summaryrefslogtreecommitdiff
path: root/luaotfload-features.lua
blob: 494d02d472a5b4ee1550d4a89ceb76c500b2f336 (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
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
if not modules then modules = { } end modules ["features"] = {
    version   = 1.000,
    comment   = "companion to luaotfload.lua",
    author    = "Hans Hagen, PRAGMA-ADE, Hasselt NL",
    copyright = "PRAGMA ADE / ConTeXt Development Team",
    license   = "see context related readme files"
}

local format, insert = string.format, table.insert
local type, next = type, next
local lpegmatch = lpeg.match

---[[ begin included font-ltx.lua ]]
--- this appears to be based in part on luatex-fonts-def.lua

local fonts = fonts

-- A bit of tuning for definitions.

fonts.constructors.namemode = "specification" -- somehow latex needs this (changed name!) => will change into an overload

-- tricky: we sort of bypass the parser and directly feed all into
-- the sub parser

function fonts.definers.getspecification(str)
    return "", str, "", ":", str
end

local old_feature_list = { }

local report = logs.names_report

local stringlower      = string.lower
local stringsub        = string.sub
local stringgsub       = string.gsub
local stringfind       = string.find
local stringexplode    = string.explode
local stringis_empty   = string.is_empty

--[[doc--
Apparently, these “modifiers” are another measure of emulating \XETEX,
cf. “About \XETEX”, by Jonathan Kew, 2005; and
    “The \XETEX Reference Guide”, by Will Robertson, 2011.
--doc]]--

local supported = {
    b    = "bold",
    i    = "italic",
    bi   = "bolditalic",
    aat  = false,
    icu  = false,
    gr   = false,
}

--- this parses the optional flags after the slash
--- the original behavior is that multiple slashes
--- are valid but they might cancel prior settings
--- example: {name:Antykwa Torunska/I/B} -> bold

local isstyle = function (request)
    request = stringlower(request)
    request = stringexplode(request, "/")

    for _,v in next, request do
        local stylename = supported[v]
        if stylename then
            old_feature_list.style = stylename
        elseif stringfind(v, "^s=") then
            --- after all, we want everything after the second byte ...
            local val = stringsub(v, 3)
            old_feature_list.optsize = val
        elseif stylename == false then
            report("log", 0,
                "load", "unsupported font option: %s", v)
        elseif not stringis_empty(v) then
            old_feature_list.style = stringgsub(v, "[^%a%d]", "")
        end
    end
end

--- TODO an option to dump the default features for a script would make
---      a nice addition to luaotfload-tool

local defaults = {
    dflt = {
        "ccmp", "locl", "rlig", "liga", "clig",
        "kern", "mark", "mkmk", 'itlc',
    },
    arab = {
        "ccmp", "locl", "isol", "fina", "fin2",
        "fin3", "medi", "med2", "init", "rlig",
        "calt", "liga", "cswh", "mset", "curs",
        "kern", "mark", "mkmk",
    },
    deva = {
        "ccmp", "locl", "init", "nukt", "akhn",
        "rphf", "blwf", "half", "pstf", "vatu",
        "pres", "blws", "abvs", "psts", "haln",
        "calt", "blwm", "abvm", "dist", "kern",
        "mark", "mkmk",
    },
    khmr = {
        "ccmp", "locl", "pref", "blwf", "abvf",
        "pstf", "pres", "blws", "abvs", "psts",
        "clig", "calt", "blwm", "abvm", "dist",
        "kern", "mark", "mkmk",
    },
    thai = {
        "ccmp", "locl", "liga", "kern", "mark",
        "mkmk",
    },
    hang = {
        "ccmp", "ljmo", "vjmo", "tjmo",
    },
}

local global_defaults = { mode = "node" }

defaults.beng = defaults.deva
defaults.guru = defaults.deva
defaults.gujr = defaults.deva
defaults.orya = defaults.deva
defaults.taml = defaults.deva
defaults.telu = defaults.deva
defaults.knda = defaults.deva
defaults.mlym = defaults.deva
defaults.sinh = defaults.deva

defaults.syrc = defaults.arab
defaults.mong = defaults.arab
defaults.nko  = defaults.arab

defaults.tibt = defaults.khmr

defaults.lao  = defaults.thai

--[[doc--
Which features are active by default depends on the script requested.
--doc]]--

--- (string, string) dict -> (string, string) dict
local set_default_features = function (speclist)
    speclist = speclist or { }
    local script = speclist.script or "dflt"

    report("log", 0, "load",
        "auto-selecting default features for script: %s",
        script)

    local requested = defaults[script]
    if not requested then
        report("log", 0, "load",
            "no defaults for script “%s”, falling back to “dflt”",
            script)
        requested = defaults.dflt
    end

    for i=1, #requested do
        local feat = requested[i]
        if speclist[feat] ~= false then speclist[feat] = true end
    end

    for feat, state in next, global_defaults do
        --- This is primarily intended for setting node
        --- mode unless “base” is requested, as stated
        --- in the manual.
        if not speclist[feat] then speclist[feat] = state end
    end
    return speclist
end

-- --[==[obsolete--
local function issome ()    old_feature_list.lookup = 'name' end
local function isfile ()    old_feature_list.lookup = 'file' end
local function isname ()    old_feature_list.lookup = 'name' end
local function thename(s)   old_feature_list.name   = s end
local function issub  (v)   old_feature_list.sub    = v end
local function istrue (s)   old_feature_list[s]     = true end
local function isfalse(s)   old_feature_list[s]     = false end
local function iskey  (k,v) old_feature_list[k]     = v end

local P, S, R, C = lpeg.P, lpeg.S, lpeg.R, lpeg.C

local spaces     = P(" ")^0
--local namespec   = (1-S("/:("))^0 -- was: (1-S("/: ("))^0
--[[phg-- this prevents matching of absolute paths as file names --]]--
local namespec   = (1-S("/:("))^1
local filespec   = (R("az", "AZ") * P(":"))^-1 * (1-S(":("))^1
local stylespec  = spaces * P("/") * (((1-P(":"))^0)/isstyle) * spaces
local filename   = (P("file:")/isfile * (filespec/thename))
                 + (P("[") * P(true)/isname * (((1-P("]"))^0)/thename) * P("]"))
local fontname   = (P("name:")/isname * (namespec/thename)) + P(true)/issome * (namespec/thename)
local sometext   = (R("az","AZ","09") + S("+-.,"))^1
local truevalue  = P("+") * spaces * (sometext/istrue)
local falsevalue = P("-") * spaces * (sometext/isfalse)
local keyvalue   = P("+") + (C(sometext) * spaces * P("=") * spaces * C(sometext))/iskey
local somevalue  = sometext/istrue
local subvalue   = P("(") * (C(P(1-S("()"))^1)/issub) * P(")") -- for Kim
local option     = spaces * (keyvalue + falsevalue + truevalue + somevalue) * spaces
local options    = P(":") * spaces * (P(";")^0  * option)^0
local oldsyntax  = (filename + fontname) * subvalue^0 * stylespec^0 * options^0

--- to be annihilated
local function old_behavior (specification) -- xetex mode
    old_feature_list = { }
    lpeg.match(oldsyntax,specification.specification)
    old_feature_list = set_default_features(old_feature_list)
    if old_feature_list.style then
        specification.style = old_feature_list.style
        old_feature_list.style = nil
    end
    if old_feature_list.optsize then
        specification.optsize = old_feature_list.optsize
        old_feature_list.optsize = nil
    end
    if old_feature_list.name then
        if resolvers.findfile(old_feature_list.name, "tfm") then
            old_feature_list.lookup = "file"
            old_feature_list.name   = file.addsuffix(old_feature_list.name, "tfm")
        elseif resolvers.findfile(old_feature_list.name, "ofm") then
            old_feature_list.lookup = "file"
            old_feature_list.name   = file.addsuffix(old_feature_list.name, "ofm")
        end

        specification.name = old_feature_list.name
        old_feature_list.name = nil
    end
    --- this test overwrites valid file: requests for xetex bracket
    --- syntax
    if old_feature_list.lookup then
        specification.lookup = old_feature_list.lookup
        old_feature_list.lookup = nil
    end
    if old_feature_list.sub then
        specification.sub = old_feature_list.sub
        old_feature_list.sub = nil
    end
    if not old_feature_list.mode then
        -- if no mode is set, use our default
        old_feature_list.mode = fonts.mode
    end
    specification.features.normal = fonts.handlers.otf.features.normalize(old_feature_list)
    return specification
end

--fonts.definers.registersplit(":",old_behavior,"cryptic")
--fonts.definers.registersplit("", old_behavior,"more cryptic") -- catches \font\text=[names]
--obsolete]==]--

-----------------------------------------------------------------------
---                    request syntax parser 2.2
-----------------------------------------------------------------------
--- the luaotfload font request syntax (see manual)
--- has a canonical form:
---
---     \font<csname>=<prefix>:<identifier>:<features>
---
--- where
---   <csname> is the control sequence that activates the font
---   <prefix> is either “file” or “name”, determining the lookup
---   <identifer> is either a file name (no path) or a font
---               name, depending on the lookup
---   <features> is a list of switches or options, separated by
---              semicolons or commas; a switch is of the form “+” foo
---              or “-” foo, options are of the form lhs “=” rhs
---
--- however, to ensure backward compatibility we also have
--- support for Xetex-style requests.
---
--- for the Xetex emulation see:
--- · The XeTeX Reference Guide by Will Robertson, 2011
--- · The XeTeX Companion by Michel Goosens, 2010
--- · About XeTeX by Jonathan Kew, 2005
---
---
--- caueat emptor.
---     the request is parsed into one of **four** different
---     lookup categories: the regular ones, file and name,
---     as well as the Xetex compatibility ones, path and anon.
---     (maybe a better choice of identifier would be “ambig”.)
---
---     according to my reconstruction, the correct chaining
---     of the lookups for each category is as follows:
---
---     | File -> ( db/filename lookup;
---                 db/basename lookup;
---                 kpse.find_file() )
---     | Name -> ( names.resolve() )
---     | Path -> ( db/filename lookup;
---                 db/basename lookup;
---                 kpse.find_file();
---                 fullpath lookup )
---     | Anon -> ( names.resolve();      (* most general *)
---                 db/filename lookup;
---                 db/basename lookup;
---                 kpse.find_file();
---                 fullpath lookup )
---
---     the database should be generated only if the chain has
---     been completed, and then only once.
---
---     caching of successful lookups is essential. we need
---     an additional subtable "cached" in the database. it
---     should be nil’able by issuing luaotfload-tool --flush or
---     something. if a cache miss is followed by a successful
---     lookup, then it will be counted as new addition to the
---     cache. we also need a config option to ignore caching.
---
---     also everything has to be finished by tomorrow at noon.
---
-----------------------------------------------------------------------


local stringlower = string.lower

local toboolean = function (s)
  if s == "true"  then return true  end
  if s == "false" then return false end
--if s == "yes"   then return true  end --- Context style
--if s == "no"    then return false end
  return s
end

local lpegmatch = lpeg.match
local P, S, R   = lpeg.P, lpeg.S, lpeg.R
local C, Cc, Cf, Cg, Cs, Ct
    = lpeg.C, lpeg.Cc, lpeg.Cf, lpeg.Cg, lpeg.Cs, lpeg.Ct

--- terminals and low-level classes -----------------------------------
--- note we could use the predefined ones from lpeg.patterns
local dot         = P"."
local colon       = P":"
local featuresep  = S",;"
local slash       = P"/"
local equals      = P"="
local lbrk, rbrk  = P"[", P"]"

local spacing     = S" \t\v"
local ws          = spacing^0

local digit       = R"09"
local alpha       = R("az", "AZ")
local anum        = alpha + digit
local decimal     = digit^1 * (dot * digit^0)^-1

--- modifiers ---------------------------------------------------------
--[[doc--
    The slash notation: called “modifiers” (Kew) or “font options”
    (Robertson, Goosens)
    we only support the shorthands for italic / bold / bold italic
    shapes, the rest is ignored.
--doc]]--
local style_modifier    = (P"BI" + P"IB" + P"bi" + P"ib" + S"biBI")
                        / stringlower
local other_modifier    = P"S=" * decimal --- optical size; unsupported
                        + P"AAT" + P"aat" --- apple stuff;  unsupported
                        + P"ICU" + P"icu" --- not applicable
                        + P"GR"  + P"gr"  --- sil stuff;    unsupported
local garbage_modifier  = ((1 - colon - slash)^0 * Cc(false))
local modifier          = slash * (other_modifier      --> ignore
                                 + Cs(style_modifier)  --> collect
                                 + garbage_modifier)   --> warn
local modifier_list     = Cg(Ct(modifier^0), "modifiers")

--- lookups -----------------------------------------------------------
local fontname          = C((1-S"/:(")^1) --- like luatex-fonts
local prefixed          = P"name:" * ws * Cg(fontname, "name")
                        + P"file:" * ws * Cg(fontname, "file")
local unprefixed        = Cg(fontname, "anon")
local path_lookup       = lbrk * Cg(C((1-rbrk)^1), "path") * rbrk

--- features ----------------------------------------------------------
local field             = (anum + S"+-.")^1 --- sic!
--- assignments are “lhs=rhs”
--- switches    are “+key” | “-key”
local assignment        = C(field) * ws * equals * ws * (field / toboolean)
local switch            = P"+" * ws * C(field) * Cc(true)
                        + P"-" * ws * C(field) * Cc(false)
                        +             C(field) * Cc(true) -- catch crap
local feature_expr      = ws * Cg(assignment + switch) * ws
local feature_list      = Cf(Ct""
                           * feature_expr
                           * (featuresep * feature_expr)^0
                           , rawset)
                        * featuresep^-1

--- other -------------------------------------------------------------
--- This rule is present in the original parser. It sets the “sub”
--- field of the specification which allows addressing a specific
--- font inside a TTC container. Neither in Luatex-Fonts nor in
--- Luaotfload is this documented, so we might as well silently drop
--- it. However, as backward compatibility is one of our prime goals we
--- just insert it here and leave it undocumented until someone cares
--- to ask. (Note: afair subfonts are numbered, but this rule matches a
--- string; I won’t mess with it though until someone reports a
--- problem.)
--- local subvalue   = P("(") * (C(P(1-S("()"))^1)/issub) * P(")") -- for Kim
---                                                                 Who’s Kim?
--- Note to self: subfonts apparently start at index 0. Tested with
--- Cambria.ttc that includes “Cambria Math” at 0 and “Cambria” at 1.
--- Other values cause luatex to segfault.
local subfont           = P"(" * Cg((1 - S"()")^1, "sub") * P")"
--- top-level rules ---------------------------------------------------
--- \font\foo=<specification>:<features>
local features          = Cg(feature_list, "features")
local specification     = (prefixed + unprefixed)
                        * subfont^-1
                        * modifier_list^-1
local font_request      = Ct(path_lookup   * (colon^-1 * features)^-1
                           + specification * (colon    * features)^-1)

-- lpeg.print(font_request)
--- new parser: 632 rules
--- old parser: 230 rules

local import_values = {
    --- That’s what the 1.x parser did, not quite as graciously,
    --- with an array of branch expressions.
    -- "style", "optsize",--> from slashed notation; handled otherwise
    "lookup", "sub" --[[‽]], "mode",
}

local lookup_types = { "anon", "file", "name", "path" }

local select_lookup = function (request)
    for i=1, #lookup_types do
        local lookup = lookup_types[i]
        local value  = request[lookup]
        if value then
            return lookup, value
        end
    end
end

local supported = {
    b    = "bold",
    i    = "italic",
    bi   = "bolditalic",
    aat  = false,
    icu  = false,
    gr   = false,
}

local handle_slashed = function (modifiers)
    local style, optsize
    for i=1, #modifiers do
        local mod  = modifiers[i]
        if supported[mod] then
            style = supported[mod]
        --elseif stringfind(v, "^s=") then
        elseif stringsub(v, 1, 2) == "s=" then
            local val = stringsub(v, 3)
            optsize = val
        elseif stylename == false then
            report("log", 0,
                "load", "unsupported font option: %s", v)
        elseif not stringis_empty(v) then
            style = stringgsub(v, "[^%a%d]", "")
        end
    end
    return style, optsize
end

--- spec -> spec
local handle_request = function (specification)
    local request = lpegmatch(font_request,
                              specification.specification)
    local lookup, name = select_lookup(request)
    request.features  = set_default_features(request.features)

    if name then
        specification.name    = name
        specification.lookup  = lookup or specification.lookup
    end

    if request.modifiers then
        local style, optsize = handle_slashed(request.modifiers)
        specification.style, specification.optsize = style, optsize
    end

    for n=1, #import_values do
        local feat       = import_values[n]
        local newvalue   = request.features[feat]
        if newvalue then
            specification[feat]    = request.features[feat]
            request.features[feat] = nil
        end
    end

    --- The next line sets the “rand” feature to “random”; I haven’t
    --- investigated it any further (luatex-fonts-ext), so it will
    --- just stay here.
    specification.features.normal
        = fonts.handlers.otf.features.normalize(request.features)
    return specification
end

local compare_requests = function (spec)
    local old = old_behavior(spec)
    local new = handle_request(spec)
    return new
end

--fonts.definers.registersplit(":", compare_requests, "cryptic")
--fonts.definers.registersplit("",  compare_requests, "more cryptic") -- catches \font\text=[names]

fonts.definers.registersplit(":", handle_request, "cryptic")
fonts.definers.registersplit("",  handle_request, "more cryptic") -- catches \font\text=[names]

--fonts.definers.registersplit(":",old_behavior,"cryptic")
--fonts.definers.registersplit("", old_behavior,"more cryptic") -- catches \font\text=[names]

---[[ end included font-ltx.lua ]]

--[[doc--
This uses the code from luatex-fonts-merged (<- font-otc.lua) instead
of the removed luaotfload-font-otc.lua.

TODO find out how far we get setting features without these lines,
relying on luatex-fonts only (it *does* handle features somehow, after
all).
--doc]]--

-- we assume that the other otf stuff is loaded already

---[[ begin snippet from font-otc.lua ]]
local trace_loading       = false  trackers.register("otf.loading", function(v) trace_loading = v end)
local report_otf          = logs.reporter("fonts","otf loading")

local otf                 = fonts.handlers.otf
local registerotffeature  = otf.features.register
local setmetatableindex   = table.setmetatableindex

-- In the userdata interface we can not longer tweak the loaded font as
-- conveniently as before. For instance, instead of pushing extra data in
-- in the table using the original structure, we now have to operate on
-- the mkiv representation. And as the fontloader interface is modelled
-- after fontforge we cannot change that one too much either.

local types = {
    substitution = "gsub_single",
    ligature     = "gsub_ligature",
    alternate    = "gsub_alternate",
}

setmetatableindex(types, function(t,k) t[k] = k return k end) -- "key"

local everywhere = { ["*"] = { ["*"] = true } } -- or: { ["*"] = { "*" } }
local noflags    = { }

local function addfeature(data,feature,specifications)
    local descriptions = data.descriptions
    local resources    = data.resources
    local lookups      = resources.lookups
    local gsubfeatures = resources.features.gsub
    if gsubfeatures and gsubfeatures[feature] then
        -- already present
    else
        local sequences    = resources.sequences
        local fontfeatures = resources.features
        local unicodes     = resources.unicodes
        local lookuptypes  = resources.lookuptypes
        local splitter     = lpeg.splitter(" ",unicodes)
        local done         = 0
        local skip         = 0
        if not specifications[1] then
            -- so we accept a one entry specification
            specifications = { specifications }
        end
        -- subtables are tables themselves but we also accept flattened singular subtables
        for s=1,#specifications do
            local specification = specifications[s]
            local valid         = specification.valid
            if not valid or valid(data,specification,feature) then
                local initialize = specification.initialize
                if initialize then
                    -- when false is returned we initialize only once
                    specification.initialize = initialize(specification) and initialize or nil
                end
                local askedfeatures = specification.features or everywhere
                local subtables     = specification.subtables or { specification.data } or { }
                local featuretype   = types[specification.type or "substitution"]
                local featureflags  = specification.flags or noflags
                local added         = false
                local featurename   = format("ctx_%s_%s",feature,s)
                local st = { }
                for t=1,#subtables do
                    local list = subtables[t]
                    local full = format("%s_%s",featurename,t)
                    st[t] = full
                    if featuretype == "gsub_ligature" then
                        lookuptypes[full] = "ligature"
                        for code, ligature in next, list do
                            local unicode = tonumber(code) or unicodes[code]
                            local description = descriptions[unicode]
                            if description then
                                local slookups = description.slookups
                                if type(ligature) == "string" then
                                    ligature = { lpegmatch(splitter,ligature) }
                                end
                                local present = true
                                for i=1,#ligature do
                                    if not descriptions[ligature[i]] then
                                        present = false
                                        break
                                    end
                                end
                                if present then
                                    if slookups then
                                        slookups[full] = ligature
                                    else
                                        description.slookups = { [full] = ligature }
                                    end
                                    done, added = done + 1, true
                                else
                                    skip = skip + 1
                                end
                            end
                        end
                    elseif featuretype == "gsub_single" then
                        lookuptypes[full] = "substitution"
                        for code, replacement in next, list do
                            local unicode = tonumber(code) or unicodes[code]
                            local description = descriptions[unicode]
                            if description then
                                local slookups = description.slookups
                                replacement = tonumber(replacement) or unicodes[replacement]
                                if descriptions[replacement] then
                                    if slookups then
                                        slookups[full] = replacement
                                    else
                                        description.slookups = { [full] = replacement }
                                    end
                                    done, added = done + 1, true
                                end
                            end
                        end
                    end
                end
                if added then
                    -- script = { lang1, lang2, lang3 } or script = { lang1 = true, ... }
                    for k, v in next, askedfeatures do
                        if v[1] then
                            askedfeatures[k] = table.tohash(v)
                        end
                    end
                    sequences[#sequences+1] = {
                        chain     = 0,
                        features  = { [feature] = askedfeatures },
                        flags     = featureflags,
                        name      = featurename,
                        subtables = st,
                        type      = featuretype,
                    }
                    -- register in metadata (merge as there can be a few)
                    if not gsubfeatures then
                        gsubfeatures  = { }
                        fontfeatures.gsub = gsubfeatures
                    end
                    local k = gsubfeatures[feature]
                    if not k then
                        k = { }
                        gsubfeatures[feature] = k
                    end
                    for script, languages in next, askedfeatures do
                        local kk = k[script]
                        if not kk then
                            kk = { }
                            k[script] = kk
                        end
                        for language, value in next, languages do
                            kk[language] = value
                        end
                    end
                end
            end
        end
        if trace_loading then
            report_otf("registering feature %a, affected glyphs %a, skipped glyphs %a",feature,done,skip)
        end
    end
end

otf.enhancers.addfeature = addfeature

local extrafeatures = { }

function otf.addfeature(name,specification)
    extrafeatures[name] = specification
end

local function enhance(data,filename,raw)
    for feature, specification in next, extrafeatures do
        addfeature(data,feature,specification)
    end
end

otf.enhancers.register("check extra features",enhance)

---[[ end snippet from font-otc.lua ]]

local tlig = {
    {
        type      = "substitution",
        features  = everywhere,
        data      = {
            [0x0022] = 0x201D,                   -- quotedblright
            [0x0027] = 0x2019,                   -- quoteleft
            [0x0060] = 0x2018,                   -- quoteright
        },
        flags     = { },
    },
    {
        type     = "ligature",
        features = everywhere,
        data     = {
            [0x2013] = {0x002D, 0x002D},         -- endash
            [0x2014] = {0x002D, 0x002D, 0x002D}, -- emdash
            [0x201C] = {0x2018, 0x2018},         -- quotedblleft
            [0x201D] = {0x2019, 0x2019},         -- quotedblright
            [0x201E] = {0x002C, 0x002C},         -- quotedblbase
            [0x00A1] = {0x0021, 0x2018},         -- exclamdown
            [0x00BF] = {0x003F, 0x2018},         -- questiondown
        },
        flags    = { },
    },
    {
        type     = "ligature",
        features = everywhere,
        data     = {
            [0x201C] = {0x0060, 0x0060},         -- quotedblleft
            [0x201D] = {0x0027, 0x0027},         -- quotedblright
            [0x00A1] = {0x0021, 0x0060},         -- exclamdown
            [0x00BF] = {0x003F, 0x0060},         -- questiondown
        },
        flags    = { },
    },
}

otf.addfeature("tlig", tlig)
otf.addfeature("trep", { }) -- empty, all in tlig now

local anum_arabic = { --- these are the same as in font-otc
    [0x0030] = 0x0660,
    [0x0031] = 0x0661,
    [0x0032] = 0x0662,
    [0x0033] = 0x0663,
    [0x0034] = 0x0664,
    [0x0035] = 0x0665,
    [0x0036] = 0x0666,
    [0x0037] = 0x0667,
    [0x0038] = 0x0668,
    [0x0039] = 0x0669,
}

local anum_persian = {--- these are the same as in font-otc
    [0x0030] = 0x06F0,
    [0x0031] = 0x06F1,
    [0x0032] = 0x06F2,
    [0x0033] = 0x06F3,
    [0x0034] = 0x06F4,
    [0x0035] = 0x06F5,
    [0x0036] = 0x06F6,
    [0x0037] = 0x06F7,
    [0x0038] = 0x06F8,
    [0x0039] = 0x06F9,
}

local function valid(data)
    local features = data.resources.features
    if features then
        for k, v in next, features do
            for k, v in next, v do
                if v.arab then
                    return true
                end
            end
        end
    end
end

local anum_specification = {
    {
        type     = "substitution",
        features = { arab = { far = true, urd = true, snd = true } },
        data     = anum_persian,
        flags    = { },
        valid    = valid,
    },
    {
        type     = "substitution",
        features = { arab = { ["*"] = true } },
        data     = anum_arabic,
        flags    = { },
        valid    = valid,
    },
}

--- below the specifications as given in the removed font-otc.lua
--- the rest was identical to what this file had from the beginning
--- both make the “anum.tex” test pass anyways
--
--local anum_specification = {
--    {
--        type     = "substitution",
--        features = { arab = { urd = true, dflt = true } },
--        data     = anum_arabic,
--        flags    = noflags, -- { },
--        valid    = valid,
--    },
--    {
--        type     = "substitution",
--        features = { arab = { urd = true } },
--        data     = anum_persian,
--        flags    = noflags, -- { },
--        valid    = valid,
--    },
--}
--
otf.addfeature("anum",anum_specification)

registerotffeature {
    name        = 'anum',
    description = 'arabic digits',
}

if characters.combined then

    local tcom = { }

    local function initialize()
        characters.initialize()
        for first, seconds in next, characters.combined do
            for second, combination in next, seconds do
                tcom[combination] = { first, second }
            end
        end
        -- return false
    end

    local tcom_specification = {
        type       = "ligature",
        features   = everywhere,
        data       = tcom,
        flags      = noflags,
        initialize = initialize,
    }

    otf.addfeature("tcom",tcom_specification)

    registerotffeature {
        name        = 'tcom',
        description = 'tex combinations',
    }

end

-- vim:tw=71:sw=4:ts=4:expandtab