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/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of Qt Creator.
**
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3 as published by the Free Software
** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
** included in the packaging of this file. Please review the following
** information to ensure the GNU General Public License requirements will
** be met: https://www.gnu.org/licenses/gpl-3.0.html.
**
****************************************************************************/
#pragma once
#include <QtGlobal>
#include <cstdint>
#include <type_traits>
#if defined(Q_CC_MSVC) && !defined(_WIN64)
# define ALIGNAS_16
#else
# define ALIGNAS_16 alignas(16)
#endif
namespace Utils {
namespace Internal {
using size_type = std::size_t;
template<bool Bool>
struct block_type
{
using type = uint8_t;
};
template<>
struct block_type<false> {
using type = uint16_t;
};
template <uint MaximumShortStringDataAreaSize,
typename BlockType = typename block_type<(MaximumShortStringDataAreaSize < 64)>::type>
struct AllocatedLayout {
struct Data {
char *pointer;
size_type size;
size_type capacity;
} data;
char dummy[MaximumShortStringDataAreaSize - sizeof(Data)];
BlockType shortStringSize : (sizeof(BlockType) * 8) - 2;
BlockType isReadOnlyReference : 1;
BlockType isReference : 1;
};
template <uint MaximumShortStringDataAreaSize,
typename BlockType = typename block_type<(MaximumShortStringDataAreaSize < 64)>::type>
struct ReferenceLayout {
struct Data {
const char *pointer;
size_type size;
size_type capacity;
} data;
char dummy[MaximumShortStringDataAreaSize - sizeof(Data)];
BlockType shortStringSize : (sizeof(BlockType) * 8) - 2;
BlockType isReadOnlyReference : 1;
BlockType isReference : 1;
};
template <uint MaximumShortStringDataAreaSize,
typename BlockType = typename block_type<(MaximumShortStringDataAreaSize < 64)>::type>
struct ShortStringLayout {
char string[MaximumShortStringDataAreaSize];
BlockType shortStringSize : (sizeof(BlockType) * 8) - 2;
BlockType isReadOnlyReference : 1;
BlockType isReference : 1;
};
template <uint MaximumShortStringDataAreaSize>
struct ALIGNAS_16 StringDataLayout {
static_assert(MaximumShortStringDataAreaSize >= 15, "Size must be greater equal than 15 bytes!");
static_assert(MaximumShortStringDataAreaSize < 64
? ((MaximumShortStringDataAreaSize + 1) % 16) == 0
: ((MaximumShortStringDataAreaSize + 2) % 16) == 0,
"Size + 1 must be dividable by 16 if under 64 and Size + 2 must be dividable by 16 if over 64!");
constexpr StringDataLayout() noexcept = default;
constexpr StringDataLayout(const char *string,
size_type size) noexcept
: reference({{string, size, 0}, {}, 0, true, true})
{
}
template<size_type Size,
typename std::enable_if_t<Size <= MaximumShortStringDataAreaSize, int> = 0>
constexpr StringDataLayout(const char(&string)[Size]) noexcept
#if __cpp_constexpr < 201304
: reference({{string, Size - 1, 0}, {}, 0, true, true})
#else
: shortString(ShortStringLayout<MaximumShortStringDataAreaSize>{})
#endif
{
#if __cpp_constexpr >= 201304
for (size_type i = 0; i < Size; ++i)
shortString.string[i] = string[i];
#if defined(__GNUC__)
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Woverflow"
shortString.shortStringSize = std::uint8_t(Size) - 1;
#pragma GCC diagnostic pop
#endif
shortString.isReference = false;
shortString.isReadOnlyReference = false;
#endif
}
template<size_type Size,
typename std::enable_if_t<!(Size <= MaximumShortStringDataAreaSize), int> = 1>
constexpr StringDataLayout(const char(&string)[Size]) noexcept
: reference({{string, Size - 1, 0}, {}, 0, true, true})
{
}
constexpr static
size_type shortStringCapacity() noexcept
{
return MaximumShortStringDataAreaSize - 1;
}
union {
AllocatedLayout<MaximumShortStringDataAreaSize> allocated;
ReferenceLayout<MaximumShortStringDataAreaSize> reference;
ShortStringLayout<MaximumShortStringDataAreaSize> shortString;
};
};
} // namespace Internal
} // namespace Utils
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