Changeset 7861

Timestamp:

11/05/05 23:47:32 (3 years ago)

Author:

autrijus

Message:

* Work around PGE's bug in not grokking zero-width rules

(reporte to p6[ic]), by special casing that // matches
always at position 0 with length 0. It's useful anyway
because split(//, $string) can be fast without launching
Parrot.

* Also, fix m:g// and m:P5:g// support so they won't loop

on zero-width matches. (Previously s:g// and s:P5:g//
was fixed in the same fashion.)

Files:

• src/Pugs/Prim/Match.hs (modified) (4 diffs)

src/Pugs/Prim/Match.hs

@@ -15 +15 @@
 
 doMatch :: String -> VRule -> Eval VMatch
+-- Work around PGE bug on Parrot 0.3.1 -- empty rule matches automatically
+doMatch _ MkRulePGE{ rxRule = "" } = return $ mkMatchOk 0 0 "" [] Map.empty
 doMatch cs MkRulePGE{ rxRule = re } = do
     let pwd1 = getConfig "installarchlib" ++ "/CORE/pugs/pge"
@@ -153 +155 @@
     where
     hasSubpatterns = case rx of
-        MkRulePGE{}             -> True -- bogus
+        MkRulePGE{}             -> True -- XXX bogus - use <p6rule> to parse itself
         MkRulePCRE{rxNumSubs=n} -> not (n == 0)
     matchOnce :: String -> Eval [Val]
@@ -159 +161 @@
         match <- str `doMatch` rx
         if not (matchOk match) then return [] else do
-        rest <- matchOnce (genericDrop (matchTo match) str)
-        return $ if hasSubpatterns
-                 then (matchSubPos match) ++ rest
-                 else (VMatch match):rest
+        let ret x = return $ if hasSubpatterns
+                        then (matchSubPos match) ++ x
+                        else (VMatch match):x
+        case (matchTo match, matchFrom match) of
+            (0, 0) -> if null str then ret [] else do
+                rest <- matchOnce (tail str)
+                ret rest
+            (to, _) -> do
+                rest <- matchOnce (genericDrop to str)
+                ret rest
 
 op2Match x (VRule rx) = do
@@ -210 +218 @@
         then do
             let (c:cs) = str
-            rest <- rxSplit rx (cs)
+            rest <- rxSplit rx cs
             return (VStr [c]:rest)
         else do