aboutsummaryrefslogtreecommitdiff
path: root/src/Text/Pandoc/Writers/HTML.hs
blob: 90157543464caa4123e11e11f8d8f41a9981c503 (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
{-# OPTIONS_GHC -fno-warn-deprecations #-}
{-
Copyright (C) 2006-2010 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.HTML 
   Copyright   : Copyright (C) 2006-2010 John MacFarlane
   License     : GNU GPL, version 2 or above 

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

Conversion of 'Pandoc' documents to HTML.
-}
module Text.Pandoc.Writers.HTML ( writeHtml , writeHtmlString ) where
import Text.Pandoc.Definition
import Text.Pandoc.CharacterReferences ( decodeCharacterReferences )
import Text.Pandoc.Shared
import Text.Pandoc.Templates
import Text.Pandoc.Readers.TeXMath
import Text.Pandoc.Highlighting ( highlightHtml, defaultHighlightingCss )
import Text.Pandoc.XML (stripTags, escapeStringForXML)
import Network.HTTP ( urlEncode )
import Numeric ( showHex )
import Data.Char ( ord, toLower )
import Data.List ( isPrefixOf, intersperse )
import Data.Maybe ( catMaybes )
import Control.Monad.State
import Text.XHtml.Transitional hiding ( stringToHtml )
import Text.TeXMath
import Text.XML.Light.Output

data WriterState = WriterState
    { stNotes            :: [Html]  -- ^ List of notes
    , stMath             :: Bool    -- ^ Math is used in document
    , stHighlighting     :: Bool    -- ^ Syntax highlighting is used
    , stSecNum           :: [Int]   -- ^ Number of current section
    } deriving Show

defaultWriterState :: WriterState
defaultWriterState = WriterState {stNotes= [], stMath = False, stHighlighting = False, stSecNum = []}

-- Helpers to render HTML with the appropriate function.

renderFragment :: (HTML html) => WriterOptions -> html -> String
renderFragment opts = if writerWrapText opts
                         then renderHtmlFragment
                         else showHtmlFragment

-- | Modified version of Text.XHtml's stringToHtml.
-- Use unicode characters wherever possible.
stringToHtml :: String -> Html
stringToHtml = primHtml . escapeStringForXML

-- | Convert Pandoc document to Html string.
writeHtmlString :: WriterOptions -> Pandoc -> String
writeHtmlString opts d =
  let (tit, auths, date, toc, body', newvars) = evalState (pandocToHtml opts d)
                                                 defaultWriterState
  in  if writerStandalone opts
         then inTemplate opts tit auths date toc body' newvars
         else renderFragment opts body'

-- | Convert Pandoc document to Html structure.
writeHtml :: WriterOptions -> Pandoc -> Html
writeHtml opts d =
  let (tit, auths, date, toc, body', newvars) = evalState (pandocToHtml opts d)
                                                 defaultWriterState
  in  if writerStandalone opts
         then inTemplate opts tit auths date toc body' newvars
         else body'

-- result is (title, authors, date, toc, body, new variables)
pandocToHtml :: WriterOptions
             -> Pandoc
             -> State WriterState (Html, [Html], Html, Maybe Html, Html, [(String,String)])
pandocToHtml opts (Pandoc (Meta title' authors' date') blocks) = do
  let standalone = writerStandalone opts
  tit <- if standalone
            then inlineListToHtml opts title'
            else return noHtml
  auths <- if standalone
              then mapM (inlineListToHtml opts) authors'
              else return [] 
  date <- if standalone
             then inlineListToHtml opts date'
             else return noHtml 
  let sects = hierarchicalize blocks
  toc <- if writerTableOfContents opts 
            then tableOfContents opts sects
            else return Nothing
  let startSlide = RawHtml "<div class=\"slide\">\n"
      endSlide   = RawHtml "</div>\n"
  let cutUp (HorizontalRule : Header 1 ys : xs) = cutUp (Header 1 ys : xs)
      cutUp (HorizontalRule : xs) = [endSlide, startSlide] ++ cutUp xs
      cutUp (Header 1 ys : xs)    = [endSlide, startSlide] ++
                                    (Header 1 ys : cutUp xs)
      cutUp (x:xs)                = x : cutUp xs
      cutUp []                    = [] 
  let slides = case blocks of
                (HorizontalRule : xs) -> [startSlide] ++ cutUp xs ++ [endSlide]
                (Header 1 ys : xs)    -> [startSlide, Header 1 ys] ++
                                           cutUp xs ++ [endSlide]
                _                     -> [startSlide] ++ cutUp blocks ++
                                           [endSlide]
  blocks' <- liftM toHtmlFromList $
              if writerSlideVariant opts `elem` [SlidySlides, S5Slides]
                 then mapM (blockToHtml opts) slides
                 else mapM (elementToHtml opts) sects
  st <- get
  let notes = reverse (stNotes st)
  let thebody = blocks' +++ footnoteSection notes
  let  math = if stMath st
                then case writerHTMLMathMethod opts of
                           LaTeXMathML (Just url) ->
                              script ! 
                              [src url, thetype "text/javascript"] $ noHtml
                           MathML (Just url) ->
                              script ! 
                              [src url, thetype "text/javascript"] $ noHtml
                           MathJax url ->
                              script ! [src url, thetype "text/javascript"] $ noHtml
                           JsMath (Just url) ->
                              script !
                              [src url, thetype "text/javascript"] $ noHtml
                           _ -> case lookup "mathml-script" (writerVariables opts) of
                                      Just s -> 
                                        script ! [thetype "text/javascript"] <<
                                           primHtml s
                                      Nothing -> noHtml
                else noHtml
  let newvars = [("highlighting-css", defaultHighlightingCss) |
                   stHighlighting st] ++
                [("math", renderHtmlFragment math) | stMath st]
  return (tit, auths, date, toc, thebody, newvars)

inTemplate :: TemplateTarget a
           => WriterOptions
           -> Html
           -> [Html]
           -> Html
           -> Maybe Html
           -> Html
           -> [(String,String)]
           -> a
inTemplate opts tit auths date toc body' newvars =
  let renderedTit = showHtmlFragment tit
      topTitle'   = stripTags renderedTit
      authors     = map (stripTags . showHtmlFragment) auths
      date'       = stripTags $ showHtmlFragment date
      variables   = writerVariables opts ++ newvars
      context     = variables ++
                    [ ("body", renderHtmlFragment body')
                    , ("pagetitle", topTitle')
                    , ("title", renderHtmlFragment tit)
                    , ("date", date') ] ++
                    [ ("html5","true") | writerHtml5 opts ] ++
                    (case toc of
                         Just t  -> [ ("toc", renderHtmlFragment t)]
                         Nothing -> [])  ++
                    [ ("author", a) | a <- authors ]
  in  renderTemplate context $ writerTemplate opts

-- | Like Text.XHtml's identifier, but adds the writerIdentifierPrefix
prefixedId :: WriterOptions -> String -> HtmlAttr
prefixedId opts s = identifier $ writerIdentifierPrefix opts ++ s

-- | Construct table of contents from list of elements.
tableOfContents :: WriterOptions -> [Element] -> State WriterState (Maybe Html)
tableOfContents _ [] = return Nothing
tableOfContents opts sects = do
  let opts'        = opts { writerIgnoreNotes = True }
  contents  <- mapM (elementToListItem opts') sects
  let tocList = catMaybes contents
  return $ if null tocList
              then Nothing
              else Just $
                   if writerHtml5 opts
                      then tag "nav" ! [prefixedId opts' "TOC"] $
                           unordList tocList
                      else thediv ! [prefixedId opts' "TOC"] $
                           unordList tocList

-- | Convert section number to string
showSecNum :: [Int] -> String
showSecNum = concat . intersperse "." . map show

-- | Converts an Element to a list item for a table of contents,
-- retrieving the appropriate identifier from state.
elementToListItem :: WriterOptions -> Element -> State WriterState (Maybe Html)
elementToListItem _ (Blk _) = return Nothing
elementToListItem opts (Sec _ num id' headerText subsecs) = do
  let sectnum = if writerNumberSections opts
                   then (thespan ! [theclass "toc-section-number"] << showSecNum num) +++
                         stringToHtml " "
                   else noHtml
  txt <- liftM (sectnum +++) $ inlineListToHtml opts headerText
  subHeads <- mapM (elementToListItem opts) subsecs >>= return . catMaybes
  let subList = if null subHeads
                   then noHtml
                   else unordList subHeads
  return $ Just $ (anchor ! [href ("#" ++ writerIdentifierPrefix opts ++ id')] $ txt) +++ subList

-- | Convert an Element to Html.
elementToHtml :: WriterOptions -> Element -> State WriterState Html
elementToHtml opts (Blk block) = blockToHtml opts block 
elementToHtml opts (Sec level num id' title' elements) = do
  innerContents <- mapM (elementToHtml opts) elements
  modify $ \st -> st{stSecNum = num}  -- update section number
  header' <- blockToHtml opts (Header level title')
  let slides = writerSlideVariant opts `elem` [SlidySlides, S5Slides]
  let header'' = header' !  [prefixedId opts id' |
                             not (writerStrictMarkdown opts ||
                                  writerSectionDivs opts || slides)]
  let stuff = header'' : innerContents
  return $ if slides   -- S5 gets confused by the extra divs around sections
              then toHtmlFromList stuff
              else if writerSectionDivs opts
                      then if writerHtml5 opts
                              then tag "section" << stuff
                              else thediv ! [prefixedId opts id'] << stuff
                      else toHtmlFromList stuff

-- | Convert list of Note blocks to a footnote <div>.
-- Assumes notes are sorted.
footnoteSection :: [Html] -> Html
footnoteSection notes =
  if null notes 
     then noHtml
     else thediv ! [theclass "footnotes"] $ hr +++ (olist << notes)


-- | Parse a mailto link; return Just (name, domain) or Nothing.
parseMailto :: String -> Maybe (String, String)
parseMailto ('m':'a':'i':'l':'t':'o':':':addr) =
  let (name', rest) = span (/='@') addr
      domain = drop 1 rest
  in  Just (name', domain)
parseMailto _ = Nothing 

-- | Obfuscate a "mailto:" link.
obfuscateLink :: WriterOptions -> String -> String -> Html
obfuscateLink opts txt s | writerEmailObfuscation opts == NoObfuscation =
  anchor ! [href s] << txt
obfuscateLink opts txt s =
  let meth = writerEmailObfuscation opts
      s' = map toLower s 
  in  case parseMailto s' of
        (Just (name', domain)) ->
          let domain'  = substitute "." " dot " domain
              at'      = obfuscateChar '@'
              (linkText, altText) = 
                 if txt == drop 7 s' -- autolink
                    then ("'<code>'+e+'</code>'", name' ++ " at " ++ domain')
                    else ("'" ++ txt ++ "'", txt ++ " (" ++ name' ++ " at " ++ 
                          domain' ++ ")")
          in  case meth of
                ReferenceObfuscation ->
                     -- need to use primHtml or &'s are escaped to &amp; in URL
                     primHtml $ "<a href=\"" ++ (obfuscateString s')
                     ++ "\">" ++ (obfuscateString txt) ++ "</a>"
                JavascriptObfuscation ->
                     (script ! [thetype "text/javascript"] $
                     primHtml ("\n<!--\nh='" ++ 
                     obfuscateString domain ++ "';a='" ++ at' ++ "';n='" ++ 
                     obfuscateString name' ++ "';e=n+a+h;\n" ++
                     "document.write('<a h'+'ref'+'=\"ma'+'ilto'+':'+e+'\">'+" ++ 
                     linkText  ++ "+'<\\/'+'a'+'>');\n// -->\n")) +++  
                     noscript (primHtml $ obfuscateString altText)
                _ -> error $ "Unknown obfuscation method: " ++ show meth
        _ -> anchor ! [href s] $ stringToHtml txt  -- malformed email

-- | Obfuscate character as entity.
obfuscateChar :: Char -> String
obfuscateChar char = 
  let num    = ord char
      numstr = if even num then show num else "x" ++ showHex num ""
  in  "&#" ++ numstr ++ ";"

-- | Obfuscate string using entities.
obfuscateString :: String -> String
obfuscateString = concatMap obfuscateChar . decodeCharacterReferences

-- | Convert Pandoc block element to HTML.
blockToHtml :: WriterOptions -> Block -> State WriterState Html
blockToHtml _ Null = return $ noHtml 
blockToHtml opts (Plain lst) = inlineListToHtml opts lst
blockToHtml opts (Para [Image txt (s,tit)]) = do
  img <- inlineToHtml opts (Image txt (s,tit))
  capt <- inlineListToHtml opts txt
  return $ if writerHtml5 opts
              then tag "figure" <<
                    [img, tag "figcaption" << capt]
              else thediv ! [theclass "figure"] <<
                    [img, paragraph ! [theclass "caption"] << capt]
blockToHtml opts (Para lst) = inlineListToHtml opts lst >>= (return . paragraph)
blockToHtml _ (RawHtml str) = return $ primHtml str
blockToHtml _ (HorizontalRule) = return $ hr
blockToHtml opts (CodeBlock (id',classes,keyvals) rawCode) = do
  let classes' = if writerLiterateHaskell opts
                    then classes
                    else filter (/= "literate") classes
  case highlightHtml (id',classes',keyvals) rawCode of
         Left _  -> -- change leading newlines into <br /> tags, because some
                    -- browsers ignore leading newlines in pre blocks
                    let (leadingBreaks, rawCode') = span (=='\n') rawCode
                        attrs = [theclass (unwords classes') | not (null classes')] ++
                                [prefixedId opts id' | not (null id')] ++
                                map (\(x,y) -> strAttr x y) keyvals
                        addBird = if "literate" `elem` classes'
                                     then unlines . map ("> " ++) . lines
                                     else unlines . lines
                    in  return $ pre ! attrs $ thecode <<
                                 (replicate (length leadingBreaks) br +++
                                 [stringToHtml $ addBird rawCode'])
         Right h -> modify (\st -> st{ stHighlighting = True }) >> return h
blockToHtml opts (BlockQuote blocks) =
  -- in S5, treat list in blockquote specially
  -- if default is incremental, make it nonincremental; 
  -- otherwise incremental
  if writerSlideVariant opts /= NoSlides
     then let inc = not (writerIncremental opts) in
          case blocks of 
             [BulletList lst]  -> blockToHtml (opts {writerIncremental = inc})
                                  (BulletList lst)
             [OrderedList attribs lst] -> 
                                  blockToHtml (opts {writerIncremental = inc})
                                  (OrderedList attribs lst)
             _                 -> blockListToHtml opts blocks >>= 
                                  (return . blockquote)
     else blockListToHtml opts blocks >>= (return . blockquote)
blockToHtml opts (Header level lst) = do 
  contents <- inlineListToHtml opts lst
  secnum <- liftM stSecNum get
  let contents' = if writerNumberSections opts
                     then (thespan ! [theclass "header-section-number"] << showSecNum secnum) +++
                            stringToHtml " " +++ contents
                     else contents
  let contents''  = if writerTableOfContents opts
                       then anchor ! [href $ "#" ++ writerIdentifierPrefix opts ++ "TOC"] $ contents'
                       else contents'
  return $ case level of
              1 -> h1 contents''
              2 -> h2 contents''
              3 -> h3 contents''
              4 -> h4 contents''
              5 -> h5 contents''
              6 -> h6 contents''
              _ -> paragraph contents''
blockToHtml opts (BulletList lst) = do
  contents <- mapM (blockListToHtml opts) lst
  let attribs = if writerIncremental opts
                   then [theclass "incremental"]
                   else []
  return $ unordList ! attribs $ contents
blockToHtml opts (OrderedList (startnum, numstyle, _) lst) = do
  contents <- mapM (blockListToHtml opts) lst
  let numstyle' = camelCaseToHyphenated $ show numstyle
  let attribs = (if writerIncremental opts
                   then [theclass "incremental"]
                   else []) ++
                (if startnum /= 1
                   then [start startnum]
                   else []) ++
                (if numstyle /= DefaultStyle
                   then if writerHtml5 opts
                           then [strAttr "type" $
                                 case numstyle of
                                      Decimal    -> "1"
                                      LowerAlpha -> "a"
                                      UpperAlpha -> "A"
                                      LowerRoman -> "i"
                                      UpperRoman -> "I"
                                      _          -> "1"]
                           else [thestyle $ "list-style-type: " ++
                                   numstyle']
                   else [])
  return $ ordList ! attribs $ contents
blockToHtml opts (DefinitionList lst) = do
  contents <- mapM (\(term, defs) ->
                  do term' <- liftM (dterm <<) $ inlineListToHtml opts term
                     defs' <- mapM (liftM (ddef <<) . blockListToHtml opts) defs
                     return $ term' : defs') lst
  let attribs = if writerIncremental opts
                   then [theclass "incremental"]
                   else []
  return $ dlist ! attribs << concat contents
blockToHtml opts (Table capt aligns widths headers rows') = do
  captionDoc <- if null capt
                   then return noHtml
                   else inlineListToHtml opts capt >>= return . caption
  let percent w = show (truncate (100*w) :: Integer) ++ "%"
  let widthAttrs w = if writerHtml5 opts
                        then [thestyle $ "width: " ++ percent w]
                        else [width $ percent w]
  let coltags = if all (== 0.0) widths
                   then noHtml
                   else concatHtml $ map
                         (\w -> col ! (widthAttrs w) $ noHtml) widths
  head' <- if all null headers
              then return noHtml
              else liftM (thead <<) $ tableRowToHtml opts aligns 0 headers
  body' <- liftM (tbody <<) $
               zipWithM (tableRowToHtml opts aligns) [1..] rows'
  return $ table $ captionDoc +++ coltags +++ head' +++ body'

tableRowToHtml :: WriterOptions
               -> [Alignment]
               -> Int
               -> [[Block]]
               -> State WriterState Html
tableRowToHtml opts aligns rownum cols' = do
  let mkcell = if rownum == 0 then th else td
  let rowclass = case rownum of
                      0                  -> "header"
                      x | x `rem` 2 == 1 -> "odd"
                      _                  -> "even"
  cols'' <- sequence $ zipWith 
            (\alignment item -> tableItemToHtml opts mkcell alignment item) 
            aligns cols'
  return $ tr ! [theclass rowclass] $ toHtmlFromList cols''

alignmentToString :: Alignment -> [Char]
alignmentToString alignment = case alignment of
                                 AlignLeft    -> "left"
                                 AlignRight   -> "right"
                                 AlignCenter  -> "center"
                                 AlignDefault -> "left"

tableItemToHtml :: WriterOptions
                -> (Html -> Html)
                -> Alignment
                -> [Block]
                -> State WriterState Html
tableItemToHtml opts tag' align' item = do
  contents <- blockListToHtml opts item
  let alignAttrs = if writerHtml5 opts
                      then [thestyle $ "align: " ++ alignmentToString align']
                      else [align $ alignmentToString align']
  return $ tag' ! alignAttrs $ contents

blockListToHtml :: WriterOptions -> [Block] -> State WriterState Html
blockListToHtml opts lst = 
  mapM (blockToHtml opts) lst >>= return . toHtmlFromList

-- | Convert list of Pandoc inline elements to HTML.
inlineListToHtml :: WriterOptions -> [Inline] -> State WriterState Html
inlineListToHtml opts lst = 
  mapM (inlineToHtml opts) lst >>= return . toHtmlFromList

-- | Convert Pandoc inline element to HTML.
inlineToHtml :: WriterOptions -> Inline -> State WriterState Html
inlineToHtml opts inline =
  case inline of  
    (Str str)        -> return $ stringToHtml str
    (Space)          -> return $ stringToHtml " "
    (LineBreak)      -> return br
    (EmDash)         -> return $ stringToHtml "—"
    (EnDash)         -> return $ stringToHtml "–"
    (Ellipses)       -> return $ stringToHtml "…"
    (Apostrophe)     -> return $ stringToHtml "’"
    (Emph lst)       -> inlineListToHtml opts lst >>= return . emphasize
    (Strong lst)     -> inlineListToHtml opts lst >>= return . strong
    (Code str)       -> return $ thecode << str
    (Strikeout lst)  -> inlineListToHtml opts lst >>=
                        return . (thespan ! [thestyle "text-decoration: line-through;"])
    (SmallCaps lst)   -> inlineListToHtml opts lst >>=
                         return . (thespan ! [thestyle "font-variant: small-caps;"])
    (Superscript lst) -> inlineListToHtml opts lst >>= return . sup
    (Subscript lst)   -> inlineListToHtml opts lst >>= return . sub
    (Quoted quoteType lst) ->
                        let (leftQuote, rightQuote) = case quoteType of
                              SingleQuote -> (stringToHtml "‘",
                                              stringToHtml "’")
                              DoubleQuote -> (stringToHtml "“",
                                              stringToHtml "”")
                        in  do contents <- inlineListToHtml opts lst
                               return $ leftQuote +++ contents +++ rightQuote
    (Math t str) ->     modify (\st -> st {stMath = True}) >> 
                        (case writerHTMLMathMethod opts of
                               LaTeXMathML _ -> 
                                  -- putting LaTeXMathML in container with class "LaTeX" prevents
                                  -- non-math elements on the page from being treated as math by
                                  -- the javascript
                                  return $ thespan ! [theclass "LaTeX"] $
                                         case t of
                                           InlineMath  -> primHtml ("$" ++ str ++ "$")
                                           DisplayMath -> primHtml ("$$" ++ str ++ "$$")
                               JsMath _ -> do
                                  let m = primHtml str
                                  return $ case t of
                                           InlineMath -> thespan ! [theclass "math"] $ m
                                           DisplayMath -> thediv ! [theclass "math"] $ m
                               WebTeX url -> do
                                  let m = image ! [src (url ++ urlEncode str),
                                                         alt str, title str]
                                  return $ case t of
                                            InlineMath  -> m
                                            DisplayMath -> br +++ m +++ br
                               GladTeX ->
                                  return $ case t of
                                             InlineMath -> primHtml $ "<EQ ENV=\"math\">" ++ str ++ "</EQ>"
                                             DisplayMath -> primHtml $ "<EQ ENV=\"displaymath\">" ++ str ++ "</EQ>"
                               MathML _ -> do
                                  let dt = if t == InlineMath
                                              then DisplayInline
                                              else DisplayBlock
                                  let conf = useShortEmptyTags (const False)
                                               defaultConfigPP
                                  case texMathToMathML dt str of
                                        Right r -> return $ primHtml $
                                                    ppcElement conf r
                                        Left  _ -> inlineListToHtml opts
                                                   (readTeXMath str) >>= return .
                                                     (thespan !  [theclass "math"])
                               MathJax _ -> return $ primHtml $
                                  case t of
                                    InlineMath  -> "\\(" ++ str ++ "\\)"
                                    DisplayMath -> "\\[" ++ str ++ "\\]"
                               PlainMath -> do
                                  x <- inlineListToHtml opts (readTeXMath str)
                                  let m = thespan ! [theclass "math"] $ x
                                  return  $ case t of
                                             InlineMath  -> m
                                             DisplayMath -> br +++ m +++ br )
    (TeX str)        -> case writerHTMLMathMethod opts of
                              LaTeXMathML _ -> do modify (\st -> st {stMath = True})
                                                  return $ primHtml str
                              _             -> return noHtml
    (HtmlInline str) -> return $ primHtml str 
    (Link [Code str] (s,_)) | "mailto:" `isPrefixOf` s ->
                        return $ obfuscateLink opts str s
    (Link txt (s,_)) | "mailto:" `isPrefixOf` s -> do
                        linkText <- inlineListToHtml opts txt  
                        return $ obfuscateLink opts (show linkText) s
    (Link txt (s,tit)) -> do
                        linkText <- inlineListToHtml opts txt
                        return $ anchor ! ([href s] ++ 
                                 if null tit then [] else [title tit]) $ 
                                 linkText
    (Image txt (s,tit)) -> do
                        alternate <- inlineListToHtml opts txt
                        let alternate' = renderFragment opts alternate
                        let attributes = [src s] ++
                                         (if null tit 
                                            then [] 
                                            else [title tit]) ++ 
                                         if null txt 
                                            then [] 
                                            else [alt alternate']
                        return $ image ! attributes 
                        -- note:  null title included, as in Markdown.pl 
    (Note contents)          -> do 
                        st <- get
                        let notes = stNotes st
                        let number = (length notes) + 1
                        let ref = show number
                        htmlContents <- blockListToNote opts ref contents 
                        -- push contents onto front of notes
                        put $ st {stNotes = (htmlContents:notes)} 
                        return $ sup <<
                                 anchor ! [href ("#" ++ writerIdentifierPrefix opts ++ "fn" ++ ref),
                                           theclass "footnoteRef",
                                           prefixedId opts ("fnref" ++ ref)] << ref
    (Cite _ il)  -> inlineListToHtml opts il

blockListToNote :: WriterOptions -> String -> [Block] -> State WriterState Html
blockListToNote opts ref blocks =
  -- If last block is Para or Plain, include the backlink at the end of
  -- that block. Otherwise, insert a new Plain block with the backlink.
  let backlink = [HtmlInline $ " <a href=\"#" ++ writerIdentifierPrefix opts ++ "fnref" ++ ref ++ 
                 "\" class=\"footnoteBackLink\"" ++
                 " title=\"Jump back to footnote " ++ ref ++ "\">↩</a>"]
      blocks'  = if null blocks
                    then []
                    else let lastBlock   = last blocks
                             otherBlocks = init blocks
                         in  case lastBlock of
                                  (Para lst)  -> otherBlocks ++
                                                 [Para (lst ++ backlink)]
                                  (Plain lst) -> otherBlocks ++
                                                 [Plain (lst ++ backlink)]
                                  _           -> otherBlocks ++ [lastBlock,
                                                 Plain backlink]
  in  do contents <- blockListToHtml opts blocks'
         return $ li ! [prefixedId opts ("fn" ++ ref)] $ contents