THUAI6/CAPI/cpp/grpc/include/absl/flags/internal/usage.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_USAGE_H_
#define ABSL_FLAGS_INTERNAL_USAGE_H_

#include <iosfwd>
#include <string>

#include "absl/base/config.h"
#include "absl/flags/commandlineflag.h"
#include "absl/flags/declare.h"
#include "absl/strings/string_view.h"

// --------------------------------------------------------------------
// Usage reporting interfaces

namespace absl
{
    ABSL_NAMESPACE_BEGIN
    namespace flags_internal
    {

        // The format to report the help messages in.
        enum class HelpFormat
        {
            kHumanReadable,
        };

        // Streams the help message describing `flag` to `out`.
        // The default value for `flag` is included in the output.
        void FlagHelp(std::ostream& out, const CommandLineFlag& flag, HelpFormat format = HelpFormat::kHumanReadable);

        // Produces the help messages for all flags matching the filter. A flag matches
        // the filter if it is defined in a file with a filename which includes
        // filter string as a substring. You can use '/' and '.' to restrict the
        // matching to a specific file names. For example:
        //   FlagsHelp(out, "/path/to/file.");
        // restricts help to only flags which resides in files named like:
        //  .../path/to/file.<ext>
        // for any extension 'ext'. If the filter is empty this function produces help
        // messages for all flags.
        void FlagsHelp(std::ostream& out, absl::string_view filter, HelpFormat format, absl::string_view program_usage_message);

        // --------------------------------------------------------------------

        // If any of the 'usage' related command line flags (listed on the bottom of
        // this file) has been set this routine produces corresponding help message in
        // the specified output stream and returns:
        //  0 - if "version" or "only_check_flags" flags were set and handled.
        //  1 - if some other 'usage' related flag was set and handled.
        // -1 - if no usage flags were set on a commmand line.
        // Non negative return values are expected to be used as an exit code for a
        // binary.
        int HandleUsageFlags(std::ostream& out, absl::string_view program_usage_message);

        // --------------------------------------------------------------------
        // Globals representing usage reporting flags

        enum class HelpMode
        {
            kNone,
            kImportant,
            kShort,
            kFull,
            kPackage,
            kMatch,
            kVersion,
            kOnlyCheckArgs
        };

        // Returns substring to filter help output (--help=substr argument)
        std::string GetFlagsHelpMatchSubstr();
        // Returns the requested help mode.
        HelpMode GetFlagsHelpMode();
        // Returns the requested help format.
        HelpFormat GetFlagsHelpFormat();

        // These are corresponding setters to the attributes above.
        void SetFlagsHelpMatchSubstr(absl::string_view);
        void SetFlagsHelpMode(HelpMode);
        void SetFlagsHelpFormat(HelpFormat);

        // Deduces usage flags from the input argument in a form --name=value or
        // --name. argument is already split into name and value before we call this
        // function.
        bool DeduceUsageFlags(absl::string_view name, absl::string_view value);

    }  // namespace flags_internal
    ABSL_NAMESPACE_END
}  // namespace absl

#endif  // ABSL_FLAGS_INTERNAL_USAGE_H_