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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/* An iterator that acts like another iterator, but iterating in
* the negative direction. (Note that not all iterators can iterate
* in the negative direction.) */
#ifndef mozilla_ReverseIterator_h
#define mozilla_ReverseIterator_h
#include "mozilla/Attributes.h"
#include "mozilla/TypeTraits.h"
namespace mozilla {
template<typename IteratorT>
class ReverseIterator
{
public:
template<typename Iterator>
explicit ReverseIterator(Iterator aIter)
: mCurrent(aIter) { }
template<typename Iterator>
MOZ_IMPLICIT ReverseIterator(const ReverseIterator<Iterator>& aOther)
: mCurrent(aOther.mCurrent) { }
decltype(*DeclVal<IteratorT>()) operator*() const
{
IteratorT tmp = mCurrent;
return *--tmp;
}
/* Increments and decrements operators */
ReverseIterator& operator++() { --mCurrent; return *this; }
ReverseIterator& operator--() { ++mCurrent; return *this; }
ReverseIterator operator++(int) { auto ret = *this; mCurrent--; return ret; }
ReverseIterator operator--(int) { auto ret = *this; mCurrent++; return ret; }
/* Comparison operators */
template<typename Iterator1, typename Iterator2>
friend bool operator==(const ReverseIterator<Iterator1>& aIter1,
const ReverseIterator<Iterator2>& aIter2);
template<typename Iterator1, typename Iterator2>
friend bool operator!=(const ReverseIterator<Iterator1>& aIter1,
const ReverseIterator<Iterator2>& aIter2);
template<typename Iterator1, typename Iterator2>
friend bool operator<(const ReverseIterator<Iterator1>& aIter1,
const ReverseIterator<Iterator2>& aIter2);
template<typename Iterator1, typename Iterator2>
friend bool operator<=(const ReverseIterator<Iterator1>& aIter1,
const ReverseIterator<Iterator2>& aIter2);
template<typename Iterator1, typename Iterator2>
friend bool operator>(const ReverseIterator<Iterator1>& aIter1,
const ReverseIterator<Iterator2>& aIter2);
template<typename Iterator1, typename Iterator2>
friend bool operator>=(const ReverseIterator<Iterator1>& aIter1,
const ReverseIterator<Iterator2>& aIter2);
private:
IteratorT mCurrent;
};
template<typename Iterator1, typename Iterator2>
bool
operator==(const ReverseIterator<Iterator1>& aIter1,
const ReverseIterator<Iterator2>& aIter2)
{
return aIter1.mCurrent == aIter2.mCurrent;
}
template<typename Iterator1, typename Iterator2>
bool
operator!=(const ReverseIterator<Iterator1>& aIter1,
const ReverseIterator<Iterator2>& aIter2)
{
return aIter1.mCurrent != aIter2.mCurrent;
}
template<typename Iterator1, typename Iterator2>
bool
operator<(const ReverseIterator<Iterator1>& aIter1,
const ReverseIterator<Iterator2>& aIter2)
{
return aIter1.mCurrent > aIter2.mCurrent;
}
template<typename Iterator1, typename Iterator2>
bool
operator<=(const ReverseIterator<Iterator1>& aIter1,
const ReverseIterator<Iterator2>& aIter2)
{
return aIter1.mCurrent >= aIter2.mCurrent;
}
template<typename Iterator1, typename Iterator2>
bool
operator>(const ReverseIterator<Iterator1>& aIter1,
const ReverseIterator<Iterator2>& aIter2)
{
return aIter1.mCurrent < aIter2.mCurrent;
}
template<typename Iterator1, typename Iterator2>
bool
operator>=(const ReverseIterator<Iterator1>& aIter1,
const ReverseIterator<Iterator2>& aIter2)
{
return aIter1.mCurrent <= aIter2.mCurrent;
}
namespace detail {
template<typename IteratorT>
class IteratorRange
{
public:
typedef IteratorT iterator;
typedef IteratorT const_iterator;
typedef ReverseIterator<IteratorT> reverse_iterator;
typedef ReverseIterator<IteratorT> const_reverse_iterator;
template<typename Iterator1, typename Iterator2>
MOZ_IMPLICIT IteratorRange(Iterator1 aIterBegin, Iterator2 aIterEnd)
: mIterBegin(aIterBegin), mIterEnd(aIterEnd) { }
template<typename Iterator>
MOZ_IMPLICIT IteratorRange(const IteratorRange<Iterator>& aOther)
: mIterBegin(aOther.mIterBegin), mIterEnd(aOther.mIterEnd) { }
iterator begin() const { return mIterBegin; }
const_iterator cbegin() const { return begin(); }
iterator end() const { return mIterEnd; }
const_iterator cend() const { return end(); }
reverse_iterator rbegin() const { return reverse_iterator(mIterEnd); }
const_reverse_iterator crbegin() const { return rbegin(); }
reverse_iterator rend() const { return reverse_iterator(mIterBegin); }
const_reverse_iterator crend() const { return rend(); }
private:
IteratorT mIterBegin;
IteratorT mIterEnd;
};
} // namespace detail
template<typename Range>
detail::IteratorRange<typename Range::reverse_iterator>
Reversed(Range& aRange)
{
return {aRange.rbegin(), aRange.rend()};
}
template<typename Range>
detail::IteratorRange<typename Range::const_reverse_iterator>
Reversed(const Range& aRange)
{
return {aRange.rbegin(), aRange.rend()};
}
} // namespace mozilla
#endif // mozilla_ReverseIterator_h
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