text: // Copyright (c) 2017-2020, The Troutbucks 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.
  // 
  // Most of this file is originally copyright (c) 2017 Raymond Chen, Microsoft
  // This algorithm is adapted from Raymond Chen's code:
  // https://blogs.msdn.microsoft.com/oldnewthing/20170109-00/?p=95145
  
  #pragma once
  
  #include <vector>
  #include <functional>
  #include "misc_log_ex.h"
  
  namespace tools
  {
  
  template<typename F>
  void apply_permutation(std::vector<size_t> permutation, const F &swap)
  {
    //sanity check
    for (size_t n = 0; n < permutation.size(); ++n)
      CHECK_AND_ASSERT_THROW_MES(std::find(permutation.begin(), permutation.end(), n) != permutation.end(), "Bad permutation");
  
    for (size_t i = 0; i < permutation.size(); ++i)
    {
      size_t current = i;
      while (i != permutation[current])
      {
        size_t next = permutation[current];
        swap(current, next);
        permutation[current] = current;
        current = next;
      }
      permutation[current] = current;
    }
  }
  
  template<typename T>
  void apply_permutation(const std::vector<size_t> &permutation, std::vector<T> &v)
  {
    CHECK_AND_ASSERT_THROW_MES(permutation.size() == v.size(), "Mismatched vector sizes");
    apply_permutation(permutation, [&v](size_t i0, size_t i1){ std::swap(v[i0], v[i1]); });
  }
  
  }
  