Improved syntax for markdown definition lists.

Definition lists are now more compatible with PHP Markdown Extra.
Resolves Issue #24.

+ You can have multiple definitions for a term (but still not
  multiple terms).
+ Multi-block definitions no longer need a
  column before each block (indeed, this will now cause
  multiple definitions).
+ The marker no longer needs to be flush with the left margin,
  but can be indented at or two spaces.  Also, ~ as well as :
  can be used as the marker (this suggestion due to David
  Wheeler.)
+ There can now be a blank line between the term and
  the definitions.

git-svn-id: https://pandoc.googlecode.com/svn/trunk@1656 788f1e2b-df1e-0410-8736-df70ead52e1b

4 files changed, 42 insertions, 19 deletions

diff --git a/src/Text/Pandoc/Readers/HTML.hs b/src/Text/Pandoc/Readers/HTML.hs
index a38450713..e6ca05d87 100644
--- a/src/Text/Pandoc/Readers/HTML.hs
+++ b/src/Text/Pandoc/Readers/HTML.hs
@@ -545,12 +545,12 @@ definitionList = try $ do
   htmlEndTag "dl"
   return $ DefinitionList items
 
-definitionListItem :: GenParser Char ParserState ([Inline], [Block])
+definitionListItem :: GenParser Char ParserState ([Inline], [[Block]])
 definitionListItem = try $ do
   terms <- sepEndBy1 (inlinesIn "dt") spaces
   defs <- sepEndBy1 (blocksIn "dd") spaces
   let term = intercalate [LineBreak] terms
-  return (term, concat defs)
+  return (term, defs)
 
 --
 -- paragraph block
diff --git a/src/Text/Pandoc/Readers/LaTeX.hs b/src/Text/Pandoc/Readers/LaTeX.hs
index 0ae24a387..b4c01fe19 100644
--- a/src/Text/Pandoc/Readers/LaTeX.hs
+++ b/src/Text/Pandoc/Readers/LaTeX.hs
@@ -282,7 +282,7 @@ definitionList = try $ do
   items <- many listItem
   end "description"
   spaces
-  return (DefinitionList items)
+  return $ DefinitionList $ map (\(t,d) -> (t,[d])) items
 
 --
 -- paragraph block
diff --git a/src/Text/Pandoc/Readers/Markdown.hs b/src/Text/Pandoc/Readers/Markdown.hs
index dc556d24f..0de700537 100644
--- a/src/Text/Pandoc/Readers/Markdown.hs
+++ b/src/Text/Pandoc/Readers/Markdown.hs
@@ -555,38 +555,61 @@ bulletList = try $ do
 
 -- definition lists
 
-definitionListItem :: GenParser Char ParserState ([Inline], [Block])
+defListMarker :: GenParser Char ParserState ()
+defListMarker = do
+  sps <- nonindentSpaces
+  char ':' <|> char '~'
+  st <- getState
+  let tabStop = stateTabStop st
+  let remaining = tabStop - (length sps + 1)
+  if remaining > 0
+     then count remaining (char ' ') <|> string "\t"
+     else pzero
+  return ()
+
+definitionListItem :: GenParser Char ParserState ([Inline], [[Block]])
 definitionListItem = try $ do
-  notFollowedBy blankline
-  notFollowedBy' indentSpaces
   -- first, see if this has any chance of being a definition list:
-  lookAhead (anyLine >> char ':')
+  lookAhead (anyLine >> optional blankline >> defListMarker)
   term <- manyTill inline newline
+  optional blankline
   raw <- many1 defRawBlock
   state <- getState
   let oldContext = stateParserContext state
   -- parse the extracted block, which may contain various block elements:
-  contents <- parseFromString parseBlocks $ concat raw
+  contents <- mapM (parseFromString parseBlocks) raw
   updateState (\st -> st {stateParserContext = oldContext})
   return ((normalizeSpaces term), contents)
 
 defRawBlock :: GenParser Char ParserState [Char]
 defRawBlock = try $ do
-  char ':'
-  state <- getState
-  let tabStop = stateTabStop state
-  try (count (tabStop - 1) (char ' ')) <|> (many (char ' ') >> string "\t")
+  defListMarker
   firstline <- anyLine
   rawlines <- many (notFollowedBy blankline >> indentSpaces >> anyLine)
   trailing <- option "" blanklines
-  return $ firstline ++ "\n" ++ unlines rawlines ++ trailing
+  cont <- liftM concat $ many $ do
+            lns <- many1 $ notFollowedBy blankline >> indentSpaces >> anyLine
+            trl <- option "" blanklines
+            return $ unlines lns ++ trl
+  return $ firstline ++ "\n" ++ unlines rawlines ++ trailing ++ cont
 
 definitionList :: GenParser Char ParserState Block
 definitionList = do
   items <- many1 definitionListItem
-  let (terms, defs) = unzip items
-  let defs' = compactify defs
-  let items' = zip terms defs'
+  -- "compactify" the definition list:
+  let defs = map snd items
+  let defBlocks = reverse $ concat $ concat defs
+  let isPara (Para _) = True
+      isPara _        = False
+  let items' = case take 1 defBlocks of
+                [Para x]   -> if not $ any isPara (drop 1 defBlocks)
+                                 then let (t,ds) = last items
+                                          lastDef = last ds
+                                          ds' = init ds ++
+                                                [init lastDef ++ [Plain x]]
+                                       in init items ++ [(t, ds')]
+                                 else items
+                _          -> items
   return $ DefinitionList items'
 
 --
diff --git a/src/Text/Pandoc/Readers/RST.hs b/src/Text/Pandoc/Readers/RST.hs
index 9e38b1872..d1515c4d5 100644
--- a/src/Text/Pandoc/Readers/RST.hs
+++ b/src/Text/Pandoc/Readers/RST.hs
@@ -174,7 +174,7 @@ fieldList = try $ do
               else do terms <- mapM (return . (:[]) . Str . fst) remaining
                       defs  <- mapM (parseFromString (many block) . snd) 
                                     remaining
-                      return $ DefinitionList $ zip terms defs
+                      return $ DefinitionList $ zip terms $ map (:[]) defs
 
 --
 -- line block
@@ -397,7 +397,7 @@ blockQuote = do
 list :: GenParser Char ParserState Block
 list = choice [ bulletList, orderedList, definitionList ] <?> "list"
 
-definitionListItem :: GenParser Char ParserState ([Inline], [Block])
+definitionListItem :: GenParser Char ParserState ([Inline], [[Block]])
 definitionListItem = try $ do
   -- avoid capturing a directive or comment
   notFollowedBy (try $ char '.' >> char '.')
@@ -405,7 +405,7 @@ definitionListItem = try $ do
   raw <- indentedBlock
   -- parse the extracted block, which may contain various block elements:
   contents <- parseFromString parseBlocks $ raw ++ "\n\n"
-  return (normalizeSpaces term, contents)
+  return (normalizeSpaces term, [contents])
 
 definitionList :: GenParser Char ParserState Block
 definitionList = many1 definitionListItem >>= return . DefinitionList