From 4e29081e93aadb902ebbcc27d9c2049d73434adb Mon Sep 17 00:00:00 2001
From: Chris Double <chris@bethia.(none)>
Date: Thu, 27 Mar 2008 18:07:30 +1300
Subject: [PATCH] Make left recursion in pegs a failed parse Eventually left
 recursion will work fine, but this is prevents an infinite loop for now.

---
 extra/peg/peg-tests.factor | 4 +++-
 extra/peg/peg.factor       | 4 ++--
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/extra/peg/peg-tests.factor b/extra/peg/peg-tests.factor
index bd4699f097..bd8abb63e6 100644
--- a/extra/peg/peg-tests.factor
+++ b/extra/peg/peg-tests.factor
@@ -175,6 +175,8 @@ IN: peg.tests
       [ "1" token , "+" token , "1" token , ] seq* ,
     ] choice* 
     "1-1" over parse parse-result-ast swap
-    "1+1" swap parse parse-result-ast
   ] with-packrat
+  [
+    "1+1" swap parse parse-result-ast
+  ] with-packrat 
 ] unit-test
\ No newline at end of file
diff --git a/extra/peg/peg.factor b/extra/peg/peg.factor
index bbd55ec6fa..1361f9fdbd 100755
--- a/extra/peg/peg.factor
+++ b/extra/peg/peg.factor
@@ -34,12 +34,12 @@ GENERIC: (compile) ( parser -- quot )
   #! that maps the input string position to the parser result.
   [ drop H{ } clone ] cache ;
 
-: cached-result ( n input-cache input quot -- result )
+:: cached-result ( n input-cache input quot -- result )
   #! Get the cached result for input position n
   #! from the input cache. If the item is not in the cache,
   #! call 'quot' with 'input' on the stack to get the result
   #! and store that in the cache and return it.
-  [ nip ] swap compose curry cache ; inline
+  n input-cache [ drop input quot call ] cache ; inline
 
 :: run-packrat-parser ( input quot c -- result )
   input input-from