commandlineflag.h (2501B)
1 // 2 // Copyright 2019 The Abseil Authors. 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 // https://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 #ifndef ABSL_FLAGS_INTERNAL_COMMANDLINEFLAG_H_ 17 #define ABSL_FLAGS_INTERNAL_COMMANDLINEFLAG_H_ 18 19 #include "absl/base/config.h" 20 #include "absl/base/internal/fast_type_id.h" 21 22 namespace absl { 23 ABSL_NAMESPACE_BEGIN 24 namespace flags_internal { 25 26 // An alias for flag fast type id. This value identifies the flag value type 27 // similarly to typeid(T), without relying on RTTI being available. In most 28 // cases this id is enough to uniquely identify the flag's value type. In a few 29 // cases we'll have to resort to using actual RTTI implementation if it is 30 // available. 31 using FlagFastTypeId = absl::base_internal::FastTypeIdType; 32 33 // Options that control SetCommandLineOptionWithMode. 34 enum FlagSettingMode { 35 // update the flag's value unconditionally (can call this multiple times). 36 SET_FLAGS_VALUE, 37 // update the flag's value, but *only if* it has not yet been updated 38 // with SET_FLAGS_VALUE, SET_FLAG_IF_DEFAULT, or "FLAGS_xxx = nondef". 39 SET_FLAG_IF_DEFAULT, 40 // set the flag's default value to this. If the flag has not been updated 41 // yet (via SET_FLAGS_VALUE, SET_FLAG_IF_DEFAULT, or "FLAGS_xxx = nondef") 42 // change the flag's current value to the new default value as well. 43 SET_FLAGS_DEFAULT 44 }; 45 46 // Options that control ParseFrom: Source of a value. 47 enum ValueSource { 48 // Flag is being set by value specified on a command line. 49 kCommandLine, 50 // Flag is being set by value specified in the code. 51 kProgrammaticChange, 52 }; 53 54 // Handle to FlagState objects. Specific flag state objects will restore state 55 // of a flag produced this flag state from method CommandLineFlag::SaveState(). 56 class FlagStateInterface { 57 public: 58 virtual ~FlagStateInterface(); 59 60 // Restores the flag originated this object to the saved state. 61 virtual void Restore() const = 0; 62 }; 63 64 } // namespace flags_internal 65 ABSL_NAMESPACE_END 66 } // namespace absl 67 68 #endif // ABSL_FLAGS_INTERNAL_COMMANDLINEFLAG_H_