dart/pkg/analyzer/lib/options.dart - external/dart - Git at Google

 // Copyright (c) 2013, 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.

 library options;

 import 'dart:io';

 import 'package:args/args.dart';

 const _BINARY_NAME = 'dartanalyzer';

 /**
  * Analyzer commandline configuration options.
  */
 class CommandLineOptions {
   /** The path to the dart SDK */
   final String dartSdkPath;

   /** A table mapping the names of defined variables to their values. */
   final Map<String, String> definedVariables;

   /** Whether to report hints */
   final bool disableHints;

   /** Whether to display version information */
   final bool displayVersion;

   /**
    * Whether to enable null-aware operators (DEP 9).
    */
   final bool enableNullAwareOperators;

   /**
    * Whether to strictly follow the specification when generating warnings on
    * "call" methods (fixes dartbug.com/21938).
    */
   final bool enableStrictCallChecks;

   /**
    * Whether to treat type mismatches found during constant evaluation as
    * errors.
    */
   final bool enableTypeChecks;

   /** Whether to ignore unrecognized flags */
   final bool ignoreUnrecognizedFlags;

   /** Whether to log additional analysis messages and exceptions */
   final bool log;

   /** Whether to use machine format for error display */
   final bool machineFormat;

   /** The path to the package root */
   final String packageRootPath;

   /** Whether to show performance statistics */
   final bool perf;

   /** Batch mode (for unit testing) */
   final bool shouldBatch;

   /** Whether to show package: warnings */
   final bool showPackageWarnings;

   /** Whether to show SDK warnings */
   final bool showSdkWarnings;

   /** The source files to analyze */
   final List<String> sourceFiles;

   /** Whether to show both cold and hot performance statistics */
   final bool warmPerf;

   /** Whether to treat warnings as fatal */
   final bool warningsAreFatal;

   /** A table mapping library URIs to the file system path where the library
    *  source is located.
    */
   final Map<String, String> customUrlMappings;

   /**
    * Initialize options from the given parsed [args].
    */
   CommandLineOptions._fromArgs(ArgResults args,
       Map<String, String> definedVariables,
       Map<String, String> customUrlMappings)
       : dartSdkPath = args['dart-sdk'],
         this.definedVariables = definedVariables,
         disableHints = args['no-hints'],
         displayVersion = args['version'],
         enableNullAwareOperators = args['enable-null-aware-operators'],
         enableStrictCallChecks = args['enable-strict-call-checks'],
         enableTypeChecks = args['enable_type_checks'],
         ignoreUnrecognizedFlags = args['ignore-unrecognized-flags'],
         log = args['log'],
         machineFormat = args['machine'] || args['format'] == 'machine',
         packageRootPath = args['package-root'],
         perf = args['perf'],
         shouldBatch = args['batch'],
         showPackageWarnings = args['show-package-warnings'] ||
             args['package-warnings'],
         showSdkWarnings = args['show-sdk-warnings'] || args['warnings'],
         sourceFiles = args.rest,
         warmPerf = args['warm-perf'],
         warningsAreFatal = args['fatal-warnings'],
         this.customUrlMappings = customUrlMappings;

   /**
    * Parse [args] into [CommandLineOptions] describing the specified
    * analyzer options. In case of a format error, prints error and exists.
    */
   static CommandLineOptions parse(List<String> args) {
     CommandLineOptions options = _parse(args);
     // check SDK
     {
       var sdkPath = options.dartSdkPath;
       // check that SDK is specified
       if (sdkPath == null) {
         print('Usage: $_BINARY_NAME: no Dart SDK found.');
         exit(15);
       }
       // check that SDK is existing directory
       if (!(new Directory(sdkPath)).existsSync()) {
         print('Usage: $_BINARY_NAME: invalid Dart SDK path: $sdkPath');
         exit(15);
       }
     }
     // OK
     return options;
   }

   static String _getVersion() {
     try {
       // This is relative to bin/snapshot, so ../..
       String versionPath =
           Platform.script.resolve('../../version').toFilePath();
       File versionFile = new File(versionPath);
       return versionFile.readAsStringSync().trim();
     } catch (_) {
       // This happens when the script is not running in the context of an SDK.
       return "<unknown>";
     }
   }

   static CommandLineOptions _parse(List<String> args) {
     args = args.expand((String arg) => arg.split('=')).toList();
     var parser = new CommandLineParser()
       ..addFlag('batch',
           abbr: 'b',
           help: 'Run in batch mode',
           defaultsTo: false,
           negatable: false)
       ..addOption('dart-sdk', help: 'The path to the Dart SDK')
       ..addOption('package-root',
           abbr: 'p',
           help: 'The path to the package root. The flag package-root is deprecated. Remove to use package information computed by pub.')
       ..addOption('format',
           help: 'Specifies the format in which errors are displayed')
       ..addFlag('machine',
           help: 'Print errors in a format suitable for parsing (deprecated)',
           defaultsTo: false,
           negatable: false)
       ..addFlag('version',
           help: 'Print the analyzer version',
           defaultsTo: false,
           negatable: false)
       ..addFlag('no-hints',
           help: 'Do not show hint results', defaultsTo: false, negatable: false)
       ..addFlag('ignore-unrecognized-flags',
           help: 'Ignore unrecognized command line flags',
           defaultsTo: false,
           negatable: false)
       ..addFlag('fatal-warnings',
           help: 'Treat non-type warnings as fatal',
           defaultsTo: false,
           negatable: false)
       ..addFlag('package-warnings',
           help: 'Show warnings from package: imports',
           defaultsTo: false,
           negatable: false)
       ..addFlag('show-package-warnings',
           help: 'Show warnings from package: imports (deprecated)',
           defaultsTo: false,
           negatable: false)
       ..addFlag('perf',
           help: 'Show performance statistics',
           defaultsTo: false,
           negatable: false)
       ..addFlag('warnings',
           help: 'Show warnings from SDK imports',
           defaultsTo: false,
           negatable: false)
       ..addFlag('show-sdk-warnings',
           help: 'Show warnings from SDK imports (deprecated)',
           defaultsTo: false,
           negatable: false)
       ..addFlag('help',
           abbr: 'h',
           help: 'Display this help message',
           defaultsTo: false,
           negatable: false)
       ..addOption('url-mapping',
           help: '--url-mapping=libraryUri,/path/to/library.dart directs the '
           'analyzer to use "library.dart" as the source for an import ' 'of "libraryUri"',
           allowMultiple: true)
       //
       // Hidden flags.
       //
       ..addFlag('enable-async',
           help: 'Enable support for the proposed async feature',
           defaultsTo: false,
           negatable: false,
           hide: true)
       ..addFlag('enable-enum',
           help: 'Enable support for the proposed enum feature',
           defaultsTo: false,
           negatable: false,
           hide: true)
       ..addFlag('enable-null-aware-operators',
           help: 'Enable support for null-aware operators (DEP 9)',
           defaultsTo: false,
           negatable: false,
           hide: true)
       ..addFlag('enable-strict-call-checks',
           help: 'Fix issue 21938',
           defaultsTo: false,
           negatable: false,
           hide: true)
       ..addFlag('log',
           help: 'Log additional messages and exceptions',
           defaultsTo: false,
           negatable: false,
           hide: true)
       ..addFlag('warm-perf',
           help: 'Show both cold and warm performance statistics',
           defaultsTo: false,
           negatable: false,
           hide: true)
       ..addFlag('enable_type_checks',
           help: 'Check types in constant evaluation',
           defaultsTo: false,
           negatable: false,
           hide: true);

     try {
       // TODO(scheglov) https://code.google.com/p/dart/issues/detail?id=11061
       args =
           args.map((String arg) => arg == '-batch' ? '--batch' : arg).toList();
       Map<String, String> definedVariables = <String, String>{};
       var results = parser.parse(args, definedVariables);
       // help requests
       if (results['help']) {
         _showUsage(parser);
         exit(0);
       }
       // batch mode and input files
       if (results['batch']) {
         if (results.rest.isNotEmpty) {
           print('No source files expected in the batch mode.');
           _showUsage(parser);
           exit(15);
         }
       } else if (results['version']) {
         print('$_BINARY_NAME version ${_getVersion()}');
         exit(0);
       } else {
         if (results.rest.isEmpty) {
           _showUsage(parser);
           exit(15);
         }
       }
       Map<String, String> customUrlMappings = <String, String>{};
       for (String mapping in results['url-mapping']) {
         List<String> splitMapping = mapping.split(',');
         if (splitMapping.length != 2) {
           _showUsage(parser);
           exit(15);
         }
         customUrlMappings[splitMapping[0]] = splitMapping[1];
       }
       return new CommandLineOptions._fromArgs(
           results, definedVariables, customUrlMappings);
     } on FormatException catch (e) {
       print(e.message);
       _showUsage(parser);
       exit(15);
     }
   }

   static _showUsage(parser) {
     print('Usage: $_BINARY_NAME [options...] <libraries to analyze...>');
     print(parser.getUsage());
     print('');
     print('For more information, see http://www.dartlang.org/tools/analyzer.');
   }
 }

 /**
  * Commandline argument parser.
  *
  * TODO(pquitslund): when the args package supports ignoring unrecognized
  * options/flags, this class can be replaced with a simple [ArgParser] instance.
  */
 class CommandLineParser {
   final List<String> _knownFlags;
   final bool _alwaysIgnoreUnrecognized;
   final ArgParser _parser;

   /** Creates a new command line parser */
   CommandLineParser({bool alwaysIgnoreUnrecognized: false})
       : _knownFlags = <String>[],
         _alwaysIgnoreUnrecognized = alwaysIgnoreUnrecognized,
         _parser = new ArgParser(allowTrailingOptions: true);

   ArgParser get parser => _parser;

   /**
    * Defines a flag.
    *
    * See [ArgParser.addFlag()].
    */
   void addFlag(String name, {String abbr, String help, bool defaultsTo: false,
       bool negatable: true, void callback(bool value), bool hide: false}) {
     _knownFlags.add(name);
     _parser.addFlag(name,
         abbr: abbr,
         help: help,
         defaultsTo: defaultsTo,
         negatable: negatable,
         callback: callback,
         hide: hide);
   }

   /**
    * Defines a value-taking option.
    *
    * See [ArgParser.addOption()].
    */
   void addOption(String name, {String abbr, String help, List<String> allowed,
       Map<String, String> allowedHelp, String defaultsTo, void callback(value),
       bool allowMultiple: false}) {
     _knownFlags.add(name);
     _parser.addOption(name,
         abbr: abbr,
         help: help,
         allowed: allowed,
         allowedHelp: allowedHelp,
         defaultsTo: defaultsTo,
         callback: callback,
         allowMultiple: allowMultiple);
   }

   /**
    * Generates a string displaying usage information for the defined options.
    *
    * See [ArgParser.usage].
    */
   String getUsage() => _parser.usage;

   /**
    * Parses [args], a list of command-line arguments, matches them against the
    * flags and options defined by this parser, and returns the result. The
    * values of any defined variables are captured in the given map.
    *
    * See [ArgParser].
    */
   ArgResults parse(
       List<String> args, Map<String, String> definedVariables) => _parser
       .parse(_filterUnknowns(parseDefinedVariables(args, definedVariables)));

   List<String> parseDefinedVariables(
       List<String> args, Map<String, String> definedVariables) {
     int count = args.length;
     List<String> remainingArgs = <String>[];
     for (int i = 0; i < count; i++) {
       String arg = args[i];
       if (arg == '--') {
         while (i < count) {
           remainingArgs.add(args[i++]);
         }
       } else if (arg.startsWith("-D")) {
         definedVariables[arg.substring(2)] = args[++i];
       } else {
         remainingArgs.add(arg);
       }
     }
     return remainingArgs;
   }

   List<String> _filterUnknowns(List<String> args) {

     // Only filter args if the ignore flag is specified, or if
     // _alwaysIgnoreUnrecognized was set to true
     if (_alwaysIgnoreUnrecognized ||
         args.contains('--ignore-unrecognized-flags')) {

       //TODO(pquitslund): replace w/ the following once library skew issues are
       // sorted out
       //return args.where((arg) => !arg.startsWith('--') ||
       //  _knownFlags.contains(arg.substring(2)));

       // Filter all unrecognized flags and options.
       List<String> filtered = <String>[];
       for (int i = 0; i < args.length; ++i) {
         String arg = args[i];
         if (arg.startsWith('--') && arg.length > 2) {
           String option = arg.substring(2);
           // strip the last '=value'
           int equalsOffset = option.lastIndexOf('=');
           if (equalsOffset != -1) {
             option = option.substring(0, equalsOffset);
           }
           // check the option
           if (!_knownFlags.contains(option)) {
             //print('remove: $arg');
             //"eat" params by advancing to the next flag/option
             i = _getNextFlagIndex(args, i);
           } else {
             filtered.add(arg);
           }
         } else {
           filtered.add(arg);
         }
       }

       return filtered;
     } else {
       return args;
     }
   }

   _getNextFlagIndex(args, i) {
     for (; i < args.length; ++i) {
       if (args[i].startsWith('--')) {
         return i;
       }
     }
     return i;
   }
 }
	// Copyright (c) 2013, 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.

	library options;

	import 'dart:io';

	import 'package:args/args.dart';

	const _BINARY_NAME = 'dartanalyzer';

	/**
	* Analyzer commandline configuration options.
	*/
	class CommandLineOptions {
	/** The path to the dart SDK */
	final String dartSdkPath;

	/** A table mapping the names of defined variables to their values. */
	final Map<String, String> definedVariables;

	/** Whether to report hints */
	final bool disableHints;

	/** Whether to display version information */
	final bool displayVersion;

	/**
	* Whether to enable null-aware operators (DEP 9).
	*/
	final bool enableNullAwareOperators;

	/**
	* Whether to strictly follow the specification when generating warnings on
	* "call" methods (fixes dartbug.com/21938).
	*/
	final bool enableStrictCallChecks;

	/**
	* Whether to treat type mismatches found during constant evaluation as
	* errors.
	*/
	final bool enableTypeChecks;

	/** Whether to ignore unrecognized flags */
	final bool ignoreUnrecognizedFlags;

	/** Whether to log additional analysis messages and exceptions */
	final bool log;

	/** Whether to use machine format for error display */
	final bool machineFormat;

	/** The path to the package root */
	final String packageRootPath;

	/** Whether to show performance statistics */
	final bool perf;

	/** Batch mode (for unit testing) */
	final bool shouldBatch;

	/** Whether to show package: warnings */
	final bool showPackageWarnings;

	/** Whether to show SDK warnings */
	final bool showSdkWarnings;

	/** The source files to analyze */
	final List<String> sourceFiles;

	/** Whether to show both cold and hot performance statistics */
	final bool warmPerf;

	/** Whether to treat warnings as fatal */
	final bool warningsAreFatal;

	/** A table mapping library URIs to the file system path where the library
	* source is located.
	*/
	final Map<String, String> customUrlMappings;

	/**
	* Initialize options from the given parsed [args].
	*/
	CommandLineOptions._fromArgs(ArgResults args,
	Map<String, String> definedVariables,
	Map<String, String> customUrlMappings)
	: dartSdkPath = args['dart-sdk'],
	this.definedVariables = definedVariables,
	disableHints = args['no-hints'],
	displayVersion = args['version'],
	enableNullAwareOperators = args['enable-null-aware-operators'],
	enableStrictCallChecks = args['enable-strict-call-checks'],
	enableTypeChecks = args['enable_type_checks'],
	ignoreUnrecognizedFlags = args['ignore-unrecognized-flags'],
	log = args['log'],
	machineFormat = args['machine'] \|\| args['format'] == 'machine',
	packageRootPath = args['package-root'],
	perf = args['perf'],
	shouldBatch = args['batch'],
	showPackageWarnings = args['show-package-warnings'] \|\|
	args['package-warnings'],
	showSdkWarnings = args['show-sdk-warnings'] \|\| args['warnings'],
	sourceFiles = args.rest,
	warmPerf = args['warm-perf'],
	warningsAreFatal = args['fatal-warnings'],
	this.customUrlMappings = customUrlMappings;

	/**
	* Parse [args] into [CommandLineOptions] describing the specified
	* analyzer options. In case of a format error, prints error and exists.
	*/
	static CommandLineOptions parse(List<String> args) {
	CommandLineOptions options = _parse(args);
	// check SDK
	{
	var sdkPath = options.dartSdkPath;
	// check that SDK is specified
	if (sdkPath == null) {
	print('Usage: $_BINARY_NAME: no Dart SDK found.');
	exit(15);
	}
	// check that SDK is existing directory
	if (!(new Directory(sdkPath)).existsSync()) {
	print('Usage: $_BINARY_NAME: invalid Dart SDK path: $sdkPath');
	exit(15);
	}
	}
	// OK
	return options;
	}

	static String _getVersion() {
	try {
	// This is relative to bin/snapshot, so ../..
	String versionPath =
	Platform.script.resolve('../../version').toFilePath();
	File versionFile = new File(versionPath);
	return versionFile.readAsStringSync().trim();
	} catch (_) {
	// This happens when the script is not running in the context of an SDK.
	return "<unknown>";
	}
	}

	static CommandLineOptions _parse(List<String> args) {
	args = args.expand((String arg) => arg.split('=')).toList();
	var parser = new CommandLineParser()
	..addFlag('batch',
	abbr: 'b',
	help: 'Run in batch mode',
	defaultsTo: false,
	negatable: false)
	..addOption('dart-sdk', help: 'The path to the Dart SDK')
	..addOption('package-root',
	abbr: 'p',
	help: 'The path to the package root. The flag package-root is deprecated. Remove to use package information computed by pub.')
	..addOption('format',
	help: 'Specifies the format in which errors are displayed')
	..addFlag('machine',
	help: 'Print errors in a format suitable for parsing (deprecated)',
	defaultsTo: false,
	negatable: false)
	..addFlag('version',
	help: 'Print the analyzer version',
	defaultsTo: false,
	negatable: false)
	..addFlag('no-hints',
	help: 'Do not show hint results', defaultsTo: false, negatable: false)
	..addFlag('ignore-unrecognized-flags',
	help: 'Ignore unrecognized command line flags',
	defaultsTo: false,
	negatable: false)
	..addFlag('fatal-warnings',
	help: 'Treat non-type warnings as fatal',
	defaultsTo: false,
	negatable: false)
	..addFlag('package-warnings',
	help: 'Show warnings from package: imports',
	defaultsTo: false,
	negatable: false)
	..addFlag('show-package-warnings',
	help: 'Show warnings from package: imports (deprecated)',
	defaultsTo: false,
	negatable: false)
	..addFlag('perf',
	help: 'Show performance statistics',
	defaultsTo: false,
	negatable: false)
	..addFlag('warnings',
	help: 'Show warnings from SDK imports',
	defaultsTo: false,
	negatable: false)
	..addFlag('show-sdk-warnings',
	help: 'Show warnings from SDK imports (deprecated)',
	defaultsTo: false,
	negatable: false)
	..addFlag('help',
	abbr: 'h',
	help: 'Display this help message',
	defaultsTo: false,
	negatable: false)
	..addOption('url-mapping',
	help: '--url-mapping=libraryUri,/path/to/library.dart directs the '
	'analyzer to use "library.dart" as the source for an import ' 'of "libraryUri"',
	allowMultiple: true)
	//
	// Hidden flags.
	//
	..addFlag('enable-async',
	help: 'Enable support for the proposed async feature',
	defaultsTo: false,
	negatable: false,
	hide: true)
	..addFlag('enable-enum',
	help: 'Enable support for the proposed enum feature',
	defaultsTo: false,
	negatable: false,
	hide: true)
	..addFlag('enable-null-aware-operators',
	help: 'Enable support for null-aware operators (DEP 9)',
	defaultsTo: false,
	negatable: false,
	hide: true)
	..addFlag('enable-strict-call-checks',
	help: 'Fix issue 21938',
	defaultsTo: false,
	negatable: false,
	hide: true)
	..addFlag('log',
	help: 'Log additional messages and exceptions',
	defaultsTo: false,
	negatable: false,
	hide: true)
	..addFlag('warm-perf',
	help: 'Show both cold and warm performance statistics',
	defaultsTo: false,
	negatable: false,
	hide: true)
	..addFlag('enable_type_checks',
	help: 'Check types in constant evaluation',
	defaultsTo: false,
	negatable: false,
	hide: true);

	try {
	// TODO(scheglov) https://code.google.com/p/dart/issues/detail?id=11061
	args =
	args.map((String arg) => arg == '-batch' ? '--batch' : arg).toList();
	Map<String, String> definedVariables = <String, String>{};
	var results = parser.parse(args, definedVariables);
	// help requests
	if (results['help']) {
	_showUsage(parser);
	exit(0);
	}
	// batch mode and input files
	if (results['batch']) {
	if (results.rest.isNotEmpty) {
	print('No source files expected in the batch mode.');
	_showUsage(parser);
	exit(15);
	}
	} else if (results['version']) {
	print('$_BINARY_NAME version ${_getVersion()}');
	exit(0);
	} else {
	if (results.rest.isEmpty) {
	_showUsage(parser);
	exit(15);
	}
	}
	Map<String, String> customUrlMappings = <String, String>{};
	for (String mapping in results['url-mapping']) {
	List<String> splitMapping = mapping.split(',');
	if (splitMapping.length != 2) {
	_showUsage(parser);
	exit(15);
	}
	customUrlMappings[splitMapping[0]] = splitMapping[1];
	}
	return new CommandLineOptions._fromArgs(
	results, definedVariables, customUrlMappings);
	} on FormatException catch (e) {
	print(e.message);
	_showUsage(parser);
	exit(15);
	}
	}

	static _showUsage(parser) {
	print('Usage: $_BINARY_NAME [options...] <libraries to analyze...>');
	print(parser.getUsage());
	print('');
	print('For more information, see http://www.dartlang.org/tools/analyzer.');
	}
	}

	/**
	* Commandline argument parser.
	*
	* TODO(pquitslund): when the args package supports ignoring unrecognized
	* options/flags, this class can be replaced with a simple [ArgParser] instance.
	*/
	class CommandLineParser {
	final List<String> _knownFlags;
	final bool _alwaysIgnoreUnrecognized;
	final ArgParser _parser;

	/** Creates a new command line parser */
	CommandLineParser({bool alwaysIgnoreUnrecognized: false})
	: _knownFlags = <String>[],
	_alwaysIgnoreUnrecognized = alwaysIgnoreUnrecognized,
	_parser = new ArgParser(allowTrailingOptions: true);

	ArgParser get parser => _parser;

	/**
	* Defines a flag.
	*
	* See [ArgParser.addFlag()].
	*/
	void addFlag(String name, {String abbr, String help, bool defaultsTo: false,
	bool negatable: true, void callback(bool value), bool hide: false}) {
	_knownFlags.add(name);
	_parser.addFlag(name,
	abbr: abbr,
	help: help,
	defaultsTo: defaultsTo,
	negatable: negatable,
	callback: callback,
	hide: hide);
	}

	/**
	* Defines a value-taking option.
	*
	* See [ArgParser.addOption()].
	*/
	void addOption(String name, {String abbr, String help, List<String> allowed,
	Map<String, String> allowedHelp, String defaultsTo, void callback(value),
	bool allowMultiple: false}) {
	_knownFlags.add(name);
	_parser.addOption(name,
	abbr: abbr,
	help: help,
	allowed: allowed,
	allowedHelp: allowedHelp,
	defaultsTo: defaultsTo,
	callback: callback,
	allowMultiple: allowMultiple);
	}

	/**
	* Generates a string displaying usage information for the defined options.
	*
	* See [ArgParser.usage].
	*/
	String getUsage() => _parser.usage;

	/**
	* Parses [args], a list of command-line arguments, matches them against the
	* flags and options defined by this parser, and returns the result. The
	* values of any defined variables are captured in the given map.
	*
	* See [ArgParser].
	*/
	ArgResults parse(
	List<String> args, Map<String, String> definedVariables) => _parser
	.parse(_filterUnknowns(parseDefinedVariables(args, definedVariables)));

	List<String> parseDefinedVariables(
	List<String> args, Map<String, String> definedVariables) {
	int count = args.length;
	List<String> remainingArgs = <String>[];
	for (int i = 0; i < count; i++) {
	String arg = args[i];
	if (arg == '--') {
	while (i < count) {
	remainingArgs.add(args[i++]);
	}
	} else if (arg.startsWith("-D")) {
	definedVariables[arg.substring(2)] = args[++i];
	} else {
	remainingArgs.add(arg);
	}
	}
	return remainingArgs;
	}

	List<String> _filterUnknowns(List<String> args) {

	// Only filter args if the ignore flag is specified, or if
	// _alwaysIgnoreUnrecognized was set to true
	if (_alwaysIgnoreUnrecognized \|\|
	args.contains('--ignore-unrecognized-flags')) {

	//TODO(pquitslund): replace w/ the following once library skew issues are
	// sorted out
	//return args.where((arg) => !arg.startsWith('--') \|\|
	// _knownFlags.contains(arg.substring(2)));

	// Filter all unrecognized flags and options.
	List<String> filtered = <String>[];
	for (int i = 0; i < args.length; ++i) {
	String arg = args[i];
	if (arg.startsWith('--') && arg.length > 2) {
	String option = arg.substring(2);
	// strip the last '=value'
	int equalsOffset = option.lastIndexOf('=');
	if (equalsOffset != -1) {
	option = option.substring(0, equalsOffset);
	}
	// check the option
	if (!_knownFlags.contains(option)) {
	//print('remove: $arg');
	//"eat" params by advancing to the next flag/option
	i = _getNextFlagIndex(args, i);
	} else {
	filtered.add(arg);
	}
	} else {
	filtered.add(arg);
	}
	}

	return filtered;
	} else {
	return args;
	}
	}

	_getNextFlagIndex(args, i) {
	for (; i < args.length; ++i) {
	if (args[i].startsWith('--')) {
	return i;
	}
	}
	return i;
	}
	}