From df8451e6062029cb23593679317be97d1c218c7b Mon Sep 17 00:00:00 2001
From: marcandre <marcandre@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Tue, 6 Nov 2012 17:12:50 +0000
Subject: [PATCH] * enum.c (enum_each_slice): Support for
 Enumerable#each_slice.size   [Feature #6636]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@37508 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 enum.c                       | 22 +++++++++++++++++++++-
 test/ruby/test_enumerator.rb |  8 ++++++++
 2 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/enum.c b/enum.c
index f9fa993633..2f636ed07b 100644
--- a/enum.c
+++ b/enum.c
@@ -18,8 +18,12 @@
 #define STATIC_ASSERT(name, expr) typedef int static_assert_##name##_check[1 - 2*!(expr)]
 
 VALUE rb_mEnumerable;
+
 static ID id_next;
+static ID id_div;
 static ID id_call;
+static ID id_size;
+
 #define id_each idEach
 #define id_eqq  idEqq
 #define id_cmp  idCmp
@@ -1778,6 +1782,20 @@ each_slice_i(VALUE i, VALUE m, int argc, VALUE *argv)
     return v;
 }
 
+static VALUE
+enum_each_slice_size(VALUE obj, VALUE args)
+{
+    VALUE n, size;
+    long slice_size = NUM2LONG(RARRAY_PTR(args)[0]);
+    if (slice_size <= 0) rb_raise(rb_eArgError, "invalid slice size");
+
+    size = enum_size(obj, 0);
+    if (size == Qnil) return Qnil;
+
+    n = rb_funcall(size, '+', 1, LONG2NUM(slice_size-1));
+    return rb_funcall(n, id_div, 1, LONG2FIX(slice_size));
+}
+
 /*
  *  call-seq:
  *    enum.each_slice(n) { ... }  ->  nil
@@ -1802,7 +1820,7 @@ enum_each_slice(VALUE obj, VALUE n)
     NODE *memo;
 
     if (size <= 0) rb_raise(rb_eArgError, "invalid slice size");
-    RETURN_ENUMERATOR(obj, 1, &n);
+    RETURN_SIZED_ENUMERATOR(obj, 1, &n, enum_each_slice_size);
     ary = rb_ary_new2(size);
     memo = NEW_MEMO(ary, 0, size);
     rb_block_call(obj, id_each, 0, 0, each_slice_i, (VALUE)memo);
@@ -2743,4 +2761,6 @@ Init_Enumerable(void)
 
     id_next = rb_intern("next");
     id_call = rb_intern("call");
+    id_size = rb_intern("size");
+    id_div = rb_intern("div");
 }
diff --git a/test/ruby/test_enumerator.rb b/test/ruby/test_enumerator.rb
index 4757855533..1e3eb7c8b8 100644
--- a/test/ruby/test_enumerator.rb
+++ b/test/ruby/test_enumerator.rb
@@ -482,5 +482,13 @@ class TestEnumerator < Test::Unit::TestCase
   def test_size_for_loops
     assert_equal Float::INFINITY, loop.size
   end
+
+  def test_size_for_each_slice
+    assert_equal nil, @obj.each_slice(3).size
+    assert_equal 6, @sized.each_slice(7).size
+    assert_equal 5, @sized.each_slice(10).size
+    assert_equal 1, @sized.each_slice(70).size
+    assert_raise(ArgumentError){ @obj.each_slice(0).size }
+  end
 end