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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-*/
/* vim: set ts=2 sw=2 et tw=79: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this file,
* You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef mozilla_dom_Nullable_h
#define mozilla_dom_Nullable_h
#include "mozilla/Assertions.h"
namespace mozilla {
namespace dom {
// Support for nullable types
template <typename T>
struct Nullable
{
private:
T mValue;
bool mIsNull;
public:
Nullable()
: mIsNull(true)
{}
Nullable(T aValue)
: mValue(aValue)
, mIsNull(false)
{}
void SetValue(T aValue) {
mValue = aValue;
mIsNull = false;
}
// For cases when |T| is some type with nontrivial copy behavior, we may want
// to get a reference to our internal copy of T and work with it directly
// instead of relying on the copying version of SetValue().
T& SetValue() {
mIsNull = false;
return mValue;
}
void SetNull() {
mIsNull = true;
}
const T& Value() const {
MOZ_ASSERT(!mIsNull);
return mValue;
}
T& Value() {
MOZ_ASSERT(!mIsNull);
return mValue;
}
bool IsNull() const {
return mIsNull;
}
};
} // namespace dom
} // namespace mozilla
#endif /* mozilla_dom_Nullable_h */
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