkerns trickery
    for l=1,#lookuplist do
        local lookupname = lookuplist[l]
        local lookupdata = lookuphash[lookupname]
        for unicode, data in next, lookupdata do
            local character = characters[unicode]
            local kerns = character.kerns
            if not kerns then
                kerns = { }
                character.kerns = kerns
            end
            if traceindeed then
                for otherunicode, kern in next, data do
                    if not kerns[otherunicode] and kern ~= 0 then
                        kerns[otherunicode] = kern
                        report_kern(feature,lookuptags,lookup,descriptions,unicode,otherunicode,kern)
                    end
                end
            else
                for otherunicode, kern in next, data do
                    if not kerns[otherunicode] and kern ~= 0 then
                        kerns[otherunicode] = kern
                    end
                end
            end
        end
    end

end

local function initializehashes(tfmdata)
    nodeinitializers.features(tfmdata)
end

basemethods.shared = {
    initializehashes     = initializehashes,
    preparesubstitutions = preparesubstitutions,
    preparepositionings  = preparepositionings,
}

basemethod = "independent"

local function featuresinitializer(tfmdata,value)
    if true then -- value then
        local starttime = trace_preparing and os.clock()
        local features  = tfmdata.shared.features
        local fullname  = tfmdata.properties.fullname or "?"
        if features then
            applybasemethod("initializehashes",tfmdata)
            local collectlookups    = otf.collectlookups
            local rawdata           = tfmdata.shared.rawdata
            local properties        = tfmdata.properties
            local script            = properties.script   -- or "dflt" -- can be nil
            local language          = properties.language -- or "dflt" -- can be nil
            local basesubstitutions = rawdata.resources.features.gsub
            local basepositionings  = rawdata.resources.features.gpos
            --
         -- if basesubstitutions then
         --     for feature, data in next, basesubstitutions do
         --         local value = features[feature]
         --         if value then
         --             local validlookups, lookuplist = collectlookups(rawdata,feature,script,language)
         --             if validlookups then
         --                 applybasemethod("preparesubstitutions",tfmdata,feature,value,validlookups,lookuplist)
         --                 registerbasefeature(feature,value)
         --             end
         --         end
         --     end
         -- end
         -- if basepositionings then
         --     for feature, data in next, basepositionings do
         --         local value = features[feature]
         --         if value then
         --             local validlookups, lookuplist = collectlookups(rawdata,feature,script,language)
         --             if validlookups then
         --                 applybasemethod("preparepositionings",tfmdata,feature,features[feature],validlookups,lookuplist)
         --                 registerbasefeature(feature,value)
         --             end
         --         end
         --     end
         -- end
            --
            if basesubstitutions or basepositionings then
                local sequences = tfmdata.resources.sequences
                for s=1,#sequences do
                    local sequence = sequences[s]
                    local sfeatures = sequence.features
                    if sfeatures then
                        local order = sequence.order
                        if order then
                            for i=1,#order do --
                                local feature = order[i]
                                local value = features[feature]
                                if value then
                                    local validlookups, lookuplist = collectlookups(rawdata,feature,script,language)
                                    if not validlookups then
                                        -- skip
                                    elseif basesubstitutions and basesubstitutions[feature] then
                                        if trace_preparing then
                                            report_prepare("filtering base %s feature %a for %a with value %a","sub",feature,fullname,value)
                                        end
                                        applybasemethod("preparesubstitutions",tfmdata,feature,value,validlookups,lookuplist)
                                        registerbasefeature(feature,value)
                                    elseif basepositionings and basepositionings[feature] then
                                        if trace_preparing then
                                            report_prepare("filtering base %a feature %a for %a with value %a","pos",feature,fullname,value)
                                        end
                                        applybasemethod("preparepositionings",tfmdata,feature,value,validlookups,lookuplist)
                                        registerbasefeature(feature,value)
                                    end
                                end
                            end
                        end
                    end
                end
            end
            --
            registerbasehash(tfmdata)
        end
        if trace_preparing then
            report_prepare("preparation time is %0.3f seconds for %a",os.clock()-starttime,fullname)
        end
    end
end

registerotffeature {
    name         = "features",
    description  = "features",
    default      = true,
    initializers = {
 --     position = 1, -- after setscript (temp hack ... we need to force script / language to 1
        base     = featuresinitializer,
    }
}

-- independent : collect lookups independently (takes more runtime ... neglectable)
-- shared      : shares lookups with node mode (takes more memory unless also a node mode variant is used ... noticeable)

directives.register("fonts.otf.loader.basemethod", function(v)
    if basemethods[v] then
        basemethod = v
    end
end)