parse_args 0.2.1

A Dart package to parse command-line options simple way and in a portable style (bash/find/java/PowerShell)

example/parse_args_example.dart

// Copyright (c) 2022, Alexander Iurovetski
// All rights reserved under MIT license (see LICENSE file)

import 'dart:io';
import 'package:path/path.dart' as p;
import 'package:parse_args/parse_args.dart';

/// Application options

class Options {
  static const appName = 'sampleapp';
  static const appVersion = '2.0.1';

  var _appConfigPath = '';
  get appConfigPath => _appConfigPath;

  var _compression = 6;
  get compression => _compression;

  var _isForced = false;
  get isForced => _isForced;

  var _isQuiet = false;
  get isQuiet => _isQuiet;

  var _isVerbose = false;
  get isVerbose => _isVerbose;

  var _startDirName = '';
  get startDirName => _startDirName;

  final _inputFiles = <String>[];
  get inputFiles => _inputFiles;

  final _outputFiles = <String>[];
  get outputFiles => _outputFiles;

  /// General-purpose method to add file paths to destinaltion list

  void addPaths(List<String> to, List from) {
    for (var x in from) {
      to.add(p.isAbsolute(x) ? x : p.join(_startDirName, x));
    }
  }

  /// Sample application's command-line parser

  void parse(List<String> args) {
    parseArgs(
        '+|q,quiet|v,verbose|?,h,help|c,app-config:|d,dir:|f,force|i,inp,inp-files::|o,out,out-files::|p,compression:i|::',
        args, (isFirstRun, optName, values) {
      if (isFirstRun) {
        switch (optName) {
          case 'compression':
            _compression = values[0];
            return;
          case 'help':
            printUsage();
          case 'dir':
            _startDirName = values[0];
            return;
          case 'force':
            _isForced = true;
            return;
          case 'quiet':
            _isQuiet = true;
            return;
          case 'verbose':
            _isVerbose = true;
            return;
          default:
            return;
        }
      } else {
        printVerbose('Parsing $optName => $values');

        // No need to assign any option value which does not depend on another one, just
        // printing the info. Essentially, these cases can be omitted for the second run

        switch (optName) {
          case '':
            printInfo('...plain arg count: ${values.length}');
            return;
          case 'appconfig':
            _appConfigPath = p.join(_startDirName, values[0]);
            printInfo('...appConfigPath: $_appConfigPath');
            return;
          case 'compression':
            printInfo('...compression: $_compression');
            return;
          case 'dir':
            printInfo('...startDirName: $_startDirName');
            return;
          case 'force':
            printInfo('...isForced: $_isForced');
            return;
          case 'inpfiles':
            addPaths(_inputFiles, values);
            printInfo('...inp file(s): $_inputFiles');
            return;
          case 'outfiles':
            addPaths(_outputFiles, values);
            printInfo('...out file(s): $_outputFiles');
            return;
          case 'quiet':
            printInfo('...quiet: $_isQuiet');
            return;
          case 'verbose':
            printInfo('...verbose: $_isVerbose');
            return;
          default:
            return;
        }
      }
    });
  }

  /// A very simple info logger

  void printInfo(String line) {
    if (!_isQuiet) {
      print(line);
    }
  }

  /// A very simple verbose logger

  void printVerbose(String line) {
    if (!_isQuiet && _isVerbose) {
      print(line);
    }
  }

  /// Displaying the help and optionally, an error message

  Never printUsage([String? error]) {
    stderr.writeln('''

${Options.appName} ${Options.appVersion} (c) My Name 2022

Long description of the application functionality

USAGE:

${Options.appName} [OPTIONS]

OPTIONS (case-insensitive and dash-insensitive):

-?, -h, -help                      - this help screen
-c, --app-config FILE              - configuration file path/name
-d, --dir DIR                      - directory to start in
-f, --force                        - overwrite existing output file
-i, --inp[-files] FILE1 [FILE2...] - the input file paths/names
-o, --out[-files] FILE1 [FILE2...] - the output file paths/names
-p, --compression INT              - compression level
-v, --verbose                      - detailed application log

EXAMPLE:

${Options.appName} -AppConfig default.json --dir somedir/Documents -inp a*.txt ../Downloads/bb.xml --out-files ../Uploads/result.txt -- -result_more.txt

${(error == null) || error.isEmpty ? '' : '*** ERROR: $error'}
''');

    exit(1);
  }
}

/// Sample application entry point

void main(List<String> args) {
  try {
    var o = Options();
    o.parse(args);
    // the rest of processing
  } on OptException catch (e) {
    e.print();
  } on Exception catch (e) {
    stderr.writeln(e.toString());
  } on Error catch (e) {
    stderr.writeln(e.toString());
  }
}