Move citeKey from Readers.Markdown to Parsing

The function can be used by other readers, so it is made accessible for
all parsers.

src/Text/Pandoc/Parsing.hs

@@ -94,6 +94,7 @@ module Text.Pandoc.Parsing ( (>>~),
                              apostrophe,
                              dash,
                              nested,
+                             citeKey,
                              macro,
                              applyMacros',
                              Parser,
@@ -1144,6 +1145,18 @@ nested p = do
   updateState $ \st -> st{ stateMaxNestingLevel = nestlevel }
   return res
 
+citeKey :: HasLastStrPosition st => Parser [Char] st (Bool, String)
+citeKey = try $ do
+  guard =<< notAfterString
+  suppress_author <- option False (char '-' *> return True)
+  char '@'
+  firstChar <- letter <|> char '_'
+  let regchar = satisfy (\c -> isAlphaNum c || c == '_')
+  let internal p = try $ p <* lookAhead regchar
+  rest <- many $ regchar <|> internal (oneOf ":.#$%&-+?<>~/")
+  let key = firstChar:rest
+  return (suppress_author, key)
+
 --
 -- Macros
 --

src/Text/Pandoc/Readers/Markdown.hs

@@ -1814,20 +1814,6 @@ normalCite = try $ do
   char ']'
   return citations
 
-citeKey :: MarkdownParser (Bool, String)
-citeKey = try $ do
-  -- make sure we're not right after an alphanumeric,
-  -- since foo@bar.baz is probably an email address
-  guard =<< notAfterString
-  suppress_author <- option False (char '-' >> return True)
-  char '@'
-  first <- letter <|> char '_'
-  let regchar = satisfy (\c -> isAlphaNum c || c == '_')
-  let internal p = try $ p >>~ lookAhead regchar
-  rest <- many $ regchar <|> internal (oneOf ":.#$%&-+?<>~/")
-  let key = first:rest
-  return (suppress_author, key)
-
 suffix :: MarkdownParser (F Inlines)
 suffix = try $ do
   hasSpace <- option False (notFollowedBy nonspaceChar >> return True)