Org reader: extract parsing function to module

The Org-mode reader uses many functions defined in the
`Text.Pandoc.Parsing` utility module.  Some of the functions are
overwritten with versions adapted to Org-mode idiosyncrasies.  These
special functions, as well as the normal Pandoc versions, are combined
in a single module to increase the ease of use.

This leads to decoupling of Org-mode and Pandoc and hence to slightly
cleaner code.  The downside is code-bloat due to repeated import/export
statements.

2 files changed, 187 insertions, 2 deletions

diff --git a/src/Text/Pandoc/Readers/Org/ParserState.hs b/src/Text/Pandoc/Readers/Org/ParserState.hs
index 6a902cd46..e648a883e 100644
--- a/src/Text/Pandoc/Readers/Org/ParserState.hs
+++ b/src/Text/Pandoc/Readers/Org/ParserState.hs
@@ -29,9 +29,11 @@ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 Define the Org-mode parser state.
 -}
 module Text.Pandoc.Readers.Org.ParserState
-  ( OrgParserState(..)
-  , OrgParserLocal(..)
+  ( OrgParserState (..)
+  , OrgParserLocal (..)
   , OrgNoteRecord
+  , HasReaderOptions (..)
+  , HasQuoteContext (..)
   , F(..)
   , askF
   , asksF
@@ -184,6 +186,7 @@ modifyExportSettings :: ExportSettingSetter a -> a -> OrgParserState -> OrgParse
 modifyExportSettings setter val state =
   state { orgStateExportSettings = setter val . orgStateExportSettings $ state }
 
+
 --
 -- Parser state reader
 --
diff --git a/src/Text/Pandoc/Readers/Org/Parsing.hs b/src/Text/Pandoc/Readers/Org/Parsing.hs
new file mode 100644
index 000000000..efe2ae25f
--- /dev/null
+++ b/src/Text/Pandoc/Readers/Org/Parsing.hs
@@ -0,0 +1,182 @@
+{-
+Copyright (C) 2014-2016 Albert Krewinkel <tarleb+pandoc@moltkeplatz.de>
+
+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.Org.Options
+   Copyright   : Copyright (C) 2014-2016 Albert Krewinkel
+   License     : GNU GPL, version 2 or above
+
+   Maintainer  : Albert Krewinkel <tarleb+pandoc@moltkeplatz.de>
+
+Org-mode parsing utilities.
+
+Most functions are simply re-exports from @Text.Pandoc.Parsing@, some
+functions are adapted to Org-mode specific functionality.
+-}
+module Text.Pandoc.Readers.Org.Parsing
+  ( OrgParser
+  , anyLine
+  , blanklines
+  , newline
+  , parseFromString
+  , inList
+  , withContext
+  , updateLastForbiddenCharPos
+  , updateLastPreCharPos
+  -- * Re-exports from Text.Pandoc.Parser
+  , ParserContext (..)
+  , many1Till
+  , notFollowedBy'
+  , spaceChar
+  , nonspaceChar
+  , skipSpaces
+  , blankline
+  , enclosed
+  , stringAnyCase
+  , charsInBalanced
+  , uri
+  , withRaw
+  , readWithM
+  , guardEnabled
+  , updateLastStrPos
+  , notAfterString
+  , ParserState (..)
+  , registerHeader
+  , QuoteContext (..)
+  , singleQuoteStart
+  , singleQuoteEnd
+  , doubleQuoteStart
+  , doubleQuoteEnd
+  , dash
+  , ellipses
+  , citeKey
+  -- * Re-exports from Text.Pandoc.Parsec
+  , runParser
+  , getInput
+  , char
+  , letter
+  , digit
+  , alphaNum
+  , skipMany1
+  , spaces
+  , anyChar
+  , string
+  , count
+  , eof
+  , noneOf
+  , oneOf
+  , lookAhead
+  , notFollowedBy
+  , many
+  , many1
+  , manyTill
+  , (<|>)
+  , (<?>)
+  , choice
+  , try
+  , sepBy
+  , sepBy1
+  , option
+  , optional
+  , optionMaybe
+  , getState
+  , updateState
+  , SourcePos
+  , getPosition
+  ) where
+
+import           Text.Pandoc.Readers.Org.ParserState
+
+import qualified Text.Pandoc.Parsing as P
+import           Text.Pandoc.Parsing hiding ( anyLine, blanklines, newline
+                                            , parseFromString )
+
+import           Control.Monad ( guard )
+import           Control.Monad.Reader ( Reader )
+
+-- | The parser used to read org files.
+type OrgParser = ParserT [Char] OrgParserState (Reader OrgParserLocal)
+
+--
+-- Adaptions and specializations of parsing utilities
+--
+
+-- | Parse any line of text
+anyLine :: OrgParser String
+anyLine =
+  P.anyLine
+    <* updateLastPreCharPos
+    <* updateLastForbiddenCharPos
+
+-- The version Text.Pandoc.Parsing cannot be used, as we need additional parts
+-- of the state saved and restored.
+parseFromString :: OrgParser a -> String -> OrgParser a
+parseFromString parser str' = do
+  oldLastPreCharPos <- orgStateLastPreCharPos <$> getState
+  updateState $ \s -> s{ orgStateLastPreCharPos = Nothing }
+  result <- P.parseFromString parser str'
+  updateState $ \s -> s{ orgStateLastPreCharPos = oldLastPreCharPos }
+  return result
+
+-- | Like @Text.Parsec.Char.newline@, but causes additional state changes.
+newline :: OrgParser Char
+newline =
+  P.newline
+       <* updateLastPreCharPos
+       <* updateLastForbiddenCharPos
+
+-- | Like @Text.Parsec.Char.blanklines@, but causes additional state changes.
+blanklines :: OrgParser [Char]
+blanklines =
+  P.blanklines
+       <* updateLastPreCharPos
+       <* updateLastForbiddenCharPos
+
+-- | Succeeds when we're in list context.
+inList :: OrgParser ()
+inList = do
+  ctx <- orgStateParserContext <$> getState
+  guard (ctx == ListItemState)
+
+-- | Parse in different context
+withContext :: ParserContext -- ^ New parser context
+            -> OrgParser a   -- ^ Parser to run in that context
+            -> OrgParser a
+withContext context parser = do
+  oldContext <- orgStateParserContext <$> getState
+  updateState $ \s -> s{ orgStateParserContext = context }
+  result <- parser
+  updateState $ \s -> s{ orgStateParserContext = oldContext }
+  return result
+
+--
+-- Parser state update functions
+--
+
+-- | Set the current position as the last position at which a forbidden char
+-- was found (i.e. a character which is not allowed at the inner border of
+-- markup).
+updateLastForbiddenCharPos :: OrgParser ()
+updateLastForbiddenCharPos = getPosition >>= \p ->
+  updateState $ \s -> s{ orgStateLastForbiddenCharPos = Just p}
+
+-- | Set the current parser position as the position at which a character was
+-- seen which allows inline markup to follow.
+updateLastPreCharPos :: OrgParser ()
+updateLastPreCharPos = getPosition >>= \p ->
+  updateState $ \s -> s{ orgStateLastPreCharPos = Just p}