pkg/analyzer/lib/src/summary2/linked_element_factory.dart - sdk.git - Git at Google

 // Copyright (c) 2019, 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.

 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/src/context/context.dart';
 import 'package:analyzer/src/dart/analysis/session.dart';
 import 'package:analyzer/src/dart/ast/ast.dart';
 import 'package:analyzer/src/dart/element/element.dart';
 import 'package:analyzer/src/dart/element/type_provider.dart';
 import 'package:analyzer/src/dart/resolver/scope.dart';
 import 'package:analyzer/src/summary2/bundle_reader.dart';
 import 'package:analyzer/src/summary2/linked_library_context.dart';
 import 'package:analyzer/src/summary2/linked_unit_context.dart';
 import 'package:analyzer/src/summary2/reference.dart';

 class LinkedElementFactory {
   final AnalysisContextImpl analysisContext;
   final AnalysisSessionImpl analysisSession;
   final Reference rootReference;
   final Map<String, List<Reference>> linkingExports = {};
   final Map<String, LibraryReader> libraryReaders = {};

   LinkedElementFactory(
     this.analysisContext,
     this.analysisSession,
     this.rootReference,
   ) {
     ArgumentError.checkNotNull(analysisContext, 'analysisContext');
     ArgumentError.checkNotNull(analysisSession, 'analysisSession');
     _declareDartCoreDynamicNever();
   }

   Reference get dynamicRef {
     return rootReference.getChild('dart:core').getChild('dynamic');
   }

   bool get hasDartCore {
     return libraryReaders.containsKey('dart:core');
   }

   void addBundle(BundleReader bundle) {
     addLibraries(bundle.libraryMap);
   }

   void addLibraries(Map<String, LibraryReader> libraries) {
     libraryReaders.addAll(libraries);
   }

   Namespace buildExportNamespace(Uri uri) {
     var exportedNames = <String, Element>{};

     var exportedReferences = exportsOfLibrary('$uri');
     for (var exportedReference in exportedReferences) {
       var element = elementOfReference(exportedReference);
       // TODO(scheglov) Remove after https://github.com/dart-lang/sdk/issues/41212
       if (element == null) {
         throw StateError(
           '[No element]'
           '[uri: $uri]'
           '[exportedReferences: $exportedReferences]'
           '[exportedReference: $exportedReference]',
         );
       }
       exportedNames[element.name!] = element;
     }

     return Namespace(exportedNames);
   }

   LibraryElementImpl? createLibraryElementForLinking(
     LinkedLibraryContext libraryContext,
   ) {
     var sourceFactory = analysisContext.sourceFactory;
     var libraryUriStr = libraryContext.uriStr;
     var librarySource = sourceFactory.forUri(libraryUriStr);

     // The URI cannot be resolved, we don't know the library.
     if (librarySource == null) return null;

     var definingUnitContext = libraryContext.units[0];
     var definingUnitNode = definingUnitContext.unit!;

     // TODO(scheglov) Do we need this?
     var name = '';
     var nameOffset = -1;
     var nameLength = 0;
     for (var directive in definingUnitNode.directives) {
       if (directive is LibraryDirective) {
         name = directive.name.components.map((e) => e.name).join('.');
         nameOffset = directive.name.offset;
         nameLength = directive.name.length;
         break;
       }
     }

     var libraryElement = LibraryElementImpl.forLinkedNode(
       analysisContext,
       analysisSession,
       name,
       nameOffset,
       nameLength,
       definingUnitContext,
       libraryContext.reference,
       definingUnitNode,
     );
     _setLibraryTypeSystem(libraryElement);

     var units = <CompilationUnitElementImpl>[];
     var unitContainerRef = libraryContext.reference.getChild('@unit');
     for (var unitContext in libraryContext.units) {
       var unitNode = unitContext.unit as CompilationUnitImpl;

       var unitSource = sourceFactory.forUri(unitContext.uriStr);
       if (unitSource == null) continue;

       var unitElement = CompilationUnitElementImpl.forLinkedNode(
         libraryElement,
         unitContext,
         unitContext.reference,
         unitNode,
       );
       unitElement.lineInfo = unitNode.lineInfo;
       unitElement.source = unitSource;
       unitElement.librarySource = librarySource;
       unitElement.uri = unitContext.partUriStr;
       units.add(unitElement);
       unitContainerRef.getChild(unitContext.uriStr).element = unitElement;
     }

     libraryElement.definingCompilationUnit = units[0];
     libraryElement.parts = units.skip(1).toList();
     libraryContext.reference.element = libraryElement;

     return libraryElement;
   }

   LibraryElementImpl? createLibraryElementForReading(String uriStr) {
     var sourceFactory = analysisContext.sourceFactory;
     var librarySource = sourceFactory.forUri(uriStr);

     // The URI cannot be resolved, we don't know the library.
     if (librarySource == null) return null;

     var reader = libraryReaders[uriStr];
     if (reader == null) {
       throw ArgumentError(
         'Missing library: $uriStr\n'
         'Available libraries: ${libraryReaders.keys.toList()}',
       );
     }

     var libraryContext = LinkedLibraryContext(this, uriStr, reader.reference);
     var unitContainerRef = reader.reference.getChild('@unit');

     var unitContexts = <LinkedUnitContext>[];
     var indexInLibrary = 0;
     var unitReaders = reader.units;
     for (var unitReader in unitReaders) {
       var unitReference = unitContainerRef.getChild(unitReader.uriStr);
       var unitContext = LinkedUnitContext(
         libraryContext,
         indexInLibrary++,
         unitReader.partUriStr,
         unitReader.uriStr,
         unitReference,
         unitReader.isSynthetic,
         unit: unitReader.unit,
         unitReader: unitReader,
       );
       unitContexts.add(unitContext);
       libraryContext.units.add(unitContext);
     }

     var definingUnitContext = unitContexts[0];
     var libraryElement = LibraryElementImpl.forLinkedNode(
       analysisContext,
       analysisSession,
       reader.name,
       reader.nameOffset,
       reader.nameLength,
       definingUnitContext,
       reader.reference,
       unitReaders.first.unit,
     );
     _setLibraryTypeSystem(libraryElement);

     var units = <CompilationUnitElementImpl>[];
     for (var unitContext in unitContexts) {
       var unitNode = unitContext.unit as CompilationUnitImpl;

       var unitSource = sourceFactory.forUri(unitContext.uriStr);
       if (unitSource == null) continue;

       var unitElement = CompilationUnitElementImpl.forLinkedNode(
         libraryElement,
         unitContext,
         unitContext.reference,
         unitNode,
       );
       unitElement.lineInfo = unitNode.lineInfo;
       unitElement.source = unitSource;
       unitElement.librarySource = librarySource;
       unitElement.uri = unitContext.partUriStr;
       units.add(unitElement);
       unitContainerRef.getChild(unitContext.uriStr).element = unitElement;
     }

     libraryElement.definingCompilationUnit = units[0];
     libraryElement.parts = units.skip(1).toList();
     reader.reference.element = libraryElement;

     return libraryElement;
   }

   void createTypeProviders(
     LibraryElementImpl /*!*/ dartCore,
     LibraryElementImpl /*!*/ dartAsync,
   ) {
     if (analysisContext.hasTypeProvider) {
       return;
     }

     analysisContext.setTypeProviders(
       legacy: TypeProviderImpl(
         coreLibrary: dartCore,
         asyncLibrary: dartAsync,
         isNonNullableByDefault: false,
       ),
       nonNullableByDefault: TypeProviderImpl(
         coreLibrary: dartCore,
         asyncLibrary: dartAsync,
         isNonNullableByDefault: true,
       ),
     );

     // During linking we create libraries when typeProvider is not ready.
     // Update these libraries now, when typeProvider is ready.
     for (var reference in rootReference.children) {
       var libraryElement = reference.element as LibraryElementImpl?;
       if (libraryElement != null && !libraryElement.hasTypeProviderSystemSet) {
         _setLibraryTypeSystem(libraryElement);
       }
     }
   }

   Element? elementOfReference(Reference reference) {
     if (reference.element != null) {
       return reference.element;
     }
     if (reference.parent == null) {
       return null;
     }

     if (reference.isLibrary) {
       var uriStr = reference.name;
       return createLibraryElementForReading(uriStr);
     }

     var parent = reference.parent!.parent!;
     var parentElement = elementOfReference(parent);

     // Named formal parameters are created when we apply resolution to the
     // executable declaration, e.g. a constructor, or a method.
     if (reference.isParameter) {
       (parentElement as ExecutableElement).parameters;
       assert(reference.element != null);
       return reference.element;
     }

     // The default constructor might be synthetic, and has no node.
     // TODO(scheglov) We resynthesize all constructors here.
     if (reference.isConstructor && reference.name == '') {
       return (parentElement as ClassElement).unnamedConstructor;
     }

     if (parentElement is EnumElementImpl) {
       parentElement.constants;
       assert(reference.element != null);
       return reference.element;
     }

     if (reference.element != null) {
       return reference.element;
     }

     if (reference.isUnit) {
       assert(reference.element != null);
       return reference.element;
     }

     if (reference.isPrefix) {
       (parentElement as LibraryElement).prefixes;
       assert(reference.element != null);
       return reference.element;
     }

     // For class, mixin, extension - index members.
     parent.nodeAccessor!.readIndex();

     // For any element - class, method, etc - read the node.
     var node = reference.nodeAccessor!.node;

     if (node is ClassDeclaration) {
       ClassElementImpl.forLinkedNode(
           parentElement as CompilationUnitElementImpl, reference, node);
       assert(reference.element != null);
       return reference.element;
     } else if (node is ClassTypeAlias) {
       ClassElementImpl.forLinkedNode(
           parentElement as CompilationUnitElementImpl, reference, node);
       assert(reference.element != null);
       return reference.element;
     } else if (node is ConstructorDeclarationImpl) {
       ConstructorElementImpl.forLinkedNode(
           parentElement as ClassElementImpl, reference, node);
       var element = reference.element as ConstructorElementImpl;
       return element;
     } else if (node is EnumDeclaration) {
       EnumElementImpl.forLinkedNode(
           parentElement as CompilationUnitElementImpl, reference, node);
       assert(reference.element != null);
       return reference.element;
     } else if (node is ExtensionDeclarationImpl) {
       ExtensionElementImpl.forLinkedNode(
           parentElement as CompilationUnitElementImpl, reference, node);
       assert(reference.element != null);
       return reference.element;
     } else if (node is FieldDeclaration) {
       var variable = _variableDeclaration(node.fields, reference.name);
       if (variable.isConst) {
         ConstFieldElementImpl.forLinkedNode(
             parentElement as ElementImpl, reference, variable);
       } else {
         FieldElementImpl.forLinkedNodeFactory(
             parentElement as ElementImpl, reference, variable);
       }
       assert(reference.element != null);
       return reference.element;
     } else if (node is FunctionDeclaration) {
       if (node.propertyKeyword != null) {
         _topLevelPropertyAccessor(parent,
             parentElement as CompilationUnitElementImpl, reference, node);
       } else {
         FunctionElementImpl.forLinkedNode(
             parentElement as CompilationUnitElementImpl, reference, node);
       }
       assert(reference.element != null);
       return reference.element;
     } else if (node is FunctionTypeAlias || node is GenericTypeAlias) {
       TypeAliasElementImpl.forLinkedNodeFactory(
           parentElement as CompilationUnitElementImpl,
           reference,
           node as TypeAlias);
       assert(reference.element != null);
       return reference.element;
     } else if (node is MethodDeclaration) {
       if (node.propertyKeyword != null) {
         _classPropertyAccessor(
             parent, parentElement as ElementImpl, reference, node);
       } else {
         MethodElementImpl.forLinkedNode(
             parentElement as TypeParameterizedElementMixin, reference, node);
       }
       assert(reference.element != null);
       return reference.element;
     } else if (node is MixinDeclaration) {
       MixinElementImpl.forLinkedNode(
           parentElement as CompilationUnitElementImpl, reference, node);
       assert(reference.element != null);
       return reference.element;
     } else if (node is TopLevelVariableDeclaration) {
       var variable = _variableDeclaration(node.variables, reference.name);
       if (variable.isConst) {
         ConstTopLevelVariableElementImpl.forLinkedNode(
             parentElement as ElementImpl, reference, variable);
       } else {
         TopLevelVariableElementImpl.forLinkedNode(
             parentElement as CompilationUnitElementImpl, reference, variable);
       }
       assert(reference.element != null);
       return reference.element;
     }

     throw UnimplementedError('$reference');
   }

   List<Reference> exportsOfLibrary(String uriStr) {
     var linkingExportedReferences = linkingExports[uriStr];
     if (linkingExportedReferences != null) {
       return linkingExportedReferences;
     }

     var library = libraryReaders[uriStr];
     if (library == null) return const [];

     return library.exports;
   }

   bool hasLibrary(String uriStr) {
     return libraryReaders[uriStr] != null;
   }

   bool isLibraryUri(String uriStr) {
     var libraryContext = libraryReaders[uriStr]!;
     return !libraryContext.hasPartOfDirective;
   }

   LibraryElementImpl? libraryOfUri(String uriStr) {
     var reference = rootReference.getChild(uriStr);
     return elementOfReference(reference) as LibraryElementImpl?;
   }

   LibraryElementImpl libraryOfUri2(String uriStr) {
     var element = libraryOfUri(uriStr);
     if (element == null) {
       throw StateError('No library: $uriStr');
     }
     return element;
   }

   /// We have linked the bundle, and need to disconnect its libraries, so
   /// that the client can re-add the bundle, this time read from bytes.
   void removeBundle(Set<String> uriStrSet) {
     removeLibraries(uriStrSet);

     // This is the bundle with dart:core and dart:async, based on full ASTs.
     // To link them, the linker set the type provider. We are removing these
     // libraries, and we should also remove the type provider.
     if (uriStrSet.contains('dart:core')) {
       if (!uriStrSet.contains('dart:async')) {
         throw StateError(
           'Expected to link dart:core and dart:async together: '
           '${uriStrSet.toList()}',
         );
       }
       if (libraryReaders.isNotEmpty) {
         throw StateError(
           'Expected to link dart:core and dart:async first: '
           '${libraryReaders.keys.toList()}',
         );
       }
       analysisContext.clearTypeProvider();
       _declareDartCoreDynamicNever();
     }
   }

   /// Remove libraries with the specified URIs from the reference tree, and
   /// any session level caches.
   void removeLibraries(Set<String> uriStrSet) {
     for (var uriStr in uriStrSet) {
       libraryReaders.remove(uriStr);
       linkingExports.remove(uriStr);
       rootReference.removeChild(uriStr);
     }

     analysisSession.classHierarchy.removeOfLibraries(uriStrSet);
     analysisSession.inheritanceManager.removeOfLibraries(uriStrSet);
   }

   void _classPropertyAccessor(
     Reference parentReference,
     ElementImpl parentElement,
     Reference reference,
     MethodDeclaration node,
   ) {
     var accessor = PropertyAccessorElementImpl.forLinkedNode(
         parentElement, reference, node);

     var name = reference.name;
     var fieldRef = parentReference.getChild('@field').getChild(name);
     var field = fieldRef.element as FieldElementImpl?;
     if (field == null) {
       field = FieldElementImpl(name, -1);
       fieldRef.element = field;
       field.enclosingElement = parentElement;
       field.isSynthetic = true;
       field.isFinal = node.isGetter;
       field.isStatic = accessor.isStatic;
     } else {
       field.isFinal = false;
     }

     var isSetter = node.isSetter;
     if (isSetter) {
       field.isFinal = false;
     }

     accessor.variable = field;
     if (isSetter) {
       field.setter = accessor;
     } else {
       field.getter = accessor;
     }
   }

   void _declareDartCoreDynamicNever() {
     var dartCoreRef = rootReference.getChild('dart:core');
     dartCoreRef.getChild('dynamic').element = DynamicElementImpl.instance;
     dartCoreRef.getChild('Never').element = NeverElementImpl.instance;
   }

   void _setLibraryTypeSystem(LibraryElementImpl libraryElement) {
     // During linking we create libraries when typeProvider is not ready.
     // And if we link dart:core and dart:async, we cannot create it.
     // We will set typeProvider later, during [createTypeProviders].
     if (!analysisContext.hasTypeProvider) {
       return;
     }

     var isNonNullable = libraryElement.isNonNullableByDefault;
     libraryElement.typeProvider = isNonNullable
         ? analysisContext.typeProviderNonNullableByDefault
         : analysisContext.typeProviderLegacy;
     libraryElement.typeSystem = isNonNullable
         ? analysisContext.typeSystemNonNullableByDefault
         : analysisContext.typeSystemLegacy;
     libraryElement.hasTypeProviderSystemSet = true;

     libraryElement.createLoadLibraryFunction();
   }

   void _topLevelPropertyAccessor(
     Reference parentReference,
     CompilationUnitElementImpl parentElement,
     Reference reference,
     FunctionDeclaration node,
   ) {
     var accessor = PropertyAccessorElementImpl.forLinkedNode(
         parentElement, reference, node);

     var name = reference.name;
     var fieldRef = parentReference.getChild('@field').getChild(name);
     var field = fieldRef.element as TopLevelVariableElementImpl?;
     if (field == null) {
       field = TopLevelVariableElementImpl(name, -1);
       fieldRef.element = field;
       field.enclosingElement = parentElement;
       field.isFinal = true;
       field.isSynthetic = true;
     }

     var isSetter = node.isSetter;
     if (isSetter) {
       field.isFinal = false;
     }

     accessor.variable = field;
     if (isSetter) {
       field.setter = accessor;
     } else {
       field.getter = accessor;
     }
   }

   static VariableDeclaration _variableDeclaration(
     VariableDeclarationList variableList,
     String name,
   ) {
     for (var variable in variableList.variables) {
       if (variable.name.name == name) {
         return variable;
       }
     }
     throw StateError('No "$name" in: $variableList');
   }
 }
	// Copyright (c) 2019, 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.

	import 'package:analyzer/dart/ast/ast.dart';
	import 'package:analyzer/dart/element/element.dart';
	import 'package:analyzer/src/context/context.dart';
	import 'package:analyzer/src/dart/analysis/session.dart';
	import 'package:analyzer/src/dart/ast/ast.dart';
	import 'package:analyzer/src/dart/element/element.dart';
	import 'package:analyzer/src/dart/element/type_provider.dart';
	import 'package:analyzer/src/dart/resolver/scope.dart';
	import 'package:analyzer/src/summary2/bundle_reader.dart';
	import 'package:analyzer/src/summary2/linked_library_context.dart';
	import 'package:analyzer/src/summary2/linked_unit_context.dart';
	import 'package:analyzer/src/summary2/reference.dart';

	class LinkedElementFactory {
	final AnalysisContextImpl analysisContext;
	final AnalysisSessionImpl analysisSession;
	final Reference rootReference;
	final Map<String, List<Reference>> linkingExports = {};
	final Map<String, LibraryReader> libraryReaders = {};

	LinkedElementFactory(
	this.analysisContext,
	this.analysisSession,
	this.rootReference,
	) {
	ArgumentError.checkNotNull(analysisContext, 'analysisContext');
	ArgumentError.checkNotNull(analysisSession, 'analysisSession');
	_declareDartCoreDynamicNever();
	}

	Reference get dynamicRef {
	return rootReference.getChild('dart:core').getChild('dynamic');
	}

	bool get hasDartCore {
	return libraryReaders.containsKey('dart:core');
	}

	void addBundle(BundleReader bundle) {
	addLibraries(bundle.libraryMap);
	}

	void addLibraries(Map<String, LibraryReader> libraries) {
	libraryReaders.addAll(libraries);
	}

	Namespace buildExportNamespace(Uri uri) {
	var exportedNames = <String, Element>{};

	var exportedReferences = exportsOfLibrary('$uri');
	for (var exportedReference in exportedReferences) {
	var element = elementOfReference(exportedReference);
	// TODO(scheglov) Remove after https://github.com/dart-lang/sdk/issues/41212
	if (element == null) {
	throw StateError(
	'[No element]'
	'[uri: $uri]'
	'[exportedReferences: $exportedReferences]'
	'[exportedReference: $exportedReference]',
	);
	}
	exportedNames[element.name!] = element;
	}

	return Namespace(exportedNames);
	}

	LibraryElementImpl? createLibraryElementForLinking(
	LinkedLibraryContext libraryContext,
	) {
	var sourceFactory = analysisContext.sourceFactory;
	var libraryUriStr = libraryContext.uriStr;
	var librarySource = sourceFactory.forUri(libraryUriStr);

	// The URI cannot be resolved, we don't know the library.
	if (librarySource == null) return null;

	var definingUnitContext = libraryContext.units[0];
	var definingUnitNode = definingUnitContext.unit!;

	// TODO(scheglov) Do we need this?
	var name = '';
	var nameOffset = -1;
	var nameLength = 0;
	for (var directive in definingUnitNode.directives) {
	if (directive is LibraryDirective) {
	name = directive.name.components.map((e) => e.name).join('.');
	nameOffset = directive.name.offset;
	nameLength = directive.name.length;
	break;
	}
	}

	var libraryElement = LibraryElementImpl.forLinkedNode(
	analysisContext,
	analysisSession,
	name,
	nameOffset,
	nameLength,
	definingUnitContext,
	libraryContext.reference,
	definingUnitNode,
	);
	_setLibraryTypeSystem(libraryElement);

	var units = <CompilationUnitElementImpl>[];
	var unitContainerRef = libraryContext.reference.getChild('@unit');
	for (var unitContext in libraryContext.units) {
	var unitNode = unitContext.unit as CompilationUnitImpl;

	var unitSource = sourceFactory.forUri(unitContext.uriStr);
	if (unitSource == null) continue;

	var unitElement = CompilationUnitElementImpl.forLinkedNode(
	libraryElement,
	unitContext,
	unitContext.reference,
	unitNode,
	);
	unitElement.lineInfo = unitNode.lineInfo;
	unitElement.source = unitSource;
	unitElement.librarySource = librarySource;
	unitElement.uri = unitContext.partUriStr;
	units.add(unitElement);
	unitContainerRef.getChild(unitContext.uriStr).element = unitElement;
	}

	libraryElement.definingCompilationUnit = units[0];
	libraryElement.parts = units.skip(1).toList();
	libraryContext.reference.element = libraryElement;

	return libraryElement;
	}

	LibraryElementImpl? createLibraryElementForReading(String uriStr) {
	var sourceFactory = analysisContext.sourceFactory;
	var librarySource = sourceFactory.forUri(uriStr);

	// The URI cannot be resolved, we don't know the library.
	if (librarySource == null) return null;

	var reader = libraryReaders[uriStr];
	if (reader == null) {
	throw ArgumentError(
	'Missing library: $uriStr\n'
	'Available libraries: ${libraryReaders.keys.toList()}',
	);
	}

	var libraryContext = LinkedLibraryContext(this, uriStr, reader.reference);
	var unitContainerRef = reader.reference.getChild('@unit');

	var unitContexts = <LinkedUnitContext>[];
	var indexInLibrary = 0;
	var unitReaders = reader.units;
	for (var unitReader in unitReaders) {
	var unitReference = unitContainerRef.getChild(unitReader.uriStr);
	var unitContext = LinkedUnitContext(
	libraryContext,
	indexInLibrary++,
	unitReader.partUriStr,
	unitReader.uriStr,
	unitReference,
	unitReader.isSynthetic,
	unit: unitReader.unit,
	unitReader: unitReader,
	);
	unitContexts.add(unitContext);
	libraryContext.units.add(unitContext);
	}

	var definingUnitContext = unitContexts[0];
	var libraryElement = LibraryElementImpl.forLinkedNode(
	analysisContext,
	analysisSession,
	reader.name,
	reader.nameOffset,
	reader.nameLength,
	definingUnitContext,
	reader.reference,
	unitReaders.first.unit,
	);
	_setLibraryTypeSystem(libraryElement);

	var units = <CompilationUnitElementImpl>[];
	for (var unitContext in unitContexts) {
	var unitNode = unitContext.unit as CompilationUnitImpl;

	var unitSource = sourceFactory.forUri(unitContext.uriStr);
	if (unitSource == null) continue;

	var unitElement = CompilationUnitElementImpl.forLinkedNode(
	libraryElement,
	unitContext,
	unitContext.reference,
	unitNode,
	);
	unitElement.lineInfo = unitNode.lineInfo;
	unitElement.source = unitSource;
	unitElement.librarySource = librarySource;
	unitElement.uri = unitContext.partUriStr;
	units.add(unitElement);
	unitContainerRef.getChild(unitContext.uriStr).element = unitElement;
	}

	libraryElement.definingCompilationUnit = units[0];
	libraryElement.parts = units.skip(1).toList();
	reader.reference.element = libraryElement;

	return libraryElement;
	}

	void createTypeProviders(
	LibraryElementImpl /!/ dartCore,
	LibraryElementImpl /!/ dartAsync,
	) {
	if (analysisContext.hasTypeProvider) {
	return;
	}

	analysisContext.setTypeProviders(
	legacy: TypeProviderImpl(
	coreLibrary: dartCore,
	asyncLibrary: dartAsync,
	isNonNullableByDefault: false,
	),
	nonNullableByDefault: TypeProviderImpl(
	coreLibrary: dartCore,
	asyncLibrary: dartAsync,
	isNonNullableByDefault: true,
	),
	);

	// During linking we create libraries when typeProvider is not ready.
	// Update these libraries now, when typeProvider is ready.
	for (var reference in rootReference.children) {
	var libraryElement = reference.element as LibraryElementImpl?;
	if (libraryElement != null && !libraryElement.hasTypeProviderSystemSet) {
	_setLibraryTypeSystem(libraryElement);
	}
	}
	}

	Element? elementOfReference(Reference reference) {
	if (reference.element != null) {
	return reference.element;
	}
	if (reference.parent == null) {
	return null;
	}

	if (reference.isLibrary) {
	var uriStr = reference.name;
	return createLibraryElementForReading(uriStr);
	}

	var parent = reference.parent!.parent!;
	var parentElement = elementOfReference(parent);

	// Named formal parameters are created when we apply resolution to the
	// executable declaration, e.g. a constructor, or a method.
	if (reference.isParameter) {
	(parentElement as ExecutableElement).parameters;
	assert(reference.element != null);
	return reference.element;
	}

	// The default constructor might be synthetic, and has no node.
	// TODO(scheglov) We resynthesize all constructors here.
	if (reference.isConstructor && reference.name == '') {
	return (parentElement as ClassElement).unnamedConstructor;
	}

	if (parentElement is EnumElementImpl) {
	parentElement.constants;
	assert(reference.element != null);
	return reference.element;
	}

	if (reference.element != null) {
	return reference.element;
	}

	if (reference.isUnit) {
	assert(reference.element != null);
	return reference.element;
	}

	if (reference.isPrefix) {
	(parentElement as LibraryElement).prefixes;
	assert(reference.element != null);
	return reference.element;
	}

	// For class, mixin, extension - index members.
	parent.nodeAccessor!.readIndex();

	// For any element - class, method, etc - read the node.
	var node = reference.nodeAccessor!.node;

	if (node is ClassDeclaration) {
	ClassElementImpl.forLinkedNode(
	parentElement as CompilationUnitElementImpl, reference, node);
	assert(reference.element != null);
	return reference.element;
	} else if (node is ClassTypeAlias) {
	ClassElementImpl.forLinkedNode(
	parentElement as CompilationUnitElementImpl, reference, node);
	assert(reference.element != null);
	return reference.element;
	} else if (node is ConstructorDeclarationImpl) {
	ConstructorElementImpl.forLinkedNode(
	parentElement as ClassElementImpl, reference, node);
	var element = reference.element as ConstructorElementImpl;
	return element;
	} else if (node is EnumDeclaration) {
	EnumElementImpl.forLinkedNode(
	parentElement as CompilationUnitElementImpl, reference, node);
	assert(reference.element != null);
	return reference.element;
	} else if (node is ExtensionDeclarationImpl) {
	ExtensionElementImpl.forLinkedNode(
	parentElement as CompilationUnitElementImpl, reference, node);
	assert(reference.element != null);
	return reference.element;
	} else if (node is FieldDeclaration) {
	var variable = _variableDeclaration(node.fields, reference.name);
	if (variable.isConst) {
	ConstFieldElementImpl.forLinkedNode(
	parentElement as ElementImpl, reference, variable);
	} else {
	FieldElementImpl.forLinkedNodeFactory(
	parentElement as ElementImpl, reference, variable);
	}
	assert(reference.element != null);
	return reference.element;
	} else if (node is FunctionDeclaration) {
	if (node.propertyKeyword != null) {
	_topLevelPropertyAccessor(parent,
	parentElement as CompilationUnitElementImpl, reference, node);
	} else {
	FunctionElementImpl.forLinkedNode(
	parentElement as CompilationUnitElementImpl, reference, node);
	}
	assert(reference.element != null);
	return reference.element;
	} else if (node is FunctionTypeAlias \|\| node is GenericTypeAlias) {
	TypeAliasElementImpl.forLinkedNodeFactory(
	parentElement as CompilationUnitElementImpl,
	reference,
	node as TypeAlias);
	assert(reference.element != null);
	return reference.element;
	} else if (node is MethodDeclaration) {
	if (node.propertyKeyword != null) {
	_classPropertyAccessor(
	parent, parentElement as ElementImpl, reference, node);
	} else {
	MethodElementImpl.forLinkedNode(
	parentElement as TypeParameterizedElementMixin, reference, node);
	}
	assert(reference.element != null);
	return reference.element;
	} else if (node is MixinDeclaration) {
	MixinElementImpl.forLinkedNode(
	parentElement as CompilationUnitElementImpl, reference, node);
	assert(reference.element != null);
	return reference.element;
	} else if (node is TopLevelVariableDeclaration) {
	var variable = _variableDeclaration(node.variables, reference.name);
	if (variable.isConst) {
	ConstTopLevelVariableElementImpl.forLinkedNode(
	parentElement as ElementImpl, reference, variable);
	} else {
	TopLevelVariableElementImpl.forLinkedNode(
	parentElement as CompilationUnitElementImpl, reference, variable);
	}
	assert(reference.element != null);
	return reference.element;
	}

	throw UnimplementedError('$reference');
	}

	List<Reference> exportsOfLibrary(String uriStr) {
	var linkingExportedReferences = linkingExports[uriStr];
	if (linkingExportedReferences != null) {
	return linkingExportedReferences;
	}

	var library = libraryReaders[uriStr];
	if (library == null) return const [];

	return library.exports;
	}

	bool hasLibrary(String uriStr) {
	return libraryReaders[uriStr] != null;
	}

	bool isLibraryUri(String uriStr) {
	var libraryContext = libraryReaders[uriStr]!;
	return !libraryContext.hasPartOfDirective;
	}

	LibraryElementImpl? libraryOfUri(String uriStr) {
	var reference = rootReference.getChild(uriStr);
	return elementOfReference(reference) as LibraryElementImpl?;
	}

	LibraryElementImpl libraryOfUri2(String uriStr) {
	var element = libraryOfUri(uriStr);
	if (element == null) {
	throw StateError('No library: $uriStr');
	}
	return element;
	}

	/// We have linked the bundle, and need to disconnect its libraries, so
	/// that the client can re-add the bundle, this time read from bytes.
	void removeBundle(Set<String> uriStrSet) {
	removeLibraries(uriStrSet);

	// This is the bundle with dart:core and dart:async, based on full ASTs.
	// To link them, the linker set the type provider. We are removing these
	// libraries, and we should also remove the type provider.
	if (uriStrSet.contains('dart:core')) {
	if (!uriStrSet.contains('dart:async')) {
	throw StateError(
	'Expected to link dart:core and dart:async together: '
	'${uriStrSet.toList()}',
	);
	}
	if (libraryReaders.isNotEmpty) {
	throw StateError(
	'Expected to link dart:core and dart:async first: '
	'${libraryReaders.keys.toList()}',
	);
	}
	analysisContext.clearTypeProvider();
	_declareDartCoreDynamicNever();
	}
	}

	/// Remove libraries with the specified URIs from the reference tree, and
	/// any session level caches.
	void removeLibraries(Set<String> uriStrSet) {
	for (var uriStr in uriStrSet) {
	libraryReaders.remove(uriStr);
	linkingExports.remove(uriStr);
	rootReference.removeChild(uriStr);
	}

	analysisSession.classHierarchy.removeOfLibraries(uriStrSet);
	analysisSession.inheritanceManager.removeOfLibraries(uriStrSet);
	}

	void _classPropertyAccessor(
	Reference parentReference,
	ElementImpl parentElement,
	Reference reference,
	MethodDeclaration node,
	) {
	var accessor = PropertyAccessorElementImpl.forLinkedNode(
	parentElement, reference, node);

	var name = reference.name;
	var fieldRef = parentReference.getChild('@field').getChild(name);
	var field = fieldRef.element as FieldElementImpl?;
	if (field == null) {
	field = FieldElementImpl(name, -1);
	fieldRef.element = field;
	field.enclosingElement = parentElement;
	field.isSynthetic = true;
	field.isFinal = node.isGetter;
	field.isStatic = accessor.isStatic;
	} else {
	field.isFinal = false;
	}

	var isSetter = node.isSetter;
	if (isSetter) {
	field.isFinal = false;
	}

	accessor.variable = field;
	if (isSetter) {
	field.setter = accessor;
	} else {
	field.getter = accessor;
	}
	}

	void _declareDartCoreDynamicNever() {
	var dartCoreRef = rootReference.getChild('dart:core');
	dartCoreRef.getChild('dynamic').element = DynamicElementImpl.instance;
	dartCoreRef.getChild('Never').element = NeverElementImpl.instance;
	}

	void _setLibraryTypeSystem(LibraryElementImpl libraryElement) {
	// During linking we create libraries when typeProvider is not ready.
	// And if we link dart:core and dart:async, we cannot create it.
	// We will set typeProvider later, during [createTypeProviders].
	if (!analysisContext.hasTypeProvider) {
	return;
	}

	var isNonNullable = libraryElement.isNonNullableByDefault;
	libraryElement.typeProvider = isNonNullable
	? analysisContext.typeProviderNonNullableByDefault
	: analysisContext.typeProviderLegacy;
	libraryElement.typeSystem = isNonNullable
	? analysisContext.typeSystemNonNullableByDefault
	: analysisContext.typeSystemLegacy;
	libraryElement.hasTypeProviderSystemSet = true;

	libraryElement.createLoadLibraryFunction();
	}

	void _topLevelPropertyAccessor(
	Reference parentReference,
	CompilationUnitElementImpl parentElement,
	Reference reference,
	FunctionDeclaration node,
	) {
	var accessor = PropertyAccessorElementImpl.forLinkedNode(
	parentElement, reference, node);

	var name = reference.name;
	var fieldRef = parentReference.getChild('@field').getChild(name);
	var field = fieldRef.element as TopLevelVariableElementImpl?;
	if (field == null) {
	field = TopLevelVariableElementImpl(name, -1);
	fieldRef.element = field;
	field.enclosingElement = parentElement;
	field.isFinal = true;
	field.isSynthetic = true;
	}

	var isSetter = node.isSetter;
	if (isSetter) {
	field.isFinal = false;
	}

	accessor.variable = field;
	if (isSetter) {
	field.setter = accessor;
	} else {
	field.getter = accessor;
	}
	}

	static VariableDeclaration _variableDeclaration(
	VariableDeclarationList variableList,
	String name,
	) {
	for (var variable in variableList.variables) {
	if (variable.name.name == name) {
	return variable;
	}
	}
	throw StateError('No "$name" in: $variableList');
	}
	}