78 lines
2.3 KiB
C++
78 lines
2.3 KiB
C++
/*
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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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* http://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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* Copyright 2012-2017 Danny Robson <danny@nerdcruft.net>
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*/
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#ifndef UTIL_TYPES_COMPARATOR_HPP
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#define UTIL_TYPES_COMPARATOR_HPP
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#include <memory>
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#include "../iterator.hpp"
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namespace util::comparator {
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///////////////////////////////////////////////////////////////////////////
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/// Compares standard types that can be reduced to pointers.
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template <typename T>
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struct pointer {
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constexpr
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bool
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operator() (const std::unique_ptr<T> &a, const std::unique_ptr<T> &b)
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{
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return a < b;
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}
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constexpr
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bool
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operator() (const T *a, const std::unique_ptr<T> &b)
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{
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return a < b.get ();
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}
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constexpr
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bool
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operator() (const std::unique_ptr<T> &a, const T *b)
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{
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return a.get () < b;
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}
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};
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///////////////////////////////////////////////////////////////////////////
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/// Provides a comparison interface for types exposing an index operator.
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///
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/// Will return true if the first parameter has the first index that
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/// compares less than the second parameter. Useful for providing a total
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/// order of coordinate types where this doesn't make sense by default.
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///
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/// \tparam T The container data type to compare. Must provide an index
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/// operator.
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template <typename T>
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struct indexed {
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constexpr
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bool operator() (const T &a, const T &b) const
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{
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for (auto x: util::zip (a, b)) {
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const auto &[i,j] = x; // BUG: clang-4.0: workaround for segfault.
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if (i < j) return true;
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if (i != j) return false;
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}
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return false;
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}
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};
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}
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#endif
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