Markdown reader: Support RST-style line blocks.

This depends on the new Ext_line_blocks extension.

src/Text/Pandoc/Options.hs

@@ -95,6 +95,7 @@ data Extension =
     | Ext_auto_identifiers    -- ^ Automatic identifiers for headers
     | Ext_header_attributes   -- ^ Explicit header attributes {#id .class k=v}
     | Ext_implicit_header_references -- ^ Implicit reference links for headers
+    | Ext_line_blocks         -- ^ RST style line blocks
     deriving (Show, Read, Enum, Eq, Ord, Bounded)
 
 pandocExtensions :: Set Extension
@@ -134,6 +135,7 @@ pandocExtensions = Set.fromList
   , Ext_auto_identifiers
   , Ext_header_attributes
   , Ext_implicit_header_references
+  , Ext_line_blocks
   ]
 
 phpMarkdownExtraExtensions :: Set Extension

src/Text/Pandoc/Readers/Markdown.hs

@@ -31,7 +31,7 @@ Conversion of markdown-formatted plain text to 'Pandoc' document.
 module Text.Pandoc.Readers.Markdown ( readMarkdown,
                                       readMarkdownWithWarnings ) where
 
-import Data.List ( transpose, sortBy, findIndex, intercalate )
+import Data.List ( transpose, sortBy, findIndex, intersperse, intercalate )
 import qualified Data.Map as M
 import Data.Ord ( comparing )
 import Data.Char ( isAlphaNum, toLower )
@@ -350,6 +350,7 @@ block = choice [ codeBlockFenced
                , header
                , rawTeXBlock
                , htmlBlock
+               , lineBlock
                , table
                , codeBlockIndented
                , lhsCodeBlock
@@ -868,6 +869,17 @@ stripMarkdownAttribute s = renderTags' $ map filterAttrib $ parseTags s
                                         [(k,v) | (k,v) <- as, k /= "markdown"]
         filterAttrib              x = x
 
+--
+-- line block
+--
+
+lineBlock :: MarkdownParser (F Blocks)
+lineBlock = try $ do
+  guardEnabled Ext_line_blocks
+  lines' <- lineBlockLines >>=
+            mapM (parseFromString (trimInlinesF . mconcat <$> many inline))
+  return $ B.para <$> (mconcat $ intersperse (return B.linebreak) lines')
+
 --
 -- Tables
 --