content: /*
   * Copyright (C) 2015 The Android Open Source Project
   *
   * 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 android.os;
  
  import java.util.HashMap;
  
  /**
   * Helper class for writing pooled strings into a Parcel.  It must be used
   * in conjunction with {@link android.os.PooledStringReader}.  This really needs
   * to be pushed in to Parcel itself, but doing that is...  complicated.
   * @hide
   */
  public class PooledStringWriter {
      private final Parcel mOut;
  
      /**
       * Book-keeping for writing pooled string objects, mapping strings we have
       * written so far to their index in the pool.  We deliberately use HashMap
       * here since performance is critical, we expect to be doing lots of adds to
       * it, and it is only a temporary object so its overall memory footprint is
       * not a signifciant issue.
       */
      private final HashMap<String, Integer> mPool;
  
      /**
       * Book-keeping for writing pooling string objects, indicating where we
       * started writing the pool, which is where we need to ultimately store
       * how many strings are in the pool.
       */
      private int mStart;
  
      /**
       * Next available index in the pool.
       */
      private int mNext;
  
      public PooledStringWriter(Parcel out) {
          mOut = out;
          mPool = new HashMap<>();
          mStart = out.dataPosition();
          out.writeInt(0); // reserve space for final pool size.
      }
  
      public void writeString(String str) {
          final Integer cur = mPool.get(str);
          if (cur != null) {
              mOut.writeInt(cur);
          } else {
              mPool.put(str, mNext);
              mOut.writeInt(-(mNext+1));
              mOut.writeString(str);
              mNext++;
          }
      }
  
      public int getStringCount() {
          return mPool.size();
      }
  
      public void finish() {
          final int pos = mOut.dataPosition();
          mOut.setDataPosition(mStart);
          mOut.writeInt(mNext);
          mOut.setDataPosition(pos);
      }
  }
  