Stop allocating backref strings within gsub's search loop

* internal.h: add prototype for rb_reg_search0

* re.c: rename rb_reg_search to rb_reg_search0, add set_backref_str
  argument to allow callers to indicate that they don't require the
  backref string to be allocated

* string.c: don't allocate backref str if replacement string is provided

Closes GH-578. [Bug #9676] [ruby-core:61682]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45414 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 12 insertions, 3 deletions

diff --git a/re.c b/re.c
index 106cf593ac..1ceb6eaaf1 100644
--- a/re.c
+++ b/re.c
@@ -1375,7 +1375,7 @@ rb_reg_adjust_startpos(VALUE re, VALUE str, long pos, int reverse)
 
 /* returns byte offset */
 long
-rb_reg_search(VALUE re, VALUE str, long pos, int reverse)
+rb_reg_search0(VALUE re, VALUE str, long pos, int reverse, int set_backref_str)
 {
     long result;
     VALUE match;
@@ -1450,17 +1450,26 @@ rb_reg_search(VALUE re, VALUE str, long pos, int reverse)
 	    FL_UNSET(match, FL_TAINT);
     }
 
-    RMATCH(match)->str = rb_str_new4(str);
+    if (set_backref_str) {
+	RMATCH(match)->str = rb_str_new4(str);
+	OBJ_INFECT(match, str);
+    }
+
     RMATCH(match)->regexp = re;
     RMATCH(match)->rmatch->char_offset_updated = 0;
     rb_backref_set(match);
 
     OBJ_INFECT(match, re);
-    OBJ_INFECT(match, str);
 
     return result;
 }
 
+long
+rb_reg_search(VALUE re, VALUE str, long pos, int reverse)
+{
+	return rb_reg_search0(re, str, pos, reverse, 1);
+}
+
 VALUE
 rb_reg_nth_defined(int nth, VALUE match)
 {