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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 <memory>
#include <type_traits>
namespace Utils {
namespace Internal {
using size_type = std::size_t;
template <uint MaximumShortStringDataAreaSize,
typename ControlType = typename std::conditional_t<(MaximumShortStringDataAreaSize < 64), uint8_t, uint16_t>>
struct ControlBlock
{
using SizeType = ControlType;
constexpr ControlBlock() noexcept = default;
constexpr ControlBlock(ControlType shortStringSize, bool isReadOnlyReference, bool isReference) noexcept
: m_shortStringSize(shortStringSize),
m_isReadOnlyReference(isReadOnlyReference),
m_isReference(isReference)
{}
void setShortStringSize(size_type size)
{
m_shortStringSize = static_cast<SizeType>(size);
}
size_type shortStringSize() const
{
return m_shortStringSize;
}
void setIsReadOnlyReference(bool isReadOnlyReference)
{
m_isReadOnlyReference = isReadOnlyReference;
}
void setIsReference(bool isReference)
{
m_isReference = isReference;
}
void setIsShortString(bool isShortString)
{
m_isReference = !isShortString;
}
constexpr
SizeType stringSize() const
{
return m_shortStringSize;
}
constexpr
bool isReadOnlyReference() const
{
return m_isReadOnlyReference;
}
constexpr
bool isReference() const
{
return m_isReference;
}
constexpr
bool isShortString() const
{
return !m_isReference;
}
private:
ControlType m_shortStringSize : (sizeof(ControlType) * 8) - 2;
ControlType m_isReadOnlyReference : 1;
ControlType m_isReference : 1;
};
template <uint MaximumShortStringDataAreaSize>
struct AllocatedLayout
{
struct Data
{
char *pointer;
size_type size;
size_type capacity;
};
ControlBlock<MaximumShortStringDataAreaSize> control;
Data data;
};
template <uint MaximumShortStringDataAreaSize>
struct ReferenceLayout
{
constexpr ReferenceLayout() noexcept = default;
constexpr ReferenceLayout(const char *stringPointer,
size_type size,
size_type capacity) noexcept
: control(0, true, true),
data{stringPointer, size, capacity}
{}
struct Data
{
const char *pointer;
size_type size;
size_type capacity;
};
ControlBlock<MaximumShortStringDataAreaSize> control;
Data data;
};
template <uint MaximumShortStringDataAreaSize>
struct ShortStringLayout
{
ControlBlock<MaximumShortStringDataAreaSize> control;
char string[MaximumShortStringDataAreaSize];
};
template <uint MaximumShortStringDataAreaSize>
struct 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!");
StringDataLayout() noexcept
{
reset();
}
constexpr StringDataLayout(const char *string,
size_type size) noexcept
: reference(string, size, 0)
{
}
template<size_type Size,
typename std::enable_if_t<Size <= MaximumShortStringDataAreaSize, int> = 0>
StringDataLayout(const char(&string)[Size]) noexcept
: shortString(ShortStringLayout<MaximumShortStringDataAreaSize>{})
{
for (size_type i = 0; i < Size; ++i)
shortString.string[i] = string[i];
shortString.control.setShortStringSize(Size - 1);
shortString.control.setIsShortString(true);
shortString.control.setIsReadOnlyReference(false);
}
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)
{
}
constexpr static
size_type shortStringCapacity() noexcept
{
return MaximumShortStringDataAreaSize - 1;
}
void reset()
{
shortString.control = ControlBlock<MaximumShortStringDataAreaSize>();
shortString.string[0] = '\0';
}
union {
AllocatedLayout<MaximumShortStringDataAreaSize> allocated;
ReferenceLayout<MaximumShortStringDataAreaSize> reference;
ShortStringLayout<MaximumShortStringDataAreaSize> shortString;
};
};
} // namespace Internal
} // namespace Utils
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