aboutsummaryrefslogtreecommitdiff
path: root/src/Text/Pandoc/Readers/Creole.hs
blob: 040ce365079d9cc920d7776ae31cfa83065c1cd6 (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
{-# LANGUAGE NoImplicitPrelude #-}
{-# LANGUAGE OverloadedStrings #-}
{-
  Copyright (C) 2017 Sascha Wilde <wilde@sha-bang.de>

  partly based on all the other readers, especially the work by
  John MacFarlane <jgm@berkeley.edu> and
  Alexander Sulfrian <alexander.sulfrian@fu-berlin.de>
  all bugs are solely created by me.

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.Creole
   Copyright   : Copyright (C) 2017 Sascha Wilde
   License     : GNU GPL, version 2 or above

   Maintainer  : Sascha Wilde <wilde@sha-bang.de>
   Stability   : alpha
   Portability : portable

Conversion of creole text to 'Pandoc' document.
-}
module Text.Pandoc.Readers.Creole ( readCreole
                                  ) where

import Prelude
import Control.Monad.Except (guard, liftM2, throwError)
import qualified Data.Foldable as F
import Data.Maybe (fromMaybe)
import Data.Text (Text)
import qualified Text.Pandoc.Builder as B
import Text.Pandoc.Class (PandocMonad (..))
import Text.Pandoc.Definition
import Text.Pandoc.Options
import Text.Pandoc.Parsing hiding (enclosed)
import Text.Pandoc.Shared (crFilter)


-- | Read creole from an input string and return a Pandoc document.
readCreole :: PandocMonad m
          => ReaderOptions
          -> Text
          -> m Pandoc
readCreole opts s = do
  res <- readWithM parseCreole def{ stateOptions = opts } $ crFilter s <> "\n\n"
  case res of
       Left e  -> throwError e
       Right d -> return d

type CRLParser = ParserT Text ParserState

--
-- Utility functions
--

(<+>) :: (Monad m, Semigroup a) => m a -> m a -> m a
(<+>) = liftM2 (<>)

-- we have to redefine `enclosed' from Text.Pandoc.Parsing, because it
-- assumes, that there can't be a space after the start parser, but
-- with creole this is possible.
enclosed :: (Show end, PandocMonad m) => CRLParser m start   -- ^ start parser
         -> CRLParser m end  -- ^ end parser
         -> CRLParser m a    -- ^ content parser (to be used repeatedly)
         -> CRLParser m [a]
enclosed start end parser = try $ start >> many1Till parser end

--
-- main parser
--

specialChars :: [Char]
specialChars = "*/~{}\\|[]()<>\"'"

parseCreole :: PandocMonad m => CRLParser m Pandoc
parseCreole = do
  bs <- mconcat <$> many block
  spaces
  eof
  return $ B.doc bs


--
-- block parsers
--

block :: PandocMonad m => CRLParser m B.Blocks
block = do
  res <- mempty <$ skipMany1 blankline
         <|> nowiki
         <|> header
         <|> horizontalRule
         <|> anyList 1
         <|> table
         <|> para
  skipMany blankline
  return res

nowiki :: PandocMonad m => CRLParser m B.Blocks
nowiki = try $ fmap (B.codeBlock . mconcat) (nowikiStart
                                             >> manyTill content nowikiEnd)
  where
    content = brackets <|> line
    brackets = try $ option "" ((:[]) <$> newline)
               <+> (char ' ' >> (many (char ' ') <+> string "}}}") <* eol)
    line = option "" ((:[]) <$> newline) <+> manyTill anyChar eol
    eol = lookAhead $ try $ nowikiEnd <|> newline
    nowikiStart = optional newline >> string "{{{" >> skipMany spaceChar >> newline
    nowikiEnd = try $ linebreak >> string "}}}" >> skipMany spaceChar >> newline

header :: PandocMonad m => CRLParser m B.Blocks
header = try $ do
  skipSpaces
  level <-
    fmap length (many1 (char '='))
  guard $ level <= 6
  skipSpaces
  content <- B.str <$> manyTill (noneOf "\n") headerEnd
  return $ B.header level content
  where
    headerEnd = try $ skipSpaces >> many (char '=') >> skipSpaces >> newline

unorderedList :: PandocMonad m => Int -> CRLParser m B.Blocks
unorderedList = list '*' B.bulletList

orderedList :: PandocMonad m => Int -> CRLParser m B.Blocks
orderedList = list '#' B.orderedList

anyList :: PandocMonad m => Int -> CRLParser m B.Blocks
anyList n = unorderedList n <|> orderedList n

anyListItem :: PandocMonad m => Int -> CRLParser m B.Blocks
anyListItem n = listItem '*' n <|> listItem '#' n

list :: PandocMonad m => Char -> ([B.Blocks] -> B.Blocks) -> Int -> CRLParser m B.Blocks
list c f n =
  fmap f (many1 (itemPlusSublist <|> listItem c n))
  where itemPlusSublist = try $ listItem c n <+> anyList (n+1)

listItem :: PandocMonad m => Char -> Int -> CRLParser m B.Blocks
listItem c n =
  fmap (B.plain . B.trimInlines .mconcat) (listStart >> many1Till inline itemEnd)
  where
    listStart = try $ skipSpaces >> optional newline >> skipSpaces
                >> count n (char c)
                >> lookAhead (noneOf [c]) >> skipSpaces
    itemEnd = endOfParaElement <|> nextItem n
              <|> if n < 3 then nextItem (n+1)
                  else nextItem (n+1) <|> nextItem (n-1)
    nextItem x = lookAhead $ try $ blankline >> anyListItem x >> return mempty

table :: PandocMonad m => CRLParser m B.Blocks
table = try $ do
  headers <- optionMaybe headerRow
  rows <- many1 row
  return $ B.simpleTable (fromMaybe [mempty] headers) rows
  where
    headerRow = try $ skipSpaces >> many1Till headerCell rowEnd
    headerCell = B.plain . B.trimInlines . mconcat
                 <$> (string "|=" >> many1Till inline cellEnd)
    row = try $ skipSpaces >> many1Till cell rowEnd
    cell = B.plain . B.trimInlines . mconcat
           <$> (char '|' >> many1Till inline cellEnd)
    rowEnd = try $ optional (char '|') >> skipSpaces >> newline
    cellEnd = lookAhead $ try $ char '|' <|> rowEnd

para :: PandocMonad m => CRLParser m B.Blocks
para = fmap (result . mconcat) (many1Till inline endOfParaElement)
 where
   result content   = if F.all (==Space) content
                      then mempty
                      else B.para $ B.trimInlines content

endOfParaElement :: PandocMonad m => CRLParser m ()
endOfParaElement = lookAhead $ endOfInput <|> endOfPara
                   <|> startOfList <|> startOfTable
                   <|> startOfHeader <|> hr <|> startOfNowiki
  where
   endOfInput    = try $ skipMany blankline >> skipSpaces >> eof
   endOfPara     = try $ blankline >> skipMany1 blankline
   startOf      :: PandocMonad m => CRLParser m a -> CRLParser m ()
   startOf p     = try $ blankline >> p >> return mempty
   startOfList   = startOf $ anyListItem 1
   startOfTable  = startOf table
   startOfHeader = startOf header
   startOfNowiki = startOf nowiki
   hr            = startOf horizontalRule

horizontalRule :: PandocMonad m => CRLParser m B.Blocks
horizontalRule = try $ skipSpaces >> string "----" >> skipSpaces >> newline
                 >> return B.horizontalRule

--
-- inline parsers
--

inline :: PandocMonad m => CRLParser m B.Inlines
inline = choice [ whitespace
                , escapedLink
                , escapedChar
                , link
                , inlineNowiki
                , placeholder
                , image
                , forcedLinebreak
                , bold
                , finalBold
                , italics
                , finalItalics
                , str
                , symbol
                ] <?> "inline"

escapedChar :: PandocMonad m => CRLParser m B.Inlines
escapedChar =
  fmap (B.str . (:[])) (try $ char '~' >> noneOf "\t\n ")

escapedLink :: PandocMonad m => CRLParser m B.Inlines
escapedLink = try $ do
  char '~'
  (orig, _) <- uri
  return $ B.str orig

image :: PandocMonad m => CRLParser m B.Inlines
image = try $ do
  (orig, src) <- wikiImg
  return $ B.image src "" (B.str orig)
  where
    linkSrc = many $ noneOf "|}\n\r\t"
    linkDsc = char '|' >> many (noneOf "}\n\r\t")
    wikiImg = try $ do
      string "{{"
      src <- linkSrc
      dsc <- option "" linkDsc
      string "}}"
      return (dsc, src)

link :: PandocMonad m => CRLParser m B.Inlines
link = try $ do
  (orig, src) <- uriLink <|> wikiLink
  return $ B.link src "" orig
  where
    linkSrc = many $ noneOf "|]\n\r\t"
    linkDsc :: PandocMonad m => String -> CRLParser m B.Inlines
    linkDsc otxt = B.str
                   <$> try (option otxt
                         (char '|' >> many (noneOf "]\n\r\t")))
    linkImg = try $ char '|' >> image
    wikiLink = try $ do
      string "[["
      src <- linkSrc
      dsc <- linkImg <|> linkDsc src
      string "]]"
      return (dsc, src)
    uriLink = try $ do
      (orig, src) <- uri
      return (B.str orig, src)

inlineNowiki :: PandocMonad m => CRLParser m B.Inlines
inlineNowiki = B.code <$> (start >> manyTill (noneOf "\n\r") end)
  where
    start = try $ string "{{{"
    end = try $ string "}}}" >> lookAhead (noneOf "}")

placeholder :: PandocMonad m => CRLParser m B.Inlines
-- The semantics of the placeholder is basicallly implementation
-- dependent, so there is no way to DTRT for all cases.
-- So for now we just drop them.
placeholder = B.text <$> try (string "<<<" >> manyTill anyChar (string ">>>")
              >> return "")

whitespace :: PandocMonad m => CRLParser m B.Inlines
whitespace = lb <|> regsp
  where lb = try $ skipMany spaceChar >> linebreak >> return B.space
        regsp = try $ skipMany1 spaceChar >> return B.space

linebreak :: PandocMonad m => CRLParser m B.Inlines
linebreak = newline >> notFollowedBy newline >> (lastNewline <|> innerNewline)
  where lastNewline  = eof >> return mempty
        innerNewline = return B.space

symbol :: PandocMonad m => CRLParser m B.Inlines
symbol = fmap (B.str . (:[])) (oneOf specialChars)

str :: PandocMonad m => CRLParser m B.Inlines
str = let strChar = noneOf ("\t\n " ++ specialChars) in
        fmap B.str (many1 strChar)

bold :: PandocMonad m => CRLParser m B.Inlines
bold = B.strong . mconcat <$>
       enclosed (string "**") (try $ string "**") inline

italics :: PandocMonad m => CRLParser m B.Inlines
italics = B.emph . mconcat <$>
          enclosed (string "//") (try $ string "//") inline

finalBold :: PandocMonad m => CRLParser m B.Inlines
finalBold = B.strong . mconcat <$>
            try (string "**" >> many1Till inline endOfParaElement)

finalItalics :: PandocMonad m => CRLParser m B.Inlines
finalItalics = B.emph . mconcat <$>
               try (string "//" >> many1Till inline endOfParaElement)

forcedLinebreak :: PandocMonad m => CRLParser m B.Inlines
forcedLinebreak = try $ string "\\\\" >> return B.linebreak