Improve 'length' instance property reference encoding.

pkg/analyzer/lib/src/summary/summarize_elements.dart

 // 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.
 
 library serialization.elements;
 
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/dart/element/type.dart';
 import 'package:analyzer/src/dart/element/element.dart';
 import 'package:analyzer/src/dart/element/type.dart';
@@ skipping 781 matching lines @@
           .add(() => serializeTypeRef(type, context, linked: true, slot: slot));
     }
     return slot;
   }
 
   int _getElementReferenceId(Element element, {bool linked: false}) {
     return referenceMap.putIfAbsent(element, () {
       if (element is ConstructorElement && element.displayName.isEmpty) {
         return _getElementReferenceId(element.enclosingElement, linked: linked);
       }
+      if (element is PropertyAccessorElement) {
+        Element enclosing = element.enclosingElement;
+        if (!(enclosing is CompilationUnitElement || element.isStatic)) {
+          throw new StateError(
+              'Only top-level or static property accessors can be serialized.');
+        }
+      }
       LibraryElement dependentLibrary = element?.library;
       int unit;
       if (dependentLibrary == null) {
         assert(element == librarySerializer.typeProvider.dynamicType.element ||
             element == null);
         unit = 0;
         dependentLibrary = librarySerializer.libraryElement;
       } else {
         CompilationUnitElement unitElement =
             element.getAncestor((Element e) => e is CompilationUnitElement);
@@ skipping 30 matching lines @@
           prefixReference = _getElementReferenceId(enclosing, linked: linked);
         }
         unlinkedReferences.add(new UnlinkedReferenceBuilder(
             name: name, prefixReference: prefixReference));
       }
       int index = linkedReferences.length;
       linkedReferences.add(linkedReference);
       return index;
     });
   }
+
+  int _getLengthPropertyReference(int prefix) {
+    assert(unlinkedReferences.length == linkedReferences.length);
+    int index = linkedReferences.length;
+    unlinkedReferences.add(
+        new UnlinkedReferenceBuilder(name: 'length', prefixReference: prefix));
+    LinkedReferenceBuilder linkedReference =
+        new LinkedReferenceBuilder(kind: ReferenceKind.length);
+    linkedReferences.add(linkedReference);
+    return index;
+  }
 }
 
 /**
  * Instances of this class keep track of intermediate state during
  * serialization of a single constant [Expression].
  */
 class _ConstExprSerializer extends AbstractConstExprSerializer {
   final _CompilationUnitSerializer serializer;
 
   _ConstExprSerializer(this.serializer);
 
   @override
   EntityRefBuilder serializeConstructorName(ConstructorName constructor) {
     ConstructorElement element = constructor.staticElement;
     assert(element != null);
     int referenceId = serializer._getElementReferenceId(element);
     return new EntityRefBuilder(reference: referenceId);
   }
 
   EntityRefBuilder serializeIdentifier(Identifier identifier) {
     Element element = identifier.staticElement;
     assert(element != null);
+    // The only supported instance property accessor - `length`.
+    if (identifier is PrefixedIdentifier &&
+        element is PropertyAccessorElement &&
+        !element.isStatic) {
+      assert(element.name == 'length');
+      Element prefixElement = identifier.prefix.staticElement;
+      int prefixRef = serializer._getElementReferenceId(prefixElement);
+      int lengthRef = serializer._getLengthPropertyReference(prefixRef);
+      return new EntityRefBuilder(reference: lengthRef);
+    }
     return new EntityRefBuilder(
         reference: serializer._getElementReferenceId(element));
   }
 
   @override
   EntityRefBuilder serializePropertyAccess(PropertyAccess access) {
     Element element = access.propertyName.staticElement;
     assert(element != null);
+    // The only supported instance property accessor - `length`.
+    Expression target = access.target;
+    if (target is Identifier && element is PropertyAccessorElement &&
+        !element.isStatic) {
+      assert(element.name == 'length');
+      Element prefixElement = target.staticElement;
+      int prefixRef = serializer._getElementReferenceId(prefixElement);
+      int lengthRef = serializer._getLengthPropertyReference(prefixRef);
+      return new EntityRefBuilder(reference: lengthRef);
+    }
     return new EntityRefBuilder(
         reference: serializer._getElementReferenceId(element));
   }
 
   @override
   EntityRefBuilder serializeType(TypeName typeName) {
     DartType type = typeName != null ? typeName.type : DynamicTypeImpl.instance;
     return serializer.serializeTypeRef(type, null);
   }
 }
@@ skipping 181 matching lines @@
       exportNames.add(new LinkedExportNameBuilder(
           name: name,
           dependency: serializeDependency(dependentLibrary),
           unit: unit,
           kind: kind));
     }
     pb.exportNames = exportNames;
     return pb;
   }
 }