common: add apply_permutation file and function

This algorithm is adapted from Raymond Chen's code:
https://blogs.msdn.microsoft.com/oldnewthing/20170109-00/?p=95145

2 files changed, 46 insertions, 0 deletions

diff --git a/tests/unit_tests/CMakeLists.txt b/tests/unit_tests/CMakeLists.txt
index 2f62dc2aa..4286e0374 100644
--- a/tests/unit_tests/CMakeLists.txt
+++ b/tests/unit_tests/CMakeLists.txt
@@ -27,6 +27,7 @@
 # THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 set(unit_tests_sources
+  apply_permutation.cpp
   address_from_url.cpp
   ban.cpp
   base58.cpp
diff --git a/tests/unit_tests/apply_permutation.cpp b/tests/unit_tests/apply_permutation.cpp
new file mode 100644
index 000000000..888a00746
--- /dev/null
+++ b/tests/unit_tests/apply_permutation.cpp
@@ -0,0 +1,45 @@
+// Copyright (c) 2017, The Monero Project
+// 
+// All rights reserved.
+// 
+// Redistribution and use in source and binary forms, with or without modification, are
+// permitted provided that the following conditions are met:
+// 
+// 1. Redistributions of source code must retain the above copyright notice, this list of
+//    conditions and the following disclaimer.
+// 
+// 2. Redistributions in binary form must reproduce the above copyright notice, this list
+//    of conditions and the following disclaimer in the documentation and/or other
+//    materials provided with the distribution.
+// 
+// 3. Neither the name of the copyright holder nor the names of its contributors may be
+//    used to endorse or promote products derived from this software without specific
+//    prior written permission.
+// 
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
+// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include "gtest/gtest.h"
+#include "common/apply_permutation.h"
+
+TEST(apply_permutation, empty)
+{
+  std::vector<int> v = {};
+  tools::apply_permutation({}, v);
+  ASSERT_EQ(v, std::vector<int>({}));
+}
+
+TEST(apply_permutation, reorder)
+{
+  //                    0  1  2  3  4  5  6
+  std::vector<int> v = {8, 4, 6, 1, 7, 2, 4};
+  tools::apply_permutation({3, 5, 6, 1, 2, 4, 0}, v);
+  ASSERT_EQ(v, std::vector<int>({1, 2, 4, 4, 6, 7, 8}));
+}