aboutsummaryrefslogtreecommitdiff
path: root/src/Text/Pandoc/Writers/Markdown.hs
blob: f42a1b54cfbb262725a4ac82bc4844e68104d700 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
{-# LANGUAGE OverloadedStrings, TupleSections, ScopedTypeVariables #-}
{-
Copyright (C) 2006-2014 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.Writers.Markdown
   Copyright   : Copyright (C) 2006-2014 John MacFarlane
   License     : GNU GPL, version 2 or above

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

Conversion of 'Pandoc' documents to markdown-formatted plain text.

Markdown:  <http://daringfireball.net/projects/markdown/>
-}
module Text.Pandoc.Writers.Markdown (writeMarkdown, writePlain) where
import Text.Pandoc.Definition
import Text.Pandoc.Walk
import Text.Pandoc.Templates (renderTemplate')
import Text.Pandoc.Shared
import Text.Pandoc.Writers.Shared
import Text.Pandoc.Options
import Text.Pandoc.Parsing hiding (blankline, char, space)
import Data.List ( group, isPrefixOf, find, intersperse, transpose, sortBy )
import Data.Char ( isSpace, isPunctuation )
import Data.Ord ( comparing )
import Text.Pandoc.Pretty
import Control.Monad.State
import qualified Data.Set as Set
import Text.Pandoc.Writers.HTML (writeHtmlString)
import Text.Pandoc.Readers.TeXMath (readTeXMath')
import Text.HTML.TagSoup (renderTags, parseTags, isTagText, Tag(..))
import Network.URI (isURI)
import Data.Default
import Data.Yaml (Value(Object,String,Array,Bool,Number))
import qualified Data.HashMap.Strict as H
import qualified Data.Vector as V
import qualified Data.Text as T

type Notes = [[Block]]
type Refs = [([Inline], Target)]
data WriterState = WriterState { stNotes :: Notes
                               , stRefs  :: Refs
                               , stIds   :: [String]
                               , stPlain :: Bool }
instance Default WriterState
  where def = WriterState{ stNotes = [], stRefs = [], stIds = [], stPlain = False }

-- | Convert Pandoc to Markdown.
writeMarkdown :: WriterOptions -> Pandoc -> String
writeMarkdown opts document =
  evalState (pandocToMarkdown opts{
                  writerWrapText = writerWrapText opts &&
                  not (isEnabled Ext_hard_line_breaks opts) }
             document) def

-- | Convert Pandoc to plain text (like markdown, but without links,
-- pictures, or inline formatting).
writePlain :: WriterOptions -> Pandoc -> String
writePlain opts document =
  evalState (pandocToMarkdown opts{
                 writerExtensions = Set.delete Ext_escaped_line_breaks $
                                    writerExtensions opts }
              document') def{ stPlain = True }
    where document' = plainify document

plainify :: Pandoc -> Pandoc
plainify = walk go
  where go :: Inline -> Inline
        go (Emph xs) = SmallCaps xs
        go (Strong xs) = SmallCaps xs
        go (Strikeout xs) = SmallCaps xs
        go (Superscript xs) = SmallCaps xs
        go (Subscript xs) = SmallCaps xs
        go (SmallCaps xs) = SmallCaps xs
        go (Code _ s) = Str s
        go (Math _ s) = Str s
        go (RawInline _ _) = Str ""
        go (Link xs _) = SmallCaps xs
        go (Image xs _) = SmallCaps $ [Str "["] ++ xs ++ [Str "]"]
        go (Cite _ cits) = SmallCaps cits
        go x = x

pandocTitleBlock :: Doc -> [Doc] -> Doc -> Doc
pandocTitleBlock tit auths dat =
  hang 2 (text "% ") tit <> cr <>
  hang 2 (text "% ") (vcat $ map nowrap auths) <> cr <>
  hang 2 (text "% ") dat <> cr

mmdTitleBlock :: Value -> Doc
mmdTitleBlock (Object hashmap) =
  vcat $ map go $ sortBy (comparing fst) $ H.toList hashmap
  where go (k,v) =
          case (text (T.unpack k), v) of
               (k', Array vec)
                 | V.null vec     -> empty
                 | otherwise      -> k' <> ":" <> space <>
                                      hcat (intersperse "; "
                                           (map fromstr $ V.toList vec))
               (_, String "")  -> empty
               (k', x)         -> k' <> ":" <> space <> nest 2 (fromstr x)
        fromstr (String s) = text (removeBlankLines $ T.unpack s)
        fromstr (Bool b)   = text (show b)
        fromstr (Number n) = text (show n)
        fromstr _          = empty
        -- blank lines not allowed in MMD metadata - we replace with .
        removeBlankLines   = trimr . unlines . map (\x ->
                               if all isSpace x then "." else x) . lines
mmdTitleBlock _ = empty

plainTitleBlock :: Doc -> [Doc] -> Doc -> Doc
plainTitleBlock tit auths dat =
  tit <> cr <>
  (hcat (intersperse (text "; ") auths)) <> cr <>
  dat <> cr

yamlMetadataBlock :: Value -> Doc
yamlMetadataBlock v = "---" $$ (jsonToYaml v) $$ "..."

jsonToYaml :: Value -> Doc
jsonToYaml (Object hashmap) =
  vcat $ map (\(k,v) ->
          case (text (T.unpack k), v, jsonToYaml v) of
               (k', Array vec, x)
                 | V.null vec     -> empty
                 | otherwise      -> (k' <> ":") $$ x
               (k', Object _, x)  -> (k' <> ":") $$ nest 2 x
               (_, String "", _)  -> empty
               (k', _, x)         -> k' <> ":" <> space <> hang 2 "" x)
       $ sortBy (comparing fst) $ H.toList hashmap
jsonToYaml (Array vec) =
  vcat $ map (\v -> hang 2 "- " (jsonToYaml v)) $ V.toList vec
jsonToYaml (String "") = empty
jsonToYaml (String s) =
  case T.unpack s of
     x | '\n' `elem` x -> hang 2 ("|" <> cr) $ text x
       | not (any isPunctuation x) -> text x
       | otherwise     -> text $ "'" ++ substitute "'" "''" x ++ "'"
jsonToYaml (Bool b) = text $ show b
jsonToYaml (Number n) = text $ show n
jsonToYaml _ = empty

-- | Return markdown representation of document.
pandocToMarkdown :: WriterOptions -> Pandoc -> State WriterState String
pandocToMarkdown opts (Pandoc meta blocks) = do
  let colwidth = if writerWrapText opts
                    then Just $ writerColumns opts
                    else Nothing
  isPlain <- gets stPlain
  metadata <- metaToJSON opts
               (fmap (render colwidth) . blockListToMarkdown opts)
               (fmap (render colwidth) . inlineListToMarkdown opts)
               meta
  let title' = maybe empty text $ getField "title" metadata
  let authors' = maybe [] (map text) $ getField "author" metadata
  let date' = maybe empty text $ getField "date" metadata
  let titleblock = case writerStandalone opts of
                        True | isPlain ->
                                plainTitleBlock title' authors' date'
                             | isEnabled Ext_yaml_metadata_block opts ->
                                 yamlMetadataBlock metadata
                             | isEnabled Ext_pandoc_title_block opts ->
                                 pandocTitleBlock title' authors' date'
                             | isEnabled Ext_mmd_title_block opts ->
                                 mmdTitleBlock metadata
                             | otherwise -> empty
                        False -> empty
  let headerBlocks = filter isHeaderBlock blocks
  let toc = if writerTableOfContents opts
               then tableOfContents opts headerBlocks
               else empty
  -- Strip off final 'references' header if markdown citations enabled
  let blocks' = if not isPlain && isEnabled Ext_citations opts
                   then case reverse blocks of
                             (Div (_,["references"],_) _):xs -> reverse xs
                             _ -> blocks
                   else blocks
  body <- blockListToMarkdown opts blocks'
  st <- get
  notes' <- notesToMarkdown opts (reverse $ stNotes st)
  st' <- get  -- note that the notes may contain refs
  refs' <- refsToMarkdown opts (reverse $ stRefs st')
  let render' :: Doc -> String
      render' = render colwidth
  let main = render' $ body <>
               (if isEmpty notes' then empty else blankline <> notes') <>
               (if isEmpty refs' then empty else blankline <> refs')
  let context  = defField "toc" (render' toc)
               $ defField "body" main
               $ (if isNullMeta meta
                     then id
                     else defField "titleblock" (render' titleblock))
               $ metadata
  if writerStandalone opts
     then return $ renderTemplate' (writerTemplate opts) context
     else return main

-- | Return markdown representation of reference key table.
refsToMarkdown :: WriterOptions -> Refs -> State WriterState Doc
refsToMarkdown opts refs = mapM (keyToMarkdown opts) refs >>= return . vcat

-- | Return markdown representation of a reference key.
keyToMarkdown :: WriterOptions
              -> ([Inline], (String, String))
              -> State WriterState Doc
keyToMarkdown opts (label, (src, tit)) = do
  label' <- inlineListToMarkdown opts label
  let tit' = if null tit
                then empty
                else space <> "\"" <> text tit <> "\""
  return $ nest 2 $ hang 2
            ("[" <> label' <> "]:" <> space) (text src <> tit')

-- | Return markdown representation of notes.
notesToMarkdown :: WriterOptions -> [[Block]] -> State WriterState Doc
notesToMarkdown opts notes =
  mapM (\(num, note) -> noteToMarkdown opts num note) (zip [1..] notes) >>=
  return . vsep

-- | Return markdown representation of a note.
noteToMarkdown :: WriterOptions -> Int -> [Block] -> State WriterState Doc
noteToMarkdown opts num blocks = do
  contents  <- blockListToMarkdown opts blocks
  let num' = text $ writerIdentifierPrefix opts ++ show num
  let marker = if isEnabled Ext_footnotes opts
                  then text "[^" <> num' <> text "]:"
                  else text "[" <> num' <> text "]"
  let markerSize = 4 + offset num'
  let spacer = case writerTabStop opts - markerSize of
                     n | n > 0  -> text $ replicate n ' '
                     _          -> text " "
  return $ if isEnabled Ext_footnotes opts
              then hang (writerTabStop opts) (marker <> spacer) contents
              else marker <> spacer <> contents

-- | Escape special characters for Markdown.
escapeString :: String -> String
escapeString = escapeStringUsing markdownEscapes
  where markdownEscapes = backslashEscapes "\\`*_$<>#~^"

-- | Construct table of contents from list of header blocks.
tableOfContents :: WriterOptions -> [Block] -> Doc
tableOfContents opts headers =
  let opts' = opts { writerIgnoreNotes = True }
      contents = BulletList $ map (elementToListItem opts) $ hierarchicalize headers
  in  evalState (blockToMarkdown opts' contents) def

-- | Converts an Element to a list item for a table of contents,
elementToListItem :: WriterOptions -> Element -> [Block]
elementToListItem opts (Sec lev _ _ headerText subsecs)
  = Plain headerText :
    [ BulletList (map (elementToListItem opts) subsecs) |
      not (null subsecs) && lev < writerTOCDepth opts ]
elementToListItem _ (Blk _) = []

attrsToMarkdown :: Attr -> Doc
attrsToMarkdown attribs = braces $ hsep [attribId, attribClasses, attribKeys]
        where attribId = case attribs of
                                ([],_,_) -> empty
                                (i,_,_)  -> "#" <> text i
              attribClasses = case attribs of
                                (_,[],_) -> empty
                                (_,cs,_) -> hsep $
                                            map (text . ('.':))
                                            cs
              attribKeys = case attribs of
                                (_,_,[]) -> empty
                                (_,_,ks) -> hsep $
                                            map (\(k,v) -> text k
                                              <> "=\"" <> text v <> "\"") ks

-- | Ordered list start parser for use in Para below.
olMarker :: Parser [Char] ParserState Char
olMarker = do (start, style', delim) <- anyOrderedListMarker
              if delim == Period &&
                          (style' == UpperAlpha || (style' == UpperRoman &&
                          start `elem` [1, 5, 10, 50, 100, 500, 1000]))
                          then spaceChar >> spaceChar
                          else spaceChar

-- | True if string begins with an ordered list marker
beginsWithOrderedListMarker :: String -> Bool
beginsWithOrderedListMarker str =
  case runParser olMarker defaultParserState "para start" (take 10 str) of
         Left  _  -> False
         Right _  -> True

-- | Convert Pandoc block element to markdown.
blockToMarkdown :: WriterOptions -- ^ Options
                -> Block         -- ^ Block element
                -> State WriterState Doc
blockToMarkdown _ Null = return empty
blockToMarkdown opts (Div attrs ils) = do
  isPlain <- gets stPlain
  contents <- blockListToMarkdown opts ils
  return $ if isPlain || not (isEnabled Ext_markdown_in_html_blocks opts)
              then contents <> blankline
              else tagWithAttrs "div" attrs <> blankline <>
                      contents <> blankline <> "</div>" <> blankline
blockToMarkdown opts (Plain inlines) = do
  contents <- inlineListToMarkdown opts inlines
  -- escape if para starts with ordered list marker
  st <- get
  let colwidth = if writerWrapText opts
                    then Just $ writerColumns opts
                    else Nothing
  let rendered = render colwidth contents
  let escapeDelimiter (x:xs) | x `elem` ".()" = '\\':x:xs
                             | otherwise      = x : escapeDelimiter xs
      escapeDelimiter []                      = []
  let contents' = if isEnabled Ext_all_symbols_escapable opts &&
                     not (stPlain st) && beginsWithOrderedListMarker rendered
                     then text $ escapeDelimiter rendered
                     else contents
  return $ contents' <> cr
-- title beginning with fig: indicates figure
blockToMarkdown opts (Para [Image alt (src,'f':'i':'g':':':tit)]) =
  blockToMarkdown opts (Para [Image alt (src,tit)])
blockToMarkdown opts (Para inlines) =
  (<> blankline) `fmap` blockToMarkdown opts (Plain inlines)
blockToMarkdown opts (RawBlock f str)
  | f == "html" = do
    st <- get
    if stPlain st
       then return empty
       else return $ if isEnabled Ext_markdown_attribute opts
                        then text (addMarkdownAttribute str) <> text "\n"
                        else text str <> text "\n"
  | f `elem` ["latex", "tex", "markdown"] = do
    st <- get
    if stPlain st
       then return empty
       else return $ text str <> text "\n"
blockToMarkdown _ (RawBlock _ _) = return empty
blockToMarkdown _ HorizontalRule =
  return $ blankline <> text "* * * * *" <> blankline
blockToMarkdown opts (Header level attr inlines) = do
  -- we calculate the id that would be used by auto_identifiers
  -- so we know whether to print an explicit identifier
  ids <- gets stIds
  let autoId = uniqueIdent inlines ids
  modify $ \st -> st{ stIds = autoId : ids }
  let attr' = case attr of
                   ("",[],[]) -> empty
                   (id',[],[]) | isEnabled Ext_auto_identifiers opts
                                 && id' == autoId -> empty
                   (id',_,_)   | isEnabled Ext_mmd_header_identifiers opts ->
                                    space <> brackets (text id')
                   _ | isEnabled Ext_header_attributes opts ->
                                    space <> attrsToMarkdown attr
                     | otherwise -> empty
  contents <- inlineListToMarkdown opts inlines
  st <- get
  let setext = writerSetextHeaders opts
  return $ nowrap
         $ case level of
            1 | setext ->
                  contents <> attr' <> cr <> text (replicate (offset contents) '=') <>
                  blankline
            2 | setext ->
                  contents <> attr' <> cr <> text (replicate (offset contents) '-') <>
                  blankline
            -- ghc interprets '#' characters in column 1 as linenum specifiers.
            _ | stPlain st || isEnabled Ext_literate_haskell opts ->
                contents <> blankline
            _ -> text (replicate level '#') <> space <> contents <> attr' <> blankline
blockToMarkdown opts (CodeBlock (_,classes,_) str)
  | "haskell" `elem` classes && "literate" `elem` classes &&
    isEnabled Ext_literate_haskell opts =
  return $ prefixed "> " (text str) <> blankline
blockToMarkdown opts (CodeBlock attribs str) = return $
  case attribs == nullAttr of
     False | isEnabled Ext_backtick_code_blocks opts ->
          backticks <> attrs <> cr <> text str <> cr <> backticks <> blankline
           | isEnabled Ext_fenced_code_blocks opts ->
          tildes <> attrs <> cr <> text str <> cr <> tildes <> blankline
     _ -> nest (writerTabStop opts) (text str) <> blankline
   where tildes    = text $ case [ln | ln <- lines str, all (=='~') ln] of
                               [] -> "~~~~"
                               xs -> case maximum $ map length xs of
                                          n | n < 3 -> "~~~~"
                                            | otherwise -> replicate (n+1) '~'
         backticks = text $ case [ln | ln <- lines str, all (=='`') ln] of
                               [] -> "```"
                               xs -> case maximum $ map length xs of
                                          n | n < 3 -> "```"
                                            | otherwise -> replicate (n+1) '`'
         attrs  = if isEnabled Ext_fenced_code_attributes opts
                     then nowrap $ " " <> attrsToMarkdown attribs
                     else case attribs of
                                (_,[cls],_) -> " " <> text cls
                                _           -> empty
blockToMarkdown opts (BlockQuote blocks) = do
  st <- get
  -- if we're writing literate haskell, put a space before the bird tracks
  -- so they won't be interpreted as lhs...
  let leader = if isEnabled Ext_literate_haskell opts
                  then " > "
                  else if stPlain st
                          then "  "
                          else "> "
  contents <- blockListToMarkdown opts blocks
  return $ (prefixed leader contents) <> blankline
blockToMarkdown opts t@(Table caption aligns widths headers rows) =  do
  caption' <- inlineListToMarkdown opts caption
  let caption'' = if null caption || not (isEnabled Ext_table_captions opts)
                     then empty
                     else blankline <> ": " <> caption' <> blankline
  rawHeaders <- mapM (blockListToMarkdown opts) headers
  rawRows <- mapM (mapM (blockListToMarkdown opts)) rows
  let isSimple = all (==0) widths
  let isPlainBlock (Plain _) = True
      isPlainBlock _         = False
  let hasBlocks = not (all isPlainBlock $ concat . concat $ headers:rows)
  (nst,tbl) <- case True of
                _ | isSimple &&
                    isEnabled Ext_simple_tables opts -> fmap (nest 2,) $
                         pandocTable opts (all null headers) aligns widths
                             rawHeaders rawRows
                  | isSimple &&
                    isEnabled Ext_pipe_tables opts -> fmap (id,) $
                         pipeTable (all null headers) aligns rawHeaders rawRows
                  | not hasBlocks &&
                    isEnabled Ext_multiline_tables opts -> fmap (nest 2,) $
                         pandocTable opts (all null headers) aligns widths
                             rawHeaders rawRows
                  | isEnabled Ext_grid_tables opts -> fmap (id,) $
                         gridTable opts (all null headers) aligns widths
                             rawHeaders rawRows
                  | otherwise -> fmap (id,) $
                         return $ text $ writeHtmlString def
                                $ Pandoc nullMeta [t]
  return $ nst $ tbl $$ blankline $$ caption'' $$ blankline
blockToMarkdown opts (BulletList items) = do
  contents <- mapM (bulletListItemToMarkdown opts) items
  return $ cat contents <> blankline
blockToMarkdown opts (OrderedList (start,sty,delim) items) = do
  let start' = if isEnabled Ext_startnum opts then start else 1
  let sty'   = if isEnabled Ext_fancy_lists opts then sty else DefaultStyle
  let delim' = if isEnabled Ext_fancy_lists opts then delim else DefaultDelim
  let attribs = (start', sty', delim')
  let markers  = orderedListMarkers attribs
  let markers' = map (\m -> if length m < 3
                               then m ++ replicate (3 - length m) ' '
                               else m) markers
  contents <- mapM (\(item, num) -> orderedListItemToMarkdown opts item num) $
              zip markers' items
  return $ cat contents <> blankline
blockToMarkdown opts (DefinitionList items) = do
  contents <- mapM (definitionListItemToMarkdown opts) items
  return $ cat contents <> blankline

addMarkdownAttribute :: String -> String
addMarkdownAttribute s =
  case span isTagText $ reverse $ parseTags s of
       (xs,(TagOpen t attrs:rest)) ->
            renderTags $ reverse rest ++ (TagOpen t attrs' : reverse xs)
              where attrs' = ("markdown","1"):[(x,y) | (x,y) <- attrs,
                                 x /= "markdown"]
       _ -> s

pipeTable :: Bool -> [Alignment] -> [Doc] -> [[Doc]] -> State WriterState Doc
pipeTable headless aligns rawHeaders rawRows = do
  let torow cs = nowrap $ text "|" <>
                 hcat (intersperse (text "|") $ map chomp cs) <> text "|"
  let toborder (a, h) = let wid = max (offset h) 3
                        in  text $ case a of
                             AlignLeft    -> ':':replicate (wid - 1) '-'
                             AlignCenter  -> ':':replicate (wid - 2) '-' ++ ":"
                             AlignRight   -> replicate (wid - 1) '-' ++ ":"
                             AlignDefault -> replicate wid '-'
  let header = if headless then empty else torow rawHeaders
  let border = torow $ map toborder $ zip aligns rawHeaders
  let body   = vcat $ map torow rawRows
  return $ header $$ border $$ body

pandocTable :: WriterOptions -> Bool -> [Alignment] -> [Double]
            -> [Doc] -> [[Doc]] -> State WriterState Doc
pandocTable opts headless aligns widths rawHeaders rawRows =  do
  let isSimple = all (==0) widths
  let alignHeader alignment = case alignment of
                                AlignLeft    -> lblock
                                AlignCenter  -> cblock
                                AlignRight   -> rblock
                                AlignDefault -> lblock
  let numChars = maximum . map offset
  let widthsInChars = if isSimple
                         then map ((+2) . numChars)
                              $ transpose (rawHeaders : rawRows)
                         else map
                              (floor . (fromIntegral (writerColumns opts) *))
                              widths
  let makeRow = hcat . intersperse (lblock 1 (text " ")) .
                   (zipWith3 alignHeader aligns widthsInChars)
  let rows' = map makeRow rawRows
  let head' = makeRow rawHeaders
  let maxRowHeight = maximum $ map height (head':rows')
  let underline = cat $ intersperse (text " ") $
                  map (\width -> text (replicate width '-')) widthsInChars
  let border = if maxRowHeight > 1
                  then text (replicate (sum widthsInChars +
                          length widthsInChars - 1) '-')
                  else if headless
                          then underline
                          else empty
  let head'' = if headless
                  then empty
                  else border <> cr <> head'
  let body = if maxRowHeight > 1
                then vsep rows'
                else vcat rows'
  let bottom = if headless
                  then underline
                  else border
  return $ head'' $$ underline $$ body $$ bottom

gridTable :: WriterOptions -> Bool -> [Alignment] -> [Double]
          -> [Doc] -> [[Doc]] -> State WriterState Doc
gridTable opts headless _aligns widths headers' rawRows =  do
  let numcols = length headers'
  let widths' = if all (==0) widths
                   then replicate numcols (1.0 / fromIntegral numcols)
                   else widths
  let widthsInChars = map (floor . (fromIntegral (writerColumns opts) *)) widths'
  let hpipeBlocks blocks = hcat [beg, middle, end]
        where h       = maximum (map height blocks)
              sep'    = lblock 3 $ vcat (map text $ replicate h " | ")
              beg     = lblock 2 $ vcat (map text $ replicate h "| ")
              end     = lblock 2 $ vcat (map text $ replicate h " |")
              middle  = chomp $ hcat $ intersperse sep' blocks
  let makeRow = hpipeBlocks . zipWith lblock widthsInChars
  let head' = makeRow headers'
  let rows' = map (makeRow . map chomp) rawRows
  let border ch = char '+' <> char ch <>
                  (hcat $ intersperse (char ch <> char '+' <> char ch) $
                          map (\l -> text $ replicate l ch) widthsInChars) <>
                  char ch <> char '+'
  let body = vcat $ intersperse (border '-') rows'
  let head'' = if headless
                  then empty
                  else head' $$ border '='
  return $ border '-' $$ head'' $$ body $$ border '-'

-- | Convert bullet list item (list of blocks) to markdown.
bulletListItemToMarkdown :: WriterOptions -> [Block] -> State WriterState Doc
bulletListItemToMarkdown opts items = do
  contents <- blockListToMarkdown opts items
  let sps = replicate (writerTabStop opts - 2) ' '
  let start = text ('-' : ' ' : sps)
  -- remove trailing blank line if it is a tight list
  let contents' = case reverse items of
                       (BulletList xs:_) | isTightList xs ->
                            chomp contents <> cr
                       (OrderedList _ xs:_) | isTightList xs ->
                            chomp contents <> cr
                       _ -> contents
  return $ hang (writerTabStop opts) start $ contents' <> cr

-- | Convert ordered list item (a list of blocks) to markdown.
orderedListItemToMarkdown :: WriterOptions -- ^ options
                          -> String        -- ^ list item marker
                          -> [Block]       -- ^ list item (list of blocks)
                          -> State WriterState Doc
orderedListItemToMarkdown opts marker items = do
  contents <- blockListToMarkdown opts items
  let sps = case length marker - writerTabStop opts of
                   n | n > 0 -> text $ replicate n ' '
                   _         -> text " "
  let start = text marker <> sps
  return $ hang (writerTabStop opts) start $ contents <> cr

-- | Convert definition list item (label, list of blocks) to markdown.
definitionListItemToMarkdown :: WriterOptions
                             -> ([Inline],[[Block]])
                             -> State WriterState Doc
definitionListItemToMarkdown opts (label, defs) = do
  labelText <- inlineListToMarkdown opts label
  defs' <- mapM (mapM (blockToMarkdown opts)) defs
  if isEnabled Ext_definition_lists opts
     then do
       let tabStop = writerTabStop opts
       st <- get
       let leader  = if stPlain st then "   " else ":  "
       let sps = case writerTabStop opts - 3 of
                      n | n > 0   -> text $ replicate n ' '
                      _           -> text " "
       let contents = vcat $ map (\d -> hang tabStop (leader <> sps) $ vcat d <> cr) defs'
       return $ nowrap labelText <> cr <> contents <> cr
     else do
       return $ nowrap labelText <> text "  " <> cr <>
                vsep (map vsep defs') <> blankline

-- | Convert list of Pandoc block elements to markdown.
blockListToMarkdown :: WriterOptions -- ^ Options
                    -> [Block]       -- ^ List of block elements
                    -> State WriterState Doc
blockListToMarkdown opts blocks =
  mapM (blockToMarkdown opts) (fixBlocks blocks) >>= return . cat
    -- insert comment between list and indented code block, or the
    -- code block will be treated as a list continuation paragraph
    where fixBlocks (b : CodeBlock attr x : rest)
            | (not (isEnabled Ext_fenced_code_blocks opts) || attr == nullAttr)
                && isListBlock b =
               b : RawBlock "html" "<!-- -->\n" : CodeBlock attr x :
                   fixBlocks rest
          fixBlocks (x : xs)             = x : fixBlocks xs
          fixBlocks []                   = []
          isListBlock (BulletList _)     = True
          isListBlock (OrderedList _ _)  = True
          isListBlock (DefinitionList _) = True
          isListBlock _                  = False

-- | Get reference for target; if none exists, create unique one and return.
--   Prefer label if possible; otherwise, generate a unique key.
getReference :: [Inline] -> Target -> State WriterState [Inline]
getReference label (src, tit) = do
  st <- get
  case find ((== (src, tit)) . snd) (stRefs st) of
    Just (ref, _) -> return ref
    Nothing       -> do
      let label' = case find ((== label) . fst) (stRefs st) of
                      Just _ -> -- label is used; generate numerical label
                             case find (\n -> notElem [Str (show n)]
                                                      (map fst (stRefs st)))
                                       [1..(10000 :: Integer)] of
                                  Just x  -> [Str (show x)]
                                  Nothing -> error "no unique label"
                      Nothing -> label
      modify (\s -> s{ stRefs = (label', (src,tit)) : stRefs st })
      return label'

-- | Convert list of Pandoc inline elements to markdown.
inlineListToMarkdown :: WriterOptions -> [Inline] -> State WriterState Doc
inlineListToMarkdown opts lst =
  mapM (inlineToMarkdown opts) lst >>= return . cat

escapeSpaces :: Inline -> Inline
escapeSpaces (Str s) = Str $ substitute " " "\\ " s
escapeSpaces Space = Str "\\ "
escapeSpaces x = x

-- | Convert Pandoc inline element to markdown.
inlineToMarkdown :: WriterOptions -> Inline -> State WriterState Doc
inlineToMarkdown opts (Span attrs ils) = do
  st <- get
  contents <- inlineListToMarkdown opts ils
  return $ if stPlain st
              then contents
              else tagWithAttrs "span" attrs <> contents <> text "</span>"
inlineToMarkdown opts (Emph lst) = do
  contents <- inlineListToMarkdown opts lst
  return $ "*" <> contents <> "*"
inlineToMarkdown opts (Strong lst) = do
  contents <- inlineListToMarkdown opts lst
  return $ "**" <> contents <> "**"
inlineToMarkdown opts (Strikeout lst) = do
  contents <- inlineListToMarkdown opts lst
  return $ if isEnabled Ext_strikeout opts
              then "~~" <> contents <> "~~"
              else "<s>" <> contents <> "</s>"
inlineToMarkdown opts (Superscript lst) = do
  let lst' = walk escapeSpaces lst
  contents <- inlineListToMarkdown opts lst'
  return $ if isEnabled Ext_superscript opts
              then "^" <> contents <> "^"
              else "<sup>" <> contents <> "</sup>"
inlineToMarkdown opts (Subscript lst) = do
  let lst' = walk escapeSpaces lst
  contents <- inlineListToMarkdown opts lst'
  return $ if isEnabled Ext_subscript opts
              then "~" <> contents <> "~"
              else "<sub>" <> contents <> "</sub>"
inlineToMarkdown opts (SmallCaps lst) = inlineListToMarkdown opts lst
inlineToMarkdown opts (Quoted SingleQuote lst) = do
  contents <- inlineListToMarkdown opts lst
  return $ "‘" <> contents <> "’"
inlineToMarkdown opts (Quoted DoubleQuote lst) = do
  contents <- inlineListToMarkdown opts lst
  return $ "“" <> contents <> "”"
inlineToMarkdown opts (Code attr str) =
  let tickGroups = filter (\s -> '`' `elem` s) $ group str
      longest    = if null tickGroups
                     then 0
                     else maximum $ map length tickGroups
      marker     = replicate (longest + 1) '`'
      spacer     = if (longest == 0) then "" else " "
      attrs      = if isEnabled Ext_inline_code_attributes opts && attr /= nullAttr
                      then attrsToMarkdown attr
                      else empty
  in  return $ text (marker ++ spacer ++ str ++ spacer ++ marker) <> attrs
inlineToMarkdown _ (Str str) = do
  st <- get
  if stPlain st
     then return $ text str
     else return $ text $ escapeString str
inlineToMarkdown opts (Math InlineMath str)
  | isEnabled Ext_tex_math_dollars opts =
      return $ "$" <> text str <> "$"
  | isEnabled Ext_tex_math_single_backslash opts =
      return $ "\\(" <> text str <> "\\)"
  | isEnabled Ext_tex_math_double_backslash opts =
      return $ "\\\\(" <> text str <> "\\\\)"
  | otherwise = inlineListToMarkdown opts $ readTeXMath' InlineMath str
inlineToMarkdown opts (Math DisplayMath str)
  | isEnabled Ext_tex_math_dollars opts =
      return $ "$$" <> text str <> "$$"
  | isEnabled Ext_tex_math_single_backslash opts =
      return $ "\\[" <> text str <> "\\]"
  | isEnabled Ext_tex_math_double_backslash opts =
      return $ "\\\\[" <> text str <> "\\\\]"
  | otherwise = (\x -> cr <> x <> cr) `fmap`
        inlineListToMarkdown opts (readTeXMath' DisplayMath str)
inlineToMarkdown opts (RawInline f str)
  | f == "html" || f == "markdown" ||
    (isEnabled Ext_raw_tex opts && (f == "latex" || f == "tex")) =
    return $ text str
inlineToMarkdown _ (RawInline _ _) = return empty
inlineToMarkdown opts (LineBreak)
  | isEnabled Ext_hard_line_breaks opts    = return cr
  | isEnabled Ext_escaped_line_breaks opts = return $ "\\" <> cr
  | otherwise                              = return $ "  " <> cr
inlineToMarkdown _ Space = return space
inlineToMarkdown opts (Cite [] lst) = inlineListToMarkdown opts lst
inlineToMarkdown opts (Cite (c:cs) lst)
  | not (isEnabled Ext_citations opts) = inlineListToMarkdown opts lst
  | otherwise =
      if citationMode c == AuthorInText
         then do
           suffs <- inlineListToMarkdown opts $ citationSuffix c
           rest <- mapM convertOne cs
           let inbr = suffs <+> joincits rest
               br   = if isEmpty inbr then empty else char '[' <> inbr <> char ']'
           return $ text ("@" ++ citationId c) <+> br
         else do
           cits <- mapM convertOne (c:cs)
           return $ text "[" <> joincits cits <> text "]"
  where
        joincits = hcat . intersperse (text "; ") . filter (not . isEmpty)
        convertOne Citation { citationId      = k
                            , citationPrefix  = pinlines
                            , citationSuffix  = sinlines
                            , citationMode    = m }
                               = do
           pdoc <- inlineListToMarkdown opts pinlines
           sdoc <- inlineListToMarkdown opts sinlines
           let k' = text (modekey m ++ "@" ++ k)
               r = case sinlines of
                        Str (y:_):_ | y `elem` ",;]@" -> k' <> sdoc
                        _                             -> k' <+> sdoc
           return $ pdoc <+> r
        modekey SuppressAuthor = "-"
        modekey _              = ""
inlineToMarkdown opts (Link txt (src, tit)) = do
  linktext <- inlineListToMarkdown opts txt
  let linktitle = if null tit
                     then empty
                     else text $ " \"" ++ tit ++ "\""
  let srcSuffix = if isPrefixOf "mailto:" src then drop 7 src else src
  let useAuto = isURI src &&
                case txt of
                      [Str s] | escapeURI s == srcSuffix -> True
                      _                                  -> False
  let useRefLinks = writerReferenceLinks opts && not useAuto
  ref <- if useRefLinks then getReference txt (src, tit) else return []
  reftext <- inlineListToMarkdown opts ref
  return $ if useAuto
              then "<" <> text srcSuffix <> ">"
              else if useRefLinks
                      then let first  = "[" <> linktext <> "]"
                               second = if txt == ref
                                           then "[]"
                                           else "[" <> reftext <> "]"
                           in  first <> second
                      else "[" <> linktext <> "](" <>
                           text src <> linktitle <> ")"
inlineToMarkdown opts (Image alternate (source, tit)) = do
  let txt = if null alternate || alternate == [Str source]
                                 -- to prevent autolinks
               then [Str ""]
               else alternate
  linkPart <- inlineToMarkdown opts (Link txt (source, tit))
  return $ "!" <> linkPart
inlineToMarkdown opts (Note contents) = do
  modify (\st -> st{ stNotes = contents : stNotes st })
  st <- get
  let ref = text $ writerIdentifierPrefix opts ++ show (length $ stNotes st)
  if isEnabled Ext_footnotes opts
     then return $ "[^" <> ref <> "]"
     else return $ "[" <> ref <> "]"