1 files changed, 66 insertions, 0 deletions
diff --git a/test/std/algorithms/alg.sorting/alg.permutation.generators/prev_permutation.pass.cpp b/test/std/algorithms/alg.sorting/alg.permutation.generators/prev_permutation.pass.cpp
new file mode 100644
index 000000000000..d2fa2cb98b03
--- /dev/null
+++ b/test/std/algorithms/alg.sorting/alg.permutation.generators/prev_permutation.pass.cpp
@@ -0,0 +1,66 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <algorithm>
+
+// template<BidirectionalIterator Iter>
+//   requires ShuffleIterator<Iter>
+//         && LessThanComparable<Iter::value_type>
+//   bool
+//   prev_permutation(Iter first, Iter last);
+
+#include <algorithm>
+#include <cassert>
+
+#include "test_iterators.h"
+
+#include <cstdio>
+
+int factorial(int x)
+{
+    int r = 1;
+    for (; x; --x)
+        r *= x;
+    return r;
+}
+
+template <class Iter>
+void
+test()
+{
+    int ia[] = {6, 5, 4, 3, 2, 1};
+    const int sa = sizeof(ia)/sizeof(ia[0]);
+    int prev[sa];
+    for (int e = 0; e <= sa; ++e)
+    {
+        int count = 0;
+        bool x;
+        do
+        {
+            std::copy(ia, ia+e, prev);
+            x = std::prev_permutation(Iter(ia), Iter(ia+e));
+            if (e > 1)
+            {
+                if (x)
+                    assert(std::lexicographical_compare(ia, ia+e, prev, prev+e));
+                else
+                    assert(std::lexicographical_compare(prev, prev+e, ia, ia+e));
+            }
+            ++count;
+        } while (x);
+        assert(count == factorial(e));
+    }
+}
+
+int main()
+{
+    test<bidirectional_iterator<int*> >();
+    test<random_access_iterator<int*> >();
+    test<int*>();
+}