flags/internal/commandlineflag.h

0001 //
0002 // Copyright 2019 The Abseil Authors.
0003 //
0004 // Licensed under the Apache License, Version 2.0 (the "License");
0005 // you may not use this file except in compliance with the License.
0006 // You may obtain a copy of the License at
0007 //
0008 //      https://www.apache.org/licenses/LICENSE-2.0
0009 //
0010 // Unless required by applicable law or agreed to in writing, software
0011 // distributed under the License is distributed on an "AS IS" BASIS,
0012 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
0013 // See the License for the specific language governing permissions and
0014 // limitations under the License.
0015
0016 #ifndef ABSL_FLAGS_INTERNAL_COMMANDLINEFLAG_H_
0017 #define ABSL_FLAGS_INTERNAL_COMMANDLINEFLAG_H_
0018
0019 #include "absl/base/config.h"
0020 #include "absl/base/internal/fast_type_id.h"
0021
0022 namespace absl {
0023 ABSL_NAMESPACE_BEGIN
0024 namespace flags_internal {
0025
0026 // An alias for flag fast type id. This value identifies the flag value type
0027 // similarly to typeid(T), without relying on RTTI being available. In most
0028 // cases this id is enough to uniquely identify the flag's value type. In a few
0029 // cases we'll have to resort to using actual RTTI implementation if it is
0030 // available.
0031 using FlagFastTypeId = absl::base_internal::FastTypeIdType;
0032
0033 // Options that control SetCommandLineOptionWithMode.
0034 enum FlagSettingMode {
0035   // update the flag's value unconditionally (can call this multiple times).
0036   SET_FLAGS_VALUE,
0037   // update the flag's value, but *only if* it has not yet been updated
0038   // with SET_FLAGS_VALUE, SET_FLAG_IF_DEFAULT, or "FLAGS_xxx = nondef".
0039   SET_FLAG_IF_DEFAULT,
0040   // set the flag's default value to this.  If the flag has not been updated
0041   // yet (via SET_FLAGS_VALUE, SET_FLAG_IF_DEFAULT, or "FLAGS_xxx = nondef")
0042   // change the flag's current value to the new default value as well.
0043   SET_FLAGS_DEFAULT
0044 };
0045
0046 // Options that control ParseFrom: Source of a value.
0047 enum ValueSource {
0048   // Flag is being set by value specified on a command line.
0049   kCommandLine,
0050   // Flag is being set by value specified in the code.
0051   kProgrammaticChange,
0052 };
0053
0054 // Handle to FlagState objects. Specific flag state objects will restore state
0055 // of a flag produced this flag state from method CommandLineFlag::SaveState().
0056 class FlagStateInterface {
0057  public:
0058   virtual ~FlagStateInterface();
0059
0060   // Restores the flag originated this object to the saved state.
0061   virtual void Restore() const = 0;
0062 };
0063
0064 }  // namespace flags_internal
0065 ABSL_NAMESPACE_END
0066 }  // namespace absl
0067
0068 #endif  // ABSL_FLAGS_INTERNAL_COMMANDLINEFLAG_H_