LaTeX reader: improve `\def` and implement `\newif`.

- Improve parsing of `\def` macros.  We previously set "verbatim mode"
  even for parsing the initial `\def`; this caused problems for things
  like
  ```
  \def\foo{\def\bar{BAR}}
  \foo
  \bar
  ```
- Implement `\newif`.
- Add tests.

1 files changed, 18 insertions, 1 deletions

diff --git a/src/Text/Pandoc/Readers/LaTeX/Parsing.hs b/src/Text/Pandoc/Readers/LaTeX/Parsing.hs
index 1c77eb299..a17b1f324 100644
--- a/src/Text/Pandoc/Readers/LaTeX/Parsing.hs
+++ b/src/Text/Pandoc/Readers/LaTeX/Parsing.hs
@@ -113,7 +113,6 @@ import Text.Pandoc.Readers.LaTeX.Types (ExpansionPoint (..), Macro (..),
                                         ArgSpec (..), Tok (..), TokType (..))
 import Text.Pandoc.Shared
 import Text.Parsec.Pos
--- import Debug.Trace
 
 newtype DottedNum = DottedNum [Int]
   deriving (Show, Eq)
@@ -563,8 +562,26 @@ trySpecialMacro "xspace" ts = do
     Tok pos Word t : _
       | startsWithAlphaNum t -> return $ Tok pos Spaces " " : ts'
     _ -> return ts'
+trySpecialMacro "iftrue" ts = handleIf True ts
+trySpecialMacro "iffalse" ts = handleIf False ts
 trySpecialMacro _ _ = mzero
 
+handleIf :: PandocMonad m => Bool -> [Tok] -> LP m [Tok]
+handleIf b ts = do
+  res' <- lift $ runParserT (ifParser b) defaultLaTeXState "tokens" ts
+  case res' of
+    Left _ -> Prelude.fail "Could not parse conditional"
+    Right ts' -> return ts'
+
+ifParser :: PandocMonad m => Bool -> LP m [Tok]
+ifParser b = do
+  ifToks <- many (notFollowedBy (controlSeq "else" <|> controlSeq "fi")
+                    *> anyTok)
+  elseToks <- (controlSeq "else" >> manyTill anyTok (controlSeq "fi"))
+                 <|> ([] <$ controlSeq "fi")
+  rest <- getInput
+  return $ (if b then ifToks else elseToks) ++ rest
+
 startsWithAlphaNum :: Text -> Bool
 startsWithAlphaNum t =
   case T.uncons t of