Analyzer support for `@factory` methods (linter#253).

pkg/analyzer/lib/src/dart/element/element.dart

 // Copyright (c) 2014, 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.
 
 library analyzer.src.dart.element.element;
 
 import 'dart:collection';
 import 'dart:math' show min;
 
 import 'package:analyzer/dart/ast/ast.dart';
@@ skipping 2444 matching lines @@
    */
   static String _DEPRECATED_CLASS_NAME = "Deprecated";
 
   /**
    * The name of the top-level variable used to mark an element as being
    * deprecated.
    */
   static String _DEPRECATED_VARIABLE_NAME = "deprecated";
 
   /**
+   * The name of the top-level variable used to mark a method as being a
+   * factory.
+   */
+  static String _FACTORY_VARIABLE_NAME = "factory";
+
+  /**
    * The name of the class used to JS annotate an element.
    */
   static String _JS_CLASS_NAME = "JS";
 
   /**
    * The name of `js` library, used to define JS annotations.
    */
   static String _JS_LIB_NAME = "js";
 
   /**
@@ skipping 78 matching lines @@
       if (element is ConstructorElement) {
         return element.enclosingElement.name == _DEPRECATED_CLASS_NAME;
       } else if (element is PropertyAccessorElement) {
         return element.name == _DEPRECATED_VARIABLE_NAME;
       }
     }
     return false;
   }
 
   @override
+  bool get isFactory =>
+      element is PropertyAccessorElement &&
+          element.name == _FACTORY_VARIABLE_NAME &&
+          element.library?.name == _META_LIB_NAME;
+
+  @override
   bool get isJS =>
       element is ConstructorElement &&
       element.enclosingElement.name == _JS_CLASS_NAME &&
       element.library?.name == _JS_LIB_NAME;
 
   @override
   bool get isMustCallSuper =>
       element is PropertyAccessorElement &&
       element.name == _MUST_CALL_SUPER_VARIABLE_NAME &&
       element.library?.name == _META_LIB_NAME;
@@ skipping 223 matching lines @@
   bool get isDeprecated {
     for (ElementAnnotation annotation in metadata) {
       if (annotation.isDeprecated) {
         return true;
       }
     }
     return false;
   }
 
   @override
+  bool get isFactory {
+    for (ElementAnnotation annotation in metadata) {
+      if (annotation.isFactory) {
+        return true;
+      }
+    }
+    return false;
+  }
+
+  @override
   bool get isJS {
     for (ElementAnnotation annotation in metadata) {
       if (annotation.isJS) {
         return true;
       }
     }
     return false;
   }
 
   @override
@@ skipping 3659 matching lines @@
   @override
   String get documentationComment => null;
 
   @override
   Element get enclosingElement => null;
 
   @override
   bool get isDeprecated => false;
 
   @override
+  bool get isFactory => false;
+
+  @override
   bool get isJS => false;
 
   @override
   bool get isOverride => false;
 
   @override
   bool get isPrivate {
     String name = displayName;
     if (name == null) {
       return false;
@@ skipping 1947 matching lines @@
 
   @override
   void visitElement(Element element) {
     int offset = element.nameOffset;
     if (offset != -1) {
       map[offset] = element;
     }
     super.visitElement(element);
   }
 }