hashes.h

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// ========================================================================= //
// This file is part of MyraMath, copyright (c) 2014-2019 by Ryan A Chilton  //
// and distributed by MyraCore, LLC. See LICENSE.txt for license terms.      //
// ========================================================================= //

#ifndef MYRAMATH_UTILITY_HASHES_H
#define MYRAMATH_UTILITY_HASHES_H

#include <vector>
#include <functional>

#ifdef MYRAMATH_ENABLE_CPP11

namespace myra {

template <class T> void hash_combine(size_t& seed, const T& t)
  { 
  std::hash<T> hasher;
  seed ^= hasher(t) + 0x9e3779b9 + (seed<<6) + (seed>>2); 
  }

} // namespace myra

namespace std {

template <class First, class Second> struct hash < std::pair<First,Second> >
  {
  
  public:
  
    size_t operator() (const std::pair<First,Second>& p) const
      {
      size_t seed = 0;
      myra::hash_combine(seed,p.first);
      myra::hash_combine(seed,p.second);      
      return seed;
      }
    
  };

template <class T> struct hash < std::vector<T> >
  {
  
  public:
  
    size_t operator() (const std::vector<T>& v) const
      {
      size_t seed = 0;
      for (const T& t : v)
        myra::hash_combine(seed,t);
      return seed;
      }
    
  };

} // namespace std

#endif

#endif