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// Copyright (C) 2021 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0+ OR GPL-3.0 WITH Qt-GPL-exception-1.0
#pragma once
#include "utils_global.h"
#include <QtGlobal>
#include <type_traits>
namespace Utils {
/// A class useful for the implementation of the -> operator of proxy iterators.
template <typename Reference>
struct ArrowProxy {
Reference r;
Reference *operator->() {
return &r;
}
};
/// Random-access const iterator over elements of a container providing an overloaded operator[]
/// (which may return a proxy object, like std::vector<bool>, rather than a reference).
template <typename Container>
class IndexedContainerProxyConstIterator
{
public:
typedef std::random_access_iterator_tag iterator_category;
typedef typename std::make_signed<typename Container::size_type>::type difference_type;
typedef typename Container::value_type value_type;
typedef value_type reference;
typedef ArrowProxy<reference> pointer;
typedef typename Container::size_type size_type;
IndexedContainerProxyConstIterator()
: m_container(nullptr), m_index(0)
{}
IndexedContainerProxyConstIterator(const Container &container, size_type index)
: m_container(&container), m_index(index)
{}
reference operator*() const
{
Q_ASSERT(m_container);
return (*m_container)[m_index];
}
pointer operator->() const
{
Q_ASSERT(m_container);
return pointer{(*m_container)[m_index]};
}
reference operator[](difference_type j) const
{
Q_ASSERT(m_container);
return (*m_container)[m_index + j];
}
bool operator==(const IndexedContainerProxyConstIterator &other) const
{
Q_ASSERT(m_container == other.m_container);
return m_index == other.m_index;
}
bool operator!=(const IndexedContainerProxyConstIterator &other) const
{
Q_ASSERT(m_container == other.m_container);
return m_index != other.m_index;
}
bool operator<(const IndexedContainerProxyConstIterator &other) const
{
Q_ASSERT(m_container == other.m_container);
return m_index < other.m_index;
}
bool operator<=(const IndexedContainerProxyConstIterator &other) const
{
Q_ASSERT(m_container == other.m_container);
return m_index <= other.m_index;
}
bool operator>(const IndexedContainerProxyConstIterator &other) const
{
Q_ASSERT(m_container == other.m_container);
return m_index > other.m_index;
}
bool operator>=(const IndexedContainerProxyConstIterator &other) const
{
Q_ASSERT(m_container == other.m_container);
return m_index >= other.m_index;
}
IndexedContainerProxyConstIterator &operator++()
{
++m_index;
return *this;
}
IndexedContainerProxyConstIterator operator++(int)
{
IndexedContainerProxyConstIterator copy(*this);
++m_index;
return copy;
}
IndexedContainerProxyConstIterator &operator--()
{
--m_index;
return *this;
}
IndexedContainerProxyConstIterator operator--(int)
{
IndexedContainerProxyConstIterator copy(*this);
--m_index;
return copy;
}
IndexedContainerProxyConstIterator &operator+=(difference_type j)
{
m_index += j;
return *this;
}
IndexedContainerProxyConstIterator &operator-=(difference_type j)
{
m_index -= j;
return *this;
}
IndexedContainerProxyConstIterator operator+(difference_type j) const
{
IndexedContainerProxyConstIterator result(*this);
result += j;
return result;
}
IndexedContainerProxyConstIterator operator-(difference_type j) const
{
IndexedContainerProxyConstIterator result(*this);
result -= j;
return result;
}
friend IndexedContainerProxyConstIterator operator+(
difference_type j, const IndexedContainerProxyConstIterator &other)
{
return other + j;
}
difference_type operator-(const IndexedContainerProxyConstIterator &other) const
{
return static_cast<difference_type>(m_index) - static_cast<difference_type>(other.m_index);
}
private:
const Container *m_container;
size_type m_index;
};
} // namespace Utils
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