aboutsummaryrefslogtreecommitdiff
path: root/src/Text/Pandoc/Readers/Markdown.hs
blob: 2556c0aac95cdf57438ffd411a7f6a08d6ab4c3b (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
{-
Copyright (C) 2006 John MacFarlane <jgm at berkeley dot edu>

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
-}

{- |
   Module      : Text.Pandoc.Readers.Markdown
   Copyright   : Copyright (C) 2006 John MacFarlane
   License     : GNU GPL, version 2 or above 

   Maintainer  : John MacFarlane <jgm at berkeley dot edu>
   Stability   : alpha
   Portability : portable

Conversion of markdown-formatted plain text to 'Pandoc' document.
-}
module Text.Pandoc.Readers.Markdown ( 
                                     readMarkdown 
                                    ) where

import Data.List ( findIndex, sortBy )
import Text.ParserCombinators.Pandoc
import Text.Pandoc.Definition
import Text.Pandoc.Readers.LaTeX ( rawLaTeXInline, rawLaTeXEnvironment )
import Text.Pandoc.Shared 
import Text.Pandoc.Readers.HTML ( rawHtmlInline, rawHtmlBlock, 
                                  anyHtmlBlockTag, anyHtmlInlineTag )
import Text.Pandoc.HtmlEntities ( decodeEntities )
import Text.Regex ( matchRegex, mkRegex )
import Text.ParserCombinators.Parsec

-- | Read markdown from an input string and return a Pandoc document.
readMarkdown :: ParserState -> String -> Pandoc
readMarkdown = readWith parseMarkdown

-- | Parse markdown string with default options and print result (for testing).
testString :: String -> IO ()
testString = testStringWith parseMarkdown 

--
-- Constants and data structure definitions
--

spaceChars = " \t"
endLineChars = "\n"
labelStart = '['
labelEnd = ']'
labelSep = ':'
srcStart = '('
srcEnd = ')'
imageStart = '!'
noteStart = '^'
codeStart = '`'
codeEnd = '`'
emphStart = '*'
emphEnd = '*'
emphStartAlt = '_'
emphEndAlt = '_'
autoLinkStart = '<'
autoLinkEnd = '>'
mathStart = '$'
mathEnd = '$'
bulletListMarkers = "*+-"
orderedListDelimiters = ".)"
escapeChar = '\\'
hruleChars = "*-_"
quoteChars = "'\""
atxHChar = '#'
titleOpeners = "\"'("
setextHChars = ['=','-']
blockQuoteChar = '>'
hyphenChar = '-'

-- treat these as potentially non-text when parsing inline:
specialChars = [escapeChar, labelStart, labelEnd, emphStart, emphEnd,
                emphStartAlt, emphEndAlt, codeStart, codeEnd, autoLinkEnd,
                autoLinkStart, mathStart, mathEnd, imageStart, noteStart,
                hyphenChar]

--
-- auxiliary functions
--

-- | Skip a single endline if there is one.
skipEndline = option Space endline

indentSpaces = do
  state <- getState
  let tabStop = stateTabStop state
  oneOfStrings [ "\t", (replicate tabStop ' ') ] <?> "indentation"

skipNonindentSpaces = do
  state <- getState
  let tabStop = stateTabStop state
  choice (map (\n -> (try (count n (char ' ')))) (reverse [0..(tabStop - 1)]))

--
-- document structure
--

titleLine = try (do
  char '%'
  skipSpaces
  line <- manyTill inline newline
  return line)

authorsLine = try (do
  char '%'
  skipSpaces
  authors <- sepEndBy (many1 (noneOf ",;\n")) (oneOf ",;")
  newline
  return (map removeLeadingTrailingSpace authors))

dateLine = try (do
  char '%'
  skipSpaces
  date <- many (noneOf "\n")
  newline
  return (removeTrailingSpace date))

titleBlock = try (do
  title <- option [] titleLine
  author <- option [] authorsLine
  date <- option "" dateLine
  option "" blanklines
  return (title, author, date))

-- | Returns the number assigned to a Note block
numberOfNote :: Block -> Int
numberOfNote (Note ref _) = (read ref) 
numberOfNote _ = 0 

parseMarkdown = do
  updateState (\state -> state { stateParseRaw = True }) 
  -- need to parse raw HTML, since markdown allows it
  (title, author, date) <- option ([],[],"") titleBlock
  blocks <- parseBlocks
  let blocks' = filter (/= Null) blocks
  state <- getState
  let keys = reverse $ stateKeyBlocks state
  let notes = reverse $ stateNoteBlocks state
  let sortedNotes = sortBy (\x y -> compare (numberOfNote x) 
                           (numberOfNote y)) notes
  return (Pandoc (Meta title author date) (blocks' ++ sortedNotes ++ keys))

--
-- parsing blocks
--

parseBlocks = do
  result <- manyTill block eof
  return result

block = choice [ codeBlock, note, referenceKey, header, hrule, list, 
                 blockQuote, rawHtmlBlocks, rawLaTeXEnvironment, para,
                 plain, blankBlock, nullBlock ] <?> "block"

--
-- header blocks
--

header = choice [ setextHeader, atxHeader ] <?> "header"

atxHeader = try (do
  lead <- many1 (char atxHChar)
  skipSpaces
  txt <- manyTill inline atxClosing
  return (Header (length lead) (normalizeSpaces txt)))

atxClosing = try (do
  skipMany (char atxHChar)
  skipSpaces
  newline
  option "" blanklines)

setextHeader = choice $ 
               map (\x -> setextH x) (enumFromTo 1 (length setextHChars))

setextH n = try (do
  txt <- many1 (do {notFollowedBy newline; inline})
  endline
  many1 (char (setextHChars !! (n-1)))
  skipSpaces
  newline
  option "" blanklines
  return (Header n (normalizeSpaces txt)))

--
-- hrule block
--

hruleWith chr = try (do
  skipSpaces
  char chr
  skipSpaces
  char chr
  skipSpaces
  char chr
  skipMany (oneOf (chr:spaceChars))
  newline
  option "" blanklines
  return HorizontalRule)

hrule = choice (map hruleWith hruleChars) <?> "hrule"

--
-- code blocks
--

indentedLine = try (do
  indentSpaces
  result <- manyTill anyChar newline
  return (result ++ "\n"))

-- two or more indented lines, possibly separated by blank lines
indentedBlock = try (do 
  res1 <- indentedLine
  blanks <- many blankline 
  res2 <- choice [indentedBlock, indentedLine]
  return (res1 ++ blanks ++ res2))

codeBlock = do
  result <- choice [indentedBlock, indentedLine]
  option "" blanklines
  return (CodeBlock (stripTrailingNewlines result))

--
-- note block
--

rawLine = try (do
  notFollowedBy' blankline
  notFollowedBy' noteMarker
  contents <- many1 nonEndline
  end <- option "" (do
                      newline
                      option "" indentSpaces
                      return "\n")
  return (contents ++ end))

rawLines = do
    lines <- many1 rawLine
    return (concat lines)

note = try (do
  ref <- noteMarker
  char ':'
  skipSpaces
  skipEndline
  raw <- sepBy rawLines (try (do {blankline; indentSpaces}))
  option "" blanklines
  -- parse the extracted text, which may contain various block elements:
  rest <- getInput
  setInput $ (joinWithSep "\n" raw) ++ "\n\n"
  contents <- parseBlocks
  setInput rest
  state <- getState
  let identifiers = stateNoteIdentifiers state
  case (findIndex (== ref) identifiers) of
    Just n  -> updateState (\s -> s {stateNoteBlocks = 
               (Note (show (n+1)) contents):(stateNoteBlocks s)})
    Nothing -> updateState id 
  return Null)

--
-- block quotes
--

emacsBoxQuote = try (do
  string ",----"
  manyTill anyChar newline
  raw <- manyTill (try (do 
                          char '|'
                          option ' ' (char ' ')
                          result <- manyTill anyChar newline
                          return result))
                   (string "`----")
  manyTill anyChar newline
  option "" blanklines
  return raw)

emailBlockQuoteStart = try (do
  skipNonindentSpaces
  char blockQuoteChar
  option ' ' (char ' ')
  return "> ")

emailBlockQuote = try (do
  emailBlockQuoteStart
  raw <- sepBy (many (choice [nonEndline, 
                              (try (do 
                                      endline
                                      notFollowedBy' emailBlockQuoteStart
                                      return '\n'))]))
               (try (do {newline; emailBlockQuoteStart}))
  newline <|> (do{ eof; return '\n' })
  option "" blanklines
  return raw)

blockQuote = do 
  raw <- choice [ emailBlockQuote, emacsBoxQuote ]
  -- parse the extracted block, which may contain various block elements:
  rest <- getInput
  setInput $ (joinWithSep "\n" raw) ++ "\n\n"
  contents <- parseBlocks
  setInput rest
  return (BlockQuote contents)
 
--
-- list blocks
--

list = choice [ bulletList, orderedList ] <?> "list"

bulletListStart = try (do
  option ' ' newline -- if preceded by a Plain block in a list context
  skipNonindentSpaces
  notFollowedBy' hrule  -- because hrules start out just like lists
  oneOf bulletListMarkers
  spaceChar
  skipSpaces)

orderedListStart = try (do
  option ' ' newline -- if preceded by a Plain block in a list context
  skipNonindentSpaces
  many1 digit <|> count 1 letter
  oneOf orderedListDelimiters
  oneOf spaceChars
  skipSpaces)

-- parse a line of a list item (start = parser for beginning of list item)
listLine start = try (do
  notFollowedBy' start
  notFollowedBy blankline
  notFollowedBy' (do 
                    indentSpaces
                    many (spaceChar)
                    choice [bulletListStart, orderedListStart])
  line <- manyTill anyChar newline
  return (line ++ "\n"))

-- parse raw text for one list item, excluding start marker and continuations
rawListItem start = try (do
  start
  result <- many1 (listLine start)
  blanks <- many blankline
  return ((concat result) ++ blanks))

-- continuation of a list item - indented and separated by blankline 
-- or (in compact lists) endline.
-- note: nested lists are parsed as continuations
listContinuation start = try (do
  followedBy' indentSpaces
  result <- many1 (listContinuationLine start)
  blanks <- many blankline
  return ((concat result) ++ blanks))

listContinuationLine start = try (do
  notFollowedBy' blankline
  notFollowedBy' start
  option "" indentSpaces
  result <- manyTill anyChar newline
  return (result ++ "\n"))

listItem start = try (do 
  first <- rawListItem start
  continuations <- many (listContinuation start)
  -- parsing with ListItemState forces markers at beginning of lines to
  -- count as list item markers, even if not separated by blank space.
  -- see definition of "endline"
  state <- getState
  let oldContext = stateParserContext state
  setState $ state {stateParserContext = ListItemState}
  -- parse the extracted block, which may contain various block elements:
  rest <- getInput
  let raw = concat (first:continuations)
  setInput $ raw
  contents <- parseBlocks
  setInput rest
  updateState (\st -> st {stateParserContext = oldContext})
  return contents)

orderedList = try (do
  items <- many1 (listItem orderedListStart)
  let items' = compactify items
  return (OrderedList items'))

bulletList = try (do
  items <- many1 (listItem bulletListStart)
  let items' = compactify items
  return (BulletList items'))

--
-- paragraph block
--

para = try (do 
  result <- many1 inline
  newline
  choice [ (do 
              followedBy' (oneOfStrings [">", ",----"])
              return "" ), 
           blanklines ]  
  let result' = normalizeSpaces result
  return (Para result'))

plain = do
  result <- many1 inline
  let result' = normalizeSpaces result
  return (Plain result')

-- 
-- raw html
--

rawHtmlBlocks = try (do
  htmlBlocks <- many1 rawHtmlBlock    
  let combined = concatMap (\(RawHtml str) -> str) htmlBlocks
  let combined' = if (last combined == '\n')
                     then init combined  -- strip extra newline 
                     else combined 
  return (RawHtml combined'))

-- 
-- reference key
--

referenceKey = try (do
  skipSpaces
  label <- reference
  char labelSep
  skipSpaces
  option ' ' (char autoLinkStart)
  src <- many (noneOf (titleOpeners ++ [autoLinkEnd] ++ endLineChars))
  option ' ' (char autoLinkEnd)
  tit <- option "" title 
  blanklines 
  return (Key label (Src (removeTrailingSpace src) tit))) 

-- 
-- inline
--

text = choice [ math, strong, emph, code2, code1, str, linebreak, tabchar, 
                whitespace, endline ] <?> "text"

inline = choice [ rawLaTeXInline, escapedChar, special, hyphens, text, 
                  ltSign, symbol ] <?> "inline"

special = choice [ noteRef, inlineNote, link, referenceLink, rawHtmlInline, 
                   autoLink, image ] <?> "link, inline html, note, or image"

escapedChar = escaped anyChar

ltSign = try (do
  notFollowedBy' rawHtmlBlocks -- don't return < if it starts html
  char '<'
  return (Str ['<']))

specialCharsMinusLt = filter (/= '<') specialChars

symbol = do 
  result <- oneOf specialCharsMinusLt
  return (Str [result])

hyphens = try (do
  result <- many1 (char '-')
  if (length result) == 1
     then skipEndline   -- don't want to treat endline after hyphen as a space
     else do{ string ""; return Space }
  return (Str result))

-- parses inline code, between codeStart and codeEnd
code1 = try (do 
  char codeStart
  result <- many (noneOf [codeEnd])
  char codeEnd
  -- get rid of any internal newlines
  let result' = removeLeadingTrailingSpace $ joinWithSep " " $ lines result
  return (Code result'))

-- parses inline code, between 2 codeStarts and 2 codeEnds
code2 = try (do
  string [codeStart, codeStart]
  result <- manyTill anyChar (try (string [codeEnd, codeEnd]))
  let result' = removeLeadingTrailingSpace $ joinWithSep " " $ lines result
  -- get rid of any internal newlines
  return (Code result'))

mathWord = many1 (choice [ (noneOf (" \t\n\\" ++ [mathEnd])), 
                           (try (do
                                   c <- char '\\'
                                   notFollowedBy (char mathEnd)
                                   return c))])

math = try (do
  char mathStart
  notFollowedBy space
  words <- sepBy1 mathWord (many1 space)
  char mathEnd
  return (TeX ("$" ++ (joinWithSep " " words) ++ "$")))

emph = do
  result <- choice [ (enclosed (char emphStart) (char emphEnd) inline), 
                     (enclosed (char emphStartAlt) (char emphEndAlt) inline) ]
  return (Emph (normalizeSpaces result))

strong = do
  result <- choice [ (enclosed (count 2 (char emphStart)) 
                               (count 2 (char emphEnd)) inline), 
                     (enclosed (count 2 (char emphStartAlt)) 
                               (count 2 (char emphEndAlt)) inline) ]
  return (Strong (normalizeSpaces result))

whitespace = do
  many1 (oneOf spaceChars) <?> "whitespace"
  return Space

tabchar = do
  tab
  return (Str "\t")

-- hard line break
linebreak = try (do
  oneOf spaceChars
  many1 (oneOf spaceChars) 
  endline
  return LineBreak )

nonEndline = noneOf endLineChars

str = do 
  result <- many1 ((noneOf (specialChars ++ spaceChars ++ endLineChars))) 
  return (Str (decodeEntities result))

-- an endline character that can be treated as a space, not a structural break
endline = try (do
  newline
  -- next line would allow block quotes without preceding blank line
  -- Markdown.pl does allow this, but there's a chance of a wrapped
  -- greater-than sign triggering a block quote by accident...
  -- notFollowedBy' (choice [emailBlockQuoteStart, string ",----"])  
  notFollowedBy blankline
  -- parse potential list-starts differently if in a list:
  st <- getState
  if (stateParserContext st) == ListItemState
     then do
            notFollowedBy' orderedListStart
            notFollowedBy' bulletListStart
     else option () pzero
  return Space)

--
-- links
--

-- a reference label for a link
reference = do
  char labelStart
  notFollowedBy (char noteStart)
  label <- manyTill inline (char labelEnd)
  return (normalizeSpaces label)

-- source for a link, with optional title
source = try (do 
  char srcStart
  option ' ' (char autoLinkStart)
  src <- many (noneOf ([srcEnd, autoLinkEnd] ++ titleOpeners))
  option ' ' (char autoLinkEnd)
  tit <- option "" title
  skipSpaces
  char srcEnd
  return (Src (removeTrailingSpace src) tit))

titleWith startChar endChar = try (do
  skipSpaces
  skipEndline  -- a title can be on the next line from the source
  skipSpaces
  char startChar
  tit <- manyTill (choice [ try (do {char '\\'; char endChar}), 
                            (noneOf (endChar:endLineChars)) ]) (char endChar) 
  let tit' = gsub "\"" "&quot;" tit
  return tit')

title = choice [ titleWith '(' ')', 
                 titleWith '"' '"', 
                 titleWith '\'' '\''] <?> "title"

link = choice [explicitLink, referenceLink] <?> "link"

explicitLink = try (do
  label <- reference
  src <- source 
  return (Link label src)) 

referenceLink = choice [referenceLinkDouble, referenceLinkSingle]

-- a link like [this][/url/]
referenceLinkDouble = try (do
  label <- reference
  skipSpaces
  skipEndline
  skipSpaces
  ref <- reference 
  return (Link label (Ref ref))) 

-- a link like [this]
referenceLinkSingle = try (do
  label <- reference
  return (Link label (Ref []))) 

-- a link <like.this.com>
autoLink = try (do
  notFollowedBy' anyHtmlBlockTag
  src <- between (char autoLinkStart) (char autoLinkEnd) 
         (many (noneOf (spaceChars ++ endLineChars ++ [autoLinkEnd])))
  case (matchRegex emailAddress src) of
    Just _  -> return (Link [Str src] (Src ("mailto:" ++ src) ""))
    Nothing -> return (Link [Str src] (Src src ""))) 

emailAddress = 
    mkRegex "([^@:/]+)@(([^.]+[.]?)*([^.]+))"  -- presupposes no whitespace

image = try (do
  char imageStart
  (Link label src) <- link
  return (Image label src)) 

noteMarker = try (do
  char labelStart
  char noteStart
  manyTill (noneOf " \t\n") (char labelEnd))

noteRef = try (do
  ref <- noteMarker
  state <- getState
  let identifiers = (stateNoteIdentifiers state) ++ [ref] 
  updateState (\st -> st {stateNoteIdentifiers = identifiers})
  return (NoteRef (show (length identifiers))))

inlineNote = try (do
  char noteStart
  char labelStart
  contents <- manyTill inline (char labelEnd)
  state <- getState
  let identifiers = stateNoteIdentifiers state
  let ref = show $ (length identifiers) + 1
  let noteBlocks = stateNoteBlocks state
  updateState (\st -> st {stateNoteIdentifiers = (identifiers ++ [ref]),
                          stateNoteBlocks = 
                               (Note ref [Para contents]):noteBlocks})
  return (NoteRef ref))