* hash.c (rb_hash_assoc): performance improvement by replacing

compare function in RHASH(hash)->ntbl->type temporarily like r42224.
  it falls back to rb_hash_foreach() if st_lookup() doesn't find the key.

* test/ruby/test_hash.rb: add a test for above.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@42237 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,11 @@
+Mon Jul 29 21:29:48 2013  Masaki Matsushita  <glass.saga@gmail.com>
+
+	* hash.c (rb_hash_assoc): performance improvement by replacing
+	  compare function in RHASH(hash)->ntbl->type temporarily like r42224.
+	  it falls back to rb_hash_foreach() if st_lookup() doesn't find the key.
+
+	* test/ruby/test_hash.rb: add a test for above.
+
 Mon Jul 29 21:15:30 2013  Akinori MUSHA  <knu@iDaemons.org>
 
 	* test/ruby/test_lazy_enumerator.rb

hash.c

@@ -2122,6 +2122,32 @@ rb_hash_merge(VALUE hash1, VALUE hash2)
     return rb_hash_update(rb_obj_dup(hash1), hash2);
 }
 
+static int
+assoc_cmp(VALUE a, VALUE b)
+{
+    return !RTEST(rb_equal(a, b));
+}
+
+static VALUE
+lookup2_call(VALUE arg)
+{
+    VALUE *args = (VALUE *)arg;
+    return rb_hash_lookup2(args[0], args[1], Qundef);
+}
+
+struct reset_hash_type_arg {
+    VALUE hash;
+    const struct st_hash_type *orighash;
+};
+
+static VALUE
+reset_hash_type(VALUE arg)
+{
+    struct reset_hash_type_arg *p = (struct reset_hash_type_arg *)arg;
+    RHASH(p->hash)->ntbl->type = p->orighash;
+    return Qundef;
+}
+
 static int
 assoc_i(VALUE key, VALUE val, VALUE arg)
 {
@@ -2149,11 +2175,33 @@ assoc_i(VALUE key, VALUE val, VALUE arg)
  */
 
 VALUE
-rb_hash_assoc(VALUE hash, VALUE obj)
+rb_hash_assoc(VALUE hash, VALUE key)
 {
+    st_table *table;
+    const struct st_hash_type *orighash;
     VALUE args[2];
 
-    args[0] = obj;
+    if (RHASH_EMPTY_P(hash)) return Qnil;
+    table = RHASH(hash)->ntbl;
+    orighash = table->type;
+
+    if (orighash != &identhash) {
+	VALUE value;
+	struct reset_hash_type_arg ensure_arg;
+	struct st_hash_type assochash;
+
+	assochash.compare = assoc_cmp;
+	assochash.hash = orighash->hash;
+	table->type = &assochash;
+	args[0] = hash;
+	args[1] = key;
+	ensure_arg.hash = hash;
+	ensure_arg.orighash = orighash;
+	value = rb_ensure(lookup2_call, (VALUE)&args, reset_hash_type, (VALUE)&ensure_arg);
+	if (value != Qundef) return rb_assoc_new(key, value);
+    }
+
+    args[0] = key;
     args[1] = Qnil;
     rb_hash_foreach(hash, assoc_i, (VALUE)args);
     return args[1];

test/ruby/test_hash.rb

@@ -879,6 +879,14 @@ class TestHash < Test::Unit::TestCase
     assert_equal([1.0,1], {1.0=>1}.assoc(1))
   end
 
+  def test_assoc_compare_by_identity
+    h = {}
+    h.compare_by_identity
+    h["a"] = 1
+    h["a"] = 2
+    assert_equal(["a",1], h.assoc("a"))
+  end
+
   def test_rassoc
     assert_equal([3,4], {1=>2, 3=>4, 5=>6}.rassoc(4))
     assert_nil({1=>2, 3=>4, 5=>6}.rassoc(3))