pkg/analyzer_plugin/lib/utilities/navigation/navigation_dart.dart - sdk.git - 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.

 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart';
 import 'package:analyzer/dart/ast/visitor.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/src/dart/ast/extensions.dart';
 import 'package:analyzer/src/dart/ast/utilities.dart';
 import 'package:analyzer/src/dart/element/element.dart';
 import 'package:analyzer_plugin/protocol/protocol_common.dart' as protocol;
 import 'package:analyzer_plugin/utilities/analyzer_converter.dart';
 import 'package:analyzer_plugin/utilities/navigation/navigation.dart';

 NavigationCollector computeDartNavigation(
     ResourceProvider resourceProvider,
     NavigationCollector collector,
     CompilationUnit unit,
     int? offset,
     int? length) {
   var dartCollector = _DartNavigationCollector(collector, offset, length);
   var visitor = _DartNavigationComputerVisitor(resourceProvider, dartCollector);
   if (offset == null || length == null) {
     unit.accept(visitor);
   } else {
     var node = _getNodeForRange(unit, offset, length);
     if (node != null) {
       node = _getNavigationTargetNode(node);
     }
     node?.accept(visitor);
   }
   return collector;
 }

 /// Gets the nearest node that should be used for navigation.
 ///
 /// This is usually the outermost node with the same offset as node but in some
 /// cases may be a different ancestor where required to produce the correct
 /// result.
 AstNode _getNavigationTargetNode(AstNode node) {
   AstNode? current = node;
   while (current != null &&
       current.parent != null &&
       current.offset == current.parent!.offset) {
     current = current.parent;
   }
   current ??= node;

   // To navigate to formal params, we need to visit the parameter and not just
   // the identifier but they don't start at the same offset as they have a
   // prefix.
   final parent = current.parent;
   if (parent is FormalParameter) {
     current = parent;
   }

   return current;
 }

 AstNode? _getNodeForRange(CompilationUnit unit, int offset, int length) {
   var node = NodeLocator(offset, offset + length).searchWithin(unit);
   for (var n = node; n != null; n = n.parent) {
     if (n is Directive) {
       return n;
     }
   }
   return node;
 }

 /// A Dart specific wrapper around [NavigationCollector].
 class _DartNavigationCollector {
   final NavigationCollector collector;
   final int? requestedOffset;
   final int? requestedLength;

   _DartNavigationCollector(
       this.collector, this.requestedOffset, this.requestedLength);

   void _addRegion(int offset, int length, Element? element) {
     element = element?.nonSynthetic;
     if (element == null || element == DynamicElementImpl.instance) {
       return;
     }
     if (element.location == null) {
       return;
     }
     // Discard elements that don't span the offset/range given (if provided).
     if (!_isWithinRequestedRange(offset, length)) {
       return;
     }
     var converter = AnalyzerConverter();
     var kind = converter.convertElementKind(element.kind);
     var location = converter.locationFromElement(element);
     if (location == null) {
       return;
     }

     collector.addRegion(offset, length, kind, location, targetElement: element);
   }

   void _addRegionForNode(AstNode? node, Element? element) {
     if (node == null) {
       return;
     }
     var offset = node.offset;
     var length = node.length;
     _addRegion(offset, length, element);
   }

   void _addRegionForToken(Token token, Element? element) {
     var offset = token.offset;
     var length = token.length;
     _addRegion(offset, length, element);
   }

   /// Checks if offset/length intersect with the range the user requested
   /// navigation regions for.
   ///
   /// If the request did not specify a range, always returns true.
   bool _isWithinRequestedRange(int offset, int length) {
     final requestedOffset = this.requestedOffset;
     if (requestedOffset == null) {
       return true;
     }
     if (offset > requestedOffset + (requestedLength ?? 0)) {
       // Starts after the requested range.
       return false;
     }
     if (offset + length < requestedOffset) {
       // Ends before the requested range.
       return false;
     }
     return true;
   }
 }

 class _DartNavigationComputerVisitor extends RecursiveAstVisitor<void> {
   final ResourceProvider resourceProvider;
   final _DartNavigationCollector computer;

   _DartNavigationComputerVisitor(this.resourceProvider, this.computer);

   @override
   void visitAnnotation(Annotation node) {
     var element = node.element;
     if (element is ConstructorElement && element.isSynthetic) {
       element = element.enclosingElement;
     }
     var name = node.name;
     if (name is PrefixedIdentifier) {
       // use constructor in: @PrefixClass.constructorName
       var prefixElement = name.prefix.staticElement;
       if (prefixElement is ClassElement) {
         prefixElement = element;
       }
       computer._addRegionForNode(name.prefix, prefixElement);
       // always constructor
       computer._addRegionForNode(name.identifier, element);
     } else {
       computer._addRegionForNode(name, element);
     }
     computer._addRegionForNode(node.constructorName, element);
     // type arguments
     node.typeArguments?.accept(this);
     // arguments
     node.arguments?.accept(this);
   }

   @override
   void visitAssignmentExpression(AssignmentExpression node) {
     node.leftHandSide.accept(this);
     computer._addRegionForToken(node.operator, node.staticElement);
     node.rightHandSide.accept(this);
   }

   @override
   void visitBinaryExpression(BinaryExpression node) {
     node.leftOperand.accept(this);
     computer._addRegionForToken(node.operator, node.staticElement);
     node.rightOperand.accept(this);
   }

   @override
   void visitComment(Comment node) {
     for (var commentReference in node.references) {
       commentReference.accept(this);
     }

     var inToolAnnotation = false;
     for (var token in node.tokens) {
       if (token.isEof) {
         break;
       }
       var strValue = token.toString();
       if (strValue.isEmpty) {
         continue;
       }

       if (inToolAnnotation) {
         if (strValue.contains('{@end-tool}')) {
           inToolAnnotation = false;
         } else if (strValue.contains('** See code in ')) {
           var startIndex = strValue.indexOf('** See code in ') + 15;
           var endIndex = strValue.indexOf('.dart') + 5;
           var pathSnippet = strValue.substring(startIndex, endIndex);
           var parentPath =
               _computeParentWithExamplesAPI(node, resourceProvider);
           if (parentPath != null) {
             var start = token.offset + startIndex;
             var end = token.offset + endIndex;
             computer.collector.addRegion(
                 start,
                 end - start,
                 protocol.ElementKind.LIBRARY,
                 protocol.Location(
                     resourceProvider.pathContext.join(parentPath, pathSnippet),
                     0,
                     0,
                     0,
                     0,
                     endLine: 0,
                     endColumn: 0));
           }
         }
       } else if (strValue.contains('{@tool ')) {
         inToolAnnotation = true;
       }
     }
   }

   @override
   void visitCompilationUnit(CompilationUnit unit) {
     // prepare top-level nodes sorted by their offsets
     var nodes = <AstNode>[];
     nodes.addAll(unit.directives);
     nodes.addAll(unit.declarations);
     nodes.sort((a, b) {
       return a.offset - b.offset;
     });
     // visit sorted nodes
     for (var node in nodes) {
       node.accept(this);
     }
   }

   @override
   void visitConfiguration(Configuration node) {
     var source = node.uriSource;
     if (source != null) {
       if (resourceProvider.getResource(source.fullName).exists) {
         // TODO(brianwilkerson) If the analyzer ever resolves the URI to a
         //  library, use that library element to create the region.
         var uriNode = node.uri;
         if (computer._isWithinRequestedRange(uriNode.offset, uriNode.length)) {
           computer.collector.addRegion(
               uriNode.offset,
               uriNode.length,
               protocol.ElementKind.LIBRARY,
               protocol.Location(source.fullName, 0, 0, 0, 0,
                   endLine: 0, endColumn: 0));
         }
       }
     }
     super.visitConfiguration(node);
   }

   @override
   void visitConstructorDeclaration(ConstructorDeclaration node) {
     // For a default constructor, override the class name to be the declaration
     // itself rather than linking to the class.
     var name = node.name;
     if (name == null) {
       computer._addRegionForNode(node.returnType, node.declaredElement);
     } else {
       node.returnType.accept(this);
       name.accept(this);
     }
     node.parameters.accept(this);
     node.initializers.accept(this);
     node.redirectedConstructor?.accept(this);
     node.body.accept(this);
   }

   @override
   void visitConstructorName(ConstructorName node) {
     Element? element = node.staticElement;
     if (element == null) {
       return;
     }
     // add regions
     var typeName = node.type;
     // [prefix].ClassName
     {
       var name = typeName.name;
       var className = name;
       if (name is PrefixedIdentifier) {
         name.prefix.accept(this);
         className = name.identifier;
       }
       // For a named constructor, the class name points at the class.
       var classNameTargetElement =
           node.name != null ? className.staticElement : element;
       computer._addRegionForNode(className, classNameTargetElement);
     }
     // <TypeA, TypeB>
     typeName.typeArguments?.accept(this);
     // optional "name"
     if (node.name != null) {
       computer._addRegionForNode(node.name, element);
     }
   }

   @override
   void visitDeclaredIdentifier(DeclaredIdentifier node) {
     if (node.type == null) {
       var token = node.keyword;
       if (token != null && token.keyword == Keyword.VAR) {
         var inferredType = node.declaredElement?.type;
         var element = inferredType?.element;
         if (element != null) {
           computer._addRegionForToken(token, element);
         }
       }
     }
     super.visitDeclaredIdentifier(node);
   }

   @override
   void visitEnumConstantDeclaration(EnumConstantDeclaration node) {
     computer._addRegionForNode(node.name, node.constructorElement);

     var arguments = node.arguments;
     if (arguments != null) {
       computer._addRegionForNode(
         arguments.constructorSelector?.name,
         node.constructorElement,
       );
       arguments.typeArguments?.accept(this);
       arguments.argumentList.accept(this);
     }
   }

   @override
   void visitExportDirective(ExportDirective node) {
     var exportElement = node.element2;
     if (exportElement != null) {
       Element? libraryElement = exportElement.exportedLibrary;
       _addUriDirectiveRegion(node, libraryElement);
     }
     super.visitExportDirective(node);
   }

   @override
   void visitFieldFormalParameter(FieldFormalParameter node) {
     final element = node.declaredElement;
     if (element is FieldFormalParameterElementImpl) {
       computer._addRegionForToken(node.thisKeyword, element.field);
       computer._addRegionForNode(node.identifier, element.field);
     }

     node.type?.accept(this);
     node.typeParameters?.accept(this);
     node.parameters?.accept(this);
   }

   @override
   void visitImportDirective(ImportDirective node) {
     var importElement = node.element2;
     if (importElement != null) {
       Element? libraryElement = importElement.importedLibrary;
       _addUriDirectiveRegion(node, libraryElement);
     }
     super.visitImportDirective(node);
   }

   @override
   void visitIndexExpression(IndexExpression node) {
     super.visitIndexExpression(node);
     var element = node.writeOrReadElement;
     computer._addRegionForToken(node.leftBracket, element);
     computer._addRegionForToken(node.rightBracket, element);
   }

   @override
   void visitLibraryDirective(LibraryDirective node) {
     computer._addRegionForNode(node.name, node.element);
   }

   @override
   void visitPartDirective(PartDirective node) {
     final element = node.element;
     if (element is PartElement) {
       final uri = element.uri;
       if (uri is DirectiveUriWithUnit) {
         computer._addRegionForNode(node.uri, uri.unit);
       } else if (uri is DirectiveUriWithSource) {
         final uriNode = node.uri;
         final source = uri.source;
         computer.collector.addRegion(
           uriNode.offset,
           uriNode.length,
           protocol.ElementKind.FILE,
           protocol.Location(source.fullName, 0, 0, 0, 0,
               endLine: 0, endColumn: 0),
         );
       }
     }

     super.visitPartDirective(node);
   }

   @override
   void visitPartOfDirective(PartOfDirective node) {
     computer._addRegionForNode(node.libraryName ?? node.uri, node.element);
     super.visitPartOfDirective(node);
   }

   @override
   void visitPostfixExpression(PostfixExpression node) {
     super.visitPostfixExpression(node);
     computer._addRegionForToken(node.operator, node.staticElement);
   }

   @override
   void visitPrefixExpression(PrefixExpression node) {
     computer._addRegionForToken(node.operator, node.staticElement);
     super.visitPrefixExpression(node);
   }

   @override
   void visitRedirectingConstructorInvocation(
       RedirectingConstructorInvocation node) {
     Element? element = node.staticElement;
     if (element != null && element.isSynthetic) {
       element = element.enclosingElement;
     }
     // add region
     computer._addRegionForToken(node.thisKeyword, element);
     computer._addRegionForNode(node.constructorName, element);
     // process arguments
     node.argumentList.accept(this);
   }

   @override
   void visitSimpleIdentifier(SimpleIdentifier node) {
     var element = node.writeOrReadElement;
     computer._addRegionForNode(node, element);
   }

   @override
   void visitSuperConstructorInvocation(SuperConstructorInvocation node) {
     Element? element = node.staticElement;
     if (element != null && element.isSynthetic) {
       element = element.enclosingElement;
     }
     // add region
     computer._addRegionForToken(node.superKeyword, element);
     computer._addRegionForNode(node.constructorName, element);
     // process arguments
     node.argumentList.accept(this);
   }

   @override
   void visitSuperFormalParameter(SuperFormalParameter node) {
     var element = node.declaredElement;
     if (element is SuperFormalParameterElementImpl) {
       var superParameter = element.superConstructorParameter;
       computer._addRegionForToken(node.superKeyword, superParameter);
       computer._addRegionForNode(node.identifier, superParameter);
     }

     node.type?.accept(this);
     node.typeParameters?.accept(this);
     node.parameters?.accept(this);
   }

   @override
   void visitVariableDeclarationList(VariableDeclarationList node) {
     /// Return the element for the type inferred for each of the variables in
     /// the given list of [variables], or `null` if not all variable have the
     /// same inferred type.
     Element? getCommonElement(List<VariableDeclaration> variables) {
       var firstElement = variables[0].declaredElement?.type.element;
       if (firstElement == null) {
         return null;
       }
       for (var i = 1; i < variables.length; i++) {
         var element = variables[1].declaredElement?.type.element;
         if (element != firstElement) {
           return null;
         }
       }
       return firstElement;
     }

     if (node.type == null) {
       var token = node.keyword;
       if (token?.keyword == Keyword.VAR) {
         var element = getCommonElement(node.variables);
         if (element != null) {
           computer._addRegionForToken(token!, element);
         }
       }
     }
     super.visitVariableDeclarationList(node);
   }

   /// If the source of the given [element] (referenced by the [node]) exists,
   /// then add the navigation region from the [node] to the [element].
   void _addUriDirectiveRegion(UriBasedDirective node, Element? element) {
     var source = element?.source;
     if (source != null) {
       if (resourceProvider.getResource(source.fullName).exists) {
         computer._addRegionForNode(node.uri, element);
       }
     }
   }

   /// Given some [Comment], compute and return the parent directory absolute
   /// path which contains the directories 'examples/api/'. Null is returned if
   /// such directories are not found.
   String? _computeParentWithExamplesAPI(
       Comment node, ResourceProvider resourceProvider) {
     var source =
         node.thisOrAncestorOfType<CompilationUnit>()?.declaredElement?.source;
     if (source == null) {
       return null;
     }

     var file = resourceProvider.getFile(source.fullName);
     if (!file.exists) {
       return null;
     }
     var parent = file.parent;
     while (parent != parent.parent) {
       var examplesFolder = parent.getChildAssumingFolder('examples');
       if (examplesFolder.exists &&
           examplesFolder.getChildAssumingFolder('api').exists) {
         return parent.path;
       }
       parent = parent.parent;
     }
     return null;
   }
 }
	// 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.

	import 'package:analyzer/dart/ast/ast.dart';
	import 'package:analyzer/dart/ast/token.dart';
	import 'package:analyzer/dart/ast/visitor.dart';
	import 'package:analyzer/dart/element/element.dart';
	import 'package:analyzer/file_system/file_system.dart';
	import 'package:analyzer/src/dart/ast/extensions.dart';
	import 'package:analyzer/src/dart/ast/utilities.dart';
	import 'package:analyzer/src/dart/element/element.dart';
	import 'package:analyzer_plugin/protocol/protocol_common.dart' as protocol;
	import 'package:analyzer_plugin/utilities/analyzer_converter.dart';
	import 'package:analyzer_plugin/utilities/navigation/navigation.dart';

	NavigationCollector computeDartNavigation(
	ResourceProvider resourceProvider,
	NavigationCollector collector,
	CompilationUnit unit,
	int? offset,
	int? length) {
	var dartCollector = _DartNavigationCollector(collector, offset, length);
	var visitor = _DartNavigationComputerVisitor(resourceProvider, dartCollector);
	if (offset == null \|\| length == null) {
	unit.accept(visitor);
	} else {
	var node = _getNodeForRange(unit, offset, length);
	if (node != null) {
	node = _getNavigationTargetNode(node);
	}
	node?.accept(visitor);
	}
	return collector;
	}

	/// Gets the nearest node that should be used for navigation.
	///
	/// This is usually the outermost node with the same offset as node but in some
	/// cases may be a different ancestor where required to produce the correct
	/// result.
	AstNode _getNavigationTargetNode(AstNode node) {
	AstNode? current = node;
	while (current != null &&
	current.parent != null &&
	current.offset == current.parent!.offset) {
	current = current.parent;
	}
	current ??= node;

	// To navigate to formal params, we need to visit the parameter and not just
	// the identifier but they don't start at the same offset as they have a
	// prefix.
	final parent = current.parent;
	if (parent is FormalParameter) {
	current = parent;
	}

	return current;
	}

	AstNode? _getNodeForRange(CompilationUnit unit, int offset, int length) {
	var node = NodeLocator(offset, offset + length).searchWithin(unit);
	for (var n = node; n != null; n = n.parent) {
	if (n is Directive) {
	return n;
	}
	}
	return node;
	}

	/// A Dart specific wrapper around [NavigationCollector].
	class _DartNavigationCollector {
	final NavigationCollector collector;
	final int? requestedOffset;
	final int? requestedLength;

	_DartNavigationCollector(
	this.collector, this.requestedOffset, this.requestedLength);

	void _addRegion(int offset, int length, Element? element) {
	element = element?.nonSynthetic;
	if (element == null \|\| element == DynamicElementImpl.instance) {
	return;
	}
	if (element.location == null) {
	return;
	}
	// Discard elements that don't span the offset/range given (if provided).
	if (!_isWithinRequestedRange(offset, length)) {
	return;
	}
	var converter = AnalyzerConverter();
	var kind = converter.convertElementKind(element.kind);
	var location = converter.locationFromElement(element);
	if (location == null) {
	return;
	}

	collector.addRegion(offset, length, kind, location, targetElement: element);
	}

	void _addRegionForNode(AstNode? node, Element? element) {
	if (node == null) {
	return;
	}
	var offset = node.offset;
	var length = node.length;
	_addRegion(offset, length, element);
	}

	void _addRegionForToken(Token token, Element? element) {
	var offset = token.offset;
	var length = token.length;
	_addRegion(offset, length, element);
	}

	/// Checks if offset/length intersect with the range the user requested
	/// navigation regions for.
	///
	/// If the request did not specify a range, always returns true.
	bool _isWithinRequestedRange(int offset, int length) {
	final requestedOffset = this.requestedOffset;
	if (requestedOffset == null) {
	return true;
	}
	if (offset > requestedOffset + (requestedLength ?? 0)) {
	// Starts after the requested range.
	return false;
	}
	if (offset + length < requestedOffset) {
	// Ends before the requested range.
	return false;
	}
	return true;
	}
	}

	class _DartNavigationComputerVisitor extends RecursiveAstVisitor<void> {
	final ResourceProvider resourceProvider;
	final _DartNavigationCollector computer;

	_DartNavigationComputerVisitor(this.resourceProvider, this.computer);

	@override
	void visitAnnotation(Annotation node) {
	var element = node.element;
	if (element is ConstructorElement && element.isSynthetic) {
	element = element.enclosingElement;
	}
	var name = node.name;
	if (name is PrefixedIdentifier) {
	// use constructor in: @PrefixClass.constructorName
	var prefixElement = name.prefix.staticElement;
	if (prefixElement is ClassElement) {
	prefixElement = element;
	}
	computer._addRegionForNode(name.prefix, prefixElement);
	// always constructor
	computer._addRegionForNode(name.identifier, element);
	} else {
	computer._addRegionForNode(name, element);
	}
	computer._addRegionForNode(node.constructorName, element);
	// type arguments
	node.typeArguments?.accept(this);
	// arguments
	node.arguments?.accept(this);
	}

	@override
	void visitAssignmentExpression(AssignmentExpression node) {
	node.leftHandSide.accept(this);
	computer._addRegionForToken(node.operator, node.staticElement);
	node.rightHandSide.accept(this);
	}

	@override
	void visitBinaryExpression(BinaryExpression node) {
	node.leftOperand.accept(this);
	computer._addRegionForToken(node.operator, node.staticElement);
	node.rightOperand.accept(this);
	}

	@override
	void visitComment(Comment node) {
	for (var commentReference in node.references) {
	commentReference.accept(this);
	}

	var inToolAnnotation = false;
	for (var token in node.tokens) {
	if (token.isEof) {
	break;
	}
	var strValue = token.toString();
	if (strValue.isEmpty) {
	continue;
	}

	if (inToolAnnotation) {
	if (strValue.contains('{@end-tool}')) {
	inToolAnnotation = false;
	} else if (strValue.contains('** See code in ')) {
	var startIndex = strValue.indexOf('** See code in ') + 15;
	var endIndex = strValue.indexOf('.dart') + 5;
	var pathSnippet = strValue.substring(startIndex, endIndex);
	var parentPath =
	_computeParentWithExamplesAPI(node, resourceProvider);
	if (parentPath != null) {
	var start = token.offset + startIndex;
	var end = token.offset + endIndex;
	computer.collector.addRegion(
	start,
	end - start,
	protocol.ElementKind.LIBRARY,
	protocol.Location(
	resourceProvider.pathContext.join(parentPath, pathSnippet),
	0,
	0,
	0,
	0,
	endLine: 0,
	endColumn: 0));
	}
	}
	} else if (strValue.contains('{@tool ')) {
	inToolAnnotation = true;
	}
	}
	}

	@override
	void visitCompilationUnit(CompilationUnit unit) {
	// prepare top-level nodes sorted by their offsets
	var nodes = <AstNode>[];
	nodes.addAll(unit.directives);
	nodes.addAll(unit.declarations);
	nodes.sort((a, b) {
	return a.offset - b.offset;
	});
	// visit sorted nodes
	for (var node in nodes) {
	node.accept(this);
	}
	}

	@override
	void visitConfiguration(Configuration node) {
	var source = node.uriSource;
	if (source != null) {
	if (resourceProvider.getResource(source.fullName).exists) {
	// TODO(brianwilkerson) If the analyzer ever resolves the URI to a
	// library, use that library element to create the region.
	var uriNode = node.uri;
	if (computer._isWithinRequestedRange(uriNode.offset, uriNode.length)) {
	computer.collector.addRegion(
	uriNode.offset,
	uriNode.length,
	protocol.ElementKind.LIBRARY,
	protocol.Location(source.fullName, 0, 0, 0, 0,
	endLine: 0, endColumn: 0));
	}
	}
	}
	super.visitConfiguration(node);
	}

	@override
	void visitConstructorDeclaration(ConstructorDeclaration node) {
	// For a default constructor, override the class name to be the declaration
	// itself rather than linking to the class.
	var name = node.name;
	if (name == null) {
	computer._addRegionForNode(node.returnType, node.declaredElement);
	} else {
	node.returnType.accept(this);
	name.accept(this);
	}
	node.parameters.accept(this);
	node.initializers.accept(this);
	node.redirectedConstructor?.accept(this);
	node.body.accept(this);
	}

	@override
	void visitConstructorName(ConstructorName node) {
	Element? element = node.staticElement;
	if (element == null) {
	return;
	}
	// add regions
	var typeName = node.type;
	// [prefix].ClassName
	{
	var name = typeName.name;
	var className = name;
	if (name is PrefixedIdentifier) {
	name.prefix.accept(this);
	className = name.identifier;
	}
	// For a named constructor, the class name points at the class.
	var classNameTargetElement =
	node.name != null ? className.staticElement : element;
	computer._addRegionForNode(className, classNameTargetElement);
	}
	// <TypeA, TypeB>
	typeName.typeArguments?.accept(this);
	// optional "name"
	if (node.name != null) {
	computer._addRegionForNode(node.name, element);
	}
	}

	@override
	void visitDeclaredIdentifier(DeclaredIdentifier node) {
	if (node.type == null) {
	var token = node.keyword;
	if (token != null && token.keyword == Keyword.VAR) {
	var inferredType = node.declaredElement?.type;
	var element = inferredType?.element;
	if (element != null) {
	computer._addRegionForToken(token, element);
	}
	}
	}
	super.visitDeclaredIdentifier(node);
	}

	@override
	void visitEnumConstantDeclaration(EnumConstantDeclaration node) {
	computer._addRegionForNode(node.name, node.constructorElement);

	var arguments = node.arguments;
	if (arguments != null) {
	computer._addRegionForNode(
	arguments.constructorSelector?.name,
	node.constructorElement,
	);
	arguments.typeArguments?.accept(this);
	arguments.argumentList.accept(this);
	}
	}

	@override
	void visitExportDirective(ExportDirective node) {
	var exportElement = node.element2;
	if (exportElement != null) {
	Element? libraryElement = exportElement.exportedLibrary;
	_addUriDirectiveRegion(node, libraryElement);
	}
	super.visitExportDirective(node);
	}

	@override
	void visitFieldFormalParameter(FieldFormalParameter node) {
	final element = node.declaredElement;
	if (element is FieldFormalParameterElementImpl) {
	computer._addRegionForToken(node.thisKeyword, element.field);
	computer._addRegionForNode(node.identifier, element.field);
	}

	node.type?.accept(this);
	node.typeParameters?.accept(this);
	node.parameters?.accept(this);
	}

	@override
	void visitImportDirective(ImportDirective node) {
	var importElement = node.element2;
	if (importElement != null) {
	Element? libraryElement = importElement.importedLibrary;
	_addUriDirectiveRegion(node, libraryElement);
	}
	super.visitImportDirective(node);
	}

	@override
	void visitIndexExpression(IndexExpression node) {
	super.visitIndexExpression(node);
	var element = node.writeOrReadElement;
	computer._addRegionForToken(node.leftBracket, element);
	computer._addRegionForToken(node.rightBracket, element);
	}

	@override
	void visitLibraryDirective(LibraryDirective node) {
	computer._addRegionForNode(node.name, node.element);
	}

	@override
	void visitPartDirective(PartDirective node) {
	final element = node.element;
	if (element is PartElement) {
	final uri = element.uri;
	if (uri is DirectiveUriWithUnit) {
	computer._addRegionForNode(node.uri, uri.unit);
	} else if (uri is DirectiveUriWithSource) {
	final uriNode = node.uri;
	final source = uri.source;
	computer.collector.addRegion(
	uriNode.offset,
	uriNode.length,
	protocol.ElementKind.FILE,
	protocol.Location(source.fullName, 0, 0, 0, 0,
	endLine: 0, endColumn: 0),
	);
	}
	}

	super.visitPartDirective(node);
	}

	@override
	void visitPartOfDirective(PartOfDirective node) {
	computer._addRegionForNode(node.libraryName ?? node.uri, node.element);
	super.visitPartOfDirective(node);
	}

	@override
	void visitPostfixExpression(PostfixExpression node) {
	super.visitPostfixExpression(node);
	computer._addRegionForToken(node.operator, node.staticElement);
	}

	@override
	void visitPrefixExpression(PrefixExpression node) {
	computer._addRegionForToken(node.operator, node.staticElement);
	super.visitPrefixExpression(node);
	}

	@override
	void visitRedirectingConstructorInvocation(
	RedirectingConstructorInvocation node) {
	Element? element = node.staticElement;
	if (element != null && element.isSynthetic) {
	element = element.enclosingElement;
	}
	// add region
	computer._addRegionForToken(node.thisKeyword, element);
	computer._addRegionForNode(node.constructorName, element);
	// process arguments
	node.argumentList.accept(this);
	}

	@override
	void visitSimpleIdentifier(SimpleIdentifier node) {
	var element = node.writeOrReadElement;
	computer._addRegionForNode(node, element);
	}

	@override
	void visitSuperConstructorInvocation(SuperConstructorInvocation node) {
	Element? element = node.staticElement;
	if (element != null && element.isSynthetic) {
	element = element.enclosingElement;
	}
	// add region
	computer._addRegionForToken(node.superKeyword, element);
	computer._addRegionForNode(node.constructorName, element);
	// process arguments
	node.argumentList.accept(this);
	}

	@override
	void visitSuperFormalParameter(SuperFormalParameter node) {
	var element = node.declaredElement;
	if (element is SuperFormalParameterElementImpl) {
	var superParameter = element.superConstructorParameter;
	computer._addRegionForToken(node.superKeyword, superParameter);
	computer._addRegionForNode(node.identifier, superParameter);
	}

	node.type?.accept(this);
	node.typeParameters?.accept(this);
	node.parameters?.accept(this);
	}

	@override
	void visitVariableDeclarationList(VariableDeclarationList node) {
	/// Return the element for the type inferred for each of the variables in
	/// the given list of [variables], or `null` if not all variable have the
	/// same inferred type.
	Element? getCommonElement(List<VariableDeclaration> variables) {
	var firstElement = variables[0].declaredElement?.type.element;
	if (firstElement == null) {
	return null;
	}
	for (var i = 1; i < variables.length; i++) {
	var element = variables[1].declaredElement?.type.element;
	if (element != firstElement) {
	return null;
	}
	}
	return firstElement;
	}

	if (node.type == null) {
	var token = node.keyword;
	if (token?.keyword == Keyword.VAR) {
	var element = getCommonElement(node.variables);
	if (element != null) {
	computer._addRegionForToken(token!, element);
	}
	}
	}
	super.visitVariableDeclarationList(node);
	}

	/// If the source of the given [element] (referenced by the [node]) exists,
	/// then add the navigation region from the [node] to the [element].
	void _addUriDirectiveRegion(UriBasedDirective node, Element? element) {
	var source = element?.source;
	if (source != null) {
	if (resourceProvider.getResource(source.fullName).exists) {
	computer._addRegionForNode(node.uri, element);
	}
	}
	}

	/// Given some [Comment], compute and return the parent directory absolute
	/// path which contains the directories 'examples/api/'. Null is returned if
	/// such directories are not found.
	String? _computeParentWithExamplesAPI(
	Comment node, ResourceProvider resourceProvider) {
	var source =
	node.thisOrAncestorOfType<CompilationUnit>()?.declaredElement?.source;
	if (source == null) {
	return null;
	}

	var file = resourceProvider.getFile(source.fullName);
	if (!file.exists) {
	return null;
	}
	var parent = file.parent;
	while (parent != parent.parent) {
	var examplesFolder = parent.getChildAssumingFolder('examples');
	if (examplesFolder.exists &&
	examplesFolder.getChildAssumingFolder('api').exists) {
	return parent.path;
	}
	parent = parent.parent;
	}
	return null;
	}
	}