From: matz@... (Yukihiro Matsumoto)
Date: 1997-12-18T10:44:47+09:00
Subject: [ruby-dev:1128] Re: Regexp#operators (Re: ruby 1.1b1 released)

まつもと ゆきひろです

In message "[ruby-dev:1109] Re: Regexp#operators (Re: ruby 1.1b1 released)"
    on 97/12/16, WATANABE Hirofumi <watanabe@ase.ptg.sony.co.jp> writes:

|rbc0> x = "barfoo"
|"barfoo"
|rbc0> x =~ /(?=.*foo).*bar/
|false
|
|うーむ. true にならない. (?=RE) がバグってますね.

そうでした．以下にパッチをつけます．
# 思ったよりずっと大変だった ^^;;;

--- regex.c~	Thu Dec 11 13:44:03 1997
+++ regex.c	Thu Dec 18 00:23:53 1997
@@ -599,3 +599,4 @@
 	case start_nowidth:
-	  printf ("/start_nowidth");
+          EXTRACT_NUMBER_AND_INCR (mcnt, p);
+	  printf ("/start_nowidth//%d", mcnt);
 	  break;
@@ -603,3 +604,4 @@
 	case stop_nowidth:
-	  printf ("/stop_nowidth");
+	  printf ("/stop_nowidth//");
+	  p += 2;
 	  break;
@@ -1335,3 +1337,3 @@
 	  if (c == '#') break;
-	  if (stackp+5 >= stacke) {
+	  if (stackp+6 >= stacke) {
 	    int *stackx;
@@ -1362,8 +1364,9 @@
 	    case '=':
-	      BUFPUSH(start_nowidth);
-	      *stackp++ = 0;
-	      break;
-
 	    case '!':
 	      BUFPUSH(start_nowidth);
+	      *stackp++ = b - bufp->buffer;
+	      BUFPUSH(0);	/* temporary value */
+	      BUFPUSH(0);
+	      if (c == '=') break;
+
 	      BUFPUSH(on_failure_jump);
@@ -1398,2 +1401,3 @@
 	      STORE_NUMBER(bufp->buffer+stackp[-1], b - bufp->buffer - stackp[-1] - 2);
+	      stackp--;
 	      /* fall through */
@@ -1401,2 +1405,6 @@
 	      BUFPUSH(stop_nowidth);
+	      /* tell stack-pos place to start_nowidth */
+	      STORE_NUMBER(bufp->buffer+stackp[-1], b - bufp->buffer - stackp[-1] - 2);
+	      BUFPUSH(0);	/* space to hold stack pos */
+	      BUFPUSH(0);
 	      break;
@@ -2052,4 +2060,2 @@
 	case wordend:
-        case start_nowidth:
-	case stop_nowidth:
 	case pop_and_fail:
@@ -2095,5 +2101,7 @@
 
+        case start_nowidth:
+	case stop_nowidth:
         case finalize_push:
 	  p += 2;
-	  break;
+	  continue;
 
@@ -2101,3 +2109,3 @@
 	  p += 4;
-	  break;
+	  continue;
 
@@ -2528,3 +2536,3 @@
     *stackp++ = string_place;                                           \
-    *stackp++ = (unsigned char *)1;                                     \
+    *stackp++ = (unsigned char *)0; /* non-greedy flag */		\
   }
@@ -2894,11 +2902,16 @@
 	  PUSH_FAILURE_POINT(0, d);
-	  break;
+	  EXTRACT_NUMBER_AND_INCR(mcnt, p);
+	  STORE_NUMBER(p+mcnt, stackp - stackb);
+	  continue;
 
 	case stop_nowidth:
+	  EXTRACT_NUMBER_AND_INCR(mcnt, p);
+	  stackp = stackb + mcnt;
 	  d = stackp[-2];
 	  POP_FAILURE_POINT();
-	  break;
+	  continue;
 
 	case pop_and_fail:
-	  POP_FAILURE_POINT();
+	  EXTRACT_NUMBER(mcnt, p+1);
+	  stackp = stackb + mcnt;
 	  POP_FAILURE_POINT();
@@ -3129,3 +3142,3 @@
 	    PUSH_FAILURE_POINT(p, d);
-	    stackp[1] = (unsigned char*)0;
+	    stackp[-1] = (unsigned char*)1;
 	  }
@@ -3138,3 +3151,3 @@
           PUSH_FAILURE_POINT(p + mcnt, d);
-	  stackp[-1] = (unsigned char*)0;
+	  stackp[-1] = (unsigned char*)1;
 	  continue;
@@ -3150,3 +3163,3 @@
 	    PUSH_FAILURE_POINT(p + mcnt, d);
-	    stackp[-1] = (unsigned char*)0;
+	    stackp[-1] = (unsigned char*)1;
 	    p += 7;		/* skip n and set_number_at after destination */
@@ -3253,3 +3266,3 @@
 	}
-      if (stackp != stackb && (int)stackp[-1] == 0)
+      if (stackp != stackb && (int)stackp[-1] == 1)
 	  POP_FAILURE_POINT();