summaryrefslogtreecommitdiff
path: root/src/Text/Pandoc/Readers/RST.hs
blob: abbf502a1933c9d3f42e7054f85f055cf464a202 (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
{-
Copyright (C) 2006-7 John MacFarlane <jgm@berkeley.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.RST 
   Copyright   : Copyright (C) 2006-7 John MacFarlane
   License     : GNU GPL, version 2 or above 

   Maintainer  : John MacFarlane <jgm@berkeley.edu>
   Stability   : alpha
   Portability : portable

Conversion from reStructuredText to 'Pandoc' document.
-}
module Text.Pandoc.Readers.RST ( 
                                readRST
                               ) where
import Text.Pandoc.Definition
import Text.Pandoc.Shared 
import Text.ParserCombinators.Parsec
import Data.List ( findIndex, delete )

-- | Parse reStructuredText string and return Pandoc document.
readRST :: ParserState -> String -> Pandoc
readRST state str = (readWith parseRST) state (str ++ "\n\n")

--
-- Constants and data structure definitions
---

bulletListMarkers = "*+-"
underlineChars = "!\"#$&'()*+,-./:;<=>?@[\\]^_`{|}~"

-- treat these as potentially non-text when parsing inline:
specialChars = "\\`|*_<>$:[-"

--
-- parsing documents
--

isAnonKey (ref, src) = ref == [Str "_"]

isHeader :: Int -> Block -> Bool
isHeader n (Header x _) = x == n
isHeader _ _ = False

-- | Promote all headers in a list of blocks.  (Part of
-- title transformation for RST.)
promoteHeaders :: Int -> [Block] -> [Block]
promoteHeaders num ((Header level text):rest) = 
    (Header (level - num) text):(promoteHeaders num rest)
promoteHeaders num (other:rest) = other:(promoteHeaders num rest)
promoteHeaders num [] = []

-- | If list of blocks starts with a header (or a header and subheader)
-- of level that are not found elsewhere, return it as a title and
-- promote all the other headers. 
titleTransform :: [Block]              -- ^ list of blocks
               -> ([Block], [Inline])  -- ^ modified list of blocks, title
titleTransform ((Header 1 head1):(Header 2 head2):rest) =  -- title subtitle
    if (any (isHeader 1) rest) || (any (isHeader 2) rest)
       then ((Header 1 head1):(Header 2 head2):rest, [])
       else ((promoteHeaders 2 rest), head1 ++ [Str ":", Space] ++ head2)
titleTransform ((Header 1 head1):rest) =       -- title, no subtitle
    if (any (isHeader 1) rest)
       then ((Header 1 head1):rest, [])
       else ((promoteHeaders 1 rest), head1)
titleTransform blocks = (blocks, [])

parseRST = do
  -- first pass: get keys
  refs <- manyTill (referenceKey <|> (lineClump >>= return . LineClump)) eof
  let keys = map (\(KeyBlock label target) -> (label, target)) $
                 filter isKeyBlock refs
  -- second pass, with keys stripped out
  let rawlines = map (\(LineClump ln) -> ln) $ filter isLineClump refs
  setInput $ concat rawlines 
  updateState (\state -> state { stateKeys = keys })
  blocks <- parseBlocks
  let blocks' = filter (/= Null) blocks
  state <- getState
  let (blocks'', title) = if stateStandalone state
                              then titleTransform blocks'
                              else (blocks', [])
  let authors = stateAuthors state
  let date = stateDate state
  let title' = if (null title) then (stateTitle state) else title
  return $ Pandoc (Meta title' authors date) blocks''

--
-- parsing blocks
--

parseBlocks = manyTill block eof

block = choice [ codeBlock
               , rawHtmlBlock
               , rawLaTeXBlock
               , blockQuote
               , imageBlock
               , unknownDirective
               , header
               , hrule
               , list
               , fieldList
               , lineBlock
               , para
               , plain
               , nullBlock ] <?> "block"

--
-- field list
--

fieldListItem = try $ do
  char ':'
  name <- many1 alphaNum
  string ": "
  skipSpaces
  first <- manyTill anyChar newline
  rest <- many (notFollowedBy ((char ':') <|> blankline)  >>
                skipSpaces >> manyTill anyChar newline)
  return $ (name, (joinWithSep " " (first:rest)))

fieldList = try $ do
  items <- many1 fieldListItem
  blanklines
  let authors = case lookup "Authors" items of
                  Just auth -> [auth]
                  Nothing  -> map snd (filter (\(x,y) -> x == "Author") items)
  let date = case (lookup "Date" items) of
                  Just dat -> dat
                  Nothing  -> ""
  let title = case (lookup "Title" items) of
                  Just tit -> [Str tit]
                  Nothing  -> []
  let remaining = filter (\(x,y) -> (x /= "Authors") && (x /= "Author") && 
                  (x /= "Date") && (x /= "Title")) items
  let result = map (\(x,y) -> 
               Para [Strong [Str x], Str ":", Space, Str y]) remaining
  updateState (\st -> st { stateAuthors = authors, 
                           stateDate = date, 
                           stateTitle = title })
  return $ BlockQuote result

--
-- line block
--

lineBlockLine = try $ do
  string "| "
  white <- many (oneOf " \t")
  line <- manyTill inline newline
  return $ (if null white then [] else [Str white]) ++ line ++ [LineBreak]

lineBlock = try $ do
  lines <- many1 lineBlockLine
  blanklines
  return $ Para (concat lines)

--
-- paragraph block
--

para = paraBeforeCodeBlock <|> paraNormal <?> "paragraph"

codeBlockStart = try $ string "::" >> blankline >> blankline

-- paragraph that ends in a :: starting a code block
paraBeforeCodeBlock = try $ do
  result <- many1 (notFollowedBy' codeBlockStart >> inline)
  lookAhead (string "::")
  return $ Para $ if last result == Space
                     then normalizeSpaces result
                     else (normalizeSpaces result) ++ [Str ":"]

-- regular paragraph
paraNormal = try $ do 
  result <- many1 inline
  newline
  blanklines
  return $ Para $ normalizeSpaces result

plain = many1 inline >>= return . Plain . normalizeSpaces 

--
-- image block
--

imageBlock = try $ do
  string ".. image:: "
  src <- manyTill anyChar newline
  return $ Plain [Image [Str "image"] (src, "")]

--
-- header blocks
--

header = doubleHeader <|> singleHeader <?> "header"

-- a header with lines on top and bottom
doubleHeader = try $ do
  c <- oneOf underlineChars
  rest <- many (char c)  -- the top line
  let lenTop = length (c:rest)
  skipSpaces
  newline
  txt <- many1 (notFollowedBy blankline >> inline)
  pos <- getPosition
  let len = (sourceColumn pos) - 1
  if (len > lenTop) then fail "title longer than border" else return ()
  blankline              -- spaces and newline
  count lenTop (char c)  -- the bottom line
  blanklines
  -- check to see if we've had this kind of header before.  
  -- if so, get appropriate level.  if not, add to list.
  state <- getState
  let headerTable = stateHeaderTable state
  let (headerTable',level) = case findIndex (== DoubleHeader c) headerTable of
        Just ind -> (headerTable, ind + 1)
        Nothing -> (headerTable ++ [DoubleHeader c], (length headerTable) + 1)
  setState (state { stateHeaderTable = headerTable' })
  return $ Header level (normalizeSpaces txt)

-- a header with line on the bottom only
singleHeader = try $ do 
  notFollowedBy' whitespace
  txt <- many1 (do {notFollowedBy blankline; inline})
  pos <- getPosition
  let len = (sourceColumn pos) - 1
  blankline
  c <- oneOf underlineChars
  rest <- count (len - 1) (char c)
  many (char c)
  blanklines
  state <- getState
  let headerTable = stateHeaderTable state
  let (headerTable',level) = case findIndex (== SingleHeader c) headerTable of
        Just ind -> (headerTable, ind + 1)
        Nothing -> (headerTable ++ [SingleHeader c], (length headerTable) + 1)
  setState (state { stateHeaderTable = headerTable' })
  return $ Header level (normalizeSpaces txt)

--
-- hrule block
--

hruleWith chr = try $ do
  count 4 (char chr)
  skipMany (char chr)
  skipSpaces
  newline
  blanklines
  return HorizontalRule

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

--
-- code blocks
--

-- read a line indented by a given string
indentedLine indents = try $ do
  string indents
  result <- manyTill anyChar newline
  return $ result ++ "\n"

-- two or more indented lines, possibly separated by blank lines.
-- if variable = True, then any indent will work, but it must be
-- consistent through the block.
-- if variable = False, indent should be one tab or equivalent in spaces.
indentedBlock variable = try $ do 
  state <- getState
  let tabStop = stateTabStop state
  indents <- if variable
                then many1 (oneOf " \t")
                else oneOfStrings ["\t", (replicate tabStop ' ')]
  firstline <- manyTill anyChar newline
  rest <- many (choice [ indentedLine indents, 
                         try (do b <- blanklines
                                 l <- indentedLine indents
                                 return (b ++ l))])
  optional blanklines
  return $ firstline ++ "\n" ++ concat rest

codeBlock = try $ do
  codeBlockStart
  result <- indentedBlock False
  -- the False means we want one tab stop indent on each line
  return $ CodeBlock $ stripTrailingNewlines result

--
-- raw html
--

rawHtmlBlock = try $ string ".. raw:: html" >> blanklines >>
                     indentedBlock True >>= return . RawHtml

--
-- raw latex
--

rawLaTeXBlock = try $ do
  string ".. raw:: latex"
  blanklines
  result <- indentedBlock True
  return $ Para [(TeX result)]

--
-- block quotes
--

blockQuote = try $ do
  raw <- indentedBlock True
  -- parse the extracted block, which may contain various block elements:
  contents <- parseFromString parseBlocks $ raw ++ "\n\n"
  return $ BlockQuote contents

--
-- list blocks
--

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

definitionListItem = try $ do
  term <- many1Till inline endline
  raw <- indentedBlock True
  -- parse the extracted block, which may contain various block elements:
  contents <- parseFromString parseBlocks $ raw ++ "\n\n"
  return (normalizeSpaces term, contents)

definitionList = try $ do
  items <- many1 definitionListItem 
  return $ DefinitionList items

-- parses bullet list start and returns its length (inc. following whitespace)
bulletListStart = try $ do
  notFollowedBy' hrule  -- because hrules start out just like lists
  marker <- oneOf bulletListMarkers
  white <- many1 spaceChar
  return $ length (marker:white)

-- parses ordered list start and returns its length (inc following whitespace)
orderedListStart style delim = try $ do
  (_, markerLen) <- withHorizDisplacement (orderedListMarker style delim)
  white <- many1 spaceChar
  return $ markerLen + length white

-- parse a line of a list item
listLine markerLength = try $ do
  notFollowedBy blankline
  indentWith markerLength
  line <- manyTill anyChar newline
  return $ line ++ "\n"

-- indent by specified number of spaces (or equiv. tabs)
indentWith num = do
  state <- getState
  let tabStop = stateTabStop state
  if (num < tabStop)
     then count num  (char ' ')
     else choice [ try (count num (char ' ')), 
                   (try (char '\t' >> count (num - tabStop) (char ' '))) ] 

-- parse raw text for one list item, excluding start marker and continuations
rawListItem start = try $ do
  markerLength <- start
  firstLine <- manyTill anyChar newline
  restLines <- many (listLine markerLength)
  return (markerLength, (firstLine ++ "\n" ++ (concat restLines)))

-- continuation of a list item - indented and separated by blankline or 
-- (in compact lists) endline.  
-- Note: nested lists are parsed as continuations.
listContinuation markerLength = try $ do
  blanks <- many1 blankline
  result <- many1 (listLine markerLength)
  return $ blanks ++ concat result

listItem start = try $ do 
  (markerLength, first) <- rawListItem start
  rest <- many (listContinuation markerLength)
  blanks <- choice [ try (many blankline >>~ lookAhead start),
                     many1 blankline ]  -- whole list must end with blank.
  -- 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 itself contain block elements
  parsed <- parseFromString parseBlocks $ concat (first:rest) ++ blanks
  updateState (\st -> st {stateParserContext = oldContext})
  return parsed

orderedList = try $ do
  (start, style, delim) <- lookAhead (anyOrderedListMarker >>~ spaceChar)
  items <- many1 (listItem (orderedListStart style delim))
  let items' = compactify items
  return $ OrderedList (start, style, delim) items'

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

--
-- unknown directive (e.g. comment)
--

unknownDirective = try $ do
  string ".. "
  manyTill anyChar newline
  many (string "   :" >> many1 (noneOf "\n:") >> char ':' >>
        many1 (noneOf "\n") >> newline)
  optional blanklines
  return Null

-- 
-- reference key
--

referenceKey = 
  choice [imageKey, anonymousKey, regularKeyQuoted, regularKey] >>~ 
  optional blanklines

targetURI = try $ do
  skipSpaces
  optional newline
  contents <- many1 (try (many spaceChar >> newline >> 
                          many1 spaceChar >> noneOf " \t\n") <|> noneOf "\n")
  blanklines
  return contents

imageKey = try $ do
  string ".. |"
  ref <- manyTill inline (char '|')
  skipSpaces
  string "image::"
  src <- targetURI
  return $ KeyBlock (normalizeSpaces ref) (removeLeadingTrailingSpace src, "")

anonymousKey = try $ do
  oneOfStrings [".. __:", "__"]
  src <- targetURI
  state <- getState
  return $ KeyBlock [Str "_"] (removeLeadingTrailingSpace src, "")

regularKeyQuoted = try $ do
  string ".. _`"
  ref <- manyTill inline (char '`')
  char ':'
  src <- targetURI
  return $ KeyBlock (normalizeSpaces ref) (removeLeadingTrailingSpace src, "")

regularKey = try $ do
  string ".. _"
  ref <- manyTill inline (char ':')
  src <- targetURI
  return $ KeyBlock (normalizeSpaces ref) (removeLeadingTrailingSpace src, "")

 -- 
 -- inline
 --

inline = choice [ superscript
                , subscript
                , escapedChar
                , link
                , image
                , hyphens
                , strong
                , emph
                , code
                , str
                , tabchar
                , whitespace
                , endline
                , symbol ] <?> "inline"

hyphens = try $ do
  result <- many1 (char '-')
  option Space endline 
  -- don't want to treat endline after hyphen or dash as a space
  return $ Str result

escapedChar = escaped anyChar

symbol = do 
  result <- oneOf specialChars
  return $ Str [result]

-- parses inline code, between codeStart and codeEnd
code = try $ do 
  string "``"
  result <- manyTill anyChar (try (string "``"))
  return $ Code $ removeLeadingTrailingSpace $ joinWithSep " " $ lines result

emph = enclosed (char '*') (char '*') inline >>= 
       return . Emph . normalizeSpaces

strong = enclosed (string "**") (string "**") inline >>= 
         return . Strong . normalizeSpaces

interpreted role = try $ do
  optional $ try $ string "\\ "
  result <- enclosed (string $ ":" ++ role ++ ":`") (char '`') anyChar
  nextChar <- lookAhead anyChar
  try (string "\\ ") <|> lookAhead (count 1 $ oneOf " \t\n") <|> (eof >> return "")
  return [Str result]

superscript = interpreted "sup" >>= (return . Superscript)

subscript = interpreted "sub" >>= (return . Subscript)

whitespace = many1 spaceChar >> return Space <?> "whitespace"

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

str = notFollowedBy' oneWordReference >> 
      many1 (noneOf (specialChars ++ "\t\n ")) >>= return . Str

-- an endline character that can be treated as a space, not a structural break
endline = try $ do
  newline
  notFollowedBy blankline
  -- parse potential list-starts at beginning of line differently in a list:
  st <- getState
  if ((stateParserContext st) == ListItemState)
     then notFollowedBy (anyOrderedListMarker >> spaceChar) >>
          notFollowedBy' bulletListStart
     else return ()
  return Space

--
-- links
--

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

explicitLink = try $ do
  char '`'
  notFollowedBy (char '`') -- `` is marks start of inline code
  label <- manyTill inline (try (do {spaces; char '<'}))
  src <- manyTill (noneOf ">\n ") (char '>')
  skipSpaces
  string "`_"
  return $ Link (normalizeSpaces label) (removeLeadingTrailingSpace src, "")

reference = try $ do
  char '`'
  notFollowedBy (char '`')
  label <- many1Till inline (char '`') 
  char '_'
  return label

oneWordReference = do
  raw <- many1 alphaNum
  char '_'
  notFollowedBy alphaNum    -- because this_is_not a link
  return [Str raw]

referenceLink = try $ do
  label <- reference <|> oneWordReference
  key <- option label (do{char '_'; return [Str "_"]}) -- anonymous link
  state <- getState
  let keyTable = stateKeys state
  src <- case lookupKeySrc keyTable key of
           Nothing     -> fail "no corresponding key"
           Just target -> return target
  -- if anonymous link, remove first anon key so it won't be used again
  let keyTable' = if (key == [Str "_"]) -- anonymous link? 
                    then delete ([Str "_"], src) keyTable -- remove first anon key 
                    else keyTable                    
  setState $ state { stateKeys = keyTable' }
  return $ Link (normalizeSpaces label) src 

uriScheme = oneOfStrings [ "http://", "https://", "ftp://", "file://", 
                           "mailto:", "news:", "telnet:" ]

uri = try $ do
  scheme <- uriScheme
  identifier <- many1 (noneOf " \t\n")
  return $ scheme ++ identifier

autoURI = try $ do
  src <- uri
  return $ Link [Str src] (src, "")

emailChar = alphaNum <|> oneOf "-+_."

emailAddress = try $ do
  firstLetter <- alphaNum
  restAddr <- many emailChar
  let addr = firstLetter:restAddr
  char '@'
  dom <- domain
  return $ addr ++ '@':dom

domainChar = alphaNum <|> char '-'

domain = try $ do
  first <- many1 domainChar
  dom <- many1 (try (do{ char '.'; many1 domainChar }))
  return $ joinWithSep "." (first:dom)

autoEmail = try $ do
  src <- emailAddress
  return $ Link [Str src] ("mailto:" ++ src, "")

autoLink = autoURI <|> autoEmail

-- For now, we assume that all substitution references are for images.
image = try $ do
  char '|'
  ref <- manyTill inline (char '|')
  state <- getState
  let keyTable = stateKeys state
  src <- case lookupKeySrc keyTable ref of
           Nothing     -> fail "no corresponding key"
           Just target -> return target
  return $ Image (normalizeSpaces ref) src