/*
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* Copyright (C) 2018 The Android Open Source Project
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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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* 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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#ifndef LIBTEXTCLASSIFIER_UTILS_OPTIONAL_H_
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#define LIBTEXTCLASSIFIER_UTILS_OPTIONAL_H_
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#include "utils/base/logging.h"
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namespace libtextclassifier3 {
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// Holds an optional value.
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template <class T>
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class Optional {
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public:
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Optional() : init_(false) {}
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Optional(const Optional& other) {
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init_ = other.init_;
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if (other.init_) {
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value_ = other.value_;
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}
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}
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explicit Optional(T value) : init_(true), value_(value) {}
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Optional& operator=(Optional&& other) {
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init_ = other.init_;
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if (other.init_) {
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value_ = std::move(other);
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}
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return *this;
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}
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Optional& operator=(T&& other) {
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init_ = true;
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value_ = std::move(other);
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return *this;
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}
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constexpr bool has_value() const { return init_; }
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T const* operator->() const {
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TC3_CHECK(init_) << "Bad optional access.";
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return value_;
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}
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T const& value() const& {
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TC3_CHECK(init_) << "Bad optional access.";
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return value_;
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}
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T const& value_or(T&& default_value) {
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return (init_ ? value_ : default_value);
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}
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void set(const T& value) {
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init_ = true;
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value_ = value;
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}
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private:
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bool init_;
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T value_;
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};
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} // namespace libtextclassifier3
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#endif // LIBTEXTCLASSIFIER_UTILS_OPTIONAL_H_
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