* 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

[Bug #8312] [ruby-core:54524] Patch by funny-falcon

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@40457 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 9 insertions, 17 deletions

diff --git a/hash.c b/hash.c
index a06e7a352b..43b6757f14 100644
--- a/hash.c
+++ b/hash.c
@@ -875,17 +875,6 @@ struct shift_var {
 };
 
 static int
-shift_i(VALUE key, VALUE value, VALUE arg)
-{
-    struct shift_var *var = (struct shift_var *)arg;
-
-    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;
@@ -916,14 +905,17 @@ rb_hash_shift(VALUE hash)
     rb_hash_modify_check(hash);
     if (RHASH(hash)->ntbl) {
 	var.key = Qundef;
-	rb_hash_foreach(hash, RHASH_ITER_LEV(hash) > 0 ? shift_i_safe : shift_i,
-			(VALUE)&var);
-
-	if (var.key != Qundef) {
-	    if (RHASH_ITER_LEV(hash) > 0) {
+	if (RHASH_ITER_LEV(hash) == 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) {
 		rb_hash_delete_key(hash, var.key);
+		return rb_assoc_new(var.key, var.val);
 	    }
-	    return rb_assoc_new(var.key, var.val);
 	}
     }
     return hash_default_value(hash, Qnil);