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/*
* Copyright (C) 2016 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#pragma once
#include <iostream>
namespace android {
namespace lshal {
template<typename S>
class NullableOStream {
public:
explicit NullableOStream(S &os) : mOs(&os) {}
explicit NullableOStream(S *os) : mOs(os) {}
NullableOStream &operator=(S &os) {
mOs = &os;
return *this;
}
NullableOStream &operator=(S *os) {
mOs = os;
return *this;
}
template<typename Other>
NullableOStream &operator=(const NullableOStream<Other> &other) {
mOs = other.mOs;
return *this;
}
const NullableOStream &operator<<(std::ostream& (*pf)(std::ostream&)) const {
if (mOs) {
(*mOs) << pf;
}
return *this;
}
template<typename T>
const NullableOStream &operator<<(const T &rhs) const {
if (mOs) {
(*mOs) << rhs;
}
return *this;
}
S& buf() const {
return *mOs;
}
operator bool() const { // NOLINT(google-explicit-constructor)
return mOs != nullptr;
}
void flush() {
if (mOs) {
mOs->flush();
}
}
private:
template<typename>
friend class NullableOStream;
S *mOs = nullptr;
};
} // namespace lshal
} // namespace android
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