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//
// Copyright (c) 2015 The ANGLE Project Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//
// Optional.h:
// Represents a type that may be invalid, similar to std::optional.
//
#ifndef COMMON_OPTIONAL_H_
#define COMMON_OPTIONAL_H_
#include <utility>
template <class T>
struct Optional
{
Optional() : mValid(false), mValue(T()) {}
Optional(const T &valueIn) : mValid(true), mValue(valueIn) {}
Optional(const Optional &other) : mValid(other.mValid), mValue(other.mValue) {}
Optional &operator=(const Optional &other)
{
this->mValid = other.mValid;
this->mValue = other.mValue;
return *this;
}
Optional &operator=(const T &value)
{
mValue = value;
mValid = true;
return *this;
}
Optional &operator=(T &&value)
{
mValue = std::move(value);
mValid = true;
return *this;
}
void reset() { mValid = false; }
static Optional Invalid() { return Optional(); }
bool valid() const { return mValid; }
const T &value() const { return mValue; }
bool operator==(const Optional &other) const
{
return ((mValid == other.mValid) && (!mValid || (mValue == other.mValue)));
}
bool operator!=(const Optional &other) const { return !(*this == other); }
bool operator==(const T &value) const { return mValid && (mValue == value); }
bool operator!=(const T &value) const { return !(*this == value); }
private:
bool mValid;
T mValue;
};
#endif // COMMON_OPTIONAL_H_
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