THUAI6/CAPI/cpp/grpc/include/absl/flags/internal/commandlineflag.h

//
// Copyright 2019 The Abseil Authors.
//
// 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
//
//      https://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.

#ifndef ABSL_FLAGS_INTERNAL_COMMANDLINEFLAG_H_
#define ABSL_FLAGS_INTERNAL_COMMANDLINEFLAG_H_

#include "absl/base/config.h"
#include "absl/base/internal/fast_type_id.h"

namespace absl
{
    ABSL_NAMESPACE_BEGIN
    namespace flags_internal
    {

        // An alias for flag fast type id. This value identifies the flag value type
        // similarly to typeid(T), without relying on RTTI being available. In most
        // cases this id is enough to uniquely identify the flag's value type. In a few
        // cases we'll have to resort to using actual RTTI implementation if it is
        // available.
        using FlagFastTypeId = absl::base_internal::FastTypeIdType;

        // Options that control SetCommandLineOptionWithMode.
        enum FlagSettingMode
        {
            // update the flag's value unconditionally (can call this multiple times).
            SET_FLAGS_VALUE,
            // update the flag's value, but *only if* it has not yet been updated
            // with SET_FLAGS_VALUE, SET_FLAG_IF_DEFAULT, or "FLAGS_xxx = nondef".
            SET_FLAG_IF_DEFAULT,
            // set the flag's default value to this.  If the flag has not been updated
            // yet (via SET_FLAGS_VALUE, SET_FLAG_IF_DEFAULT, or "FLAGS_xxx = nondef")
            // change the flag's current value to the new default value as well.
            SET_FLAGS_DEFAULT
        };

        // Options that control ParseFrom: Source of a value.
        enum ValueSource
        {
            // Flag is being set by value specified on a command line.
            kCommandLine,
            // Flag is being set by value specified in the code.
            kProgrammaticChange,
        };

        // Handle to FlagState objects. Specific flag state objects will restore state
        // of a flag produced this flag state from method CommandLineFlag::SaveState().
        class FlagStateInterface
        {
        public:
            virtual ~FlagStateInterface();

            // Restores the flag originated this object to the saved state.
            virtual void Restore() const = 0;
        };

    }  // namespace flags_internal
    ABSL_NAMESPACE_END
}  // namespace absl

#endif  // ABSL_FLAGS_INTERNAL_COMMANDLINEFLAG_H_