hash.h

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/******************************************************************************
The MIT License(MIT)

Embedded Template Library.

Copyright(c) 2014 jwellbelove

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files(the "Software"), to deal
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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******************************************************************************/

#ifndef __ETL_HASH__
#define __ETL_HASH__

#include <stdint.h>

// The default hash calculation.
#include "fnv_1.h"

#include "type_traits.h"


namespace etl
{
  namespace __private_hash__
  {
    //*************************************************************************
    //*************************************************************************
    template <typename T>
    typename enable_if<sizeof(T) == sizeof(uint32_t), size_t>::type
    generic_hash(uint8_t* begin, uint8_t* end)
    {
      return fnv_1a_32<>(begin, end);
    }

    //*************************************************************************
    //*************************************************************************
    template <typename T>
    typename enable_if<sizeof(T) == sizeof(uint64_t), size_t>::type
    generic_hash(uint8_t* begin, uint8_t* end)
    {
      return fnv_1a_64<>(begin, end);
    }
  }

  //***************************************************************************
  //***************************************************************************
  template <typename T> struct hash;

  //***************************************************************************
  //***************************************************************************
  template <> 
  struct hash <bool>
  {
    size_t operator ()(bool v) const
    {
      return static_cast<size_t>(v);
    }
  };

  //***************************************************************************
  //***************************************************************************
  template <> 
  struct hash<char>
  {
    size_t operator ()(char v) const
    {
      return static_cast<size_t>(v);
    }
  };

  //***************************************************************************
  //***************************************************************************
  template<> struct
  hash<signed char>
  {
    size_t operator ()(signed char v) const
    {
      return static_cast<size_t>(v);
    }
  };

  //***************************************************************************
  //***************************************************************************
  template<>
  struct hash<unsigned char>
  {
    size_t operator ()(unsigned char v) const
    {
      return static_cast<size_t>(v);
    }
  };

  //***************************************************************************
  //***************************************************************************
  template<>
  struct hash<wchar_t>
  {
    size_t operator ()(wchar_t v) const
    {
      return static_cast<size_t>(v);
    }
  };

  //***************************************************************************
  //***************************************************************************
  template<> 
  struct hash<short>
  {
    size_t operator ()(short v) const
    {
      return static_cast<size_t>(v);
    }
  };

  //***************************************************************************
  //***************************************************************************
  template<>
  struct hash<unsigned short>
  {
    size_t operator ()(unsigned short v) const
    {
      return static_cast<size_t>(v);
    }
  };

  //***************************************************************************
  //***************************************************************************
  template<>
  struct hash<int>
  {
    size_t operator ()(int v) const
    {
      return static_cast<size_t>(v);
    }
  };

  //***************************************************************************
  //***************************************************************************
  template<> 
  struct hash<unsigned int>
  {
    size_t operator ()(unsigned int v) const
    {
      return static_cast<size_t>(v);
    }
  };

  //***************************************************************************
  //***************************************************************************
  template<>
  struct hash<long>
  {
    size_t operator ()(long v) const
    {
      if (sizeof(size_t) == sizeof(v))
      {
        return static_cast<size_t>(v);
      }
      else
      {
        uint8_t* p = reinterpret_cast<uint8_t*>(&v);

        return __private_hash__::generic_hash<size_t>(p, p + sizeof(v));
      }
    }
  };

  //***************************************************************************
  //***************************************************************************
  template<>
  struct hash<long long>
  {
    size_t operator ()(long long v) const
    {
      if (sizeof(size_t) == sizeof(v))
      {
        return static_cast<size_t>(v);
      }
      else
      {
        uint8_t* p = reinterpret_cast<uint8_t*>(&v);

        return __private_hash__::generic_hash<size_t>(p, p + sizeof(v));
      }
    }
  };

  //***************************************************************************
  //***************************************************************************
  template<>
  struct hash<unsigned long>
  {
    size_t operator ()(unsigned long v) const
    {
      if (sizeof(size_t) == sizeof(v))
      {
        return static_cast<size_t>(v);
      }
      else
      {
        uint8_t* p = reinterpret_cast<uint8_t*>(&v);

        return __private_hash__::generic_hash<size_t>(p, p + sizeof(v));
      }
    }
  };

  //***************************************************************************
  //***************************************************************************
  template<>
  struct hash<unsigned long long>
  {
    size_t operator ()(unsigned long long v) const
    {
      if (sizeof(size_t) == sizeof(v))
      {
        return static_cast<size_t>(v);
      }
      else
      {
        uint8_t* p = reinterpret_cast<uint8_t*>(&v);

        return __private_hash__::generic_hash<size_t>(p, p + sizeof(v));
      }
    }
  };

  //***************************************************************************
  //***************************************************************************
  template<>
  struct hash<float>
  {
    size_t operator ()(float v) const
    {
      if (sizeof(size_t) == sizeof(v))
      {
        return *reinterpret_cast<size_t*>(&v);
      }
      else
      {
        uint8_t* p = reinterpret_cast<uint8_t*>(&v);

        return __private_hash__::generic_hash<size_t>(p, p + sizeof(v));
      }
    }
  };

  //***************************************************************************
  //***************************************************************************
  template<> 
  struct hash<double>
  {
    size_t operator ()(double v) const
    {
      if (sizeof(size_t) == sizeof(v))
      {
        return *reinterpret_cast<size_t*>(&v);
      }
      else
      {
        uint8_t* p = reinterpret_cast<uint8_t*>(&v);

        return __private_hash__::generic_hash<size_t>(p, p + sizeof(v));
      }
    }
  };

  //***************************************************************************
  //***************************************************************************
  template<> 
  struct hash<long double>
  {
    size_t operator ()(long double v) const
    {
      if (sizeof(size_t) == sizeof(v))
      {
        return *reinterpret_cast<size_t*>(&v);
      }
      else
      {
        uint8_t* p = reinterpret_cast<uint8_t*>(&v);

        return __private_hash__::generic_hash<size_t>(p, p + sizeof(v));
      }
    }
  };

  //***************************************************************************
  //***************************************************************************
  template <typename T> 
  struct hash<T*>
  {
    size_t operator ()(T* v) const
    {
      if (sizeof(size_t) == sizeof(v))
      {
        return reinterpret_cast<size_t>(v);
      }
      else
      {
        uint8_t* p = reinterpret_cast<uint8_t*>(&v);

        return __private_hash__::generic_hash<size_t>(p, p + sizeof(v));
      }
    }
  };
}

#endif