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Google API Client Library for Java. Supports Java 5 (or higher) desktop (SE) and web (EE), Android, and Google App Engine.

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/*
 * Copyright (c) 2010 Google Inc.
 * 
 * Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
 * 
 * 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.api.client.util;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Map;

/**
 * Utilities for working with key/value data.
 * 
 * @since 1.0
 * @author Yaniv Inbar
 */
public class DataUtil {

  /**
   * Returns the map to use for the given key/value data.
   * 
   * @param data any key value data, represented by an object or a map, or
   *        {@code null}
   * @return if {@code data} is a map returns {@code data}; else if {@code data}
   *         is {@code null}, returns an empty map; else returns
   *         {@link ReflectionMap} on the data object
   */
  public static Map mapOf(Object data) {
    if (data == null) {
      return Collections.emptyMap();
    }
    if (data instanceof Map) {
      @SuppressWarnings("unchecked")
      Map result = (Map) data;
      return result;
    }
    return new ReflectionMap(data);
  }

  /**
   * Returns a deep clone of the given key/value data, such that the result is a
   * completely independent copy.
   * 
   * Note that final fields cannot be changed and therefore their value won't be
   * copied.
   * 
   * @param data key/value data object or map to clone or {@code null} for a
   *        {@code null} return value
   * @return deep clone or {@code null} for {@code null} input
   */
  public static  T clone(T data) {
    // don't need to clone primitive
    if (FieldInfo.isPrimitive(data)) {
      return data;
    }
    T copy;
    if (data instanceof GenericData) {
      // use clone method if possible
      @SuppressWarnings("unchecked")
      T copyTmp = (T) ((GenericData) data).clone();
      copy = copyTmp;
    } else if (data instanceof ArrayMap) {
      // use ArrayMap's clone method if possible
      @SuppressWarnings("unchecked")
      T copyTmp = (T) ((ArrayMap) data).clone();
      copy = copyTmp;
    } else {
      // else new to use default constructor
      @SuppressWarnings("unchecked")
      T copyTmp = (T) ClassInfo.newInstance(data.getClass());
      copy = copyTmp;
    }
    cloneInternal(data, copy);
    return copy;
  }

  static void cloneInternal(Object src, Object dest) {
    // TODO: support Java arrays?
    Class srcClass = src.getClass();
    if (Collection.class.isAssignableFrom(srcClass)) {
      @SuppressWarnings("unchecked")
      Collection