Initial implementation of MemoryIndexStoreImpl and IndexContributor.

editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/element/ElementProxy.java

Index: editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/element/ElementProxy.java
diff --git a/editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/element/ElementProxy.java b/editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/element/ElementProxy.java
new file mode 100644
index 0000000000000000000000000000000000000000..6c9754d65471d20cffeb8f09de68f516c6375424
--- /dev/null
+++ b/editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/element/ElementProxy.java
@@ -0,0 +1,139 @@
+/*
+ * Copyright (c) 2012, the Dart project authors.
+ * 
+ * Licensed under the Eclipse Public License v1.0 (the "License"); you may not use this file except
+ * in compliance with the License. You may obtain a copy of the License at
+ * 
+ * http://www.eclipse.org/legal/epl-v10.html
+ * 
+ * Unless required by applicable law or agreed to in writing, software distributed under the License
+ * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+ * or implied. See the License for the specific language governing permissions and limitations under
+ * the License.
+ */
+package com.google.dart.engine.element;
+
+import com.google.common.base.Objects;
+import com.google.dart.engine.context.AnalysisContext;
+import com.google.dart.engine.source.Source;
+
+/**
+ * Contains some properties of {@link Element}, which can be accessed without costly access to the
+ * {@link Element} itself.
+ */
+public class ElementProxy {
+  /**
+   * @return the {@link Source} which contains given {@link Element}, may be <code>null</code>.
+   */
+  private static Source findSource(Element element) {
+    while (element != null) {
+      if (element instanceof LibraryElement) {
+        element = ((LibraryElement) element).getDefiningCompilationUnit();
+      }
+      if (element instanceof CompilationUnitElement) {
+        return ((CompilationUnitElement) element).getSource();
+      }
+      element = element.getEnclosingElement();
+    }
+    return null;
+  }
+
+  private final AnalysisContext context;
+  private final Source source;
+  private final ElementLocation location;
+  private final ElementKind kind;
+  private final String name;
+  private final int nameOffset;
+
+  /**
+   * Initializes {@link ElementProxy} using information about {@link Element}.
+   */
+  public ElementProxy(AnalysisContext context, Source source, ElementLocation location,
+      ElementKind kind, String name, int nameOffset) {
+    this.context = context;
+    this.source = source;
+    this.location = location;
+    this.kind = kind;
+    this.name = name;
+    this.nameOffset = nameOffset;
+  }
+
+  /**
+   * Initializes {@link ElementProxy} using existing {@link Element} instance.
+   */
+  public ElementProxy(Element element) {
+    context = element.getContext();
+    source = findSource(element);
+    location = element.getLocation();
+    kind = element.getKind();
+    name = element.getName();
+    nameOffset = element.getNameOffset();
+  }
+
+  @Override
+  public boolean equals(Object obj) {
+    if (!(obj instanceof ElementProxy)) {
+      return false;
+    }
+    ElementProxy proxy = (ElementProxy) obj;
+    return proxy.getContext() == context && Objects.equal(location, proxy.location)
+        && Objects.equal(source, proxy.source) && kind == proxy.kind
+        && Objects.equal(name, proxy.name) && nameOffset == proxy.nameOffset;
+  }
+
+  /**
+   * @return the {@link AnalysisContext} in which defines this {@link Element}.
+   */
+  public AnalysisContext getContext() {
+    return context;
+  }
+
+  /**
+   * @see Element#getKind()
+   */
+  public ElementKind getKind() {
+    return kind;
+  }
+
+  /**
+   * @return the {@link ElementLocation} of this {@link Element}.
+   */
+  public ElementLocation getLocation() {
+    return location;
+  }
+
+  /**
+   * @see Element#getName()
+   */
+  public String getName() {
+    return name;
+  }
+
+  /**
+   * @see Element#getNameOffset()
+   */
+  public int getNameOffset() {
+    return nameOffset;
+  }
+
+  /**
+   * @return the {@link Source} which defines this {@link Element}.
+   */
+  public Source getSource() {
+    return source;
+  }
+
+  @Override
+  public int hashCode() {
+    return Objects.hashCode(context, location);
+  }
+
+  /**
+   * Returns the actual {@link Element} instance, may be loaded from disk. This method may be slow.
+   * 
+   * @return the actual {@link Element} instance.
+   */
+  public Element requestElement() {
+    return context.getElement(location);
+  }
+}