ref(lexer): simplify delimited logic

src/Lexer.hs

@@ -16,6 +16,7 @@ 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]
@@ -125,28 +126,25 @@ 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)
 
-delimited :: Parser a -> Parser a -> Token -> Token -> Parser [LocatedToken]
+delimitedAsTuple :: Parser open -> Parser close -> Parser (Located open, LocatedToken, Located close)
-delimited a b c d = delimitedMaybe a b c (Just d)
+delimitedAsTuple openP closeP =
+    (,,)
+        <$> located openP
+        <*> located (Token <$> anyUntil closeP)
+        <*> located closeP
+
+delimited :: Parser a -> Parser b -> Token -> Token -> Parser [LocatedToken]
+delimited openP closeP openTok closeTok = asList <$> delimitedAsTuple (openTok <$ openP) (closeTok <$ closeP)
+    where
+        asList (a, tok, b) = [a, tok, b]
+
+delimitedNoTrailing :: Parser a -> Parser b -> Token -> Parser [LocatedToken]
+delimitedNoTrailing openP closeP openTok = asList <$> delimitedAsTuple (openTok <$ openP) (void closeP)
+    where
+        asList (a, tok, _) = [a, tok]
 
 delimitedSymmetric :: Parser a -> Token -> Token -> Parser [LocatedToken]
 delimitedSymmetric s t1 t2 = delimited s s t1 t2
@@ -155,22 +153,22 @@ eol :: Parser ()
 eol = void "\n" <|> void "\r\n" <|> Parsec.eof
 
 header1 :: Lexer
-header1 = delimitedMaybe (void $ "= ") eol (Header One) Nothing
+header1 = delimitedNoTrailing "= " eol (Header One)
 
 header2 :: Lexer
-header2 = delimitedMaybe (void $ "== ") eol (Header Two) Nothing
+header2 = delimitedNoTrailing "== " eol (Header Two)
 
 header3 :: Lexer
-header3 = delimitedMaybe (void $ "=== ") eol (Header Three) Nothing
+header3 = delimitedNoTrailing "=== " eol (Header Three)
 
 header4 :: Lexer
-header4 = delimitedMaybe (void $ "==== ") eol (Header Four) Nothing
+header4 = delimitedNoTrailing "==== " eol (Header Four)
 
 header5 :: Lexer
-header5 = delimitedMaybe (void $ "===== ") eol (Header Five) Nothing
+header5 = delimitedNoTrailing "===== " eol (Header Five)
 
 header6 :: Lexer
-header6 = delimitedMaybe (void $ "====== ") eol (Header Six) Nothing
+header6 = delimitedNoTrailing "====== " eol (Header Six)
 
 -- #anchors#
 anchors :: Lexer
@@ -247,16 +245,16 @@ labeledLink = do
                    ]
 
 mathsBracket :: Lexer
-mathsBracket = delimited (void $ "\\[") (void "\\]") MathsBracketOpen MathsBracketClose
+mathsBracket = delimited "\\[" "\\]" MathsBracketOpen MathsBracketClose
 
 mathsParens :: Lexer
-mathsParens = delimited (void $ "\\(") (void "\\)") MathsParenOpen MathsParenClose
+mathsParens = delimited "\\(" "\\)" MathsParenOpen MathsParenClose
 
 birdTrack :: Lexer
-birdTrack = delimitedMaybe (void ">> ") eol BirdTrack Nothing
+birdTrack = delimitedNoTrailing ">> " eol BirdTrack
 
 escape :: Lexer
-escape = delimitedMaybe (void "\\") eol Escape Nothing
+escape = delimitedNoTrailing "\\" eol Escape
 
 quotes :: Lexer
 quotes = delimitedSymmetric "\"" QuoteOpen QuoteClose