1 /* 2 * Copyright (C) 2016 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #ifndef FRAMEWORK_NATIVE_CMDS_LSHAL_NULLABLE_O_STREAM_H_ 18 #define FRAMEWORK_NATIVE_CMDS_LSHAL_NULLABLE_O_STREAM_H_ 19 20 #include <iostream> 21 22 namespace android { 23 namespace lshal { 24 25 template<typename S> 26 class NullableOStream { 27 public: 28 NullableOStream(S &os) : mOs(&os) {} 29 NullableOStream(S *os) : mOs(os) {} 30 NullableOStream &operator=(S &os) { 31 mOs = &os; 32 return *this; 33 } 34 NullableOStream &operator=(S *os) { 35 mOs = os; 36 return *this; 37 } 38 template<typename Other> 39 NullableOStream &operator=(const NullableOStream<Other> &other) { 40 mOs = other.mOs; 41 return *this; 42 } 43 44 const NullableOStream &operator<<(std::ostream& (*pf)(std::ostream&)) const { 45 if (mOs) { 46 (*mOs) << pf; 47 } 48 return *this; 49 } 50 template<typename T> 51 const NullableOStream &operator<<(const T &rhs) const { 52 if (mOs) { 53 (*mOs) << rhs; 54 } 55 return *this; 56 } 57 S& buf() const { 58 return *mOs; 59 } 60 operator bool() const { 61 return mOs != nullptr; 62 } 63 private: 64 template<typename> 65 friend class NullableOStream; 66 67 S *mOs = nullptr; 68 }; 69 70 } // namespace lshal 71 } // namespace android 72 73 #endif // FRAMEWORK_NATIVE_CMDS_LSHAL_NULLABLE_O_STREAM_H_ 74
