Org reader: allow changing emphasis syntax

The characters allowed before and after emphasis can be configured via
`#+pandoc-emphasis-pre` and `#+pandoc-emphasis-post`, respectively. This
allows to change which strings are recognized as emphasized text on a
per-document or even per-paragraph basis. The allowed characters must be
given as (Haskell) string.

    #+pandoc-emphasis-pre: "-\t ('\"{"
    #+pandoc-emphasis-post: "-\t\n .,:!?;'\")}["

If the argument cannot be read as a string, the default value is
restored.

Closes: #4378

1 files changed, 22 insertions, 0 deletions

diff --git a/src/Text/Pandoc/Readers/Org/Meta.hs b/src/Text/Pandoc/Readers/Org/Meta.hs
index 0a690028d..6ad403fd8 100644
--- a/src/Text/Pandoc/Readers/Org/Meta.hs
+++ b/src/Text/Pandoc/Readers/Org/Meta.hs
@@ -43,6 +43,7 @@ import Text.Pandoc.Builder (Blocks, Inlines)
 import qualified Text.Pandoc.Builder as B
 import Text.Pandoc.Class (PandocMonad)
 import Text.Pandoc.Definition
+import Text.Pandoc.Shared (safeRead)
 
 import Control.Monad (mzero, void, when)
 import Data.Char (toLower)
@@ -154,6 +155,8 @@ optionLine = try $ do
     "seq_todo" -> todoSequence >>= updateState . registerTodoSequence
     "typ_todo" -> todoSequence >>= updateState . registerTodoSequence
     "macro"    -> macroDefinition >>= updateState . registerMacro
+    "pandoc-emphasis-pre" -> emphChars >>= updateState . setEmphasisPreChar
+    "pandoc-emphasis-post" -> emphChars >>= updateState . setEmphasisPostChar
     _          -> mzero
 
 addLinkFormat :: Monad m => String
@@ -184,6 +187,25 @@ parseFormat = try $ replacePlain <|> replaceUrl <|> justAppend
    rest            = manyTill anyChar         (eof <|> () <$ oneOf "\n\r")
    tillSpecifier c = manyTill (noneOf "\n\r") (try $ string ('%':c:""))
 
+setEmphasisPreChar :: Maybe [Char] -> OrgParserState -> OrgParserState
+setEmphasisPreChar csMb st =
+  let preChars = case csMb of
+                   Nothing -> orgStateEmphasisPreChars defaultOrgParserState
+                   Just cs -> cs
+  in st { orgStateEmphasisPreChars = preChars }
+
+setEmphasisPostChar :: Maybe [Char] -> OrgParserState -> OrgParserState
+setEmphasisPostChar csMb st =
+  let postChars = case csMb of
+                   Nothing -> orgStateEmphasisPostChars defaultOrgParserState
+                   Just cs -> cs
+  in st { orgStateEmphasisPostChars = postChars }
+
+emphChars :: Monad m => OrgParser m (Maybe [Char])
+emphChars = do
+  skipSpaces
+  safeRead <$> anyLine
+
 inlinesTillNewline :: PandocMonad m => OrgParser m (F Inlines)
 inlinesTillNewline = do
   updateLastPreCharPos