/* Copyright (c) 2016, Arvid Norberg All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: * 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 the author 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 OWNER 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. */ #ifndef TORRENT_SPAN_HPP_INCLUDED #define TORRENT_SPAN_HPP_INCLUDED #include #include #include "libtorrent/assert.hpp" namespace libtorrent { namespace aux { template struct compatible_type { // conversions that are OK // int -> int // int const -> int const // int -> int const // int -> int volatile // int -> int const volatile // int volatile -> int const volatile // int const -> int const volatile static const bool value = std::is_same::value || std::is_same::type>::value || std::is_same::type>::value || std::is_same::type>::value ; }; } template struct span { span() noexcept : m_ptr(nullptr), m_len(0) {} template ::value>::type> span(span const& v) noexcept // NOLINT : m_ptr(v.data()), m_len(v.size()) {} span(T& p) noexcept : m_ptr(&p), m_len(1) {} // NOLINT span(T* p, std::size_t const l) noexcept : m_ptr(p), m_len(l) {} // NOLINT template span(std::array& arr) noexcept // NOLINT : m_ptr(arr.data()), m_len(arr.size()) {} // this is necessary until C++17, where data() returns a non-const pointer template span(std::basic_string& str) noexcept // NOLINT : m_ptr(&str[0]), m_len(str.size()) {} template span(U (&arr)[N]) noexcept // NOLINT : m_ptr(&arr[0]), m_len(N) {} // anything with a .data() member function is considered a container // but only if the value type is compatible with T template ().data())>::type , typename = typename std::enable_if::value>::type> span(Cont& c) // NOLINT : m_ptr(c.data()), m_len(c.size()) {} // allow construction from const containers if T is const // this allows const spans to be constructed from a temporary container template ().data())>::type , typename = typename std::enable_if::value && std::is_const::value>::type> span(Cont const& c) // NOLINT : m_ptr(c.data()), m_len(c.size()) {} std::size_t size() const noexcept { return m_len; } bool empty() const noexcept { return m_len == 0; } T* data() const noexcept { return m_ptr; } using iterator = T*; using reverse_iterator = std::reverse_iterator; T* begin() const noexcept { return m_ptr; } T* end() const noexcept { return m_ptr + m_len; } reverse_iterator rbegin() const noexcept { return reverse_iterator(end()); } reverse_iterator rend() const noexcept { return reverse_iterator(begin()); } T& front() const noexcept { TORRENT_ASSERT(m_len > 0); return m_ptr[0]; } T& back() const noexcept { TORRENT_ASSERT(m_len > 0); return m_ptr[m_len - 1]; } span first(std::size_t const n) const { TORRENT_ASSERT(size() >= n); return { data(), n }; } span last(std::size_t const n) const { TORRENT_ASSERT(size() >= n); return { data() + size() - n, n }; } span subspan(std::size_t const offset) const { TORRENT_ASSERT(size() >= offset); return { data() + offset, size() - offset }; } span subspan(std::size_t const offset, std::size_t const count) const { TORRENT_ASSERT(size() >= offset); TORRENT_ASSERT(size() >= offset + count); return { data() + offset, count }; } T& operator[](std::size_t const idx) const { TORRENT_ASSERT(idx < m_len); return m_ptr[idx]; } private: T* m_ptr; std::size_t m_len; }; template inline bool operator==(span const& lhs, span const& rhs) { return lhs.size() == rhs.size() && (lhs.begin() == rhs.begin() || std::equal(lhs.begin(), lhs.end(), rhs.begin())); } template inline bool operator!=(span const& lhs, span const& rhs) { return lhs.size() != rhs.size() || (lhs.begin() != rhs.begin() && !std::equal(lhs.begin(), lhs.end(), rhs.begin())); } } #endif // TORRENT_SPAN_HPP_INCLUDED