src/Lexer.hs

@@ -16,7 +16,6 @@ import Text.Parsec
 import Text.Parsec qualified as Parsec
 import Text.Parsec.Pos (updatePosChar)
 
-type Located a = (SourcePos, a)
 type LocatedToken = (SourcePos, Token)
 
 type Lexer = Parser [LocatedToken]
@@ -126,49 +125,52 @@ headers =
                 , header6
                 ]
 
+delimitedMaybe :: Parser a -> Parser a -> Token -> Maybe Token -> Parser [LocatedToken]
+delimitedMaybe openMark closeMark openToken closeToken = do
+    openPos <- getPosition
+    void openMark
+    tokenPos <- getPosition
+    content <- anyUntil closeMark
+    closePos <- getPosition
+    void closeMark
+
+    let openTok :: LocatedToken = (openPos, openToken)
+        res :: LocatedToken = (tokenPos, Token content)
+        closeToks :: [LocatedToken] = case closeToken of
+            Just close -> [(closePos, close)]
+            Nothing -> []
+
+    pure $ [openTok, res] <> closeToks
+
 anyUntil :: Parser a -> Parser Text
 anyUntil p = Text.pack <$> manyTill anyChar (lookAhead p)
 
-delimitedAsTuple :: Parser open -> Parser close -> Parser (Located open, LocatedToken, Located close)
+delimited :: Parser a -> Parser a -> Token -> Token -> Parser [LocatedToken]
-delimitedAsTuple openP closeP =
+delimited a b c d = delimitedMaybe a b c (Just d)
-    (,,)
-        <$> located openP
-        <*> located (Token <$> anyUntil closeP)
-        <*> located closeP
-
-delimited :: Parser a -> Parser b -> Token -> Token -> Parser [LocatedToken]
-delimited openP closeP openTok closeTok = fuse <$> delimitedAsTuple (openTok <$ openP) (closeTok <$ closeP)
-    where
-        fuse (a, tok, b) = [a, tok, b]
-
-delimitedNoTrailing :: Parser a -> Parser b -> Token -> Parser [LocatedToken]
-delimitedNoTrailing openP closeP openTok = fuse <$> delimitedAsTuple (openTok <$ openP) (void closeP)
-    where
-        fuse (a, tok, _) = [a, tok]
 
 delimitedSymmetric :: Parser a -> Token -> Token -> Parser [LocatedToken]
 delimitedSymmetric s t1 t2 = delimited s s t1 t2
 
 eol :: Parser ()
-eol = void "\n" <|> void "\r\n" <|> Parsec.eof
+eol = void "\n" <|> Parsec.eof
 
 header1 :: Lexer
-header1 = delimitedNoTrailing "= " eol (Header One)
+header1 = delimitedMaybe (void $ "= ") eol (Header One) Nothing
 
 header2 :: Lexer
-header2 = delimitedNoTrailing "== " eol (Header Two)
+header2 = delimitedMaybe (void $ "== ") eol (Header Two) Nothing
 
 header3 :: Lexer
-header3 = delimitedNoTrailing "=== " eol (Header Three)
+header3 = delimitedMaybe (void $ "=== ") eol (Header Three) Nothing
 
 header4 :: Lexer
-header4 = delimitedNoTrailing "==== " eol (Header Four)
+header4 = delimitedMaybe (void $ "==== ") eol (Header Four) Nothing
 
 header5 :: Lexer
-header5 = delimitedNoTrailing "===== " eol (Header Five)
+header5 = delimitedMaybe (void $ "===== ") eol (Header Five) Nothing
 
 header6 :: Lexer
-header6 = delimitedNoTrailing "====== " eol (Header Six)
+header6 = delimitedMaybe (void $ "====== ") eol (Header Six) Nothing
 
 -- #anchors#
 anchors :: Lexer
@@ -245,16 +247,16 @@ labeledLink = do
                    ]
 
 mathsBracket :: Lexer
-mathsBracket = delimited "\\[" "\\]" MathsBracketOpen MathsBracketClose
+mathsBracket = delimited (void $ "\\[") (void "\\]") MathsBracketOpen MathsBracketClose
 
 mathsParens :: Lexer
-mathsParens = delimited "\\(" "\\)" MathsParenOpen MathsParenClose
+mathsParens = delimited (void $ "\\(") (void "\\)") MathsParenOpen MathsParenClose
 
 birdTrack :: Lexer
-birdTrack = delimitedNoTrailing ">> " eol BirdTrack
+birdTrack = delimitedMaybe (void ">> ") eol BirdTrack Nothing
 
 escape :: Lexer
-escape = delimitedNoTrailing "\\" eol Escape
+escape = delimitedMaybe (void "\\") eol Escape Nothing
 
 quotes :: Lexer
 quotes = delimitedSymmetric "\"" QuoteOpen QuoteClose

test/Spec.hs

@@ -106,15 +106,11 @@ maths = do
                       ]
 
 escaping :: Expectation
-escaping = do
+escaping =
     "\\("
         `shouldLexTo` [ (1, 1, Escape)
                       , (1, 2, Token "(")
                       ]
-    "\\(\r\n"
-        `shouldLexTo` [ (1, 1, Escape)
-                      , (1, 2, Token "(")
-                      ]
 
 unicode :: Expectation
 unicode =