packages/flutter_tools/lib/src/build_system/targets/icon_tree_shaker.dart - external/github.com/flutter/flutter - Git at Google

 // Copyright 2014 The Flutter Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 import 'package:meta/meta.dart';
 import 'package:process/process.dart';
 import 'package:mime/mime.dart' as mime;

 import '../../artifacts.dart';
 import '../../base/common.dart';
 import '../../base/file_system.dart';
 import '../../base/io.dart';
 import '../../base/logger.dart';
 import '../../convert.dart';
 import '../../devfs.dart';
 import '../build_system.dart';
 import 'common.dart';

 /// The build define controlling whether icon fonts should be stripped down to
 /// only the glyphs used by the application.
 const String kIconTreeShakerFlag = 'TreeShakeIcons';

 /// Whether icon font subsetting is enabled by default.
 const bool kIconTreeShakerEnabledDefault = true;

 List<Map<String, dynamic>> _getList(dynamic object, String errorMessage) {
   if (object is List<dynamic>) {
     return object.cast<Map<String, dynamic>>();
   }
   throw IconTreeShakerException._(errorMessage);
 }

 /// A class that wraps the functionality of the const finder package and the
 /// font subset utility to tree shake unused icons from fonts.
 class IconTreeShaker {
   /// Creates a wrapper for icon font subsetting.
   ///
   /// The environment parameter must not be null.
   ///
   /// If the `fontManifest` parameter is null, [enabled] will return false since
   /// there are no fonts to shake.
   ///
   /// The constructor will validate the environment and print a warning if
   /// font subsetting has been requested in a debug build mode.
   IconTreeShaker(
     this._environment,
     DevFSStringContent fontManifest, {
     @required ProcessManager processManager,
     @required Logger logger,
     @required FileSystem fileSystem,
     @required Artifacts artifacts,
   }) : assert(_environment != null),
        assert(processManager != null),
        assert(logger != null),
        assert(fileSystem != null),
        assert(artifacts != null),
        _processManager = processManager,
        _logger = logger,
        _fs = fileSystem,
        _artifacts = artifacts,
        _fontManifest = fontManifest?.string {
     if (_environment.defines[kIconTreeShakerFlag] == 'true' &&
         _environment.defines[kBuildMode] == 'debug') {
       logger.printError('Font subsetting is not supported in debug mode. The '
                          '--tree-shake-icons flag will be ignored.');
     }
   }

   /// The MIME types for supported font sets.
   static const Set<String> kTtfMimeTypes = <String>{
     'font/ttf', // based on internet search
     'font/opentype',
     'font/otf',
     'application/x-font-opentype',
     'application/x-font-otf',
     'application/x-font-ttf', // based on running locally.
   };

   /// The [Source] inputs that targets using this should depend on.
   ///
   /// See [Target.inputs].
   static const List<Source> inputs = <Source>[
     Source.pattern('{FLUTTER_ROOT}/packages/flutter_tools/lib/src/build_system/targets/icon_tree_shaker.dart'),
     Source.artifact(Artifact.constFinder),
     Source.artifact(Artifact.fontSubset),
   ];

   final Environment _environment;
   final String _fontManifest;
   Future<void> _iconDataProcessing;
   Map<String, _IconTreeShakerData> _iconData;

   final ProcessManager _processManager;
   final Logger _logger;
   final FileSystem _fs;
   final Artifacts _artifacts;

   /// Whether font subsetting should be used for this [Environment].
   bool get enabled => _fontManifest != null
                    && _environment.defines[kIconTreeShakerFlag] == 'true'
                    && _environment.defines[kBuildMode] != 'debug';

   // Fills the [_iconData] map.
   Future<void> _getIconData(Environment environment) async {
     if (!enabled) {
       return;
     }

     final File appDill = environment.buildDir.childFile('app.dill');
     if (!appDill.existsSync()) {
       throw IconTreeShakerException._('Expected to find kernel file at ${appDill.path}, but no file found.');
     }
     final File constFinder = _fs.file(
       _artifacts.getArtifactPath(Artifact.constFinder),
     );
     final File dart = _fs.file(
       _artifacts.getArtifactPath(Artifact.engineDartBinary),
     );

     final Map<String, List<int>> iconData = await _findConstants(
       dart,
       constFinder,
       appDill,
     );
     final Set<String> familyKeys = iconData.keys.toSet();

     final Map<String, String> fonts = await _parseFontJson(
       _fontManifest,
       familyKeys,
     );

     if (fonts.length != iconData.length) {
       environment.logger.printStatus(
         'Expected to find fonts for ${iconData.keys}, but found '
         '${fonts.keys}. This usually means you are referring to '
         'font families in an IconData class but not including them '
         'in the assets section of your pubspec.yaml, are missing '
         'the package that would include them, or are missing '
         '"uses-material-design: true".',
       );
     }

     final Map<String, _IconTreeShakerData> result = <String, _IconTreeShakerData>{};
     for (final MapEntry<String, String> entry in fonts.entries) {
       result[entry.value] = _IconTreeShakerData(
         family: entry.key,
         relativePath: entry.value,
         codePoints: iconData[entry.key],
       );
     }
     _iconData = result;
   }

   /// Calls font-subset, which transforms the [input] font file to a
   /// subsetted version at [outputPath].
   ///
   /// All parameters are required.
   ///
   /// If [enabled] is false, or the relative path is not recognized as an icon
   /// font used in the Flutter application, this returns false.
   /// If the font-subset subprocess fails, it will [throwToolExit].
   /// Otherwise, it will return true.
   Future<bool> subsetFont({
     @required File input,
     @required String outputPath,
     @required String relativePath,
   }) async {
     if (!enabled) {
       return false;
     }
     if (input.lengthSync() < 12) {
       return false;
     }
     final String mimeType = mime.lookupMimeType(
       input.path,
       headerBytes: await input.openRead(0, 12).first,
     );
     if (!kTtfMimeTypes.contains(mimeType)) {
       return false;
     }
     await (_iconDataProcessing ??= _getIconData(_environment));
     assert(_iconData != null);

     final _IconTreeShakerData iconTreeShakerData = _iconData[relativePath];
     if (iconTreeShakerData == null) {
       return false;
     }

     final File fontSubset = _fs.file(
       _artifacts.getArtifactPath(Artifact.fontSubset),
     );
     if (!fontSubset.existsSync()) {
       throw IconTreeShakerException._('The font-subset utility is missing. Run "flutter doctor".');
     }

     final List<String> cmd = <String>[
       fontSubset.path,
       outputPath,
       input.path,
     ];
     final String codePoints = iconTreeShakerData.codePoints.join(' ');
     _logger.printTrace('Running font-subset: ${cmd.join(' ')}, '
                        'using codepoints $codePoints');
     final Process fontSubsetProcess = await _processManager.start(cmd);
     try {
       fontSubsetProcess.stdin.writeln(codePoints);
       await fontSubsetProcess.stdin.flush();
       await fontSubsetProcess.stdin.close();
     } on Exception {
       // handled by checking the exit code.
     }

     final int code = await fontSubsetProcess.exitCode;
     if (code != 0) {
       _logger.printTrace(await utf8.decodeStream(fontSubsetProcess.stdout));
       _logger.printError(await utf8.decodeStream(fontSubsetProcess.stderr));
       throw IconTreeShakerException._('Font subsetting failed with exit code $code.');
     }
     return true;
   }

   /// Returns a map of { fontFamily: relativePath } pairs.
   Future<Map<String, String>> _parseFontJson(
     String fontManifestData,
     Set<String> families,
   ) async {
     final Map<String, String> result = <String, String>{};
     final List<Map<String, dynamic>> fontList = _getList(
       json.decode(fontManifestData),
       'FontManifest.json invalid: expected top level to be a list of objects.',
     );

     for (final Map<String, dynamic> map in fontList) {
       if (map['family'] is! String) {
         throw IconTreeShakerException._(
           'FontManifest.json invalid: expected the family value to be a string, '
           'got: ${map['family']}.');
       }
       final String familyKey = map['family'] as String;
       if (!families.contains(familyKey)) {
         continue;
       }
       final List<Map<String, dynamic>> fonts = _getList(
         map['fonts'],
         'FontManifest.json invalid: expected "fonts" to be a list of objects.',
       );
       if (fonts.length != 1) {
         throw IconTreeShakerException._(
           'This tool cannot process icon fonts with multiple fonts in a '
           'single family.');
       }
       if (fonts.first['asset'] is! String) {
         throw IconTreeShakerException._(
           'FontManifest.json invalid: expected "asset" value to be a string, '
           'got: ${map['assets']}.');
       }
       result[familyKey] = fonts.first['asset'] as String;
     }
     return result;
   }

   Future<Map<String, List<int>>> _findConstants(
     File dart,
     File constFinder,
     File appDill,
   ) async {
     final List<String> cmd = <String>[
       dart.path,
       '--disable-dart-dev',
       constFinder.path,
       '--kernel-file', appDill.path,
       '--class-library-uri', 'package:flutter/src/widgets/icon_data.dart',
       '--class-name', 'IconData',
     ];
     _logger.printTrace('Running command: ${cmd.join(' ')}');
     final ProcessResult constFinderProcessResult = await _processManager.run(cmd);

     if (constFinderProcessResult.exitCode != 0) {
       throw IconTreeShakerException._('ConstFinder failure: ${constFinderProcessResult.stderr}');
     }
     final dynamic jsonDecode = json.decode(constFinderProcessResult.stdout as String);
     if (jsonDecode is! Map<String, dynamic>) {
       throw IconTreeShakerException._(
         'Invalid ConstFinder output: expected a top level JSON object, '
         'got $jsonDecode.');
     }
     final Map<String, dynamic> constFinderMap = jsonDecode as Map<String, dynamic>;
     final _ConstFinderResult constFinderResult = _ConstFinderResult(constFinderMap);
     if (constFinderResult.hasNonConstantLocations) {
       _logger.printError('This application cannot tree shake icons fonts. '
                          'It has non-constant instances of IconData at the '
                          'following locations:', emphasis: true);
       for (final Map<String, dynamic> location in constFinderResult.nonConstantLocations) {
         _logger.printError(
           '- ${location['file']}:${location['line']}:${location['column']}',
           indent: 2,
           hangingIndent: 4,
         );
       }
       throwToolExit('Avoid non-constant invocations of IconData or try to '
                     'build again with --no-tree-shake-icons.');
     }
     return _parseConstFinderResult(constFinderResult);
   }

   Map<String, List<int>> _parseConstFinderResult(_ConstFinderResult constants) {
     final Map<String, List<int>> result = <String, List<int>>{};
     for (final Map<String, dynamic> iconDataMap in constants.constantInstances) {
       if ((iconDataMap['fontPackage'] ?? '') is! String || // Null is ok here.
            iconDataMap['fontFamily'] is! String ||
            iconDataMap['codePoint'] is! num) {
         throw IconTreeShakerException._(
           'Invalid ConstFinder result. Expected "fontPackage" to be a String, '
           '"fontFamily" to be a String, and "codePoint" to be an int, '
           'got: $iconDataMap.');
       }
       final String package = iconDataMap['fontPackage'] as String;
       final String family = iconDataMap['fontFamily'] as String;
       final String key = package == null
         ? family
         : 'packages/$package/$family';
       result[key] ??= <int>[];
       result[key].add((iconDataMap['codePoint'] as num).round());
     }
     return result;
   }
 }

 class _ConstFinderResult {
   _ConstFinderResult(this.result);

   final Map<String, dynamic> result;

   List<Map<String, dynamic>> _constantInstances;
   List<Map<String, dynamic>> get constantInstances {
     _constantInstances ??= _getList(
       result['constantInstances'],
       'Invalid ConstFinder output: Expected "constInstances" to be a list of objects.',
     );
     return _constantInstances;
   }

   List<Map<String, dynamic>> _nonConstantLocations;
   List<Map<String, dynamic>> get nonConstantLocations {
     _nonConstantLocations ??= _getList(
       result['nonConstantLocations'],
       'Invalid ConstFinder output: Expected "nonConstLocations" to be a list of objects',
     );
     return _nonConstantLocations;
   }

   bool get hasNonConstantLocations => nonConstantLocations.isNotEmpty;
 }

 /// The font family name, relative path to font file, and list of code points
 /// the application is using.
 class _IconTreeShakerData {
   /// All parameters are required.
   const _IconTreeShakerData({
     @required this.family,
     @required this.relativePath,
     @required this.codePoints,
   }) : assert(family != null),
        assert(relativePath != null),
        assert(codePoints != null);

   /// The font family name, e.g. "MaterialIcons".
   final String family;

   /// The relative path to the font file.
   final String relativePath;

   /// The list of code points for the font.
   final List<int> codePoints;

   @override
   String toString() => 'FontSubsetData($family, $relativePath, $codePoints)';
 }

 class IconTreeShakerException implements Exception {
   IconTreeShakerException._(this.message);

   final String message;

   @override
   String toString() => 'IconTreeShakerException: $message\n\n'
     'To disable icon tree shaking, pass --no-tree-shake-icons to the requested '
     'flutter build command';
 }
	// Copyright 2014 The Flutter Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	import 'package:meta/meta.dart';
	import 'package:process/process.dart';
	import 'package:mime/mime.dart' as mime;

	import '../../artifacts.dart';
	import '../../base/common.dart';
	import '../../base/file_system.dart';
	import '../../base/io.dart';
	import '../../base/logger.dart';
	import '../../convert.dart';
	import '../../devfs.dart';
	import '../build_system.dart';
	import 'common.dart';

	/// The build define controlling whether icon fonts should be stripped down to
	/// only the glyphs used by the application.
	const String kIconTreeShakerFlag = 'TreeShakeIcons';

	/// Whether icon font subsetting is enabled by default.
	const bool kIconTreeShakerEnabledDefault = true;

	List<Map<String, dynamic>> _getList(dynamic object, String errorMessage) {
	if (object is List<dynamic>) {
	return object.cast<Map<String, dynamic>>();
	}
	throw IconTreeShakerException._(errorMessage);
	}

	/// A class that wraps the functionality of the const finder package and the
	/// font subset utility to tree shake unused icons from fonts.
	class IconTreeShaker {
	/// Creates a wrapper for icon font subsetting.
	///
	/// The environment parameter must not be null.
	///
	/// If the `fontManifest` parameter is null, [enabled] will return false since
	/// there are no fonts to shake.
	///
	/// The constructor will validate the environment and print a warning if
	/// font subsetting has been requested in a debug build mode.
	IconTreeShaker(
	this._environment,
	DevFSStringContent fontManifest, {
	@required ProcessManager processManager,
	@required Logger logger,
	@required FileSystem fileSystem,
	@required Artifacts artifacts,
	}) : assert(_environment != null),
	assert(processManager != null),
	assert(logger != null),
	assert(fileSystem != null),
	assert(artifacts != null),
	_processManager = processManager,
	_logger = logger,
	_fs = fileSystem,
	_artifacts = artifacts,
	_fontManifest = fontManifest?.string {
	if (_environment.defines[kIconTreeShakerFlag] == 'true' &&
	_environment.defines[kBuildMode] == 'debug') {
	logger.printError('Font subsetting is not supported in debug mode. The '
	'--tree-shake-icons flag will be ignored.');
	}
	}

	/// The MIME types for supported font sets.
	static const Set<String> kTtfMimeTypes = <String>{
	'font/ttf', // based on internet search
	'font/opentype',
	'font/otf',
	'application/x-font-opentype',
	'application/x-font-otf',
	'application/x-font-ttf', // based on running locally.
	};

	/// The [Source] inputs that targets using this should depend on.
	///
	/// See [Target.inputs].
	static const List<Source> inputs = <Source>[
	Source.pattern('{FLUTTER_ROOT}/packages/flutter_tools/lib/src/build_system/targets/icon_tree_shaker.dart'),
	Source.artifact(Artifact.constFinder),
	Source.artifact(Artifact.fontSubset),
	];

	final Environment _environment;
	final String _fontManifest;
	Future<void> _iconDataProcessing;
	Map<String, _IconTreeShakerData> _iconData;

	final ProcessManager _processManager;
	final Logger _logger;
	final FileSystem _fs;
	final Artifacts _artifacts;

	/// Whether font subsetting should be used for this [Environment].
	bool get enabled => _fontManifest != null
	&& _environment.defines[kIconTreeShakerFlag] == 'true'
	&& _environment.defines[kBuildMode] != 'debug';

	// Fills the [_iconData] map.
	Future<void> _getIconData(Environment environment) async {
	if (!enabled) {
	return;
	}

	final File appDill = environment.buildDir.childFile('app.dill');
	if (!appDill.existsSync()) {
	throw IconTreeShakerException._('Expected to find kernel file at ${appDill.path}, but no file found.');
	}
	final File constFinder = _fs.file(
	_artifacts.getArtifactPath(Artifact.constFinder),
	);
	final File dart = _fs.file(
	_artifacts.getArtifactPath(Artifact.engineDartBinary),
	);

	final Map<String, List<int>> iconData = await _findConstants(
	dart,
	constFinder,
	appDill,
	);
	final Set<String> familyKeys = iconData.keys.toSet();

	final Map<String, String> fonts = await _parseFontJson(
	_fontManifest,
	familyKeys,
	);

	if (fonts.length != iconData.length) {
	environment.logger.printStatus(
	'Expected to find fonts for ${iconData.keys}, but found '
	'${fonts.keys}. This usually means you are referring to '
	'font families in an IconData class but not including them '
	'in the assets section of your pubspec.yaml, are missing '
	'the package that would include them, or are missing '
	'"uses-material-design: true".',
	);
	}

	final Map<String, _IconTreeShakerData> result = <String, _IconTreeShakerData>{};
	for (final MapEntry<String, String> entry in fonts.entries) {
	result[entry.value] = _IconTreeShakerData(
	family: entry.key,
	relativePath: entry.value,
	codePoints: iconData[entry.key],
	);
	}
	_iconData = result;
	}

	/// Calls font-subset, which transforms the [input] font file to a
	/// subsetted version at [outputPath].
	///
	/// All parameters are required.
	///
	/// If [enabled] is false, or the relative path is not recognized as an icon
	/// font used in the Flutter application, this returns false.
	/// If the font-subset subprocess fails, it will [throwToolExit].
	/// Otherwise, it will return true.
	Future<bool> subsetFont({
	@required File input,
	@required String outputPath,
	@required String relativePath,
	}) async {
	if (!enabled) {
	return false;
	}
	if (input.lengthSync() < 12) {
	return false;
	}
	final String mimeType = mime.lookupMimeType(
	input.path,
	headerBytes: await input.openRead(0, 12).first,
	);
	if (!kTtfMimeTypes.contains(mimeType)) {
	return false;
	}
	await (_iconDataProcessing ??= _getIconData(_environment));
	assert(_iconData != null);

	final _IconTreeShakerData iconTreeShakerData = _iconData[relativePath];
	if (iconTreeShakerData == null) {
	return false;
	}

	final File fontSubset = _fs.file(
	_artifacts.getArtifactPath(Artifact.fontSubset),
	);
	if (!fontSubset.existsSync()) {
	throw IconTreeShakerException._('The font-subset utility is missing. Run "flutter doctor".');
	}

	final List<String> cmd = <String>[
	fontSubset.path,
	outputPath,
	input.path,
	];
	final String codePoints = iconTreeShakerData.codePoints.join(' ');
	_logger.printTrace('Running font-subset: ${cmd.join(' ')}, '
	'using codepoints $codePoints');
	final Process fontSubsetProcess = await _processManager.start(cmd);
	try {
	fontSubsetProcess.stdin.writeln(codePoints);
	await fontSubsetProcess.stdin.flush();
	await fontSubsetProcess.stdin.close();
	} on Exception {
	// handled by checking the exit code.
	}

	final int code = await fontSubsetProcess.exitCode;
	if (code != 0) {
	_logger.printTrace(await utf8.decodeStream(fontSubsetProcess.stdout));
	_logger.printError(await utf8.decodeStream(fontSubsetProcess.stderr));
	throw IconTreeShakerException._('Font subsetting failed with exit code $code.');
	}
	return true;
	}

	/// Returns a map of { fontFamily: relativePath } pairs.
	Future<Map<String, String>> _parseFontJson(
	String fontManifestData,
	Set<String> families,
	) async {
	final Map<String, String> result = <String, String>{};
	final List<Map<String, dynamic>> fontList = _getList(
	json.decode(fontManifestData),
	'FontManifest.json invalid: expected top level to be a list of objects.',
	);

	for (final Map<String, dynamic> map in fontList) {
	if (map['family'] is! String) {
	throw IconTreeShakerException._(
	'FontManifest.json invalid: expected the family value to be a string, '
	'got: ${map['family']}.');
	}
	final String familyKey = map['family'] as String;
	if (!families.contains(familyKey)) {
	continue;
	}
	final List<Map<String, dynamic>> fonts = _getList(
	map['fonts'],
	'FontManifest.json invalid: expected "fonts" to be a list of objects.',
	);
	if (fonts.length != 1) {
	throw IconTreeShakerException._(
	'This tool cannot process icon fonts with multiple fonts in a '
	'single family.');
	}
	if (fonts.first['asset'] is! String) {
	throw IconTreeShakerException._(
	'FontManifest.json invalid: expected "asset" value to be a string, '
	'got: ${map['assets']}.');
	}
	result[familyKey] = fonts.first['asset'] as String;
	}
	return result;
	}

	Future<Map<String, List<int>>> _findConstants(
	File dart,
	File constFinder,
	File appDill,
	) async {
	final List<String> cmd = <String>[
	dart.path,
	'--disable-dart-dev',
	constFinder.path,
	'--kernel-file', appDill.path,
	'--class-library-uri', 'package:flutter/src/widgets/icon_data.dart',
	'--class-name', 'IconData',
	];
	_logger.printTrace('Running command: ${cmd.join(' ')}');
	final ProcessResult constFinderProcessResult = await _processManager.run(cmd);

	if (constFinderProcessResult.exitCode != 0) {
	throw IconTreeShakerException._('ConstFinder failure: ${constFinderProcessResult.stderr}');
	}
	final dynamic jsonDecode = json.decode(constFinderProcessResult.stdout as String);
	if (jsonDecode is! Map<String, dynamic>) {
	throw IconTreeShakerException._(
	'Invalid ConstFinder output: expected a top level JSON object, '
	'got $jsonDecode.');
	}
	final Map<String, dynamic> constFinderMap = jsonDecode as Map<String, dynamic>;
	final _ConstFinderResult constFinderResult = _ConstFinderResult(constFinderMap);
	if (constFinderResult.hasNonConstantLocations) {
	_logger.printError('This application cannot tree shake icons fonts. '
	'It has non-constant instances of IconData at the '
	'following locations:', emphasis: true);
	for (final Map<String, dynamic> location in constFinderResult.nonConstantLocations) {
	_logger.printError(
	'- ${location['file']}:${location['line']}:${location['column']}',
	indent: 2,
	hangingIndent: 4,
	);
	}
	throwToolExit('Avoid non-constant invocations of IconData or try to '
	'build again with --no-tree-shake-icons.');
	}
	return _parseConstFinderResult(constFinderResult);
	}

	Map<String, List<int>> _parseConstFinderResult(_ConstFinderResult constants) {
	final Map<String, List<int>> result = <String, List<int>>{};
	for (final Map<String, dynamic> iconDataMap in constants.constantInstances) {
	if ((iconDataMap['fontPackage'] ?? '') is! String \|\| // Null is ok here.
	iconDataMap['fontFamily'] is! String \|\|
	iconDataMap['codePoint'] is! num) {
	throw IconTreeShakerException._(
	'Invalid ConstFinder result. Expected "fontPackage" to be a String, '
	'"fontFamily" to be a String, and "codePoint" to be an int, '
	'got: $iconDataMap.');
	}
	final String package = iconDataMap['fontPackage'] as String;
	final String family = iconDataMap['fontFamily'] as String;
	final String key = package == null
	? family
	: 'packages/$package/$family';
	result[key] ??= <int>[];
	result[key].add((iconDataMap['codePoint'] as num).round());
	}
	return result;
	}
	}

	class _ConstFinderResult {
	_ConstFinderResult(this.result);

	final Map<String, dynamic> result;

	List<Map<String, dynamic>> _constantInstances;
	List<Map<String, dynamic>> get constantInstances {
	_constantInstances ??= _getList(
	result['constantInstances'],
	'Invalid ConstFinder output: Expected "constInstances" to be a list of objects.',
	);
	return _constantInstances;
	}

	List<Map<String, dynamic>> _nonConstantLocations;
	List<Map<String, dynamic>> get nonConstantLocations {
	_nonConstantLocations ??= _getList(
	result['nonConstantLocations'],
	'Invalid ConstFinder output: Expected "nonConstLocations" to be a list of objects',
	);
	return _nonConstantLocations;
	}

	bool get hasNonConstantLocations => nonConstantLocations.isNotEmpty;
	}

	/// The font family name, relative path to font file, and list of code points
	/// the application is using.
	class _IconTreeShakerData {
	/// All parameters are required.
	const _IconTreeShakerData({
	@required this.family,
	@required this.relativePath,
	@required this.codePoints,
	}) : assert(family != null),
	assert(relativePath != null),
	assert(codePoints != null);

	/// The font family name, e.g. "MaterialIcons".
	final String family;

	/// The relative path to the font file.
	final String relativePath;

	/// The list of code points for the font.
	final List<int> codePoints;

	@override
	String toString() => 'FontSubsetData($family, $relativePath, $codePoints)';
	}

	class IconTreeShakerException implements Exception {
	IconTreeShakerException._(this.message);

	final String message;

	@override
	String toString() => 'IconTreeShakerException: $message\n\n'
	'To disable icon tree shaking, pass --no-tree-shake-icons to the requested '
	'flutter build command';
	}