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/****************************************************************************
**
** Copyright (C) 2017 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com, author Marc Mutz <marc.mutz@kdab.com>
** Contact: http://www.qt.io/licensing/
**
** This file is part of the QtCore module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** 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 Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 3 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL3 included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 3 requirements
** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 2.0 or (at your option) the GNU General
** Public license version 3 or any later version approved by the KDE Free
** Qt Foundation. The licenses are as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
** 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-2.0.html and
** https://www.gnu.org/licenses/gpl-3.0.html.
**
** $QT_END_LICENSE$
**
****************************************************************************/
#ifndef QSTRING_H
# include <QtCore/qstring.h>
#endif
#ifndef QSTRINGVIEW_H
#define QSTRINGVIEW_H
#include <string>
QT_BEGIN_NAMESPACE
#ifndef QT_NO_UNICODE_LITERAL
# ifndef QT_UNICODE_LITERAL
# error "If you change QStringLiteral, please change QStringViewLiteral, too"
# endif
# define QStringViewLiteral(str) QStringView(QT_UNICODE_LITERAL(str), sizeof(str) - 1)
#endif
namespace QtPrivate {
template <typename Char>
struct IsCompatibleCharTypeHelper
: std::integral_constant<bool,
std::is_same<Char, QChar>::value ||
std::is_same<Char, ushort>::value ||
#if !defined(Q_OS_WIN) || defined(Q_COMPILER_UNICODE_STRINGS)
std::is_same<Char, char16_t>::value ||
#endif
(std::is_same<Char, wchar_t>::value && sizeof(wchar_t) == sizeof(QChar))> {};
template <typename Char>
struct IsCompatibleCharType
: IsCompatibleCharTypeHelper<typename std::remove_cv<typename std::remove_reference<Char>::type>::type> {};
template <typename T>
struct IsCompatibleStdBasicStringHelper : std::false_type {};
template <typename Char, typename...Args>
struct IsCompatibleStdBasicStringHelper<std::basic_string<Char, Args...> >
: IsCompatibleCharType<Char> {};
template <typename T>
struct IsCompatibleStdBasicString
: IsCompatibleStdBasicStringHelper<
typename std::remove_cv<typename std::remove_reference<T>::type>::type
> {};
} // namespace QtPrivate
class QStringView
{
#if defined(Q_OS_WIN) && !defined(Q_COMPILER_UNICODE_STRINGS)
typedef wchar_t storage_type;
#else
typedef char16_t storage_type;
#endif
public:
typedef const QChar value_type;
typedef std::ptrdiff_t difference_type;
typedef QIntegerForSizeof<size_t>::Signed size_type;
typedef value_type &reference;
typedef value_type &const_reference;
typedef value_type *pointer;
typedef value_type *const_pointer;
typedef pointer iterator;
typedef const_pointer const_iterator;
typedef std::reverse_iterator<iterator> reverse_iterator;
typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
private:
template <typename Char>
using if_compatible_char = typename std::enable_if<QtPrivate::IsCompatibleCharType<Char>::value, bool>::type;
template <typename T>
using if_compatible_string = typename std::enable_if<QtPrivate::IsCompatibleStdBasicString<T>::value, bool>::type;
template <typename Char>
static Q_DECL_RELAXED_CONSTEXPR size_type lengthHelper(const Char *str) Q_DECL_NOTHROW
{
size_type result = 0;
while (*str++)
++result;
return result;
}
static Q_DECL_RELAXED_CONSTEXPR size_type lengthHelper(const QChar *str) Q_DECL_NOTHROW
{
size_type result = 0;
while (!str++->isNull())
++result;
return result;
}
template <typename Char>
static const storage_type *castHelper(const Char *str) Q_DECL_NOTHROW
{ return reinterpret_cast<const storage_type*>(str); }
static Q_DECL_CONSTEXPR const storage_type *castHelper(const storage_type *str) Q_DECL_NOTHROW
{ return str; }
// prevent
// T t; QStringView sv(t), T \in {QChar, QLatin1String, QByteArray, const char*}
// from compiling as QStringView sv(QString(t)):
QStringView(QChar) = delete;
QStringView(QLatin1String) = delete;
QStringView(const QByteArray &) = delete;
QStringView(const char *) = delete;
#ifdef Q_OS_WIN
// prevent QStringView(Char), Char compatible, from compiling due to:
// https://connect.microsoft.com/VisualStudio/feedback/details/2256407/c-two-user-defined-conversions-incorrectly-accepted-in-implicit-conversion-sequence
template <typename Char, if_compatible_char<Char> = true>
QStringView(Char) = delete;
#endif
public:
Q_DECL_CONSTEXPR QStringView() Q_DECL_NOTHROW
: m_size(0), m_data(nullptr) {}
Q_DECL_CONSTEXPR QStringView(std::nullptr_t) Q_DECL_NOTHROW
: QStringView() {}
#if QT_DEPRECATED_SINCE(5, 9)
Q_DECL_CONSTEXPR QStringView(QString::Null) Q_DECL_NOTHROW
: QStringView() {}
#endif
template <typename Char, if_compatible_char<Char> = true>
Q_DECL_CONSTEXPR QStringView(const Char *str, size_type len)
: m_size((Q_ASSERT(len >= 0), Q_ASSERT(str || !len), len)),
m_data(castHelper(str)) {}
template <typename Char, if_compatible_char<Char> = true>
Q_DECL_CONSTEXPR QStringView(const Char *str)
: QStringView(str, str ? lengthHelper(str) : 0) {}
QStringView(const QString &str) Q_DECL_NOTHROW
: QStringView(str.isNull() ? nullptr : str.data(), size_type(str.size())) {}
QStringView(const QStringRef &str) Q_DECL_NOTHROW
: QStringView(str.isNull() ? nullptr : str.data(), size_type(str.size())) {}
template <typename StdBasicString, if_compatible_string<StdBasicString> = true>
QStringView(const StdBasicString &str) Q_DECL_NOTHROW
: QStringView(str.data(), size_type(str.size())) {}
QString toString() const { return Q_ASSERT(size() == length()), QString(data(), length()); }
Q_DECL_CONSTEXPR size_type size() const Q_DECL_NOTHROW { return m_size; }
const_pointer data() const Q_DECL_NOTHROW { return reinterpret_cast<const_pointer>(m_data); }
Q_DECL_CONSTEXPR const storage_type *utf16() const Q_DECL_NOTHROW { return m_data; }
Q_DECL_CONSTEXPR QChar operator[](size_type n) const
{ return Q_ASSERT(n >= 0), Q_ASSERT(n < size()), QChar(m_data[n]); }
//
// QString API
//
Q_DECL_CONSTEXPR QChar at(size_type n) const { return (*this)[n]; }
//
// STL compatibility API:
//
const_iterator begin() const Q_DECL_NOTHROW { return data(); }
const_iterator end() const Q_DECL_NOTHROW { return data() + size(); }
const_iterator cbegin() const Q_DECL_NOTHROW { return begin(); }
const_iterator cend() const Q_DECL_NOTHROW { return end(); }
const_reverse_iterator rbegin() const Q_DECL_NOTHROW { return const_reverse_iterator(end()); }
const_reverse_iterator rend() const Q_DECL_NOTHROW { return const_reverse_iterator(begin()); }
const_reverse_iterator crbegin() const Q_DECL_NOTHROW { return rbegin(); }
const_reverse_iterator crend() const Q_DECL_NOTHROW { return rend(); }
Q_DECL_CONSTEXPR bool empty() const Q_DECL_NOTHROW { return size() == 0; }
Q_DECL_CONSTEXPR QChar front() const { return Q_ASSERT(!empty()), QChar(m_data[0]); }
Q_DECL_CONSTEXPR QChar back() const { return Q_ASSERT(!empty()), QChar(m_data[m_size - 1]); }
//
// Qt compatibility API:
//
Q_DECL_CONSTEXPR bool isNull() const Q_DECL_NOTHROW { return !m_data; }
Q_DECL_CONSTEXPR bool isEmpty() const Q_DECL_NOTHROW { return empty(); }
Q_DECL_CONSTEXPR int length() const /* not nothrow! */
{ return Q_ASSERT(int(size()) == size()), int(size()); }
Q_DECL_CONSTEXPR QChar first() const { return front(); }
Q_DECL_CONSTEXPR QChar last() const { return back(); }
private:
size_type m_size;
const storage_type *m_data;
};
Q_DECLARE_TYPEINFO(QStringView, Q_MOVABLE_TYPE);
QT_END_NAMESPACE
#endif /* QSTRINGVIEW_H */
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