自分で initializer_list の実装に問題があり、msvc、gcc、avr-gcc、clang でコンパイルする独自のバージョンを作成すると非常に役立つことがわかったときに、この投稿を見つけました。この質問は古いかもしれませんが、他の人が役立つことを願って私の解決策を共有したいと思います:
#include <stddef.h>
namespace std
{
#if defined(__GNUC__)
// Copyright (C) 2008-2020 Free Software Foundation, Inc.
// Copyright (C) 2020 Daniel Rossinsky <danielrossinsky@gmail.com>
//
// This file is part of GCC.
//
// GCC is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 3, or (at your option)
// any later version.
//
// GCC is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.
// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
// <http://www.gnu.org/licenses/>.
template<typename T>
class initializer_list
{
public:
using value_type = T;
using reference = const T&;
using const_reference = const T&;
using size_type = size_t;
using iterator = const T*;
using const_iterator = const T*;
private:
iterator m_array;
size_type m_len;
// The compiler can call a private constructor.
constexpr initializer_list(const_iterator itr, size_type st)
: m_array(itr), m_len(st) { }
public:
constexpr initializer_list() noexcept : m_array(0), m_len(0) { }
// Number of elements.
constexpr size_type size() const noexcept { return m_len; }
// First element.
constexpr const_iterator begin() const noexcept { return m_array; }
// One past the last element.
constexpr const_iterator end() const noexcept { return begin() + size(); }
};
#elif defined(__clang__)
// Copyright (c) 2019 Chandler Carruth <https://github.com/chandlerc>
// Copyright (c) 2018 Louis Dionne <https://github.com/ldionne>
// Copyright (c) 2017 Eric <https://github.com/EricWF>
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// ---- LLVM Exceptions to the Apache 2.0 License ----
//
// As an exception, if, as a result of your compiling your source code, portions
// of this Software are embedded into an Object form of such source code, you
// may redistribute such embedded portions in such Object form without complying
// with the conditions of Sections 4(a), 4(b) and 4(d) of the License.
//
// In addition, if you combine or link compiled forms of this Software with
// software that is licensed under the GPLv2 ("Combined Software") and if a
// court of competent jurisdiction determines that the patent provision (Section
// 3), the indemnity provision (Section 9) or other Section of the License
// conflicts with the conditions of the GPLv2, you may retroactively and
// prospectively choose to deem waived or otherwise exclude such Section(s) of
// the License, but only in their entirety and only with respect to the Combined
// Software.
template<typename T>
class initializer_list
{
private:
const T* m_first;
const T* m_last;
public:
using value_type = T;
using reference = const T&;
using const_reference = const T&;
using size_type = size_t;
using iterator = const T*;
using const_iterator = const T*;
initializer_list() noexcept : m_first(nullptr), m_last(nullptr) {}
// Number of elements.
size_t size() const noexcept { return m_last - m_first; }
// First element.
const T* begin() const noexcept { return m_first; }
// One past the last element.
const T* end() const noexcept { return m_last; }
};
#elif defined(_MSC_VER)
// Copyright (c) Microsoft Corporation.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// ---- LLVM Exceptions to the Apache 2.0 License ----
//
// As an exception, if, as a result of your compiling your source code, portions
// of this Software are embedded into an Object form of such source code, you
// may redistribute such embedded portions in such Object form without complying
// with the conditions of Sections 4(a), 4(b) and 4(d) of the License.
//
// In addition, if you combine or link compiled forms of this Software with
// software that is licensed under the GPLv2 ("Combined Software") and if a
// court of competent jurisdiction determines that the patent provision (Section
// 3), the indemnity provision (Section 9) or other Section of the License
// conflicts with the conditions of the GPLv2, you may retroactively and
// prospectively choose to deem waived or otherwise exclude such Section(s) of
// the License, but only in their entirety and only with respect to the Combined
// Software.
template<typename T>
class initializer_list
{
public:
using value_type = T;
using reference = const T&;
using const_reference = const T&;
using size_type = size_t;
using iterator = const T*;
using const_iterator = const T*;
constexpr initializer_list() noexcept : m_first(nullptr), m_last(nullptr) {}
constexpr initializer_list(const T* first, const T* last) noexcept
: m_first(first), m_last(last) {}
// First element.
constexpr const T* begin() const noexcept { return m_first; }
// One past the last element.
constexpr const T* end() const noexcept { return m_last; }
// Number of elements.
constexpr size_t size() const noexcept
{
return static_cast<size_t>(m_last - m_first);
}
private:
const T* m_first;
const T* m_last;
};
#else
#error "Initializer_list is not supported for this compiler"
#endif
template<typename T>
constexpr const T* begin(initializer_list<T> il) noexcept
{
return il.begin();
}
template<typename T>
constexpr const T* end(initializer_list<T> il) noexcept
{
return il.end();
}
}
ノート：
コードの著作権者にクレジットを与え、公正使用を促進するために、実装のすぐ上に各実装のライセンス前文を含む著作権表示を追加しました。
肛門:
適切に含まれていた唯一の著作権は gcc のものでした。msvc バージョンには年がなく、clang (llvm) には、私が手動で行った貢献者に著作権が割り当てられているはずです。ただし、私は専門家ではないため、コードを共有する方法を見逃したり誤解したりする可能性があります。その場合はお知らせください。すぐに変更を適用します。
また、私が理解している限り、Apache-2.0 は GPLv3 と一方向のみで互換性があります。私のコード全体を GPLv3 でサブライセンスできますが、Apache-2.0 ではサブライセンスできません
プルーフ・オブ・ワーク:
私のバージョンが機能することを証明するために使用した例は、learncppから取得したものです。
- アルドゥイーノ 1.8.9
- x86 msvc v19.28
- x86-64 clang (トランク)
- x86-64 gcc (トランク)