marcandre	2012-11-07 02:10:20 +0900 (Wed, 07 Nov 2012)

  New Revision: 37498

  http://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=rev&revision=37498

  Log:
    * enumerator.c (obj_to_enum): Have #to_enum accept a block
      [Feature #6636]

  Modified files:
    trunk/enumerator.c
    trunk/test/ruby/test_enumerator.rb

Index: enumerator.c
===================================================================
--- enumerator.c	(revision 37497)
+++ enumerator.c	(revision 37498)
@@ -186,6 +186,8 @@
  * call-seq:
  *   obj.to_enum(method = :each, *args)
  *   obj.enum_for(method = :each, *args)
+ *   obj.to_enum(method = :each, *args) {|obj, *args| block}
+ *   obj.enum_for(method = :each, *args){|obj, *args| block}
  *
  * Creates a new Enumerator which will enumerate by on calling +method+ on
  * +obj+.
@@ -195,6 +197,9 @@
  *          to the item itself.  Note that the number of args
  *          must not exceed the number expected by +method+
  *
+ *  If a block is given, it will be used to calculate the size of
+ *  the enumerator (see Enumerator#size=).
+ *
  * === Example
  *
  *   str = "xyz"
@@ -213,13 +218,17 @@
 static VALUE
 obj_to_enum(int argc, VALUE *argv, VALUE obj)
 {
-    VALUE meth = sym_each;
+    VALUE enumerator, meth = sym_each;
 
     if (argc > 0) {
 	--argc;
 	meth = *argv++;
     }
-    return rb_enumeratorize(obj, meth, argc, argv, 0);
+    enumerator = rb_enumeratorize(obj, meth, argc, argv, 0);
+    if (rb_block_given_p()) {
+	enumerator_ptr(enumerator)->size = rb_block_proc();
+    }
+    return enumerator;
 }
 
 static VALUE
Index: test/ruby/test_enumerator.rb
===================================================================
--- test/ruby/test_enumerator.rb	(revision 37497)
+++ test/ruby/test_enumerator.rb	(revision 37498)
@@ -410,6 +410,9 @@
     assert_equal Float::INFINITY, Enumerator.new(Float::INFINITY){}.size
     assert_equal nil, Enumerator.new(nil){}.size
     assert_raise(TypeError) { Enumerator.new("42"){} }
+
+    assert_equal nil, @obj.to_enum(:foo, 0, 1).size
+    assert_equal 2, @obj.to_enum(:foo, 0, 1){ 2 }.size
   end
 end
 

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