source_gen/lib/src/builder.dart - third_party/dart-pkg - Git at Google

 // Copyright (c) 2015, 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.

 //TODO(kevmoo): https://github.com/dart-lang/linter/issues/3563
 // ignore_for_file: use_super_parameters

 import 'dart:convert';

 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:build/build.dart';
 import 'package:dart_style/dart_style.dart';

 import 'generated_output.dart';
 import 'generator.dart';
 import 'generator_for_annotation.dart';
 import 'library.dart';
 import 'utils.dart';

 /// A [Builder] wrapping on one or more [Generator]s.
 class _Builder extends Builder {
   /// Function that determines how the generated code is formatted.
   final String Function(String) formatOutput;

   /// The generators run for each targeted library.
   final List<Generator> _generators;

   /// The [buildExtensions] configuration for `.dart`
   final String _generatedExtension;

   /// Whether to emit a standalone (non-`part`) file in this builder.
   bool get _isLibraryBuilder => this is LibraryBuilder;

   final String _header;

   /// Whether to allow syntax errors in input libraries.
   final bool allowSyntaxErrors;

   @override
   final Map<String, List<String>> buildExtensions;

   /// Wrap [_generators] to form a [Builder]-compatible API.
   ///
   /// If available, the `build_extensions` option will be extracted from
   /// [options] to allow output files to be generated into a different directory
   _Builder(
     this._generators, {
     String Function(String code)? formatOutput,
     String generatedExtension = '.g.dart',
     List<String> additionalOutputExtensions = const [],
     String? header,
     this.allowSyntaxErrors = false,
     BuilderOptions? options,
   })  : _generatedExtension = generatedExtension,
         buildExtensions = validatedBuildExtensionsFrom(
             options != null ? Map.of(options.config) : null, {
           '.dart': [
             generatedExtension,
             ...additionalOutputExtensions,
           ]
         }),
         formatOutput = formatOutput ?? _formatter.format,
         _header = (header ?? defaultFileHeader).trim() {
     if (_generatedExtension.isEmpty || !_generatedExtension.startsWith('.')) {
       throw ArgumentError.value(
         _generatedExtension,
         'generatedExtension',
         'Extension must be in the format of .*',
       );
     }
     if (_isLibraryBuilder && _generators.length > 1) {
       throw ArgumentError(
         'A standalone file can only be generated from a single Generator.',
       );
     }
     if (options != null && additionalOutputExtensions.isNotEmpty) {
       throw ArgumentError(
         'Either `options` or `additionalOutputExtensions` parameter '
         'can be given. Not both.',
       );
     }
   }

   @override
   Future<void> build(BuildStep buildStep) async {
     final resolver = buildStep.resolver;

     if (!await resolver.isLibrary(buildStep.inputId)) return;

     if (_generators.every((g) => g is GeneratorForAnnotation) &&
         !(await _hasAnyTopLevelAnnotations(
           buildStep.inputId,
           resolver,
           buildStep,
         ))) {
       return;
     }

     final lib = await buildStep.resolver
         .libraryFor(buildStep.inputId, allowSyntaxErrors: allowSyntaxErrors);
     await _generateForLibrary(lib, buildStep);
   }

   Future<void> _generateForLibrary(
     LibraryElement library,
     BuildStep buildStep,
   ) async {
     final generatedOutputs =
         await _generate(library, _generators, buildStep).toList();

     // Don't output useless files.
     //
     // NOTE: It is important to do this check _before_ checking for valid
     // library/part definitions because users expect some files to be skipped
     // therefore they do not have "library".
     if (generatedOutputs.isEmpty) return;
     final outputId = buildStep.allowedOutputs.first;
     final contentBuffer = StringBuffer();

     if (_header.isNotEmpty) {
       contentBuffer.writeln(_header);
     }

     if (!_isLibraryBuilder) {
       final asset = buildStep.inputId;
       final partOfUri = uriOfPartial(library, asset, outputId);
       contentBuffer.writeln();

       if (this is PartBuilder) {
         contentBuffer
           ..write(languageOverrideForLibrary(library))
           ..writeln('part of \'$partOfUri\';');
         final part = computePartUrl(buildStep.inputId, outputId);

         final libraryUnit =
             await buildStep.resolver.compilationUnitFor(buildStep.inputId);
         final hasLibraryPartDirectiveWithOutputUri =
             hasExpectedPartDirective(libraryUnit, part);
         if (!hasLibraryPartDirectiveWithOutputUri) {
           // TODO: Upgrade to error in a future breaking change?
           log.warning(
             '$part must be included as a part directive in '
             'the input library with:\n    part \'$part\';',
           );
           return;
         }
       } else {
         assert(this is SharedPartBuilder);
         // For shared-part builders, `part` statements will be checked by the
         // combining build step.
       }
     }

     for (var item in generatedOutputs) {
       contentBuffer
         ..writeln()
         ..writeln(_headerLine)
         ..writeAll(
           LineSplitter.split(item.generatorDescription)
               .map((line) => '// $line\n'),
         )
         ..writeln(_headerLine)
         ..writeln()
         ..writeln(item.output);
     }

     var genPartContent = contentBuffer.toString();

     try {
       genPartContent = formatOutput(genPartContent);
     } catch (e, stack) {
       log.severe(
         '''
 An error `${e.runtimeType}` occurred while formatting the generated source for
   `${library.identifier}`
 which was output to
   `${outputId.path}`.
 This may indicate an issue in the generator, the input source code, or in the
 source formatter.''',
         e,
         stack,
       );
     }

     await buildStep.writeAsString(outputId, genPartContent);
   }

   @override
   String toString() =>
       'Generating $_generatedExtension: ${_generators.join(', ')}';
 }

 /// A [Builder] which generates content intended for `part of` files.
 ///
 /// Generated files will be prefixed with a `partId` to ensure multiple
 /// [SharedPartBuilder]s can produce non conflicting `part of` files. When the
 /// `source_gen|combining_builder` is applied to the primary input these
 /// snippets will be concatenated into the final `.g.dart` output.
 ///
 /// This builder can be used when multiple generators may need to output to the
 /// same part file but [PartBuilder] can't be used because the generators are
 /// not all defined in the same location. As a convention most codegen which
 /// generates code should use this approach to get content into a `.g.dart` file
 /// instead of having individual outputs for each building package.
 class SharedPartBuilder extends _Builder {
   /// Wrap [generators] as a [Builder] that generates `part of` files.
   ///
   /// [partId] indicates what files will be created for each `.dart`
   /// input. This extension should be unique as to not conflict with other
   /// [SharedPartBuilder]s. The resulting file will be of the form
   /// `<generatedExtension>.g.part`. If any generator in [generators] will
   /// create additional outputs through the [BuildStep] they should be indicated
   /// in [additionalOutputExtensions].
   ///
   /// [formatOutput] is called to format the generated code. Defaults to
   /// [DartFormatter.format].
   ///
   /// [allowSyntaxErrors] indicates whether to allow syntax errors in input
   /// libraries.
   SharedPartBuilder(
     List<Generator> generators,
     String partId, {
     String Function(String code)? formatOutput,
     List<String> additionalOutputExtensions = const [],
     bool allowSyntaxErrors = false,
   }) : super(
           generators,
           formatOutput: formatOutput,
           generatedExtension: '.$partId.g.part',
           additionalOutputExtensions: additionalOutputExtensions,
           header: '',
           allowSyntaxErrors: allowSyntaxErrors,
         ) {
     if (!_partIdRegExp.hasMatch(partId)) {
       throw ArgumentError.value(
         partId,
         'partId',
         '`partId` can only contain letters, numbers, `_` and `.`. '
             'It cannot start or end with `.`.',
       );
     }
   }
 }

 /// A [Builder] which generates `part of` files.
 ///
 /// This builder should be avoided - prefer using [SharedPartBuilder] and
 /// generating content that can be merged with output from other builders into a
 /// common `.g.dart` part file.
 ///
 /// Each output should correspond to a `part` directive in the primary input,
 /// this will be validated.
 ///
 /// Content output by each generator is concatenated and written to the output.
 /// A `part of` directive will automatically be included in the output and
 /// should not need be written by any of the generators.
 class PartBuilder extends _Builder {
   /// Wrap [generators] as a [Builder] that generates `part of` files.
   ///
   /// [generatedExtension] indicates what files will be created for each
   /// `.dart` input. The [generatedExtension] should *not* be `.g.dart`. If you
   /// wish to produce `.g.dart` files please use [SharedPartBuilder].
   ///
   /// If any generator in [generators] will create additional outputs through
   /// the [BuildStep] they should be indicated in [additionalOutputExtensions].
   ///
   /// [formatOutput] is called to format the generated code. Defaults to
   /// [DartFormatter.format].
   ///
   /// [header] is used to specify the content at the top of each generated file.
   /// If `null`, the content of [defaultFileHeader] is used.
   /// If [header] is an empty `String` no header is added.
   ///
   /// [allowSyntaxErrors] indicates whether to allow syntax errors in input
   /// libraries.
   ///
   /// If available, the `build_extensions` option will be extracted from
   /// [options] to allow output files to be generated into a different directory
   PartBuilder(
     List<Generator> generators,
     String generatedExtension, {
     String Function(String code)? formatOutput,
     List<String> additionalOutputExtensions = const [],
     String? header,
     bool allowSyntaxErrors = false,
     BuilderOptions? options,
   }) : super(
           generators,
           formatOutput: formatOutput,
           generatedExtension: generatedExtension,
           additionalOutputExtensions: additionalOutputExtensions,
           header: header,
           allowSyntaxErrors: allowSyntaxErrors,
           options: options,
         );
 }

 /// A [Builder] which generates standalone Dart library files.
 ///
 /// A single [Generator] is responsible for generating the entirety of the
 /// output since it must also output any relevant import directives at the
 /// beginning of it's output.
 class LibraryBuilder extends _Builder {
   /// Wrap [generator] as a [Builder] that generates Dart library files.
   ///
   /// [generatedExtension] indicates what files will be created for each `.dart`
   /// input.
   /// Defaults to `.g.dart`, however this should usually be changed to
   /// avoid conflicts with outputs from a [SharedPartBuilder].
   /// If [generator] will create additional outputs through the [BuildStep] they
   /// should be indicated in [additionalOutputExtensions].
   ///
   /// [formatOutput] is called to format the generated code. Defaults to
   /// [DartFormatter.format].
   ///
   /// [header] is used to specify the content at the top of each generated file.
   /// If `null`, the content of [defaultFileHeader] is used.
   /// If [header] is an empty `String` no header is added.
   ///
   /// [allowSyntaxErrors] indicates whether to allow syntax errors in input
   /// libraries.
   LibraryBuilder(
     Generator generator, {
     String Function(String code)? formatOutput,
     String generatedExtension = '.g.dart',
     List<String> additionalOutputExtensions = const [],
     String? header,
     bool allowSyntaxErrors = false,
     BuilderOptions? options,
   }) : super(
           [generator],
           formatOutput: formatOutput,
           generatedExtension: generatedExtension,
           additionalOutputExtensions: additionalOutputExtensions,
           header: header,
           allowSyntaxErrors: allowSyntaxErrors,
           options: options,
         );
 }

 Stream<GeneratedOutput> _generate(
   LibraryElement library,
   List<Generator> generators,
   BuildStep buildStep,
 ) async* {
   final libraryReader = LibraryReader(library);
   for (var i = 0; i < generators.length; i++) {
     final gen = generators[i];
     var msg = 'Running $gen';
     if (generators.length > 1) {
       msg = '$msg - ${i + 1} of ${generators.length}';
     }
     log.fine(msg);
     var createdUnit = await gen.generate(libraryReader, buildStep);

     if (createdUnit == null) {
       continue;
     }

     createdUnit = createdUnit.trim();
     if (createdUnit.isEmpty) {
       continue;
     }

     yield GeneratedOutput(gen, createdUnit);
   }
 }

 Future<bool> _hasAnyTopLevelAnnotations(
   AssetId input,
   Resolver resolver,
   BuildStep buildStep,
 ) async {
   if (!await buildStep.canRead(input)) return false;
   final parsed = await resolver.compilationUnitFor(input);
   final partIds = <AssetId>[];
   for (var directive in parsed.directives) {
     if (directive.metadata.isNotEmpty) return true;
     if (directive is PartDirective) {
       partIds.add(
         AssetId.resolve(Uri.parse(directive.uri.stringValue!), from: input),
       );
     }
   }
   for (var declaration in parsed.declarations) {
     if (declaration.metadata.isNotEmpty) return true;
   }
   for (var partId in partIds) {
     if (await _hasAnyTopLevelAnnotations(partId, resolver, buildStep)) {
       return true;
     }
   }
   return false;
 }

 final _formatter = DartFormatter(fixes: [StyleFix.singleCascadeStatements]);

 const defaultFileHeader = '// GENERATED CODE - DO NOT MODIFY BY HAND';

 final _headerLine = '// '.padRight(77, '*');

 const partIdRegExpLiteral = r'[A-Za-z_\d-]+';

 final _partIdRegExp = RegExp('^$partIdRegExpLiteral\$');

 String languageOverrideForLibrary(LibraryElement library) {
   final override = library.languageVersion.override;
   return override == null
       ? ''
       : '// @dart=${override.major}.${override.minor}\n';
 }
	// Copyright (c) 2015, 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.

	//TODO(kevmoo): https://github.com/dart-lang/linter/issues/3563
	// ignore_for_file: use_super_parameters

	import 'dart:convert';

	import 'package:analyzer/dart/ast/ast.dart';
	import 'package:analyzer/dart/element/element.dart';
	import 'package:build/build.dart';
	import 'package:dart_style/dart_style.dart';

	import 'generated_output.dart';
	import 'generator.dart';
	import 'generator_for_annotation.dart';
	import 'library.dart';
	import 'utils.dart';

	/// A [Builder] wrapping on one or more [Generator]s.
	class _Builder extends Builder {
	/// Function that determines how the generated code is formatted.
	final String Function(String) formatOutput;

	/// The generators run for each targeted library.
	final List<Generator> _generators;

	/// The [buildExtensions] configuration for `.dart`
	final String _generatedExtension;

	/// Whether to emit a standalone (non-`part`) file in this builder.
	bool get _isLibraryBuilder => this is LibraryBuilder;

	final String _header;

	/// Whether to allow syntax errors in input libraries.
	final bool allowSyntaxErrors;

	@override
	final Map<String, List<String>> buildExtensions;

	/// Wrap [_generators] to form a [Builder]-compatible API.
	///
	/// If available, the `build_extensions` option will be extracted from
	/// [options] to allow output files to be generated into a different directory
	_Builder(
	this._generators, {
	String Function(String code)? formatOutput,
	String generatedExtension = '.g.dart',
	List<String> additionalOutputExtensions = const [],
	String? header,
	this.allowSyntaxErrors = false,
	BuilderOptions? options,
	}) : _generatedExtension = generatedExtension,
	buildExtensions = validatedBuildExtensionsFrom(
	options != null ? Map.of(options.config) : null, {
	'.dart': [
	generatedExtension,
	...additionalOutputExtensions,
	]
	}),
	formatOutput = formatOutput ?? _formatter.format,
	_header = (header ?? defaultFileHeader).trim() {
	if (_generatedExtension.isEmpty \|\| !_generatedExtension.startsWith('.')) {
	throw ArgumentError.value(
	_generatedExtension,
	'generatedExtension',
	'Extension must be in the format of .*',
	);
	}
	if (_isLibraryBuilder && _generators.length > 1) {
	throw ArgumentError(
	'A standalone file can only be generated from a single Generator.',
	);
	}
	if (options != null && additionalOutputExtensions.isNotEmpty) {
	throw ArgumentError(
	'Either `options` or `additionalOutputExtensions` parameter '
	'can be given. Not both.',
	);
	}
	}

	@override
	Future<void> build(BuildStep buildStep) async {
	final resolver = buildStep.resolver;

	if (!await resolver.isLibrary(buildStep.inputId)) return;

	if (_generators.every((g) => g is GeneratorForAnnotation) &&
	!(await _hasAnyTopLevelAnnotations(
	buildStep.inputId,
	resolver,
	buildStep,
	))) {
	return;
	}

	final lib = await buildStep.resolver
	.libraryFor(buildStep.inputId, allowSyntaxErrors: allowSyntaxErrors);
	await _generateForLibrary(lib, buildStep);
	}

	Future<void> _generateForLibrary(
	LibraryElement library,
	BuildStep buildStep,
	) async {
	final generatedOutputs =
	await _generate(library, _generators, buildStep).toList();

	// Don't output useless files.
	//
	// NOTE: It is important to do this check _before_ checking for valid
	// library/part definitions because users expect some files to be skipped
	// therefore they do not have "library".
	if (generatedOutputs.isEmpty) return;
	final outputId = buildStep.allowedOutputs.first;
	final contentBuffer = StringBuffer();

	if (_header.isNotEmpty) {
	contentBuffer.writeln(_header);
	}

	if (!_isLibraryBuilder) {
	final asset = buildStep.inputId;
	final partOfUri = uriOfPartial(library, asset, outputId);
	contentBuffer.writeln();

	if (this is PartBuilder) {
	contentBuffer
	..write(languageOverrideForLibrary(library))
	..writeln('part of \'$partOfUri\';');
	final part = computePartUrl(buildStep.inputId, outputId);

	final libraryUnit =
	await buildStep.resolver.compilationUnitFor(buildStep.inputId);
	final hasLibraryPartDirectiveWithOutputUri =
	hasExpectedPartDirective(libraryUnit, part);
	if (!hasLibraryPartDirectiveWithOutputUri) {
	// TODO: Upgrade to error in a future breaking change?
	log.warning(
	'$part must be included as a part directive in '
	'the input library with:\n part \'$part\';',
	);
	return;
	}
	} else {
	assert(this is SharedPartBuilder);
	// For shared-part builders, `part` statements will be checked by the
	// combining build step.
	}
	}

	for (var item in generatedOutputs) {
	contentBuffer
	..writeln()
	..writeln(_headerLine)
	..writeAll(
	LineSplitter.split(item.generatorDescription)
	.map((line) => '// $line\n'),
	)
	..writeln(_headerLine)
	..writeln()
	..writeln(item.output);
	}

	var genPartContent = contentBuffer.toString();

	try {
	genPartContent = formatOutput(genPartContent);
	} catch (e, stack) {
	log.severe(
	'''
	An error `${e.runtimeType}` occurred while formatting the generated source for
	`${library.identifier}`
	which was output to
	`${outputId.path}`.
	This may indicate an issue in the generator, the input source code, or in the
	source formatter.''',
	e,
	stack,
	);
	}

	await buildStep.writeAsString(outputId, genPartContent);
	}

	@override
	String toString() =>
	'Generating $_generatedExtension: ${_generators.join(', ')}';
	}

	/// A [Builder] which generates content intended for `part of` files.
	///
	/// Generated files will be prefixed with a `partId` to ensure multiple
	/// [SharedPartBuilder]s can produce non conflicting `part of` files. When the
	/// `source_gen\|combining_builder` is applied to the primary input these
	/// snippets will be concatenated into the final `.g.dart` output.
	///
	/// This builder can be used when multiple generators may need to output to the
	/// same part file but [PartBuilder] can't be used because the generators are
	/// not all defined in the same location. As a convention most codegen which
	/// generates code should use this approach to get content into a `.g.dart` file
	/// instead of having individual outputs for each building package.
	class SharedPartBuilder extends _Builder {
	/// Wrap [generators] as a [Builder] that generates `part of` files.
	///
	/// [partId] indicates what files will be created for each `.dart`
	/// input. This extension should be unique as to not conflict with other
	/// [SharedPartBuilder]s. The resulting file will be of the form
	/// `<generatedExtension>.g.part`. If any generator in [generators] will
	/// create additional outputs through the [BuildStep] they should be indicated
	/// in [additionalOutputExtensions].
	///
	/// [formatOutput] is called to format the generated code. Defaults to
	/// [DartFormatter.format].
	///
	/// [allowSyntaxErrors] indicates whether to allow syntax errors in input
	/// libraries.
	SharedPartBuilder(
	List<Generator> generators,
	String partId, {
	String Function(String code)? formatOutput,
	List<String> additionalOutputExtensions = const [],
	bool allowSyntaxErrors = false,
	}) : super(
	generators,
	formatOutput: formatOutput,
	generatedExtension: '.$partId.g.part',
	additionalOutputExtensions: additionalOutputExtensions,
	header: '',
	allowSyntaxErrors: allowSyntaxErrors,
	) {
	if (!_partIdRegExp.hasMatch(partId)) {
	throw ArgumentError.value(
	partId,
	'partId',
	'`partId` can only contain letters, numbers, `_` and `.`. '
	'It cannot start or end with `.`.',
	);
	}
	}
	}

	/// A [Builder] which generates `part of` files.
	///
	/// This builder should be avoided - prefer using [SharedPartBuilder] and
	/// generating content that can be merged with output from other builders into a
	/// common `.g.dart` part file.
	///
	/// Each output should correspond to a `part` directive in the primary input,
	/// this will be validated.
	///
	/// Content output by each generator is concatenated and written to the output.
	/// A `part of` directive will automatically be included in the output and
	/// should not need be written by any of the generators.
	class PartBuilder extends _Builder {
	/// Wrap [generators] as a [Builder] that generates `part of` files.
	///
	/// [generatedExtension] indicates what files will be created for each
	/// `.dart` input. The [generatedExtension] should not be `.g.dart`. If you
	/// wish to produce `.g.dart` files please use [SharedPartBuilder].
	///
	/// If any generator in [generators] will create additional outputs through
	/// the [BuildStep] they should be indicated in [additionalOutputExtensions].
	///
	/// [formatOutput] is called to format the generated code. Defaults to
	/// [DartFormatter.format].
	///
	/// [header] is used to specify the content at the top of each generated file.
	/// If `null`, the content of [defaultFileHeader] is used.
	/// If [header] is an empty `String` no header is added.
	///
	/// [allowSyntaxErrors] indicates whether to allow syntax errors in input
	/// libraries.
	///
	/// If available, the `build_extensions` option will be extracted from
	/// [options] to allow output files to be generated into a different directory
	PartBuilder(
	List<Generator> generators,
	String generatedExtension, {
	String Function(String code)? formatOutput,
	List<String> additionalOutputExtensions = const [],
	String? header,
	bool allowSyntaxErrors = false,
	BuilderOptions? options,
	}) : super(
	generators,
	formatOutput: formatOutput,
	generatedExtension: generatedExtension,
	additionalOutputExtensions: additionalOutputExtensions,
	header: header,
	allowSyntaxErrors: allowSyntaxErrors,
	options: options,
	);
	}

	/// A [Builder] which generates standalone Dart library files.
	///
	/// A single [Generator] is responsible for generating the entirety of the
	/// output since it must also output any relevant import directives at the
	/// beginning of it's output.
	class LibraryBuilder extends _Builder {
	/// Wrap [generator] as a [Builder] that generates Dart library files.
	///
	/// [generatedExtension] indicates what files will be created for each `.dart`
	/// input.
	/// Defaults to `.g.dart`, however this should usually be changed to
	/// avoid conflicts with outputs from a [SharedPartBuilder].
	/// If [generator] will create additional outputs through the [BuildStep] they
	/// should be indicated in [additionalOutputExtensions].
	///
	/// [formatOutput] is called to format the generated code. Defaults to
	/// [DartFormatter.format].
	///
	/// [header] is used to specify the content at the top of each generated file.
	/// If `null`, the content of [defaultFileHeader] is used.
	/// If [header] is an empty `String` no header is added.
	///
	/// [allowSyntaxErrors] indicates whether to allow syntax errors in input
	/// libraries.
	LibraryBuilder(
	Generator generator, {
	String Function(String code)? formatOutput,
	String generatedExtension = '.g.dart',
	List<String> additionalOutputExtensions = const [],
	String? header,
	bool allowSyntaxErrors = false,
	BuilderOptions? options,
	}) : super(
	[generator],
	formatOutput: formatOutput,
	generatedExtension: generatedExtension,
	additionalOutputExtensions: additionalOutputExtensions,
	header: header,
	allowSyntaxErrors: allowSyntaxErrors,
	options: options,
	);
	}

	Stream<GeneratedOutput> _generate(
	LibraryElement library,
	List<Generator> generators,
	BuildStep buildStep,
	) async* {
	final libraryReader = LibraryReader(library);
	for (var i = 0; i < generators.length; i++) {
	final gen = generators[i];
	var msg = 'Running $gen';
	if (generators.length > 1) {
	msg = '$msg - ${i + 1} of ${generators.length}';
	}
	log.fine(msg);
	var createdUnit = await gen.generate(libraryReader, buildStep);

	if (createdUnit == null) {
	continue;
	}

	createdUnit = createdUnit.trim();
	if (createdUnit.isEmpty) {
	continue;
	}

	yield GeneratedOutput(gen, createdUnit);
	}
	}

	Future<bool> _hasAnyTopLevelAnnotations(
	AssetId input,
	Resolver resolver,
	BuildStep buildStep,
	) async {
	if (!await buildStep.canRead(input)) return false;
	final parsed = await resolver.compilationUnitFor(input);
	final partIds = <AssetId>[];
	for (var directive in parsed.directives) {
	if (directive.metadata.isNotEmpty) return true;
	if (directive is PartDirective) {
	partIds.add(
	AssetId.resolve(Uri.parse(directive.uri.stringValue!), from: input),
	);
	}
	}
	for (var declaration in parsed.declarations) {
	if (declaration.metadata.isNotEmpty) return true;
	}
	for (var partId in partIds) {
	if (await _hasAnyTopLevelAnnotations(partId, resolver, buildStep)) {
	return true;
	}
	}
	return false;
	}

	final _formatter = DartFormatter(fixes: [StyleFix.singleCascadeStatements]);

	const defaultFileHeader = '// GENERATED CODE - DO NOT MODIFY BY HAND';

	final _headerLine = '// '.padRight(77, '*');

	const partIdRegExpLiteral = r'[A-Za-z_\d-]+';

	final _partIdRegExp = RegExp('^$partIdRegExpLiteral\$');

	String languageOverrideForLibrary(LibraryElement library) {
	final override = library.languageVersion.override;
	return override == null
	? ''
	: '// @dart=${override.major}.${override.minor}\n';
	}