serge-sans-paille
e68e3aea28
The compiler automatically generates a call to !(a==b) when (a!=b) is met and operator!= is not defined, so let's remove useless code. Cases automatically detected by an extension to the linter from Bug 2064388, also included in that patch. Differential Revision: https://phabricator.services.mozilla.com/D320346
133 lines
4.4 KiB
C++
133 lines
4.4 KiB
C++
/* 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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/* Iterator over ranges of integers */
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#ifndef mozilla_IntegerRange_h
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#define mozilla_IntegerRange_h
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#include <iterator>
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#include <type_traits>
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#include "mozilla/Assertions.h"
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#include "mozilla/ReverseIterator.h"
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namespace mozilla {
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namespace detail {
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template <typename IntTypeT>
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class IntegerIterator {
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public:
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// It is disputable whether these type definitions are correct, since
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// operator* doesn't return a reference at all. Also, the iterator_category
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// can be at most std::input_iterator_tag (rather than
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// std::bidrectional_iterator_tag, as it might seem), because it is a stashing
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// iterator. See also, e.g.,
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// https://stackoverflow.com/questions/50909701/what-should-be-iterator-category-for-a-stashing-iterator
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using value_type = const IntTypeT;
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using pointer = const value_type*;
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using reference = const value_type&;
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using difference_type = std::make_signed_t<IntTypeT>;
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using iterator_category = std::input_iterator_tag;
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template <typename IntType>
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explicit IntegerIterator(IntType aCurrent) : mCurrent(aCurrent) {}
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template <typename IntType>
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explicit IntegerIterator(const IntegerIterator<IntType>& aOther)
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: mCurrent(aOther.mCurrent) {}
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// This intentionally returns a value rather than a reference, to make
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// mozilla::ReverseIterator work with it. Still, std::reverse_iterator cannot
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// be used with IntegerIterator because it still is a "stashing iterator". See
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// Bug 1175485.
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IntTypeT operator*() const { return mCurrent; }
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/* Increment and decrement operators */
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IntegerIterator& operator++() {
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++mCurrent;
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return *this;
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}
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IntegerIterator& operator--() {
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--mCurrent;
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return *this;
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}
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IntegerIterator 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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IntegerIterator 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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bool operator==(const IntegerIterator& aOther) const = default;
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bool operator<(const IntegerIterator& aOther) const = default;
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bool operator<=(const IntegerIterator& aOther) const = default;
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bool operator>(const IntegerIterator& aOther) const = default;
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bool operator>=(const IntegerIterator& aOther) const = default;
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private:
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IntTypeT mCurrent;
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};
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template <typename IntTypeT>
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class IntegerRange {
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public:
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typedef IntegerIterator<IntTypeT> iterator;
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typedef IntegerIterator<IntTypeT> const_iterator;
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typedef ReverseIterator<IntegerIterator<IntTypeT>> reverse_iterator;
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typedef ReverseIterator<IntegerIterator<IntTypeT>> const_reverse_iterator;
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template <typename IntType>
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explicit IntegerRange(IntType aEnd) : mBegin(0), mEnd(aEnd) {}
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template <typename IntType1, typename IntType2>
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IntegerRange(IntType1 aBegin, IntType2 aEnd) : mBegin(aBegin), mEnd(aEnd) {}
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iterator begin() const { return iterator(mBegin); }
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const_iterator cbegin() const { return begin(); }
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iterator end() const { return iterator(mEnd); }
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const_iterator cend() const { return end(); }
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reverse_iterator rbegin() const { return reverse_iterator(iterator(mEnd)); }
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const_reverse_iterator crbegin() const { return rbegin(); }
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reverse_iterator rend() const { return reverse_iterator(iterator(mBegin)); }
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const_reverse_iterator crend() const { return rend(); }
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private:
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IntTypeT mBegin;
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IntTypeT mEnd;
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};
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} // namespace detail
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template <typename IntType>
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detail::IntegerRange<IntType> IntegerRange(IntType aEnd) {
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static_assert(std::is_integral_v<IntType>, "value must be integral");
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if constexpr (std::is_signed_v<IntType>) {
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MOZ_ASSERT(aEnd >= 0, "Should never have negative value here");
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}
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return detail::IntegerRange<IntType>(aEnd);
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}
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template <typename IntType1, typename IntType2>
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detail::IntegerRange<IntType2> IntegerRange(IntType1 aBegin, IntType2 aEnd) {
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static_assert(std::is_integral_v<IntType1> && std::is_integral_v<IntType2>,
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"values must both be integral");
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static_assert(std::is_signed_v<IntType1> == std::is_signed_v<IntType2>,
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"signed/unsigned mismatch");
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MOZ_ASSERT(aEnd >= aBegin, "End value should be larger than begin value");
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return detail::IntegerRange<IntType2>(aBegin, aEnd);
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}
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} // namespace mozilla
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#endif // mozilla_IntegerRange_h
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