1 /* 2 * Copyright (C) 2018 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 ANDROID_APEXD_STRING_LOG_H_ 18 #define ANDROID_APEXD_STRING_LOG_H_ 19 20 // Simple helper class to create strings similar to LOGs. 21 // Usage sample: 22 // std::string msg = StringLog() << "Hello " << std::hex << 1234; 23 24 #include <cstring> 25 #include <iomanip> 26 #include <iostream> 27 #include <sstream> 28 29 #include <errno.h> 30 31 template <typename T> 32 class BaseStringLog { 33 public: BaseStringLog()34 BaseStringLog() {} 35 36 // Pipe in values. 37 template <class U> 38 T& operator<<(const U& t) { 39 os_stream << t; 40 return static_cast<T&>(*this); 41 } 42 43 // Pipe in modifiers. 44 T& operator<<(std::ostream& (*f)(std::ostream&)) { 45 os_stream << f; 46 return static_cast<T&>(*this); 47 } 48 49 // Get the current string. 50 // NOLINTNEXTLINE(google-explicit-constructor) string()51 operator std::string() const { return os_stream.str(); } 52 53 private: 54 std::ostringstream os_stream; 55 }; 56 57 class StringLog : public BaseStringLog<StringLog> {}; 58 59 class PStringLog : public BaseStringLog<PStringLog> { 60 public: PStringLog()61 PStringLog() : errno_(errno) {} 62 63 // Get the current string. 64 // NOLINTNEXTLINE(google-explicit-constructor) string()65 operator std::string() const { 66 return (BaseStringLog::operator std::string()) 67 .append(": ") 68 .append(strerror(errno_)); 69 } 70 71 private: 72 int errno_; 73 }; 74 75 #endif // ANDROID_APEXD_STRING_LOG_H_ 76