* enumerator.c (enumerator_with_memo): New method: with_memo().

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@16795 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,7 @@
+Tue Jun  3 19:35:02 2008  Akinori MUSHA  <knu@iDaemons.org>
+
+	* enumerator.c (enumerator_with_memo): New method: with_memo().
+
 Tue Jun  3 20:04:03 2008  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* win32/Makefile.sub (miniruby$(EXEEXT)): miniruby cannot be

doc/NEWS

@@ -107,6 +107,7 @@ Compatible
     * Enumerable and Enumerator
           o Enumerable#map,collect_all called without a block returns
             an enumerator.
+          o Enumerable::Enumerator#with_memo
     * Regexp#match, String#match
           o Regexp#match, String#match
     * Fiber: coroutines/micro-threads

enumerator.c

@@ -357,6 +357,42 @@ enumerator_with_index(VALUE obj)
 			 enumerator_with_index_i, (VALUE)&memo);
 }
 
+static VALUE
+enumerator_with_memo_i(VALUE val, VALUE memo)
+{
+    return rb_yield_values(2, val, memo);
+}
+
+/*
+ *  call-seq:
+ *    e.with_memo(memo) {|(*args), memo| ... }
+ *    e.with_memo(memo)
+ *
+ *  Iterates the given block for each elements with an arbitrary
+ *  object given, and returns the memo object.
+ *
+ *  If no block is given, returns an enumerator.
+ *
+ */
+static VALUE
+enumerator_with_memo(VALUE obj, VALUE memo)
+{
+    struct enumerator *e;
+    int argc = 0;
+    VALUE *argv = 0;
+
+    RETURN_ENUMERATOR(obj, 0, 0);
+    e = enumerator_ptr(obj);
+    if (e->args) {
+	argc = RARRAY_LEN(e->args);
+	argv = RARRAY_PTR(e->args);
+    }
+    rb_block_call(e->obj, e->meth, argc, argv,
+		  enumerator_with_memo_i, memo);
+
+    return memo;
+}
+
 static VALUE
 next_ii(VALUE i, VALUE obj, int argc, VALUE *argv)
 {
@@ -454,6 +490,7 @@ Init_Enumerator(void)
     rb_define_method(rb_cEnumerator, "each", enumerator_each, 0);
     rb_define_method(rb_cEnumerator, "each_with_index", enumerator_with_index, 0);
     rb_define_method(rb_cEnumerator, "with_index", enumerator_with_index, 0);
+    rb_define_method(rb_cEnumerator, "with_memo", enumerator_with_memo, 1);
     rb_define_method(rb_cEnumerator, "next", enumerator_next, 0);
     rb_define_method(rb_cEnumerator, "rewind", enumerator_rewind, 0);
 

test/ruby/test_enumerator.rb

@@ -91,6 +91,25 @@ class TestEnumerator < Test::Unit::TestCase
     assert_equal([[1,0],[2,1],[3,2]], @obj.to_enum(:foo, 1, 2, 3).with_index.to_a)
   end
 
+  def test_with_memo
+    r = 1..10
+    assert_equal([55, 3628800], (1..10).each.with_memo([0,1]) {|i, memo|
+        memo[0] += i
+        memo[1] *= i
+      })
+
+    a = [2,5,2,1,5,3,4,2,1,0]
+    a.delete_if.with_memo({}) {|i, seen|
+      if seen.key?(i)
+        true
+      else
+        seen[i] = true
+        false
+      end
+    }
+    assert_equal([2, 5, 1, 3, 4, 0], a)
+  end
+
   def test_next_rewind
     e = @obj.to_enum(:foo, 1, 2, 3)
     assert_equal(1, e.next)