Parsing: fixed inlineMath so it handles \text{..} containing $.

For example: `$x = \text{the $n$th root of $y$}`.  Closes #1677.

src/Text/Pandoc/Parsing.hs

@@ -472,7 +472,12 @@ mathInlineWith op cl = try $ do
   string op
   notFollowedBy space
   words' <- many1Till (count 1 (noneOf " \t\n\\")
-                   <|> (char '\\' >> anyChar >>= \c -> return ['\\',c])
+                   <|> (char '\\' >>
+                           -- This next clause is needed because \text{..} can
+                           -- contain $, \(\), etc.
+                           (try (string "text" >>
+                                 (("\\text" ++) <$> inBalancedBraces 0 ""))
+                            <|>  (\c -> ['\\',c]) <$> anyChar))
                    <|> do (blankline <* notFollowedBy' blankline) <|>
                              (oneOf " \t" <* skipMany (oneOf " \t"))
                           notFollowedBy (char '$')
@@ -480,6 +485,23 @@ mathInlineWith op cl = try $ do
                     ) (try $ string cl)
   notFollowedBy digit  -- to prevent capture of $5
   return $ concat words'
+ where
+  inBalancedBraces :: Stream s m Char => Int -> String -> ParserT s st m String
+  inBalancedBraces 0 "" = do
+    c <- anyChar
+    if c == '{'
+       then inBalancedBraces 1 "{"
+       else mzero
+  inBalancedBraces 0 s = return $ reverse s
+  inBalancedBraces numOpen ('\\':xs) = do
+    c <- anyChar
+    inBalancedBraces numOpen (c:'\\':xs)
+  inBalancedBraces numOpen xs = do
+    c <- anyChar
+    case c of
+         '}' -> inBalancedBraces (numOpen - 1) (c:xs)
+         '{' -> inBalancedBraces (numOpen + 1) (c:xs)
+         _   -> inBalancedBraces numOpen (c:xs)
 
 mathDisplayWith :: Stream s m Char => String -> String -> ParserT s st m String
 mathDisplayWith op cl = try $ do

tests/markdown-reader-more.native

@@ -17,6 +17,7 @@
 ,Header 3 ("my-header",[],[]) [Str "my",Space,Str "header"]
 ,Header 2 ("in-math",[],[]) [Str "$",Space,Str "in",Space,Str "math"]
 ,Para [Math InlineMath "\\$2 + \\$3"]
+,Para [Math InlineMath "x = \\text{the $n$th root of $y$}"]
 ,Para [Str "This",Space,Str "should",Space,Str "not",Space,Str "be",Space,Str "math:"]
 ,Para [Str "$PATH",Space,Str "90",Space,Str "$PATH"]
 ,Header 2 ("commented-out-list-item",[],[]) [Str "Commented-out",Space,Str "list",Space,Str "item"]

tests/markdown-reader-more.txt

@@ -60,6 +60,8 @@
 
 $\$2 + \$3$
 
+$x = \text{the $n$th root of $y$}$
+
 This should not be math:
 
 $PATH 90 $PATH