span.hpp

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//
// Copyright (c) 2016-2017 Vinnie Falco (vinnie dot falco at gmail dot com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
// Official repository: https://github.com/boostorg/beast
//

#ifndef BOOST_BEAST_CORE_SPAN_HPP
#define BOOST_BEAST_CORE_SPAN_HPP

#include <boost/beast/config.hpp>
#include <boost/beast/core/detail/type_traits.hpp>
#include <algorithm>
#include <iterator>
#include <string>
#include <type_traits>

namespace boost {
namespace beast {

template<class T>
class span
{
    T* data_ = nullptr;
    std::size_t size_ = 0;

public:
    using element_type = T;

    using value_type = typename std::remove_const<T>::type;

    using index_type = std::ptrdiff_t;

    using pointer = T*;

    using reference = T&;

    using iterator = pointer;

    using const_pointer = T const*;

    using const_reference = T const&;

    using const_iterator = const_pointer;

    span() = default;

    span(span const&) = default;

    span& operator=(span const&) = default;

    span(T* data, std::size_t size)
        : data_(data), size_(size)
    {
    }

    template<class ContiguousContainer
#if ! BOOST_BEAST_DOXYGEN
        , class = typename std::enable_if<
          detail::is_contiguous_container<
                ContiguousContainer, T>::value>::type
#endif
    >
    explicit
    span(ContiguousContainer&& container)
        : data_(container.data())
        , size_(container.size())
    {
    }

#if ! BOOST_BEAST_DOXYGEN
    template<class CharT, class Traits, class Allocator>
    explicit
    span(std::basic_string<CharT, Traits, Allocator>& s)
        : data_(&s[0])
        , size_(s.size())
    {
    }

    template<class CharT, class Traits, class Allocator>
    explicit
    span(std::basic_string<CharT, Traits, Allocator> const& s)
        : data_(s.data())
        , size_(s.size())
    {
    }
#endif

    template<class ContiguousContainer>
#if BOOST_BEAST_DOXYGEN
    span&
#else
    typename std::enable_if<detail::is_contiguous_container<
        ContiguousContainer, T>::value,
    span&>::type
#endif
    operator=(ContiguousContainer&& container)
    {
        data_ = container.data();
        size_ = container.size();
        return *this;
    }

#if ! BOOST_BEAST_DOXYGEN
    template<class CharT, class Traits, class Allocator>
    span&
    operator=(std::basic_string<
        CharT, Traits, Allocator>& s)
    {
        data_ = &s[0];
        size_ = s.size();
        return *this;
    }

    template<class CharT, class Traits, class Allocator>
    span&
    operator=(std::basic_string<
        CharT, Traits, Allocator> const& s)
    {
        data_ = s.data();
        size_ = s.size();
        return *this;
    }
#endif

    bool
    empty() const
    {
        return size_ == 0;
    }

    T*
    data() const
    {
        return data_;
    }

    std::size_t
    size() const
    {
        return size_;
    }

    const_iterator
    begin() const
    {
        return data_;
    }
                
    const_iterator
    cbegin() const
    {
        return data_;
    }
       
    const_iterator
    end() const
    {
        return data_ + size_;
    }
        
    const_iterator
    cend() const
    {
        return data_ + size_;
    }
};

} // beast
} // boost

#endif