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https://github.com/abseil/abseil-cpp.git
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9cb62a03a4
Most usages of absl::void_t compile fine with std::void_t, so we migrate them here. A few don't compile due to overly eager template instantiations, so we leave those. PiperOrigin-RevId: 897231619 Change-Id: Iad34101916dac2b995257ebd5d6aacb9a0acfa32
76 lines
2.5 KiB
C++
76 lines
2.5 KiB
C++
// Copyright 2025 The Abseil Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// https://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//
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// -----------------------------------------------------------------------------
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// File: internal/iterator_traits.h
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// -----------------------------------------------------------------------------
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//
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// Helpers for querying traits of iterators, for implementing containers, etc.
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#ifndef ABSL_BASE_INTERNAL_ITERATOR_TRAITS_H_
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#define ABSL_BASE_INTERNAL_ITERATOR_TRAITS_H_
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#include <iterator>
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#include <type_traits>
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#include "absl/base/config.h"
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#include "absl/meta/type_traits.h"
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namespace absl {
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ABSL_NAMESPACE_BEGIN
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namespace base_internal {
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template <typename Iterator, typename = void>
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struct IteratorCategory {};
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template <typename Iterator>
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struct IteratorCategory<
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Iterator,
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std::void_t<typename std::iterator_traits<Iterator>::iterator_category>> {
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using type = typename std::iterator_traits<Iterator>::iterator_category;
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};
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template <typename Iterator, typename = void>
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struct IteratorConceptImpl : IteratorCategory<Iterator> {};
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template <typename Iterator>
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struct IteratorConceptImpl<
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Iterator,
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std::void_t<typename std::iterator_traits<Iterator>::iterator_concept>> {
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using type = typename std::iterator_traits<Iterator>::iterator_concept;
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};
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// The newer `std::iterator_traits<Iterator>::iterator_concept` if available,
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// else `std::iterator_traits<Iterator>::iterator_category`.
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template <typename Iterator>
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using IteratorConcept = typename IteratorConceptImpl<Iterator>::type;
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template <typename IteratorTag, typename Iterator>
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using IsAtLeastIterator =
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std::is_convertible<IteratorConcept<Iterator>, IteratorTag>;
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template <typename Iterator>
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using IsAtLeastInputIterator =
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IsAtLeastIterator<std::input_iterator_tag, Iterator>;
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template <typename Iterator>
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using IsAtLeastForwardIterator =
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IsAtLeastIterator<std::forward_iterator_tag, Iterator>;
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} // namespace base_internal
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ABSL_NAMESPACE_END
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} // namespace absl
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#endif // ABSL_BASE_INTERNAL_ITERATOR_TRAITS_H_
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