* array.c (rb_ary_combination): new method to give all combination

  of elements from an array.  [ruby-list:42671]

* array.c (rb_ary_product): a new method to get all combinations
  of elements from two arrays.  can be extended to combinations of
  n-arrays, e.g. a.product(b,c,d).  anyone volunteer?

* array.c (rb_ary_permutation): empty function body to calculate
  permutations of array elements.  need volunteer.

git-svn-id: http://svn.ruby-lang.org/repos/ruby/trunk@13568 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 22 insertions, 0 deletions

diff --git a/test/ruby/test_array.rb b/test/ruby/test_array.rb
index 0d88f26dc..4d2b05304 100644
--- a/test/ruby/test_array.rb
+++ b/test/ruby/test_array.rb
@@ -1177,4 +1177,26 @@ class TestArray < Test::Unit::TestCase
     assert_equal(@cls[1,2], @cls[1, 2] | @cls[1, 2])
   end
 
+# def test_permutation
+#    assert_equal(@cls[], @cls[1,2,3].permutation(0).to_a)
+#    assert_equal(@cls[[1],[2],[3]], @cls[1,2,3].permutation(1).to_a)
+#    assert_equal(@cls[[1,2],[1,3],[2,1],[2,3],[3,1],[3,2]], @cls[1,2,3].permutation(2).to_a)
+#    assert_equal(@cls[[1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2],[3,2,1]], @cls[1,2,3].permutation(3).to_a)
+#    assert_equal(@cls[], @cls[1,2,3].permutation(4).to_a)
+#  end
+
+ def test_combination
+    assert_equal(@cls[], @cls[1,2,3,4].combination(0).to_a)
+    assert_equal(@cls[[1],[2],[3],[4]], @cls[1,2,3,4].combination(1).to_a)
+    assert_equal(@cls[[1,2],[1,3],[1,4],[2,3],[2,4],[3,4]], @cls[1,2,3,4].combination(2).to_a)
+    assert_equal(@cls[[1,2,3],[1,2,4],[1,3,4],[2,3,4]], @cls[1,2,3,4].combination(3).to_a)
+    assert_equal(@cls[[1,2,3,4]], @cls[1,2,3,4].combination(4).to_a)
+    assert_equal(@cls[], @cls[1,2,3,4].combination(5).to_a)
+  end
+
+  def test_product
+    assert_equal(@cls[[1,4],[1,5],[2,4],[2,5],[3,4],[3,5]],
+                 @cls[1,2,3].product([4,5]))
+    assert_equal(@cls[[1,1],[1,2],[2,1],[2,2]], @cls[1,2].product([1,2]))
+  end
 end