summaryrefslogtreecommitdiff
path: root/src/luaotfload-parsers.lua
blob: 0461e2401934df870953d3240f7a2cf8690a2837 (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
#!/usr/bin/env texlua
-------------------------------------------------------------------------------
--         FILE:  luaotfload-parsers.lua
--  DESCRIPTION:  various lpeg-based parsers used in Luaotfload
-- REQUIREMENTS:  Luaotfload > 2.4
--       AUTHOR:  Philipp Gesang (Phg), <phg42.2a@gmail.com>
--      VERSION:  same as Luaotfload
--      CREATED:  2014-01-14 10:15:20+0100
-------------------------------------------------------------------------------
--

if not modules then modules = { } end modules ['luaotfload-parsers'] = {
  version   = "2.5",
  comment   = "companion to luaotfload-main.lua",
  author    = "Philipp Gesang",
  copyright = "Luaotfload Development Team",
  license   = "GNU GPL v2.0"
}

luaotfload              = luaotfload or { }
luaotfload.parsers      = luaotfload.parsers or { }
local parsers           = luaotfload.parsers

local rawset            = rawset

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

local kpse              = kpse
local kpseexpand_path   = kpse.expand_path
local kpsereadable_file = kpse.readable_file

local file              = file
local filejoin          = file.join
local filedirname       = file.dirname

local io                = io
local ioopen            = io.open

local log               = luaotfload.log
local logreport         = log.report

local string            = string
local stringsub         = string.sub
local stringfind        = string.find
local stringlower       = string.lower

local mathceil          = math.ceil

local lfs               = lfs
local lfsisfile         = lfs.isfile
local lfsisdir          = lfs.isdir

-------------------------------------------------------------------------------
---                         COMMON PATTERNS
-------------------------------------------------------------------------------

local dot               = P"."
local colon             = P":"
local semicolon         = P";"
local comma             = P","
local noncomma          = 1 - comma
local slash             = P"/"
local backslash         = P"\\"
local equals            = P"="
local dash              = P"-"
local gartenzaun        = P"#"
local lbrk, rbrk        = P"[", P"]"
local squote            = P"'"
local dquote            = P"\""

local newline           = P"\n"
local returnchar        = P"\r"
local spacing           = S" \t\v"
local linebreak         = S"\n\r"
local whitespace        = spacing + linebreak
local ws                = spacing^0
local xmlws             = whitespace^1
local eol               = P"\n\r" + P"\r\n" + linebreak

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

-------------------------------------------------------------------------------
---                                FONTCONFIG
-------------------------------------------------------------------------------

--[[doc--

  For fonts installed on the operating system, there are several
  options to make Luaotfload index them:

   - If OSFONTDIR is set (which is the case under windows by default
     but not on the other OSs), it scans it at the same time as the
     texmf tree, in the function scan_texmf_fonts().

   - Otherwise
     - under Windows and Mac OSX, we take a look at some hardcoded
       directories,
     - under Unix, it reads /etc/fonts/fonts.conf and processes the
       directories specified there.

  This means that if you have fonts in fancy directories, you need to
  set them in OSFONTDIR.

  Beware: OSFONTDIR is a kpathsea variable, so fonts found in these
  paths, though technically system fonts, are registered in the
  category “texmf”, not “system”. This may have consequences for the
  lookup order when a font file (or a font with the same name
  information) is located in both the system and the texmf tree.

--doc]]--

local tag_name          = C(alpha^1)
local comment           = P"<!--" * (1 - P"--")^0 * P"-->"

---> header specifica
local xml_declaration   = P"<?xml" * (1 - P"?>")^0 * P"?>"
local xml_doctype       = P"<!DOCTYPE" * xmlws
                        * "fontconfig" * (1 - P">")^0 * P">"
local header            = xml_declaration^-1
                        * (xml_doctype + comment + xmlws)^0

---> enforce root node
local root_start        = P"<"  * xmlws^-1 * P"fontconfig" * xmlws^-1 * P">"
local root_stop         = P"</" * xmlws^-1 * P"fontconfig" * xmlws^-1 * P">"

local dquote, squote    = P[["]], P"'"
local xml_namestartchar = S":_" + alpha --- ascii only, funk the rest
local xml_namechar      = S":._" + alpha + digit
local xml_name          = xmlws^-1
                        * C(xml_namestartchar * xml_namechar^0)
local xml_attvalue      = dquote * C((1 - S[[%&"]])^1) * dquote * xmlws^-1
                        + squote * C((1 - S[[%&']])^1) * squote * xmlws^-1
local xml_attr          = Cg(xml_name * P"=" * xml_attvalue)
local xml_attr_list     = Cf(Ct"" * xml_attr^1, rawset)

--[[doc--
      scan_node creates a parser for a given xml tag.
--doc]]--
--- string -> bool -> lpeg_t
local scan_node = function (tag)
    --- Node attributes go into a table with the index “attributes”
    --- (relevant for “prefix="xdg"” and the likes).
    local p_tag = P(tag)
    local with_attributes   = P"<" * p_tag
                            * Cg(xml_attr_list, "attributes")^-1
                            * xmlws^-1
                            * P">"
    local plain             = P"<" * p_tag * xmlws^-1 * P">"
    local node_start        = plain + with_attributes
    local node_stop         = P"</" * p_tag * xmlws^-1 * P">"
    --- there is no nesting, the earth is flat ...
    local node              = node_start
                            * Cc(tag) * C(comment + (1 - node_stop)^1)
                            * node_stop
    return Ct(node) -- returns {string, string [, attributes = { key = val }] }
end

--[[doc--
      At the moment, the interesting tags are “dir” for
      directory declarations, and “include” for including
      further configuration files.

      spec: http://freedesktop.org/software/fontconfig/fontconfig-user.html
--doc]]--
local include_node        = scan_node"include"
local dir_node            = scan_node"dir"

local element             = dir_node
                          + include_node
                          + comment         --> ignore
                          + P(1-root_stop)  --> skip byte

local root                = root_start * Ct(element^0) * root_stop
local p_cheapxml          = header * root

--lpeg.print(p_cheapxml) ---> 757 rules with v0.10

--[[doc--
      fonts_conf_scanner() handles configuration files.
      It is called on an abolute path to a config file (e.g.
      /home/luser/.config/fontconfig/fonts.conf) and returns a list
      of the nodes it managed to extract from the file.
--doc]]--
--- string -> path list
local fonts_conf_scanner = function (path)
  local fh = ioopen(path, "r")
  if not fh then
    logreport("both", 3, "db", "Cannot open fontconfig file %s.", path)
    return
  end
  local raw = fh:read"*all"
  fh:close()

  local confdata = lpegmatch(p_cheapxml, raw)
  if not confdata then
    logreport("both", 3, "db", "Cannot scan fontconfig file %s.", path)
    return
  end
  return confdata
end

local p_conf   = P".conf" * P(-1)
local p_filter = (1 - p_conf)^1 * p_conf

local conf_filter = function (path)
  if lpegmatch (p_filter, path) then
    return true
  end
  return false
end

--[[doc--

      read_fonts_conf_indeed() -- Scan paths included from fontconfig
      configuration files recursively. Called with eight arguments.
      The first four are

          · the path to the file
          · the expanded $HOME
          · the expanded $XDG_CONFIG_HOME
          · the expanded $XDG_DATA_HOME

      determining the path to be checked. Another three arguments are
      tables that represent the state of the current job as lists of
      strings; these are always returned. Finally a reference to the
      find_files function is passed.

--doc]]--

--- string -> string -> string -> string
---     -> string list -> string list -> string list
---     -> (string -> fun option -> string list)
---     -> tab * tab * tab
local read_fonts_conf_indeed
read_fonts_conf_indeed = function (start,
                                   home,
                                   xdg_config_home,
                                   xdg_data_home,
                                   acc,
                                   done,
                                   dirs_done,
                                   find_files)

  local paths = fonts_conf_scanner(start)
  if not paths then --- nothing to do
    return acc, done, dirs_done
  end

  for i=1, #paths do
    local pathobj = paths[i]
    local kind, path = pathobj[1], pathobj[2]
    local attributes = pathobj.attributes

    if kind == "dir" then
      if attributes and attributes.prefix == "xdg" then
        path = filejoin(xdg_data_home, path)
      end
      if stringsub(path, 1, 1) == "~" then
        path = filejoin(home, stringsub(path, 2))
      end
      --- We exclude paths with texmf in them, as they should be
      --- found anyway; also duplicates are ignored by checking
      --- if they are elements of dirs_done.
      ---
      --- FIXME does this mean we cannot access paths from
      --- distributions (e.g. Context minimals) installed
      --- separately?
      if not (stringfind(path, "texmf") or dirs_done[path]) then
        acc[#acc+1] = path
        dirs_done[path] = true
      end

    elseif kind == "include" then
      if attributes and attributes.prefix == "xdg" then
        path = filejoin(xdg_config_home, path)
      end
      --- here the path can be four things: a directory or a file,
      --- an absolute or relative path.
      if stringsub(path, 1, 1) == "~" then
        path = filejoin(home, stringsub(path, 2))
      elseif --- if the path is relative, we make it absolute
        not ( lfsisfile(path) or lfsisdir(path) )
      then
          path = filejoin(filedirname(start), path)
      end
      if  lfsisfile(path)
        and kpsereadable_file(path)
        and not done[path]
      then
        --- we exclude path with texmf in them, as they should
        --- be found otherwise
        acc = read_fonts_conf_indeed(path,
                                     home,
                                     xdg_config_home,
                                     xdg_data_home,
                                     acc,
                                     done,
                                     dirs_done,
                                     find_files)
      elseif lfsisdir(path) then --- arrow code ahead
        local config_files = find_files (path, conf_filter)
        for _, filename in next, config_files do
          if not done[filename] then
            acc = read_fonts_conf_indeed(filename,
                                         home,
                                         xdg_config_home,
                                         xdg_data_home,
                                         acc,
                                         done,
                                         dirs_done,
                                         find_files)
          end
        end
      end --- match “kind”
      end --- iterate paths
  end

  --inspect(acc)
  --inspect(done)
  return acc, done, dirs_done
end --- read_fonts_conf_indeed()

--[[doc--
      read_fonts_conf() sets up an accumulator and two sets
      for tracking what’s been done.

      Also, the environment variables HOME, XDG_DATA_HOME and
      XDG_CONFIG_HOME -- which are constants anyways -- are expanded
      so we don’t have to repeat that over and over again as with the
      old parser. Now they’re just passed on to every call of
      read_fonts_conf_indeed().
--doc]]--

--- list -> (string -> function option -> string list) -> list

local read_fonts_conf = function (path_list, find_files)
  local home      = kpseexpand_path"~" --- could be os.getenv"HOME"
  local xdg_config_home  = kpseexpand_path"$XDG_CONFIG_HOME"
  if xdg_config_home == "" then xdg_config_home = filejoin(home, ".config") end
  local xdg_data_home  = kpseexpand_path"$XDG_DATA_HOME"
  if xdg_data_home == "" then xdg_data_home = filejoin(home, ".local/share") end
  local acc       = { } ---> list: paths collected
  local done      = { } ---> set:  files inspected
  local dirs_done = { } ---> set:  dirs in list
  for i=1, #path_list do --- we keep the state between files
    acc, done, dirs_done = read_fonts_conf_indeed(path_list[i],
                                                  home,
                                                  xdg_config_home,
                                                  xdg_data_home,
                                                  acc,
                                                  done,
                                                  dirs_done,
                                                  find_files)
  end
  return acc
end

luaotfload.parsers.read_fonts_conf = read_fonts_conf



-------------------------------------------------------------------------------
---                               MISC PARSERS
-------------------------------------------------------------------------------


local trailingslashes   = slash^1 * P(-1)
local stripslashes      = C((1 - trailingslashes)^0)
parsers.stripslashes    = stripslashes

local splitcomma        = Ct((C(noncomma^1) + comma)^1)
parsers.splitcomma      = splitcomma



-------------------------------------------------------------------------------
---                              FONT REQUEST
-------------------------------------------------------------------------------


--[[doc------------------------------------------------------------------------

    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 )

        | Name -> ( db/name lookup,
                    db/filename lookup )

        | Path -> ( db/filename lookup,
                    fullpath lookup )

        | Anon -> ( kpse.find_file(),     // <- for tfm, ofm
                    db/name lookup,
                    db/filename lookup,
                    fullpath lookup )

        caching of successful lookups is essential. we now as of v2.2
        have a lookup cache that is stored in a separate file. it
        pertains only to name: lookups, and is described in more detail
        in luaotfload-database.lua.

-------------------------------------------------------------------------------

    One further incompatibility between Xetex and Luatex-Fonts consists
    in their option list syntax: apparently, Xetex requires key-value
    options to be prefixed by a "+" (ascii “plus”) character. We
    silently accept this as well, dropping the first byte if it is a
    plus or minus character.

    Reference: https://github.com/lualatex/luaotfload/issues/79#issuecomment-18104483

--doc]]------------------------------------------------------------------------


local handle_normal_option = function (key, val)
    val = stringlower(val)
    --- the former “toboolean()” handler
    if val == "true"  then
        val = true
    elseif val == "false" then
        val = false
    end
    return key, val
end

--[[doc--

    Xetex style indexing begins at zero which we just increment before
    passing it along to the font loader.  Ymmv.

--doc]]--

local handle_xetex_option = function (key, val)
    val = stringlower(val)
    local numeric = tonumber(val) --- decimal only; keeps colors intact
    if numeric then --- ugh
        if  mathceil(numeric) == numeric then -- integer, possible index
            val = tostring(numeric + 1)
        end
    elseif val == "true"  then
        val = true
    elseif val == "false" then
        val = false
    end
    return key, val
end

--[[doc--

    Instead of silently ignoring invalid options we emit a warning to
    the log.

    Note that we have to return a pair to please rawset(). This creates
    an entry on the resulting features hash which will later be removed
    during set_default_features().

--doc]]--

local handle_invalid_option = function (opt)
    logreport("log", 0, "load", "font option %q unknown.", opt)
    return "", false
end

--[[doc--

    Dirty test if a file: request is actually a path: lookup; don’t
    ask! Note this fails on Windows-style absolute paths. These will
    *really* have to use the correct request.

--doc]]--

local check_garbage = function (_,i, garbage)
    if stringfind(garbage, "/") then
        logreport("log", 0, "load",  --- ffs use path!
                  "warning: path in file: lookups is deprecated; ")
        logreport("log", 0, "load", "use bracket syntax instead!")
        logreport("log", 0, "load",
                  "position: %d; full match: %q",
                  i, garbage)
        return true
    end
    return false
end

local featuresep = comma + semicolon

--- modifiers ---------------------------------------------------------
--[[doc--
    The slash notation: called “modifiers” (Kew) or “font options”
    (Robertson, Goosens)
    we only support the shorthands for italic / bold / bold italic
    shapes, as well as setting optical size, the rest is ignored.
--doc]]--
local style_modifier    = (P"BI" + P"IB" + P"bi" + P"ib" + S"biBI")
                        / stringlower
local size_modifier     = S"Ss" * P"="    --- optical size
                        * Cc"optsize" * C(decimal)
local other_modifier    = 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
                                 + Ct(size_modifier)   --> collect
                                 + garbage_modifier)   --> warn
local modifier_list     = Cg(Ct(modifier^0), "modifiers")

--- lookups -----------------------------------------------------------
local fontname          = C((1-S":(/")^1)  --- like luatex-fonts
local unsupported       = Cmt((1-S":(")^1, check_garbage)
local prefixed          = P"name:" * ws * Cg(fontname, "name")
--- initially we intended file: to emulate the behavior of
--- luatex-fonts, i.e. no paths allowed. after all, we do have XeTeX
--- emulation with the path lookup and it interferes with db lookups.
--- turns out fontspec and other widely used packages rely on file:
--- with paths already, so we’ll add a less strict rule here.  anyways,
--- we’ll emit a warning.
                        + P"file:" * ws * Cg(unsupported, "path")
                        + P"file:" * ws * Cg(fontname, "file")
--- EXPERIMENTAL: kpse lookup
                        + P"kpse:" * ws * Cg(fontname, "kpse")
--- EXPERIMENTAL: custom lookup
                        + P"my:" * ws * Cg(fontname, "my")
local unprefixed        = Cg(fontname, "anon")
local path_lookup       = lbrk * Cg(C((1-rbrk)^1), "path") * rbrk

--- features ----------------------------------------------------------
local field_char        = anum + S"+-." --- sic!
local field             = field_char^1
--- assignments are “lhs=rhs”
---              or “+lhs=rhs” (Xetex-style)
--- switches    are “+key” | “-key”
local normal_option     = C(field) * ws * equals * ws * C(field) * ws
local xetex_option      = P"+" * ws * normal_option
local ignore_option     = (1 - equals - featuresep)^1
                        * equals
                        * (1 - featuresep)^1
local assignment        = xetex_option  / handle_xetex_option
                        + normal_option / handle_normal_option
                        + ignore_option / handle_invalid_option
local switch            = P"+" * ws * C(field) * Cc(true)
                        + P"-" * ws * C(field) * Cc(false)
                        +             C(field) * Cc(true)   --- default
local feature_expr      = ws * Cg(assignment + switch) * ws
local option            = feature_expr
local feature_list      = Cf(Ct""
                           * option
                           * (featuresep * option^-1)^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
--- 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)
--- v2.5 parser: 1065 rules
--- v1.2 parser:  230 rules

luaotfload.parsers.font_request = font_request

-------------------------------------------------------------------------------
---                                INI FILES
-------------------------------------------------------------------------------

--[[doc--

    Luaotfload uses the pervasive flavor of the INI files that allows '#' in
    addition to ';' to indicate comment lines (see git-config(1) for a
    description of the syntax we’re targeting).

--doc]]--

local truth_ids = {
  ["true"]  = true,
  ["1"]     = true,
  yes       = true,
  on        = true,
  ["false"] = false,
  ["2"]     = false,
  no        = false,
  off       = false,
}

local maybe_cast = function (var)
  local bool = truth_ids[var]
  if bool ~= nil then
    return bool
  end
  return tonumber (var) or var
end
local escape = function (chr, repl)
  return (backslash * P(chr) / (repl or chr))
end
local valid_escapes     = escape "\""
                        + escape "\\"
                        + escape ("n", "\n")
                        + escape ("t", "\t")
                        + escape ("b", "\b")
local comment_char      = semicolon + gartenzaun
local comment_line      = ws * comment_char * (1 - eol)^0 * eol
local blank_line        = ws * eol
local skip_line         = comment_line + blank_line
local ini_id_char       = alpha + (dash / "_")
local ini_id            = Cs(alpha * ini_id_char^0) / stringlower
local ini_value_char    = (valid_escapes + (1 - newline - backslash - comment_char))
local ini_value         = (Cs (ini_value_char^0) / string.strip)
                        * (comment_char * (1 - eol)^0)^-1
local ini_string_char   = (valid_escapes + (1 - newline - dquote - backslash))
local ini_string        = dquote
                        * Cs (ini_string_char^0)
                        * dquote

local ini_heading_title = Ct (Cg (ini_id, "title")
                            * (ws * Cg (ini_string / stringlower, "subtitle"))^-1)
local ini_heading       = lbrk * ws
                        * Cg (ini_heading_title, "section")
                        * ws * rbrk * ws * eol

local ini_variable_full = Cg (ws
                            * ini_id
                            * ws
                            * equals
                            * ws
                            * (ini_string + (ini_value / maybe_cast))
                            * ws
                            * eol)
local ini_variable_true = Cg (ws * ini_id * ws * eol * Cc (true))
local ini_variable      = ini_variable_full
                        + ini_variable_true
                        + skip_line
local ini_variables     = Cg (Cf (Ct "" * ini_variable^0, rawset), "variables")

local ini_section       = Ct (ini_heading * ini_variables)
local ini_sections      = skip_line^0 * ini_section^0
local config            = Ct (ini_sections)

--[=[doc--

    The INI parser converts an input of the form

            [==[
              [foo]
              bar = baz
              xyzzy = no
              buzz

              [lavernica "brutalitops"]
              # It’s a locomotive that runs on us.
                laan-ev = zip zop zooey   ; jib-jab
              Crouton = "Fibrosis \"\\ # "

            ]==]

    to a Lua table of the form

            { { section = { title = "foo" },
                variables = { bar = "baz",
                              xyzzy = false,
                              buzz = true } },
              { section = { title = "boing",
                            subtitle = "brutalitops" },
                variables = { ["laan-ev"] = "zip zop zooey",
                              crouton = "Fibrosis \"\\ # " } } }

--doc]=]--

luaotfload.parsers.config = config

-- vim:ft=lua:tw=71:et:sts=4:ts=8