traits.h

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#ifndef TRAITS_H
#define TRAITS_H
#pragma once
/***************************************************************************
 *   Copyright (C) 2013 Mike Kinghan, imk@burroingroingjoing.com           *
 *   All rights reserved.                                                  *
 *                                                                         *
 *   Contributed originally by Mike Kinghan, imk@burroingroingjoing.com    *
 *                                                                         *
 *   Redistribution and use in source and binary forms, with or without    *
 *   modification, are permitted provided that the following conditions    *
 *   are met:                                                              *
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 *   Redistributions of source code must retain the above copyright        *
 *   notice, this list of conditions and the following disclaimer.         *
 *                                                                         *
 *   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.  *
 *                                                                         *
 *   Neither the name of Mike Kinghan 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     *
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 **************************************************************************/
#include <type_traits>
#include <cstddef>

namespace traits {

using std::is_same;
using std::declval;

template<typename T, typename V>
struct has_value_type_of
{
    template<typename A>
    static constexpr bool test(typename A::value_type * ptr) {
        return is_same<decltype(ptr),V *>::value;
    }
    static constexpr bool test(...) {
        return false;
    }
    static const bool value = test<T>(nullptr);
};


template<typename T>
struct has_size_method
{
    template<typename A>
    static constexpr bool test(decltype(declval<A>().size()) * ptr) {
        return is_same<decltype(ptr),size_t *>::value;
    }
    static constexpr bool test(...) {
        return false;
    }

    static const bool value = test<T>(nullptr);
};

template< typename T>
struct has_index_operator
{
    template<typename A>
    static constexpr
    auto test( decltype(&declval<A>()[size_t(0)]) ptr) ->
        decltype(is_same<decltype(*ptr),typename A::value_type &>::value)
    {
        return is_same<decltype(*ptr),typename A::value_type &>::value;
    }

    static constexpr bool test(...) {
        return false;
    }

    static const bool value = test<T>(nullptr);
};

template< typename T>
struct has_data_method
{
    template<typename A>
    static constexpr auto test(decltype(declval<A const>().data()) ptr) ->
        decltype(is_same<decltype(ptr),typename A::value_type const *>::value)
    {
        return is_same<decltype(ptr),typename A::value_type const *>::value;
    }

    static constexpr bool test(...) {
        return false;
    }

    static const bool value = test<T>(nullptr);
};

template< typename T>
struct has_extend_method
{
    template<typename A>
    static constexpr bool test(decltype(declval<A>().extend()) * ptr) {
        return is_same<decltype(ptr),size_t *>::value;
    }

    template<typename A>
    static constexpr bool test(...) {
        return false;
    }

    static const bool value = test<T>(nullptr);
};

template<typename T>
struct is_random_access_char_sequence
{
    static const bool value =
        has_value_type_of<T,char>::value &&
        has_size_method<T>::value &&
        has_data_method<T>::value &&
        has_index_operator<T>::value;
};


} // namespace traits

#endif // EOF