code: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements. See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership. The ASF licenses this file
   * to you 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.
   */
  /*
   * $Id$
   */
  package org.apache.xml.utils;
  
  /**
   * This class pools string buffers, since they are reused so often.
   * String buffers are good candidates for pooling, because of 
   * their supporting character arrays.
   * @xsl.usage internal
   */
  public class StringBufferPool
  {
  
    /** The global pool of string buffers.   */
    private static ObjectPool m_stringBufPool =
      new ObjectPool(org.apache.xml.utils.FastStringBuffer.class);
  
    /**
     * Get the first free instance of a string buffer, or create one 
     * if there are no free instances.
     *
     * @return A string buffer ready for use.
     */
    public synchronized static FastStringBuffer get()
    {
      return (FastStringBuffer) m_stringBufPool.getInstance();
    }
  
    /**
     * Return a string buffer back to the pool.
     *
     * @param sb Must be a non-null reference to a string buffer.
     */
    public synchronized static void free(FastStringBuffer sb)
    {
      // Since this isn't synchronized, setLength must be 
      // done before the instance is freed.
      // Fix attributed to Peter Speck <speck@ruc.dk>.
      sb.setLength(0);
      m_stringBufPool.freeInstance(sb);
    }
  }
  