HTML reader: Parse LaTeX math if appropriate options are set.

* Moved inlineMath, displayMath from Markdown reader to Parsing.
* Export them from Parsing.  (API change.)
* Generalize their types.

src/Text/Pandoc/Parsing.hs

@@ -48,6 +48,8 @@ module Text.Pandoc.Parsing ( (>>~),
                              romanNumeral,
                              emailAddress,
                              uri,
+                             mathInline,
+                             mathDisplay,
                              withHorizDisplacement,
                              withRaw,
                              escaped,
@@ -455,6 +457,39 @@ uri = try $ do
   let uri' = scheme ++ ":" ++ fromEntities str'
   return (uri', escapeURI uri')
 
+mathInlineWith :: String -> String -> Parser [Char] st String
+mathInlineWith op cl = try $ do
+  string op
+  notFollowedBy space
+  words' <- many1Till (count 1 (noneOf "\n\\")
+                   <|> (char '\\' >> anyChar >>= \c -> return ['\\',c])
+                   <|> count 1 newline <* notFollowedBy' blankline
+                       *> return " ")
+              (try $ string cl)
+  notFollowedBy digit  -- to prevent capture of $5
+  return $ concat words'
+
+mathDisplayWith :: String -> String -> Parser [Char] st String
+mathDisplayWith op cl = try $ do
+  string op
+  many1Till (noneOf "\n" <|> (newline >>~ notFollowedBy' blankline)) (try $ string cl)
+
+mathDisplay :: Parser [Char] ParserState String
+mathDisplay =
+      (guardEnabled Ext_tex_math_dollars >> mathDisplayWith "$$" "$$")
+  <|> (guardEnabled Ext_tex_math_single_backslash >>
+       mathDisplayWith "\\[" "\\]")
+  <|> (guardEnabled Ext_tex_math_double_backslash >>
+       mathDisplayWith "\\\\[" "\\\\]")
+
+mathInline :: Parser [Char] ParserState String
+mathInline =
+      (guardEnabled Ext_tex_math_dollars >> mathInlineWith "$" "$")
+  <|> (guardEnabled Ext_tex_math_single_backslash >>
+       mathInlineWith "\\(" "\\)")
+  <|> (guardEnabled Ext_tex_math_double_backslash >>
+       mathInlineWith "\\\\(" "\\\\)")
+
 -- | Applies a parser, returns tuple of its results and its horizontal
 -- displacement (the difference between the source column at the end
 -- and the source column at the beginning). Vertical displacement

src/Text/Pandoc/Readers/HTML.hs

@@ -467,7 +467,13 @@ pBlank = try $ do
 
 pTagContents :: Parser [Char] ParserState Inline
 pTagContents =
-  pStr <|> pSpace <|> smartPunctuation pTagContents <|> pSymbol <|> pBad
+      Math InlineMath  `fmap` mathInline
+  <|> Math DisplayMath `fmap` mathDisplay
+  <|> pStr
+  <|> pSpace
+  <|> smartPunctuation pTagContents
+  <|> pSymbol
+  <|> pBad
 
 pStr :: Parser [Char] ParserState Inline
 pStr = do
@@ -482,6 +488,7 @@ isSpecial '"' = True
 isSpecial '\'' = True
 isSpecial '.' = True
 isSpecial '-' = True
+isSpecial '$' = True
 isSpecial '\8216' = True
 isSpecial '\8217' = True
 isSpecial '\8220' = True

src/Text/Pandoc/Readers/LaTeX.hs

@@ -38,7 +38,8 @@ import Text.Pandoc.Definition
 import Text.Pandoc.Walk
 import Text.Pandoc.Shared
 import Text.Pandoc.Options
-import Text.Pandoc.Parsing hiding ((<|>), many, optional, space)
+import Text.Pandoc.Parsing hiding ((<|>), many, optional, space,
+                                   mathDisplay, mathInline)
 import qualified Text.Pandoc.UTF8 as UTF8
 import Data.Char ( chr, ord )
 import Control.Monad

src/Text/Pandoc/Readers/Markdown.hs

@@ -1408,39 +1408,6 @@ math :: MarkdownParser (F Inlines)
 math =  (return . B.displayMath <$> (mathDisplay >>= applyMacros'))
      <|> (return . B.math <$> (mathInline >>= applyMacros'))
 
-mathDisplay :: MarkdownParser String
-mathDisplay =
-      (guardEnabled Ext_tex_math_dollars >> mathDisplayWith "$$" "$$")
-  <|> (guardEnabled Ext_tex_math_single_backslash >>
-       mathDisplayWith "\\[" "\\]")
-  <|> (guardEnabled Ext_tex_math_double_backslash >>
-       mathDisplayWith "\\\\[" "\\\\]")
-
-mathDisplayWith :: String -> String -> MarkdownParser String
-mathDisplayWith op cl = try $ do
-  string op
-  many1Till (noneOf "\n" <|> (newline >>~ notFollowedBy' blankline)) (try $ string cl)
-
-mathInline :: MarkdownParser String
-mathInline =
-      (guardEnabled Ext_tex_math_dollars >> mathInlineWith "$" "$")
-  <|> (guardEnabled Ext_tex_math_single_backslash >>
-       mathInlineWith "\\(" "\\)")
-  <|> (guardEnabled Ext_tex_math_double_backslash >>
-       mathInlineWith "\\\\(" "\\\\)")
-
-mathInlineWith :: String -> String -> MarkdownParser String
-mathInlineWith op cl = try $ do
-  string op
-  notFollowedBy space
-  words' <- many1Till (count 1 (noneOf "\n\\")
-                   <|> (char '\\' >> anyChar >>= \c -> return ['\\',c])
-                   <|> count 1 newline <* notFollowedBy' blankline
-                       *> return " ")
-              (try $ string cl)
-  notFollowedBy digit  -- to prevent capture of $5
-  return $ concat words'
-
 -- Parses material enclosed in *s, **s, _s, or __s.
 -- Designed to avoid backtracking.
 enclosure :: Char