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Public API for the Apache MyFaces Trinidad project
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/*
 * 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.
 */
package org.apache.myfaces.trinidad.util;

import java.util.Iterator;

/**
 * This class contains String utilities. The code was taken from
 * Apache Commons, LANG project.
 *
 * Reason is to provide an alternate method to java.lang.String.replace().
 * That method uses java.util.regex.Pattern.matcher(), which has a PERF
 * issue.
 *
 */
public final class StringUtils
{
  private StringUtils()
  {
    // no-op
  }

  public static String replace(String text, String searchString, String replacement)
  {
    return replace(text, searchString, replacement, -1);
  }

  // making this public, doesn't hurt... but we don't need it, now
  private static boolean isEmpty(String str)
  {
    return str == null || str.length() == 0;
  }

  // making this public, doesn't hurt... but we don't need it, now
  private static String replace(String text, String searchString, String replacement, int max)
  {
    if (isEmpty(text) || isEmpty(searchString) || replacement == null || max == 0)
    {
      return text;
    }
    int start = 0;
    int end = text.indexOf(searchString, start);
    
    if (end == -1)
    {
      return text;
    }
    int replLength = searchString.length();
    int increase = replacement.length() - replLength;
    increase = (increase < 0 ? 0 : increase);
    increase *= (max < 0 ? 16 : (max > 64 ? 64 : max));
    StringBuffer buf = new StringBuffer(text.length() + increase);
    while (end != -1)
    {
      buf.append(text.substring(start, end)).append(replacement);
      start = end + replLength;

      if (--max == 0)
      {
        break;
      }
      end = text.indexOf(searchString, start);
    }
    buf.append(text.substring(start));
    return buf.toString();
  }

  /**
   * Joins the elements of the provided array into a single String
   * containing the provided list of elements.
   *
   * No delimiter is added before or after the list.
   * Null objects or empty strings within the array are represented by
   * empty strings.
   *
   *    * StringUtils.join(null, *) = null
   * StringUtils.join([], *) = ""
   * StringUtils.join([null], *) = ""
   * StringUtils.join(["a", "b", "c"], ';') = "a;b;c"
   * StringUtils.join(["a", "b", "c"], null) = "abc"
   * StringUtils.join([null, "", "a"], ';') = ";;a"
   * 
   *
   * @param array the array of values to join together, may be null
   * @param separator the separator character to use
   * @return the joined String, null if null array input
   */

  public static String join(Object[] array, char separator)
  {
    if (array == null)
    {
      return null;
    }
    int arraySize = array.length;
    int bufSize = (arraySize == 0? 0: ((array[0] == null? 16: array[0].toString().length()) + 1) * arraySize);
    StringBuilder buf = new StringBuilder(bufSize);

    for (int i = 0; i < arraySize; i++)
    {
      if (i > 0)
      {
        buf.append(separator);
      }
      if (array[i] != null)
      {
        buf.append(array[i]);
      }
    }
    return buf.toString();
  }

  /**
   * Joins the elements of the provided Iterator into
   * a single String containing the provided elements.
   *
   * No delimiter is added before or after the list. Null objects or empty
   * strings within the iteration are represented by empty strings.
   *
   * See the examples here: {@link #join(Object[],char)}. 
   *
   * @param iterator the Iterator of values to join together, may be null
   * @param separator the separator character to use
   * @return the joined String, null if null iterator input
   */
  public static String join(Iterator iterator, char separator)
  {
    if (iterator == null)
    {
      return null;
    }
    
    StringBuilder buf = new StringBuilder(256); // Java default is 16, probably too small
    
    while (iterator.hasNext())
    {
      Object obj = iterator.next();
      if (obj != null)
      {
        buf.append(obj);
      }
      if (iterator.hasNext())
      {
        buf.append(separator);
      }
    }
    return buf.toString();
  }
}