RST reader: Added footnote suppport.

Resolves issue #258.

Note that there are some differences in how docutils and
pandoc treat footnotes.  Currently pandoc ignores the numeral
or symbol used in the note; footnotes are put in an auto-numbered
ordered list.

README

@@ -66,10 +66,8 @@ To convert `hello.html` from html to markdown:
 
 Supported output formats are listed below under the `-t/--to` option.
 Supported input formats are listed below under the `-f/--from` option. Note
-that the `rst` reader only parses a subset of reStructuredText syntax. For
-example, it doesn't handle tables, option lists, or footnotes. But for simple
-documents it should be adequate. The `textile`, `latex`, and `html` readers
-are also limited in what they can do.
+that the `rst`, `textile`, `latex`, and `html` readers are not complete;
+there are some constructs that they do not parse.
 
 If the input or output format is not specified explicitly, `pandoc`
 will attempt to guess it from the extensions of

src/Text/Pandoc/Readers/RST.hs

@@ -35,7 +35,7 @@ import Text.Pandoc.Shared
 import Text.Pandoc.Parsing
 import Text.ParserCombinators.Parsec
 import Control.Monad ( when, unless )
-import Data.List ( findIndex, intercalate, transpose, sort )
+import Data.List ( findIndex, intercalate, transpose, sort, deleteFirstsBy )
 import qualified Data.Map as M
 import Text.Printf ( printf )
 
@@ -91,11 +91,15 @@ titleTransform blocks = (blocks, [])
 parseRST :: GenParser Char ParserState Pandoc
 parseRST = do
   startPos <- getPosition
-  -- go through once just to get list of reference keys
+  -- go through once just to get list of reference keys and notes
   -- docMinusKeys is the raw document with blanks where the keys were...
-  docMinusKeys <- manyTill (referenceKey <|> lineClump) eof >>= return . concat
+  docMinusKeys <- manyTill (referenceKey <|> noteBlock <|> lineClump) eof >>=
+                   return . concat
   setInput docMinusKeys
   setPosition startPos
+  st' <- getState
+  let reversedNotes = stateNotes st'
+  updateState $ \s -> s { stateNotes = reverse reversedNotes }
   -- now parse it for real...
   blocks <- parseBlocks 
   let blocks' = filter (/= Null) blocks
@@ -508,6 +512,32 @@ unknownDirective = try $ do
   many $ blanklines <|> (oneOf " \t" >> manyTill anyChar newline)
   return Null
 
+---
+--- note block
+---
+
+noteBlock :: GenParser Char ParserState [Char]
+noteBlock = try $ do
+  startPos <- getPosition
+  string ".."
+  spaceChar >> skipMany spaceChar
+  ref <- noteMarker
+  spaceChar >> skipMany spaceChar
+  first <- anyLine
+  blanks <- option "" blanklines
+  rest <- option "" indentedBlock
+  endPos <- getPosition
+  let raw = first ++ "\n" ++ blanks ++ rest ++ "\n"
+  let newnote = (ref, raw)
+  st <- getState
+  let oldnotes = stateNotes st
+  updateState $ \s -> s { stateNotes = newnote : oldnotes }
+  -- return blanks so line count isn't affected
+  return $ replicate (sourceLine endPos - sourceLine startPos) '\n'
+
+noteMarker :: GenParser Char ParserState [Char]
+noteMarker = char '[' >> (many1 digit <|> count 1 (oneOf "#*")) >>~ char ']'
+
 -- 
 -- reference key
 --
@@ -692,6 +722,7 @@ inline = choice [ smartPunctuation inline
                 , superscript
                 , subscript
                 , escapedChar
+                , note
                 , symbol ] <?> "inline"
 
 hyphens :: GenParser Char ParserState Inline
@@ -820,3 +851,20 @@ image = try $ do
                      Nothing     -> fail "no corresponding key"
                      Just target -> return target
   return $ Image (normalizeSpaces ref) (src, tit)
+
+note :: GenParser Char ParserState Inline
+note = try $ do
+  ref <- noteMarker
+  char '_'
+  state <- getState
+  let notes = stateNotes state
+  case lookup ref notes of
+    Nothing   -> fail "note not found"
+    Just raw  -> do
+      contents <- parseFromString parseBlocks raw
+      when (ref == "*" || ref == "#") $ do -- auto-numbered
+        -- delete the note so the next auto-numbered note
+        -- doesn't get the same contents:
+        let newnotes = deleteFirstsBy (==) notes [(ref,raw)]
+        updateState $ \st -> st{ stateNotes = newnotes }
+      return $ Note contents

tests/rst-reader.native

@@ -308,4 +308,10 @@ Pandoc (Meta {docTitle = [Str "Pandoc",Space,Str "Test",Space,Str "Suite",Str ":
     , Para [Str "r1",Space,Str "bis"] ], [ BulletList
       [ [ Plain [Str "b"] ]
       , [ Plain [Str "b",Space,Str "2"] ]
-      , [ Plain [Str "b",Space,Str "2"] ] ] ], [ Plain [Str "c",Space,Str "c",Space,Str "2",Space,Str "c",Space,Str "2"] ] ] ] ]
+      , [ Plain [Str "b",Space,Str "2"] ] ] ], [ Plain [Str "c",Space,Str "c",Space,Str "2",Space,Str "c",Space,Str "2"] ] ] ]
+, Header 1 [Str "Footnotes"]
+, Para [Note [Para [Str "Note",Space,Str "with",Space,Str "one",Space,Str "line",Str "."]]]
+, Para [Note [Para [Str "Note",Space,Str "with",Space,Str "continuation",Space,Str "line",Str "."]]]
+, Para [Note [Para [Str "Note",Space,Str "with"],Para [Str "continuation",Space,Str "block",Str "."]]]
+, Para [Note [Para [Str "Note",Space,Str "with",Space,Str "continuation",Space,Str "line"],Para [Str "and",Space,Str "a",Space,Str "second",Space,Str "para",Str "."]]]
+, Para [Str "Not",Space,Str "in",Space,Str "note",Str "."] ]

tests/rst-reader.rst

@@ -508,3 +508,31 @@ Multiple blocks in a cell
 |                  | - b 2     | c 2        | 
 | r1 bis           | - b 2     | c 2        | 
 +------------------+-----------+------------+
+
+Footnotes
+=========
+
+[1]_
+
+[#]_
+
+[#]_
+
+[*]_
+
+.. [1] Note with one line.
+
+.. [#] Note with
+  continuation line.
+
+.. [#] Note with
+
+  continuation block.
+
+.. [*] Note with
+   continuation line
+
+   and a second para.
+
+Not in note.
+