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#pragma once
/**
* Optional implementation.
*
* Copyright: Copyright (C) 1999-2022 by The D Language Foundation, All Rights Reserved
* Authors: $(LINK2 https://www.digitalmars.com, Walter Bright)
* License: $(LINK2 https://www.boost.org/LICENSE_1_0.txt, Boost License 1.0)
* Source: $(LINK2 https://github.com/dlang/dmd/blob/master/src/dmd/root/optional.h, root/_optional.h)
* Documentation: https://dlang.org/phobos/dmd_root_optional.html
* Coverage: https://codecov.io/gh/dlang/dmd/src/master/src/dmd/root/optional.h
*/
/// Optional type that is either `empty` or contains a value of type `T`
template<typename T>
struct Optional final
{
private:
/** the value (if present) **/
T value;
/** whether `value` is set **/
bool present;
public:
/** Creates an `Optional` with the given value **/
Optional(T);
/** Creates an `Optional` with the given value **/
static Optional<T> create(T);
/** Checks whether this `Optional` contains a value **/
bool isPresent() const;
/** Checks whether this `Optional` does not contain a value **/
bool isEmpty() const;
/** Returns: The value if present **/
T get();
bool hasValue(const T) const;
};
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