[Backport #8328] [ruby-core:55250] Patch by funny-falcon

* benchmark/bm_hash_shift.rb: add benchmark for Hash#shift

* hash.c (rb_hash_shift): use st_shift if hash is not being iterated to
  delete element without iterating the whole hash.

* hash.c (shift_i): remove function

* include/ruby/st.h (st_shift): add st_shift function

* st.c (st_shift): ditto


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_9_3@41652 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 10 insertions, 18 deletions

diff --git a/hash.c b/hash.c
index fbd82374eb..0a5f6a600e 100644
--- a/hash.c
+++ b/hash.c
@@ -824,18 +824,6 @@ struct shift_var {
 };
 
 static int
-shift_i(VALUE key, VALUE value, VALUE arg)
-{
-    struct shift_var *var = (struct shift_var *)arg;
-
-    if (key == Qundef) return ST_CONTINUE;
-    if (var->key != Qundef) return ST_STOP;
-    var->key = key;
-    var->val = value;
-    return ST_DELETE;
-}
-
-static int
 shift_i_safe(VALUE key, VALUE value, VALUE arg)
 {
     struct shift_var *var = (struct shift_var *)arg;
@@ -866,16 +854,20 @@ rb_hash_shift(VALUE hash)
 
     rb_hash_modify(hash);
     var.key = Qundef;
-    rb_hash_foreach(hash, RHASH(hash)->iter_lev > 0 ? shift_i_safe : shift_i,
-		    (VALUE)&var);
+    if (RHASH(hash)->iter_lev == 0) {
+	if (st_shift(RHASH(hash)->ntbl, &var.key, &var.val)) {
+	    return rb_assoc_new(var.key, var.val);
+	}
+    }
+    else {
+	rb_hash_foreach(hash, shift_i_safe, (VALUE)&var);
 
-    if (var.key != Qundef) {
-	if (RHASH(hash)->iter_lev > 0) {
+	if (var.key != Qundef) {
 	    rb_hash_delete_key(hash, var.key);
+	    return rb_assoc_new(var.key, var.val);
 	}
-	return rb_assoc_new(var.key, var.val);
     }
-    else if (FL_TEST(hash, HASH_PROC_DEFAULT)) {
+    if (FL_TEST(hash, HASH_PROC_DEFAULT)) {
 	return rb_funcall(RHASH_IFNONE(hash), id_yield, 2, hash, Qnil);
     }
     else {