ladybird/AK/ReverseIterator.h

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/*
* Copyright (c) 2022, the SerenityOS developers.
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/Forward.h>
namespace AK {
template<typename Container, typename ValueType>
class SimpleReverseIterator {
public:
friend Container;
constexpr bool is_end() const { return m_index == SimpleReverseIterator::rend(m_container).m_index; }
constexpr int index() const { return m_index; }
constexpr bool operator==(SimpleReverseIterator other) const { return m_index == other.m_index; }
constexpr bool operator!=(SimpleReverseIterator other) const { return m_index != other.m_index; }
constexpr bool operator<(SimpleReverseIterator other) const { return m_index < other.m_index; }
constexpr bool operator>(SimpleReverseIterator other) const { return m_index > other.m_index; }
constexpr bool operator<=(SimpleReverseIterator other) const { return m_index <= other.m_index; }
constexpr bool operator>=(SimpleReverseIterator other) const { return m_index >= other.m_index; }
constexpr SimpleReverseIterator operator+(int delta) const { return SimpleReverseIterator { m_container, m_index - delta }; }
constexpr SimpleReverseIterator operator-(int delta) const { return SimpleReverseIterator { m_container, m_index + delta }; }
constexpr SimpleReverseIterator operator++()
{
--m_index;
return *this;
}
constexpr SimpleReverseIterator operator++(int)
{
--m_index;
return SimpleReverseIterator { m_container, m_index + 1 };
}
constexpr SimpleReverseIterator operator--()
{
++m_index;
return *this;
}
constexpr SimpleReverseIterator operator--(int)
{
++m_index;
return SimpleReverseIterator { m_container, m_index - 1 };
}
ALWAYS_INLINE constexpr ValueType const& operator*() const { return m_container[m_index]; }
ALWAYS_INLINE constexpr ValueType& operator*() { return m_container[m_index]; }
ALWAYS_INLINE constexpr ValueType const* operator->() const { return &m_container[m_index]; }
ALWAYS_INLINE constexpr ValueType* operator->() { return &m_container[m_index]; }
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SimpleReverseIterator& operator=(SimpleReverseIterator const& other)
{
m_index = other.m_index;
return *this;
}
SimpleReverseIterator(SimpleReverseIterator const& obj) = default;
private:
static constexpr SimpleReverseIterator rbegin(Container& container)
{
using RawContainerType = RemoveCV<Container>;
if constexpr (IsSame<StringView, RawContainerType> || IsSame<ByteString, RawContainerType>)
return { container, static_cast<int>(container.length()) - 1 };
else
return { container, static_cast<int>(container.size()) - 1 };
}
static constexpr SimpleReverseIterator rend(Container& container)
{
return { container, -1 };
}
constexpr SimpleReverseIterator(Container& container, int index)
: m_container(container)
, m_index(index)
{
}
Container& m_container;
int m_index { 0 };
};
namespace ReverseWrapper {
template<typename Container>
struct ReverseWrapper {
Container& container;
};
template<typename Container>
auto begin(ReverseWrapper<Container> wrapper) { return wrapper.container.rbegin(); }
template<typename Container>
auto end(ReverseWrapper<Container> wrapper) { return wrapper.container.rend(); }
template<typename Container>
ReverseWrapper<Container> in_reverse(Container&& container) { return { container }; }
}
}