sparsec

commit 349fe18411a6c293b1d43bb8b72f28cc00f5e02d
parent e39356d9a44f8894342a7f3d430fbddcbdf67369
Author: Robert Russell <robert@rr3.xyz>
Date:   Tue, 27 Aug 2024 03:45:47 -0700

Make bytesOf and spanOf modify parser state

... and as a result fix a bug in ruleWhileM.

Diffstat:
M
Sparsec.hs
 | 
17
+++++++++++------

1 file changed, 11 insertions(+), 6 deletions(-)
diff --git a/Sparsec.hs b/Sparsec.hs
@@ -213,14 +213,19 @@ lookahead p = do
     load s
     pure a
 
-spanOf :: Monad m => ParseT e m a -> ParseT e m Span
-spanOf p = Span <$> getLoc <*> lookahead (p *> getLoc)
+spanOf :: Monad m => ParseT e m a -> ParseT e m (a, Span)
+spanOf p = do
+    beg <- getLoc
+    a <- p
+    end <- getLoc
+    pure (a, Span beg end)
 
-bytesOf :: Monad m => ParseT e m a -> ParseT e m ByteString
+bytesOf :: Monad m => ParseT e m a -> ParseT e m (a, ByteString)
 bytesOf p = do
     (input, beg) <- save
-    end <- lookahead (p *> getLoc)
-    pure $ ByteString.drop (end.byte - beg.byte) input
+    a <- p
+    end <- getLoc
+    pure (a, ByteString.take (end.byte - beg.byte) input)
 
 -- Convert a failure into an error.
 -- TODO: Why do we call this "cut"?
@@ -306,7 +311,7 @@ charIf :: (Utf8Error e, Monad m) => (Char -> Bool) -> ParseT e m Char
 charIf want = charIfM (pure . want)
 
 runeWhileM :: (Utf8Error e, Monad m) => (Rune -> m Bool) -> ParseT e m ByteString
-runeWhileM want = bytesOf $ many (runeIfM want)
+runeWhileM want = snd <$> (bytesOf $ many (runeIfM want))
 
 runeWhile :: (Utf8Error e, Monad m) => (Rune -> Bool) -> ParseT e m ByteString
 runeWhile want = runeWhileM (pure . want)