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# ignore-this-changeset --HG-- extra : amend_source : 4d301d3b0b8711c4692392aa76088ba7fd7d1022
165 lines
5.3 KiB
C++
165 lines
5.3 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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/* An iterator that acts like another iterator, but iterating in
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* the negative direction. (Note that not all iterators can iterate
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* in the negative direction.) */
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#ifndef mozilla_ReverseIterator_h
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#define mozilla_ReverseIterator_h
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#include "mozilla/Attributes.h"
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#include "mozilla/TypeTraits.h"
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namespace mozilla {
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template <typename IteratorT>
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class ReverseIterator {
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public:
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template <typename Iterator>
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explicit ReverseIterator(Iterator aIter) : mCurrent(aIter) {}
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template <typename Iterator>
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MOZ_IMPLICIT ReverseIterator(const ReverseIterator<Iterator>& aOther)
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: mCurrent(aOther.mCurrent) {}
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decltype(*DeclVal<IteratorT>()) operator*() const {
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IteratorT tmp = mCurrent;
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return *--tmp;
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}
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/* Increments and decrements operators */
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ReverseIterator& operator++() {
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--mCurrent;
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return *this;
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}
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ReverseIterator& operator--() {
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++mCurrent;
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return *this;
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}
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ReverseIterator operator++(int) {
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auto ret = *this;
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mCurrent--;
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return ret;
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}
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ReverseIterator operator--(int) {
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auto ret = *this;
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mCurrent++;
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return ret;
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}
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/* Comparison operators */
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template <typename Iterator1, typename Iterator2>
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friend bool operator==(const ReverseIterator<Iterator1>& aIter1,
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const ReverseIterator<Iterator2>& aIter2);
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template <typename Iterator1, typename Iterator2>
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friend bool operator!=(const ReverseIterator<Iterator1>& aIter1,
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const ReverseIterator<Iterator2>& aIter2);
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template <typename Iterator1, typename Iterator2>
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friend bool operator<(const ReverseIterator<Iterator1>& aIter1,
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const ReverseIterator<Iterator2>& aIter2);
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template <typename Iterator1, typename Iterator2>
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friend bool operator<=(const ReverseIterator<Iterator1>& aIter1,
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const ReverseIterator<Iterator2>& aIter2);
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template <typename Iterator1, typename Iterator2>
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friend bool operator>(const ReverseIterator<Iterator1>& aIter1,
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const ReverseIterator<Iterator2>& aIter2);
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template <typename Iterator1, typename Iterator2>
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friend bool operator>=(const ReverseIterator<Iterator1>& aIter1,
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const ReverseIterator<Iterator2>& aIter2);
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private:
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IteratorT mCurrent;
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};
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template <typename Iterator1, typename Iterator2>
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bool operator==(const ReverseIterator<Iterator1>& aIter1,
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const ReverseIterator<Iterator2>& aIter2) {
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return aIter1.mCurrent == aIter2.mCurrent;
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}
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template <typename Iterator1, typename Iterator2>
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bool operator!=(const ReverseIterator<Iterator1>& aIter1,
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const ReverseIterator<Iterator2>& aIter2) {
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return aIter1.mCurrent != aIter2.mCurrent;
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}
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template <typename Iterator1, typename Iterator2>
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bool operator<(const ReverseIterator<Iterator1>& aIter1,
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const ReverseIterator<Iterator2>& aIter2) {
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return aIter1.mCurrent > aIter2.mCurrent;
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}
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template <typename Iterator1, typename Iterator2>
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bool operator<=(const ReverseIterator<Iterator1>& aIter1,
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const ReverseIterator<Iterator2>& aIter2) {
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return aIter1.mCurrent >= aIter2.mCurrent;
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}
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template <typename Iterator1, typename Iterator2>
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bool operator>(const ReverseIterator<Iterator1>& aIter1,
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const ReverseIterator<Iterator2>& aIter2) {
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return aIter1.mCurrent < aIter2.mCurrent;
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}
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template <typename Iterator1, typename Iterator2>
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bool operator>=(const ReverseIterator<Iterator1>& aIter1,
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const ReverseIterator<Iterator2>& aIter2) {
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return aIter1.mCurrent <= aIter2.mCurrent;
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}
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namespace detail {
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template <typename IteratorT>
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class IteratorRange {
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public:
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typedef IteratorT iterator;
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typedef IteratorT const_iterator;
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typedef ReverseIterator<IteratorT> reverse_iterator;
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typedef ReverseIterator<IteratorT> const_reverse_iterator;
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template <typename Iterator1, typename Iterator2>
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MOZ_IMPLICIT IteratorRange(Iterator1 aIterBegin, Iterator2 aIterEnd)
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: mIterBegin(aIterBegin), mIterEnd(aIterEnd) {}
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template <typename Iterator>
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MOZ_IMPLICIT IteratorRange(const IteratorRange<Iterator>& aOther)
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: mIterBegin(aOther.mIterBegin), mIterEnd(aOther.mIterEnd) {}
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iterator begin() const { return mIterBegin; }
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const_iterator cbegin() const { return begin(); }
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iterator end() const { return mIterEnd; }
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const_iterator cend() const { return end(); }
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reverse_iterator rbegin() const { return reverse_iterator(mIterEnd); }
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const_reverse_iterator crbegin() const { return rbegin(); }
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reverse_iterator rend() const { return reverse_iterator(mIterBegin); }
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const_reverse_iterator crend() const { return rend(); }
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private:
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IteratorT mIterBegin;
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IteratorT mIterEnd;
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};
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} // namespace detail
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template <typename Range>
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detail::IteratorRange<typename Range::reverse_iterator> Reversed(
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Range& aRange) {
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return {aRange.rbegin(), aRange.rend()};
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}
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template <typename Range>
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detail::IteratorRange<typename Range::const_reverse_iterator> Reversed(
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const Range& aRange) {
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return {aRange.rbegin(), aRange.rend()};
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}
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} // namespace mozilla
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#endif // mozilla_ReverseIterator_h
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