pkgs/characters/tool/src/args.dart

// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

// Very primitive arguments parser for the generator commands.

import 'dart:io';

typedef Flags = ({
  bool verbose,
  bool update,
  bool dryrun,
  bool optimize,
  bool acceptLicenseChange,
  File? targetFile,
});

Flags parseArgs(
  List<String> args,
  String toolName, {
  bool allowOptimize = false,
  bool allowFile = true,
}) {
  var update = false;
  var dryrun = false;
  var verbose = false;
  var optimize = false;
  var acceptLicenseChange = false;
  File? output;
  for (var arg in args) {
    if (arg == '-h' || arg == '--help') {
      stderr
        ..writeln(
          "Usage: $toolName.dart [-u] ${allowOptimize ? "[-i|-o] " : ""}[-n]"
          "${allowFile ? " <targetFile>" : ""}",
        )
        ..writeln('-h | --help          : Print this help and exit')
        ..writeln('-u | --update        : Fetch new data files')
        ..writeln('--accept-license     : Accept a changed license')
        ..writeln(
          '-n | --dryrun        : Write to stdout instead of target file',
        );
      if (allowOptimize) {
        stderr.writeln(
          '-o | -i | --optimize : Optimize size parameters for tables',
        );
      }
      stderr.writeln('-v | --verbose       : Print more information');
      if (allowFile) {
        stderr.writeln('If no target file is given, writes to stdout.');
      }
      exit(0);
    } else if (arg == '-u' || arg == '--update') {
      update = true;
    } else if (arg == '-n' || arg == '--dryrun') {
      dryrun = true;
    } else if (arg == '-v' || arg == '--verbose') {
      verbose = true;
    } else if (arg == '--accept-license') {
      acceptLicenseChange = true;
    } else if (allowOptimize && arg == '-o' ||
        arg == '-i' ||
        arg.startsWith('--opt')) {
      // Try to find a better size for the table.
      // No need to do this unless the representation changes or
      // the input tables are updated.
      // The current value is optimal for the data and representation used.
      optimize = true;
    } else if (arg.startsWith('-') || !allowFile) {
      stderr.writeln('Unrecognized flag: $arg');
    } else {
      output = File(arg);
    }
  }
  return (
    acceptLicenseChange: acceptLicenseChange,
    dryrun: dryrun,
    optimize: optimize,
    targetFile: output,
    update: update,
    verbose: verbose,
  );
}