133 lines
2.6 KiB
C++
133 lines
2.6 KiB
C++
/* Copyright (c) 2021, Arm Limited and Contributors
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*
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* SPDX-License-Identifier: Apache-2.0
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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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#pragma once
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#include <cassert>
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namespace vkb
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{
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// Simple optional class for pre c++17 std::optional
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// May be replaced by std::optional in the future
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template <typename Type>
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class Optional
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{
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public:
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virtual ~Optional() = default;
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Optional() = default;
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Optional(const Optional &optional);
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template <typename U = Type>
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Optional(const U &value);
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bool has_value() const;
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const Type &value() const;
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const Type value_or(Type &&alternative) const;
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const Type value_or(const Type &alternative = {}) const;
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Optional &operator=(Optional &&opt)
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{
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_has_value = opt._has_value;
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_value = opt._value;
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return *this;
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}
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template <typename U = Type>
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Optional &operator=(U &&value)
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{
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_has_value = true;
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_value = value;
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return *this;
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}
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Optional &operator=(const Optional &value)
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{
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_has_value = value._has_value;
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_value = value._value;
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return *this;
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}
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template <typename U = Type>
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Optional &operator=(U *value)
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{
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if (value == nullptr)
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{
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_has_value = false;
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return *this;
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}
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_has_value = true;
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_value = *value;
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return *this;
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}
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private:
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bool _has_value = false;
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Type _value;
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};
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template <typename Type>
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Optional<Type>::Optional(const Optional &optional)
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{
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_has_value = optional._has_value;
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_value = optional._value;
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}
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template <typename Type>
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template <typename U>
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Optional<Type>::Optional(const U &value)
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{
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_has_value = true;
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_value = value;
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}
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template <typename Type>
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bool Optional<Type>::has_value() const
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{
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return _has_value;
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}
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template <typename Type>
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const Type &Optional<Type>::value() const
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{
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assert(_has_value && "Value does not exist");
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return _value;
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}
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template <typename Type>
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const Type Optional<Type>::value_or(Type &&alternative) const
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{
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if (has_value())
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{
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return _value;
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}
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return alternative;
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}
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template <typename Type>
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const Type Optional<Type>::value_or(const Type &alternative) const
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{
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if (has_value())
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{
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return _value;
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}
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return alternative;
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}
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} // namespace vkb
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