Check delimiters by hand to keep accurate source pos

src/Lexer.hs

@@ -11,6 +11,7 @@ import Data.Char (isAlphaNum, isPrint)
 import Data.Functor (($>))
 import Data.Text (Text)
 import Data.Text qualified as Text
+import Debug.Trace (traceM)
 import GHC.Stack (HasCallStack)
 import ParserMonad (Parser, initialParserState)
 import Text.Parsec
@@ -94,12 +95,16 @@ textElement =
 
 delimitedMaybe :: Parser a -> Parser a -> Token -> Maybe Token -> Parser [LocatedToken]
 delimitedMaybe op cl ot ct = do
-  pos <- getPosition
-  (text, content) <- match $ between op cl any'
-  let openTok :: LocatedToken = (setSourceColumn pos 1, ot)
-      res :: LocatedToken = (setSourceColumn pos 2, Token content)
+  openPos <- getPosition
+  void op -- opening
+  tokenPos <- getPosition
+  content <- any'
+  closePos <- getPosition
+  void cl
+  let openTok :: LocatedToken = (openPos, ot)
+      res :: LocatedToken = (tokenPos, Token content)
       closeToks :: [LocatedToken] = case ct of
-        Just close -> [(setSourceColumn pos (Text.length text), close)]
+        Just close -> [(closePos, close)]
         Nothing -> []
 
   pure $ [openTok, res] <> closeToks

test/Spec.hs

@@ -41,13 +41,13 @@ maths :: IO ()
 maths = do
   "\\[some math\\]"
     `shouldLexTo` [ (1, 1, MathsBracketOpen)
-                  , (1, 2, Token "some math")
-                  , (1, 13, MathsBracketClose)
+                  , (1, 3, Token "some math")
+                  , (1, 12, MathsBracketClose)
                   ]
   "\\(other maths\\)"
     `shouldLexTo` [ (1, 1, MathsParenOpen)
-                  , (1, 2, Token "other maths")
-                  , (1, 15, MathsParenClose)
+                  , (1, 3, Token "other maths")
+                  , (1, 14, MathsParenClose)
                   ]
 
 escaping :: Expectation
@@ -74,7 +74,7 @@ birdTracks :: Expectation
 birdTracks =
   ">> code"
     `shouldLexTo` [ (1, 1, BirdTrack)
-                  , (1, 2, Token "code")
+                  , (1, 4, Token "code")
                   ]
 
 quotes :: Expectation