* string.c (str_alloc): defaults to null_str instead of NULL.

  [ruby-dev:31774]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_8@13473 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 35 insertions, 11 deletions

diff --git a/string.c b/string.c
index cc27550ebe..108a2af128 100644
--- a/string.c
+++ b/string.c
@@ -59,13 +59,17 @@ str_frozen_check(s)
     }
 }
 
+static VALUE str_alloc0 _((VALUE, int));
 static VALUE str_alloc _((VALUE));
+static VALUE str_alloc1 _((VALUE));
+
 static VALUE
-str_alloc(klass)
+str_alloc0(klass, flags)
     VALUE klass;
+    int flags;
 {
     NEWOBJ(str, struct RString);
-    OBJSETUP(str, klass, T_STRING);
+    OBJSETUP(str, klass, flags);
 
     str->ptr = 0;
     str->len = 0;
@@ -74,6 +78,25 @@ str_alloc(klass)
     return (VALUE)str;
 }
 
+static const char null_str[] = "";
+#define null_str (char *)null_str
+
+static VALUE
+str_alloc(klass)
+    VALUE klass;
+{
+    VALUE str = str_alloc0(klass, T_STRING | ELTS_SHARED);
+    RSTRING(str)->ptr = null_str;
+    return str;
+}
+
+static VALUE
+str_alloc1(klass)
+    VALUE klass;
+{
+    return str_alloc0(klass, T_STRING);
+}
+
 static VALUE
 str_new(klass, ptr, len)
     VALUE klass;
@@ -86,7 +109,7 @@ str_new(klass, ptr, len)
 	rb_raise(rb_eArgError, "negative string size (or size too big)");
     }
 
-    str = str_alloc(klass);
+    str = str_alloc1(klass);
     RSTRING(str)->len = len;
     RSTRING(str)->aux.capa = len;
     RSTRING(str)->ptr = ALLOC_N(char,len+1);
@@ -145,7 +168,6 @@ str_new3(klass, str)
     RSTRING(str2)->len = RSTRING(str)->len;
     RSTRING(str2)->ptr = RSTRING(str)->ptr;
     RSTRING(str2)->aux.shared = str;
-    FL_SET(str2, ELTS_SHARED);
 
     return str2;
 }
@@ -164,7 +186,7 @@ static VALUE
 str_new4(klass, str)
     VALUE klass, str;
 {
-    VALUE str2 = str_alloc(klass);
+    VALUE str2 = str_alloc1(klass);
 
     RSTRING(str2)->len = RSTRING(str)->len;
     RSTRING(str2)->ptr = RSTRING(str)->ptr;
@@ -223,7 +245,7 @@ VALUE
 rb_str_buf_new(capa)
     long capa;
 {
-    VALUE str = str_alloc(rb_cString);
+    VALUE str = str_alloc1(rb_cString);
 
     if (capa < STR_BUF_MIN_SIZE) {
 	capa = STR_BUF_MIN_SIZE;
@@ -257,13 +279,14 @@ rb_str_to_str(str)
     return rb_convert_type(str, T_STRING, "String", "to_str");
 }
 
+static int str_independent _((VALUE));
+
 static void
 rb_str_shared_replace(str, str2)
     VALUE str, str2;
 {
     if (str == str2) return;
-    rb_str_modify(str);
-    if (!FL_TEST(str, ELTS_SHARED)) free(RSTRING(str)->ptr);
+    if (str_independent(str)) xfree(RSTRING(str)->ptr);
     if (NIL_P(str2)) {
 	RSTRING(str)->ptr = 0;
 	RSTRING(str)->len = 0;
@@ -538,8 +561,6 @@ rb_str_associated(str)
     return Qfalse;
 }
 
-static char *null_str = "";
-
 VALUE
 rb_string_value(ptr)
     volatile VALUE *ptr;
@@ -2265,8 +2286,11 @@ rb_str_replace(str, str2)
 	FL_UNSET(str, STR_ASSOC);
 	RSTRING(str)->aux.shared = RSTRING(str2)->aux.shared;
     }
+    else if (!RSTRING(str2)->len) {
+	FL_SET(str, ELTS_SHARED);
+	RSTRING(str)->ptr = null_str;
+    }
     else {
-	rb_str_modify(str);
 	rb_str_resize(str, RSTRING(str2)->len);
 	memcpy(RSTRING(str)->ptr, RSTRING(str2)->ptr, RSTRING(str2)->len);
 	if (FL_TEST(str2, STR_ASSOC)) {