Version 1.5.6

dart/editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/internal/index/file/ContextCodec.java

+/*
+ * Copyright (c) 2014, 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.internal.index.file;
+
+import com.google.common.collect.Maps;
+import com.google.dart.engine.context.AnalysisContext;
+
+import java.util.Map;
+
+/**
+ * A helper that encodes/decodes {@link AnalysisContext}s from/to integers.
+ * 
+ * @coverage dart.engine.index
+ */
+public class ContextCodec {
+  /**
+   * A table mapping contexts to their unique indices.
+   */
+  private final Map<AnalysisContext, Integer> contextToIndex = Maps.newHashMap();
+
+  /**
+   * A table mapping indices to the corresponding contexts.
+   */
+  private final Map<Integer, AnalysisContext> indexToContext = Maps.newHashMap();
+
+  /**
+   * The next id to assign.
+   */
+  private int nextId;
+
+  /**
+   * Returns the {@link AnalysisContext} that corresponds to the given index.
+   */
+  public AnalysisContext decode(int index) {
+    return indexToContext.get(index);
+  }
+
+  /**
+   * Returns an unique index for the given {@link AnalysisContext}.
+   */
+  public int encode(AnalysisContext context) {
+    Integer index = contextToIndex.get(context);
+    if (index == null) {
+      index = nextId++;
+      contextToIndex.put(context, index);
+      indexToContext.put(index, context);
+    }
+    return index;
+  }
+
+  /**
+   * Removes the given {@link AnalysisContext}.
+   */
+  public void removeContext(AnalysisContext context) {
+    Integer id = contextToIndex.remove(context);
+    if (id != null) {
+      indexToContext.remove(id);
+    }
+  }
+}