From 852caed8a375ba761a786fc6c3d0da644422434f Mon Sep 17 00:00:00 2001
From: glass <glass@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Thu, 18 Jul 2013 08:48:12 +0000
Subject: [PATCH] * hash.c (rb_hash_flatten): performance improvement by not
 using   rb_hash_to_a() to avoid array creation with rb_assoc_new().

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@42039 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 ChangeLog |  5 +++++
 hash.c    | 28 +++++++++++++++++++++-------
 2 files changed, 26 insertions(+), 7 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 534775a1db..ab67c8a78c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Thu Jul 18 17:35:41 2013  Masaki Matsushita  <glass.saga@gmail.com>
+
+	* hash.c (rb_hash_flatten): performance improvement by not using
+	  rb_hash_to_a() to avoid array creation with rb_assoc_new().
+
 Thu Jul 18 16:16:17 2013  Koichi Sasada  <ko1@atdot.net>
 
 	* array.c: add logging feature for RGenGC's write barrier unprotect
diff --git a/hash.c b/hash.c
index 2cdf8b2dbf..447d73feb1 100644
--- a/hash.c
+++ b/hash.c
@@ -2187,6 +2187,18 @@ rb_hash_rassoc(VALUE hash, VALUE obj)
     return args[1];
 }
 
+static int
+flatten_i(VALUE key, VALUE val, VALUE ary)
+{
+    VALUE pair[2];
+
+    pair[0] = key;
+    pair[1] = val;
+    rb_ary_cat(ary, pair, 2);
+
+    return ST_CONTINUE;
+}
+
 /*
  *  call-seq:
  *     hash.flatten -> an_array
@@ -2206,15 +2218,17 @@ rb_hash_rassoc(VALUE hash, VALUE obj)
 static VALUE
 rb_hash_flatten(int argc, VALUE *argv, VALUE hash)
 {
-    VALUE ary, tmp;
+    VALUE ary;
 
-    ary = rb_hash_to_a(hash);
-    if (argc == 0) {
-	argc = 1;
-	tmp = INT2FIX(1);
-	argv = &tmp;
+    ary = rb_ary_new_capa(RHASH_SIZE(hash) * 2);
+    rb_hash_foreach(hash, flatten_i, ary);
+    if (argc) {
+	int level = FIX2INT(*argv) - 1;
+	if (level > 0) {
+	    *argv = INT2FIX(level);
+	    rb_funcall2(ary, rb_intern("flatten!"), argc, argv);
+	}
     }
-    rb_funcall2(ary, rb_intern("flatten!"), argc, argv);
     return ary;
 }