Changeset 6359 for src/Pugs/Lexer.hs

Timestamp:

08/19/05 13:37:26 (3 years ago)

Author:

scook0

svk:copy_cache_prev:

8581

Message:

* Some docs for Lexer.hs and Parser/Types.hs
* Tweak DrIFT/Binary.hs so it doesn't confuse poor Haddock

Files:

• src/Pugs/Lexer.hs (modified) (3 diffs)

src/Pugs/Lexer.hs

@@ -136 +136 @@
     aheadSym x   y   = y `elem` ";!" || x /= y
 
-interpolatingStringLiteral :: RuleParser String    -- ^ Opening delimiter
-                              -> RuleParser String   -- ^ Closing delimiter 
-                              -> RuleParser Exp -- ^ Interpolator
-                              -> RuleParser Exp -- ^ Entire string
-                                                -- ^ (without delims)
+interpolatingStringLiteral :: RuleParser String -- ^ Opening delimiter
+                           -> RuleParser String -- ^ Closing delimiter 
+                           -> RuleParser Exp    -- ^ Interpolator
+                           -> RuleParser Exp    -- ^ Entire string
+                                                --     (without delims)
 interpolatingStringLiteral startrule endrule interpolator = do
     list <- stringList 0
@@ -154 +154 @@
     
     stringList :: Int -> RuleParser [Exp]
-    stringList i = try (do
-               parse <- interpolator
-               rest  <- stringList i
-               return (parse:rest))
-           <|> try (do
-               ch <- endrule
-               if i == 0 then return []
-                         else do rest <- stringList (i-1)
-                                 return (Val (VStr ch):rest))
-           <|> try (do
-               ch <- startrule
-               rest <- stringList (i+1)
-               return (Val (VStr ch):rest))
-           <|> do
-               char <- anyChar
-               rest <- stringList i
-               return (Val (VStr [char]):rest)
-
--- | backslahed nonalphanumerics (except for \^) translate into themselves
+    stringList i = tryChoice
+        [ do
+            parse <- interpolator
+            rest  <- stringList i
+            return (parse:rest)
+        , do
+            ch <- endrule
+            if i == 0
+                then return []
+                else do
+                    rest <- stringList (i-1)
+                    return (Val (VStr ch):rest)
+        , do
+            ch <- startrule
+            rest <- stringList (i+1)
+            return (Val (VStr ch):rest)
+        , do
+            char <- anyChar
+            rest <- stringList i
+            return (Val (VStr [char]):rest)
+        ]
+
+-- | Backslashed non-alphanumerics (except for @\^@) translate into themselves.
 escapeCode      :: GenParser Char st Char
 escapeCode      = charEsc <|> charNum <|> charAscii <|> charControl <|> anyChar
@@ -306 +310 @@
     return (lead:rest)
 
-tryChoice :: [GenParser tok st a] -> GenParser tok st a
+{-|
+Attempt each of the given parsers in turn until one succeeds, but if one of
+them fails we backtrack (i.e. retroactively consume no input) before trying
+the next one.
+-}
+tryChoice :: [GenParser tok st a] -- ^ List of candidate parsers
+          -> GenParser tok st a
 tryChoice = choice . map try
 
+{-|
+Match '@(@', followed by the given parser, followed by '@)@'.
+-}
 verbatimParens :: GenParser Char st a -> GenParser Char st a
 verbatimParens = between (lexeme $ char '(') (char ')')
 
+{-|
+Match '@\[@', followed by the given parser, followed by '@\]@'.
+-}
 verbatimBrackets :: GenParser Char st a -> GenParser Char st a
 verbatimBrackets = between (lexeme $ char '[') (char ']')
 
+{-|
+Match '@{@', followed by the given parser, followed by '@}@'.
+-}
 verbatimBraces :: GenParser Char st a -> GenParser Char st a
 verbatimBraces = between (lexeme $ char '{') (char '}')