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author | Matt A. Tobin <mattatobin@localhost.localdomain> | 2018-02-02 04:16:08 -0500 |
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committer | Matt A. Tobin <mattatobin@localhost.localdomain> | 2018-02-02 04:16:08 -0500 |
commit | 5f8de423f190bbb79a62f804151bc24824fa32d8 (patch) | |
tree | 10027f336435511475e392454359edea8e25895d /mfbt/ReverseIterator.h | |
parent | 49ee0794b5d912db1f95dce6eb52d781dc210db5 (diff) | |
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Add m-esr52 at 52.6.0
Diffstat (limited to 'mfbt/ReverseIterator.h')
-rw-r--r-- | mfbt/ReverseIterator.h | 168 |
1 files changed, 168 insertions, 0 deletions
diff --git a/mfbt/ReverseIterator.h b/mfbt/ReverseIterator.h new file mode 100644 index 000000000..49c2e2792 --- /dev/null +++ b/mfbt/ReverseIterator.h @@ -0,0 +1,168 @@ +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ +/* vim: set ts=8 sts=2 et sw=2 tw=80: */ +/* 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 |