lib/src/ast.dart - linter - 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.

 /// Common AST helpers.
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/dart/element/visitor.dart';
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/src/workspace/workspace.dart'; // ignore: implementation_imports
 import 'package:path/path.dart' as path;

 import 'analyzer.dart';
 import 'utils.dart';

 /// Returns direct children of [parent].
 List<Element> getChildren(Element parent, [String name]) {
   final children = <Element>[];
   visitChildren(parent, (Element element) {
     if (name == null || element.displayName == name) {
       children.add(element);
     }
     return false;
   });
   return children;
 }

 /// Return the compilation unit of a node
 CompilationUnit getCompilationUnit(AstNode node) =>
     node.thisOrAncestorOfType<CompilationUnit>();

 /// Returns a field identifier with the given [name] in the given [decl]'s
 /// variable declaration list or `null` if none is found.
 SimpleIdentifier getFieldIdentifier(FieldDeclaration decl, String name) {
   for (var v in decl.fields.variables) {
     if (v.name?.name == name) {
       return v.name;
     }
   }
   return null;
 }

 /// Returns the most specific AST node appropriate for associating errors.
 AstNode getNodeToAnnotate(Declaration node) {
   final mostSpecific = _getNodeToAnnotate(node);
   return mostSpecific ?? node;
 }

 bool hasConstantError(LinterContext context, Expression node) {
   var result = context.evaluateConstant(node);
   return result.errors.isNotEmpty;
 }

 /// Returns `true` if this [element] has a `@literal` annotation.
 bool hasLiteralAnnotation(Element element) {
   final metadata = element.metadata;
   for (var i = 0; i < metadata.length; i++) {
     if (metadata[i].isLiteral) {
       return true;
     }
   }
   return false;
 }

 /// Returns `true` if this [element] has an `@override` annotation.
 bool hasOverrideAnnotation(Element element) {
   final metadata = element.metadata;
   for (var i = 0; i < metadata.length; i++) {
     if (metadata[i].isOverride) {
       return true;
     }
   }
   return false;
 }

 /// Returns `true` if this [node] is the child of a private compilation unit
 /// member.
 bool inPrivateMember(AstNode node) {
   final parent = node.parent;
   if (parent is NamedCompilationUnitMember) {
     return isPrivate(parent.name);
   }
   if (parent is ExtensionDeclaration) {
     return parent.name == null || isPrivate(parent.name);
   }
   return false;
 }

 /// Returns `true` if the given [declaration] is annotated `@deprecated`.
 bool isDeprecated(Declaration declaration) =>
     declaration.declaredElement.hasDeprecated;

 /// Returns `true` if this element is the `==` method declaration.
 bool isEquals(ClassMember element) =>
     element is MethodDeclaration && element.name?.name == '==';

 /// Returns `true` if the keyword associated with this token is `final` or
 /// `const`.
 bool isFinalOrConst(Token token) =>
     isKeyword(token, Keyword.FINAL) || isKeyword(token, Keyword.CONST);

 /// Returns `true` if this element is a `hashCode` method or field declaration.
 bool isHashCode(ClassMember element) =>
     (element is MethodDeclaration && element.name?.name == 'hashCode') ||
     (element is FieldDeclaration &&
         getFieldIdentifier(element, 'hashCode') != null);

 /// Return true if this compilation unit [node] is declared within the given
 /// [package]'s `lib/` directory tree.
 bool isInLibDir(CompilationUnit node, WorkspacePackage package) {
   if (package == null) return false;
   final cuPath = node.declaredElement.library?.source?.fullName;
   if (cuPath == null) return false;
   final libDir = path.join(package.root, 'lib');
   return path.isWithin(libDir, cuPath);
 }

 /// Returns `true` if the keyword associated with the given [token] matches
 /// [keyword].
 bool isKeyword(Token token, Keyword keyword) =>
     token is KeywordToken && token.keyword == keyword;

 /// Returns `true` if the given [id] is a Dart keyword.
 bool isKeyWord(String id) => Keyword.keywords.keys.contains(id);

 /// Returns `true` if the given [ClassMember] is a method.
 bool isMethod(ClassMember m) => m is MethodDeclaration;

 /// Check if the given identifier has a private name.
 bool isPrivate(SimpleIdentifier identifier) =>
     identifier != null ? Identifier.isPrivateName(identifier.name) : false;

 /// Returns `true` if the given [declaration] is annotated `@protected`.
 bool isProtected(Declaration declaration) =>
     declaration.metadata.any((Annotation a) => a.name.name == 'protected');

 /// Returns `true` if the given [ClassMember] is a public method.
 bool isPublicMethod(ClassMember m) => isMethod(m) && m.declaredElement.isPublic;

 /// Returns `true` if the given method [declaration] is a "simple getter".
 ///
 /// A simple getter takes one of these basic forms:
 ///
 ///     get x => _simpleIdentifier;
 /// or
 ///     get x {
 ///       return _simpleIdentifier;
 ///     }
 bool isSimpleGetter(MethodDeclaration declaration) {
   if (!declaration.isGetter) {
     return false;
   }
   var body = declaration.body;
   if (body is ExpressionFunctionBody) {
     return _checkForSimpleGetter(declaration, body.expression);
   } else if (body is BlockFunctionBody) {
     final block = body.block;
     if (block.statements.length == 1) {
       var statement = block.statements[0];
       if (statement is ReturnStatement) {
         return _checkForSimpleGetter(declaration, statement.expression);
       }
     }
   }
   return false;
 }

 /// Returns `true` if the given [setter] is a "simple setter".
 ///
 /// A simple setter takes this basic form:
 ///
 ///     var _x;
 ///     set(x) {
 ///       _x = x;
 ///     }
 ///
 /// or:
 ///
 ///     set(x) => _x = x;
 ///
 /// where the static type of the left and right hand sides must be the same.
 bool isSimpleSetter(MethodDeclaration setter) {
   var body = setter.body;
   if (body is ExpressionFunctionBody) {
     return _checkForSimpleSetter(setter, body.expression);
   } else if (body is BlockFunctionBody) {
     final block = body.block;
     if (block.statements.length == 1) {
       var statement = block.statements[0];
       if (statement is ExpressionStatement) {
         return _checkForSimpleSetter(setter, statement.expression);
       }
     }
   }

   return false;
 }

 /// Returns `true` if the given [id] is a valid Dart identifier.
 bool isValidDartIdentifier(String id) => !isKeyWord(id) && isIdentifier(id);

 /// Returns `true` if the keyword associated with this token is `var`.
 bool isVar(Token token) => isKeyword(token, Keyword.VAR);

 /// Return the nearest enclosing pubspec file.
 File locatePubspecFile(CompilationUnit compilationUnit) {
   final fullName = compilationUnit?.declaredElement?.source?.fullName;
   if (fullName == null) {
     return null;
   }

   final resourceProvider =
       compilationUnit?.declaredElement?.session?.resourceProvider;
   if (resourceProvider == null) {
     return null;
   }

   final file = resourceProvider.getFile(fullName);
   var folder = file.parent;

   // Look for a pubspec.yaml file.
   while (folder != null) {
     final pubspecFile = folder.getChildAssumingFile('pubspec.yaml');
     if (pubspecFile.exists) {
       return pubspecFile;
     }
     folder = folder.parent;
   }

   return null;
 }

 /// Uses [processor] to visit all of the children of [element].
 /// If [processor] returns `true`, then children of a child are visited too.
 void visitChildren(Element element, ElementProcessor processor) {
   element.visitChildren(_ElementVisitorAdapter(processor));
 }

 bool _checkForSimpleGetter(MethodDeclaration getter, Expression expression) {
   if (expression is SimpleIdentifier) {
     var staticElement = expression.staticElement;
     if (staticElement is PropertyAccessorElement) {
       Element getterElement = getter.declaredElement;
       // Skipping library level getters, test that the enclosing element is
       // the same
       if (staticElement.enclosingElement != null &&
           (staticElement.enclosingElement == getterElement.enclosingElement)) {
         return staticElement.isSynthetic && staticElement.variable.isPrivate;
       }
     }
   }
   return false;
 }

 bool _checkForSimpleSetter(MethodDeclaration setter, Expression expression) {
   if (expression is! AssignmentExpression) {
     return false;
   }
   final assignment = expression as AssignmentExpression;

   var leftHandSide = assignment.leftHandSide;
   var rightHandSide = assignment.rightHandSide;
   if (leftHandSide is SimpleIdentifier && rightHandSide is SimpleIdentifier) {
     var leftElement = leftHandSide.staticElement;
     if (leftElement is! PropertyAccessorElement || !leftElement.isSynthetic) {
       return false;
     }

     // To guard against setters used as type constraints
     if (leftHandSide.staticType != rightHandSide.staticType) {
       return false;
     }

     var rightElement = rightHandSide.staticElement;
     if (rightElement is! ParameterElement) {
       return false;
     }

     var parameters = setter.parameters.parameters;
     if (parameters.length == 1) {
       return rightElement == parameters[0].declaredElement;
     }
   }

   return false;
 }

 AstNode _getNodeToAnnotate(Declaration node) {
   if (node is MethodDeclaration) {
     return node.name;
   }
   if (node is ConstructorDeclaration) {
     return node.name;
   }
   if (node is FieldDeclaration) {
     return node.fields;
   }
   if (node is ClassTypeAlias) {
     return node.name;
   }
   if (node is FunctionTypeAlias) {
     return node.name;
   }
   if (node is ClassDeclaration) {
     return node.name;
   }
   if (node is EnumDeclaration) {
     return node.name;
   }
   if (node is FunctionDeclaration) {
     return node.name;
   }
   if (node is TopLevelVariableDeclaration) {
     return node.variables;
   }
   if (node is EnumConstantDeclaration) {
     return node.name;
   }
   if (node is TypeParameter) {
     return node.name;
   }
   if (node is VariableDeclaration) {
     return node.name;
   }
   return null;
 }

 /// An [Element] processor function type.
 /// If `true` is returned, children of [element] will be visited.
 typedef ElementProcessor = bool Function(Element element);

 /// A [GeneralizingElementVisitor] adapter for [ElementProcessor].
 class _ElementVisitorAdapter extends GeneralizingElementVisitor {
   final ElementProcessor processor;

   _ElementVisitorAdapter(this.processor);

   @override
   void visitElement(Element element) {
     final visitChildren = processor(element);
     if (visitChildren == true) {
       element.visitChildren(this);
     }
   }
 }
	// 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.

	/// Common AST helpers.
	import 'package:analyzer/dart/ast/ast.dart';
	import 'package:analyzer/dart/ast/token.dart';
	import 'package:analyzer/dart/element/element.dart';
	import 'package:analyzer/dart/element/visitor.dart';
	import 'package:analyzer/file_system/file_system.dart';
	import 'package:analyzer/src/workspace/workspace.dart'; // ignore: implementation_imports
	import 'package:path/path.dart' as path;

	import 'analyzer.dart';
	import 'utils.dart';

	/// Returns direct children of [parent].
	List<Element> getChildren(Element parent, [String name]) {
	final children = <Element>[];
	visitChildren(parent, (Element element) {
	if (name == null \|\| element.displayName == name) {
	children.add(element);
	}
	return false;
	});
	return children;
	}

	/// Return the compilation unit of a node
	CompilationUnit getCompilationUnit(AstNode node) =>
	node.thisOrAncestorOfType<CompilationUnit>();

	/// Returns a field identifier with the given [name] in the given [decl]'s
	/// variable declaration list or `null` if none is found.
	SimpleIdentifier getFieldIdentifier(FieldDeclaration decl, String name) {
	for (var v in decl.fields.variables) {
	if (v.name?.name == name) {
	return v.name;
	}
	}
	return null;
	}

	/// Returns the most specific AST node appropriate for associating errors.
	AstNode getNodeToAnnotate(Declaration node) {
	final mostSpecific = _getNodeToAnnotate(node);
	return mostSpecific ?? node;
	}

	bool hasConstantError(LinterContext context, Expression node) {
	var result = context.evaluateConstant(node);
	return result.errors.isNotEmpty;
	}

	/// Returns `true` if this [element] has a `@literal` annotation.
	bool hasLiteralAnnotation(Element element) {
	final metadata = element.metadata;
	for (var i = 0; i < metadata.length; i++) {
	if (metadata[i].isLiteral) {
	return true;
	}
	}
	return false;
	}

	/// Returns `true` if this [element] has an `@override` annotation.
	bool hasOverrideAnnotation(Element element) {
	final metadata = element.metadata;
	for (var i = 0; i < metadata.length; i++) {
	if (metadata[i].isOverride) {
	return true;
	}
	}
	return false;
	}

	/// Returns `true` if this [node] is the child of a private compilation unit
	/// member.
	bool inPrivateMember(AstNode node) {
	final parent = node.parent;
	if (parent is NamedCompilationUnitMember) {
	return isPrivate(parent.name);
	}
	if (parent is ExtensionDeclaration) {
	return parent.name == null \|\| isPrivate(parent.name);
	}
	return false;
	}

	/// Returns `true` if the given [declaration] is annotated `@deprecated`.
	bool isDeprecated(Declaration declaration) =>
	declaration.declaredElement.hasDeprecated;

	/// Returns `true` if this element is the `==` method declaration.
	bool isEquals(ClassMember element) =>
	element is MethodDeclaration && element.name?.name == '==';

	/// Returns `true` if the keyword associated with this token is `final` or
	/// `const`.
	bool isFinalOrConst(Token token) =>
	isKeyword(token, Keyword.FINAL) \|\| isKeyword(token, Keyword.CONST);

	/// Returns `true` if this element is a `hashCode` method or field declaration.
	bool isHashCode(ClassMember element) =>
	(element is MethodDeclaration && element.name?.name == 'hashCode') \|\|
	(element is FieldDeclaration &&
	getFieldIdentifier(element, 'hashCode') != null);

	/// Return true if this compilation unit [node] is declared within the given
	/// [package]'s `lib/` directory tree.
	bool isInLibDir(CompilationUnit node, WorkspacePackage package) {
	if (package == null) return false;
	final cuPath = node.declaredElement.library?.source?.fullName;
	if (cuPath == null) return false;
	final libDir = path.join(package.root, 'lib');
	return path.isWithin(libDir, cuPath);
	}

	/// Returns `true` if the keyword associated with the given [token] matches
	/// [keyword].
	bool isKeyword(Token token, Keyword keyword) =>
	token is KeywordToken && token.keyword == keyword;

	/// Returns `true` if the given [id] is a Dart keyword.
	bool isKeyWord(String id) => Keyword.keywords.keys.contains(id);

	/// Returns `true` if the given [ClassMember] is a method.
	bool isMethod(ClassMember m) => m is MethodDeclaration;

	/// Check if the given identifier has a private name.
	bool isPrivate(SimpleIdentifier identifier) =>
	identifier != null ? Identifier.isPrivateName(identifier.name) : false;

	/// Returns `true` if the given [declaration] is annotated `@protected`.
	bool isProtected(Declaration declaration) =>
	declaration.metadata.any((Annotation a) => a.name.name == 'protected');

	/// Returns `true` if the given [ClassMember] is a public method.
	bool isPublicMethod(ClassMember m) => isMethod(m) && m.declaredElement.isPublic;

	/// Returns `true` if the given method [declaration] is a "simple getter".
	///
	/// A simple getter takes one of these basic forms:
	///
	/// get x => _simpleIdentifier;
	/// or
	/// get x {
	/// return _simpleIdentifier;
	/// }
	bool isSimpleGetter(MethodDeclaration declaration) {
	if (!declaration.isGetter) {
	return false;
	}
	var body = declaration.body;
	if (body is ExpressionFunctionBody) {
	return _checkForSimpleGetter(declaration, body.expression);
	} else if (body is BlockFunctionBody) {
	final block = body.block;
	if (block.statements.length == 1) {
	var statement = block.statements[0];
	if (statement is ReturnStatement) {
	return _checkForSimpleGetter(declaration, statement.expression);
	}
	}
	}
	return false;
	}

	/// Returns `true` if the given [setter] is a "simple setter".
	///
	/// A simple setter takes this basic form:
	///
	/// var _x;
	/// set(x) {
	/// _x = x;
	/// }
	///
	/// or:
	///
	/// set(x) => _x = x;
	///
	/// where the static type of the left and right hand sides must be the same.
	bool isSimpleSetter(MethodDeclaration setter) {
	var body = setter.body;
	if (body is ExpressionFunctionBody) {
	return _checkForSimpleSetter(setter, body.expression);
	} else if (body is BlockFunctionBody) {
	final block = body.block;
	if (block.statements.length == 1) {
	var statement = block.statements[0];
	if (statement is ExpressionStatement) {
	return _checkForSimpleSetter(setter, statement.expression);
	}
	}
	}

	return false;
	}

	/// Returns `true` if the given [id] is a valid Dart identifier.
	bool isValidDartIdentifier(String id) => !isKeyWord(id) && isIdentifier(id);

	/// Returns `true` if the keyword associated with this token is `var`.
	bool isVar(Token token) => isKeyword(token, Keyword.VAR);

	/// Return the nearest enclosing pubspec file.
	File locatePubspecFile(CompilationUnit compilationUnit) {
	final fullName = compilationUnit?.declaredElement?.source?.fullName;
	if (fullName == null) {
	return null;
	}

	final resourceProvider =
	compilationUnit?.declaredElement?.session?.resourceProvider;
	if (resourceProvider == null) {
	return null;
	}

	final file = resourceProvider.getFile(fullName);
	var folder = file.parent;

	// Look for a pubspec.yaml file.
	while (folder != null) {
	final pubspecFile = folder.getChildAssumingFile('pubspec.yaml');
	if (pubspecFile.exists) {
	return pubspecFile;
	}
	folder = folder.parent;
	}

	return null;
	}

	/// Uses [processor] to visit all of the children of [element].
	/// If [processor] returns `true`, then children of a child are visited too.
	void visitChildren(Element element, ElementProcessor processor) {
	element.visitChildren(_ElementVisitorAdapter(processor));
	}

	bool _checkForSimpleGetter(MethodDeclaration getter, Expression expression) {
	if (expression is SimpleIdentifier) {
	var staticElement = expression.staticElement;
	if (staticElement is PropertyAccessorElement) {
	Element getterElement = getter.declaredElement;
	// Skipping library level getters, test that the enclosing element is
	// the same
	if (staticElement.enclosingElement != null &&
	(staticElement.enclosingElement == getterElement.enclosingElement)) {
	return staticElement.isSynthetic && staticElement.variable.isPrivate;
	}
	}
	}
	return false;
	}

	bool _checkForSimpleSetter(MethodDeclaration setter, Expression expression) {
	if (expression is! AssignmentExpression) {
	return false;
	}
	final assignment = expression as AssignmentExpression;

	var leftHandSide = assignment.leftHandSide;
	var rightHandSide = assignment.rightHandSide;
	if (leftHandSide is SimpleIdentifier && rightHandSide is SimpleIdentifier) {
	var leftElement = leftHandSide.staticElement;
	if (leftElement is! PropertyAccessorElement \|\| !leftElement.isSynthetic) {
	return false;
	}

	// To guard against setters used as type constraints
	if (leftHandSide.staticType != rightHandSide.staticType) {
	return false;
	}

	var rightElement = rightHandSide.staticElement;
	if (rightElement is! ParameterElement) {
	return false;
	}

	var parameters = setter.parameters.parameters;
	if (parameters.length == 1) {
	return rightElement == parameters[0].declaredElement;
	}
	}

	return false;
	}

	AstNode _getNodeToAnnotate(Declaration node) {
	if (node is MethodDeclaration) {
	return node.name;
	}
	if (node is ConstructorDeclaration) {
	return node.name;
	}
	if (node is FieldDeclaration) {
	return node.fields;
	}
	if (node is ClassTypeAlias) {
	return node.name;
	}
	if (node is FunctionTypeAlias) {
	return node.name;
	}
	if (node is ClassDeclaration) {
	return node.name;
	}
	if (node is EnumDeclaration) {
	return node.name;
	}
	if (node is FunctionDeclaration) {
	return node.name;
	}
	if (node is TopLevelVariableDeclaration) {
	return node.variables;
	}
	if (node is EnumConstantDeclaration) {
	return node.name;
	}
	if (node is TypeParameter) {
	return node.name;
	}
	if (node is VariableDeclaration) {
	return node.name;
	}
	return null;
	}

	/// An [Element] processor function type.
	/// If `true` is returned, children of [element] will be visited.
	typedef ElementProcessor = bool Function(Element element);

	/// A [GeneralizingElementVisitor] adapter for [ElementProcessor].
	class _ElementVisitorAdapter extends GeneralizingElementVisitor {
	final ElementProcessor processor;

	_ElementVisitorAdapter(this.processor);

	@override
	void visitElement(Element element) {
	final visitChildren = processor(element);
	if (visitChildren == true) {
	element.visitChildren(this);
	}
	}
	}