summaryrefslogtreecommitdiff
path: root/tex/context/base/typo-dir.lua
blob: 7e5f8c2d3a8a1c3bb79c383bf1c87bd0a6ff1b1c (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
if not modules then modules = { } end modules ['typo-dir'] = {
    version   = 1.001,
    comment   = "companion to typo-dir.mkiv",
    author    = "Hans Hagen, PRAGMA-ADE, Hasselt NL",
    copyright = "PRAGMA ADE / ConTeXt Development Team",
    license   = "see context related readme files"
}

-- todo: also use end_of_math here?

local next, type = next, type
local format, insert, sub, find, match = string.format, table.insert, string.sub, string.find, string.match
local utfchar = utf.char

-- vertical space handler

local nodes, node = nodes, node

local trace_directions = false  trackers.register("typesetters.directions", function(v) trace_directions = v end)

local report_directions = logs.reporter("typesetting","directions")

local traverse_id        = node.traverse_id
local insert_node_before = node.insert_before
local insert_node_after  = node.insert_after
local remove_node        = nodes.remove

local texattribute       = tex.attribute
local unsetvalue         = attributes.unsetvalue

local nodecodes          = nodes.nodecodes
local whatcodes          = nodes.whatcodes
local mathcodes          = nodes.mathcodes

local tasks              = nodes.tasks

local glyph_code         = nodecodes.glyph
local whatsit_code       = nodecodes.whatsit
local math_code          = nodecodes.math

local localpar_code      = whatcodes.localpar
local dir_code           = whatcodes.dir

local nodepool           = nodes.pool

local new_textdir        = nodepool.textdir

local beginmath_code     = mathcodes.beginmath
local endmath_code       = mathcodes.endmath

local fonthashes         = fonts.hashes
local fontdata           = fonthashes.identifiers
local fontchar           = fonthashes.characters

local chardata           = characters.data
local chardirs           = characters.directions -- maybe make a special mirror table

--~ Analysis by Idris:
--~
--~ 1. Assuming the reading- vs word-order distinction (bidi-char types) is governing;
--~ 2. Assuming that 'ARAB' represents an actual arabic string in raw input order, not word-order;
--~ 3. Assuming that 'BARA' represent the correct RL word order;
--~
--~ Then we have, with input: LATIN ARAB
--~
--~ \textdir TLT LATIN ARAB => LATIN BARA
--~ \textdir TRT LATIN ARAB => LATIN BARA
--~ \textdir TRT LRO LATIN ARAB => LATIN ARAB
--~ \textdir TLT LRO LATIN ARAB => LATIN ARAB
--~ \textdir TLT RLO LATIN ARAB => NITAL ARAB
--~ \textdir TRT RLO LATIN ARAB => NITAL ARAB

--  elseif d == "es"  then -- European Number Separator
--  elseif d == "et"  then -- European Number Terminator
--  elseif d == "cs"  then -- Common Number Separator
--  elseif d == "nsm" then -- Non-Spacing Mark
--  elseif d == "bn"  then -- Boundary Neutral
--  elseif d == "b"   then -- Paragraph Separator
--  elseif d == "s"   then -- Segment Separator
--  elseif d == "ws"  then -- Whitespace
--  elseif d == "on"  then -- Other Neutrals

typesetters.directions = typesetters.directions or { }
local directions       = typesetters.directions

local a_state          = attributes.private('state')
local a_directions     = attributes.private('directions')

local skipmath         = true
local strip            = false

-- todo: delayed inserts here
-- todo: get rid of local functions here

-- beware, math adds whatsits afterwards so that will mess things up

local finish, autodir, embedded, override, done = nil, 0, 0, 0, false
local list, glyphs = nil, false
local finished, finidir, finipos = nil, nil, 1
local head, current, inserted = nil, nil, nil

local function finish_auto_before()
    head, inserted = insert_node_before(head,current,new_textdir("-"..finish))
    finished, finidir = inserted, finish
    if trace_directions then
        insert(list,#list,format("auto finish inserted before: %s",finish))
        finipos = #list-1
    end
    finish, autodir, done = nil, 0, true
end

local function finish_auto_after()
    head, current = insert_node_after(head,current,new_textdir("-"..finish))
    finished, finidir = current, finish
    if trace_directions then
        list[#list+1] = format("auto finish inserted after: %s",finish)
        finipos = #list
    end
    finish, autodir, done = nil, 0, true
end

local function force_auto_left_before()
    if finish then
        finish_auto_before()
    end
    if embedded >= 0 then
        finish, autodir, done = "TLT", 1, true
    else
        finish, autodir, done = "TRT", -1, true
    end
    if finidir == finish then
        head = remove_node(head,finished,true)
        if trace_directions then
            list[finipos] = list[finipos] .. " (deleted afterwards)"
            insert(list,#list,format("start text dir %s (embedded: %s)",finish,embedded))
        end
    else
        head, inserted = insert_node_before(head,current,new_textdir("+"..finish))
        if trace_directions then
            insert(list,#list,format("start text dir %s (embedded: %s)",finish,embedded))
        end
    end
end

local function force_auto_right_before()
    if finish then
        finish_auto_before()
    end
    if embedded <= 0 then
        finish, autodir, done = "TRT", -1, true
    else
        finish, autodir, done = "TLT", 1, true
    end
    if finidir == finish then
        head = remove_node(head,finished,true)
        if trace_directions then
            list[finipos] = list[finipos] .. " (deleted afterwards)"
            insert(list,#list,format("start text dir %s (embedded: %s)",finish,embedded))
        end
    else
        head, inserted = insert_node_before(head,current,new_textdir("+"..finish))
        if trace_directions then
            insert(list,#list,format("start text dir %s (embedded: %s)",finish,embedded))
        end
    end
end

-- todo: use new dir functions

local s_isol = fonts.analyzers.states.isol

function directions.process(namespace,attribute,start) -- todo: make faster
    if not start.next then
        return start, false
    end
    head, current, inserted = start, start, nil
    finish, autodir, embedded, override, done = nil, 0, 0, 0, false
    list, glyphs = trace_directions and { }, false
    finished, finidir, finipos = nil, nil, 1
    local stack, top, obsolete = { }, 0, { }
    local lro, rlo, prevattr, inmath = false, false, 0, false
    while current do
        local id = current.id
        if skipmath and id == math_code then
            local subtype = current.subtype
            if subtype == beginmath_code then
                inmath = true
            elseif subtype == endmath_code then
                inmath = false
            else
                -- todo
            end
            current = current.next
        elseif inmath then
            current = current.next
        else
            local attr = current[attribute]
            if attr and attr > 0 then
             -- current[attribute] = unsetvalue -- slow, needed?
                if attr == 1 then
                    -- bidi parsing mode
                elseif attr ~= prevattr then
                    -- no pop, grouped driven (2=normal,3=lro,4=rlo)
                    if attr == 3 then
                        if trace_directions then
                            list[#list+1] = format("override right -> left (lro) (bidi=%s)",attr)
                        end
                        lro, rlo = true, false
                    elseif attr == 4 then
                        if trace_directions then
                            list[#list+1] = format("override left -> right (rlo) (bidi=%s)",attr)
                        end
                        lro, rlo = false, true
                    else
                        if trace_directions and
                            current ~= head then list[#list+1] = format("override reset (bidi=%s)",attr)
                        end
                        lro, rlo = false, false
                    end
                    prevattr = attr
                end
            end
            if id == glyph_code then
                glyphs = true
                if attr and attr > 0 then
                    local char = current.char
                    local d = chardirs[char]
                    if rlo or override > 0 then
                        if d == "l" then
                            if trace_directions then
                                list[#list+1] = format("char %s (%s / U+%04X) of class %s overidden to r (bidi=%s)",utfchar(char),char,char,d,attr)
                            end
                            d = "r"
                        elseif trace_directions then
                            if d == "lro" or d == "rlo" or d == "pdf" then -- else side effects on terminal
                                list[#list+1] = format("override char of class %s (bidi=%s)",d,attr)
                            else -- todo: rle lre
                                list[#list+1] = format("char %s (%s / U+%04X) of class %s (bidi=%s)",utfchar(char),char,char,d,attr)
                            end
                        end
                    elseif lro or override < 0 then
                        if d == "r" or d == "al" then
                            current[a_state] = s_isol -- maybe better have a special bidi attr value -> override (9) -> todo
                            if trace_directions then
                                list[#list+1] = format("char %s (%s / U+%04X) of class %s overidden to l (bidi=%s) (state=isol)",utfchar(char),char,char,d,attr)
                            end
                            d = "l"
                        elseif trace_directions then
                            if d == "lro" or d == "rlo" or d == "pdf" then -- else side effects on terminal
                                list[#list+1] = format("override char of class %s (bidi=%s)",d,attr)
                            else -- todo: rle lre
                                list[#list+1] = format("char %s (%s / U+%04X) of class %s (bidi=%s)",utfchar(char),char,char,d,attr)
                            end
                        end
                    elseif trace_directions then
                        if d == "lro" or d == "rlo" or d == "pdf" then -- else side effects on terminal
                            list[#list+1] = format("override char of class %s (bidi=%s)",d,attr)
                        else -- todo: rle lre
                            list[#list+1] = format("char %s (%s / U+%04X) of class %s (bidi=%s)",utfchar(char),char,char,d,attr)
                        end
                    end
                    if d == "on" then
                        local mirror = chardata[char].mirror -- maybe make a special mirror table
                        if mirror and fontchar[current.font][mirror] then
                            -- todo: set attribute
                            if autodir < 0 then
                                current.char = mirror
                                done = true
                            --~ elseif left or autodir > 0 then
                            --~     if not is_right(current.prev) then
                            --~         current.char = mirror
                            --~         done = true
                            --~     end
                            end
                        end
                    elseif d == "l" or d == "en" then -- european number
                        if autodir <= 0 then -- could be option
                            force_auto_left_before()
                        end
                    elseif d == "r" or d == "al" then -- arabic number
                        if autodir >= 0 then
                            force_auto_right_before()
                        end
                    elseif d == "an" then -- arabic number
                        -- actually this is language dependent ...
--                         if autodir <= 0 then
--                             force_auto_left_before()
--                         end
                        if autodir >= 0 then
                            force_auto_right_before()
                        end
                    elseif d == "lro" then -- Left-to-Right Override -> right becomes left
                        if trace_directions then
                            list[#list+1] = "override right -> left"
                        end
                        top = top + 1
                        stack[top] = { override, embedded }
                        override = -1
                        obsolete[#obsolete+1] = current
                    elseif d == "rlo" then -- Right-to-Left Override -> left becomes right
                        if trace_directions then
                            list[#list+1] = "override left -> right"
                        end
                        top = top + 1
                        stack[top] = { override, embedded }
                        override = 1
                        obsolete[#obsolete+1] = current
                    elseif d == "lre" then -- Left-to-Right Embedding -> TLT
                        if trace_directions then
                            list[#list+1] = "embedding left -> right"
                        end
                        top = top + 1
                        stack[top] = { override, embedded }
                        embedded = 1
                        obsolete[#obsolete+1] = current
                    elseif d == "rle" then -- Right-to-Left Embedding -> TRT
                        if trace_directions then
                            list[#list+1] = "embedding right -> left"
                        end
                        top = top + 1
                        stack[top] = { override, embedded }
                        embedded = -1 -- was 1
                        obsolete[#obsolete+1] = current
                    elseif d == "pdf" then -- Pop Directional Format
                    --  override = 0
                        if top > 0 then
                            local s = stack[top]
                            override, embedded = s[1], s[2]
                            top = top - 1
                            if trace_directions then
                                list[#list+1] = format("state: override: %s, embedded: %s, autodir: %s",override,embedded,autodir)
                            end
                        else
                            if trace_directions then
                                list[#list+1] = "pop (error, too many pops)"
                            end
                        end
                        obsolete[#obsolete+1] = current
                    end
                elseif trace_directions then
                    local char = current.char
                    local d = chardirs[char]
                    list[#list+1] = format("char %s (%s / U+%04X) of class %s (no bidi)",utfchar(char),char,char,d or "?")
                end
            elseif id == whatsit_code then
                if finish then
                    finish_auto_before()
                end
                local subtype = current.subtype
                if subtype == localpar_code then
                    local dir = current.dir
                    local d = sub(dir,2,2)
                    if d == 'R' then -- find(dir,".R.") / dir == "TRT"
                        autodir = -1
                    else
                        autodir = 1
                    end
                 -- embedded = autodir
                    if trace_directions then
                        list[#list+1] = format("pardir %s",dir)
                    end
                elseif subtype == dir_code then
                    local dir = current.dir
                 -- local sign = sub(dir,1,1)
                 -- local dire = sub(dir,3,3)
                    local sign, dire = match(dir,"^(.).(.)")
                    if dire == "R" then
                        if sign == "+" then
                            finish, autodir = "TRT", -1
                        else
                            finish, autodir = nil, 0
                        end
                    else
                        if sign == "+" then
                            finish, autodir = "TLT", 1
                        else
                            finish, autodir = nil, 0
                        end
                    end
                    if trace_directions then
                        list[#list+1] = format("textdir %s",dir)
                    end
                end
            else
                if trace_directions then
                    list[#list+1] = format("node %s (subtype %s)",nodecodes[id],current.subtype)
                end
                if finish then
                    finish_auto_before()
                end
            end
            local cn = current.next
            if not cn then
                if finish then
                    finish_auto_after()
                end
            end
            current = cn
        end
    end
    if trace_directions and glyphs then
        report_directions("start log")
        for i=1,#list do
            report_directions("%02i: %s",i,list[i])
        end
        report_directions("stop log")
    end
    if done and strip then
        local n = #obsolete
        if n > 0 then
            for i=1,n do
                remove_node(head,obsolete[i],true)
            end
            report_directions("%s character nodes removed",n)
        end
    end
    return head, done
end

--~         local function is_right(n) -- keep !
--~             if n then
--~                 local id = n.id
--~                 if id == glyph_code then
--~                     local attr = n[attribute]
--~                     if attr and attr > 0 then
--~                         local d = chardirs[n.char]
--~                         if d == "r" or d == "al" then -- override
--~                             return true
--~                         end
--~                     end
--~                 end
--~             end
--~             return false
--~         end

--~ function directions.enable()
--~     tasks.enableaction("processors","directions.handler")
--~ end

local enabled = false

function directions.set(n) -- todo: names and numbers
    if not enabled then
        if trace_directions then
            report_breakpoints("enabling directions handler")
        end
        tasks.enableaction("processors","typesetters.directions.handler")
        enabled = true
    end
    if not n or n == 0 then
        n = unsetvalue
        -- maybe tracing
    end
    texattribute[a_directions] = n
end

commands.setdirection = directions.set

directions.handler = nodes.installattributehandler {
    name = "directions",
    namespace = directions,
    processor = directions.process,
}