chromium/third_party/dawn/src/dawn/utils/CommandLineParser.h

// Copyright 2024 The Dawn & Tint Authors
//
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// modification, are permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice, this
//    list of conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright notice,
//    this list of conditions and the following disclaimer in the documentation
//    and/or other materials provided with the distribution.
//
// 3. Neither the name of the copyright holder nor the names of its
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//    this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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#ifndef SRC_DAWN_UTILS_COMMANDLINEPARSER_H_
#define SRC_DAWN_UTILS_COMMANDLINEPARSER_H_

#include <memory>
#include <ostream>
#include <string>
#include <utility>
#include <vector>

#include "absl/types/span.h"  // TODO(343500108): Use std::span when we have C++20.
#include "dawn/common/Assert.h"
#include "dawn/common/NonMovable.h"

namespace dawn::utils {

// A helper class to parse command line arguments.
//
//   CommandLineParser parser;
//   auto& dryRun = parser.AddBool("dry-run", "fake operations").ShortName('d');
//   auto& input = parser.AddString("input", "the input file to process").ShortName('i');
//   auto& help = opts.AddHelp();
//
//   auto result = parser.Parse(argc, argv);
//   if (!result.success) {
//       std::cerr << result.errorMessage << "\n";
//       return 1;
//   }
//
//   if (help.GetValue()) {
//       std::cout << "Usage: " << argv[0] << " <options>\n\noptions\n";
//       parser.PrintHelp(std::cout);
//       return 0;
//   }
//
//   if (dryRun.GetValue() && input.IsSet()) {
//     doStuffWith(input.GetValue());
//   }
//   // ...
//
// Command line options can use short-form for boolean options "(-f") and use both spaces or = to
// separate the value for an option ("-f=foo" and  "-f foo").

// TODO(42241992): Considering supporting more types of options and command line parsing niceties.
// - Support "-" with a bunch of short names (like grep -rniI)
// - Support returning the part that hasn't been parsed at the end so that users can do something
// with it.
// - Support "--" being used to separate remaining args.
// - Support setting a default to show it in the help.

class CommandLineParser { … };

// Option<Child>
template <typename Child>
Child& CommandLineParser::Option<Child>::ShortName(char shortName) { … }

template <typename Child>
Child& CommandLineParser::Option<Child>::Parameter(std::string parameter) { … }

// EnumOption<E>
template <typename E>
CommandLineParser::EnumOption<E>::EnumOption(
    std::vector<std::pair<std::string_view, E>> conversions,
    std::string_view name,
    std::string_view desc)
    : … { … }

template <typename E>
CommandLineParser::EnumOption<E>::~EnumOption<E>() = default;

template <typename E>
E CommandLineParser::EnumOption<E>::GetValue() const { … }

template <typename E>
CommandLineParser::OptionBase::ParseResult CommandLineParser::EnumOption<E>::ParseImpl(
    absl::Span<const std::string_view> args) { … }

template <typename E>
std::string CommandLineParser::EnumOption<E>::GetParameter() const { … }

template <typename E>
CommandLineParser::EnumOption<E>& CommandLineParser::EnumOption<E>::Default(E value) { … }

template <typename E>
std::string CommandLineParser::EnumOption<E>::JoinNames(std::string_view separator) const { … }

}  // namespace dawn::utils

#endif  // SRC_DAWN_UTILS_COMMANDLINEPARSER_H_