    1   /* CharSubSequence.java
    2    *
    3    * Created on Sep 30, 2003
    4    *
    5    * Copyright (C) 2003 Internet Archive.
    6    *
    7    * This file is part of the Heritrix web crawler (crawler.archive.org).
    8    *
    9    * Heritrix is free software; you can redistribute it and/or modify
    10   * it under the terms of the GNU Lesser Public License as published by
    11   * the Free Software Foundation; either version 2.1 of the License, or
    12   * any later version.
    13   *
    14   * Heritrix is distributed in the hope that it will be useful,
    15   * but WITHOUT ANY WARRANTY; without even the implied warranty of
    16   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    17   * GNU Lesser Public License for more details.
    18   *
    19   * You should have received a copy of the GNU Lesser Public License
    20   * along with Heritrix; if not, write to the Free Software
    21   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
    22   */
    23  package org.archive.io;
    24
    25
    26  /***
    27   * Provides a subsequence view onto a CharSequence.
    28   *
    29   * @author gojomo
    30   * @version $Revision: 3288 $, $Date: 2005-03-31 17:43:23 +0000 (Thu, 31 Mar 2005) $
    31   */
    32  public class CharSubSequence implements CharSequence {
    33
    34      CharSequence inner;
    35      int start;
    36      int end;
    37
    38      public CharSubSequence(CharSequence inner, int start, int end) {
    39          if (end < start) {
    40              throw new IllegalArgumentException("Start " + start + " is > " +
    41                  " than end " + end);
    42          }
    43
    44          if (end < 0 || start < 0) {
    45              throw new IllegalArgumentException("Start " + start + " or end " +
    46                  end + " is < 0.");
    47          }
    48
    49          if (inner ==  null) {
    50              throw new NullPointerException("Passed charsequence is null.");
    51          }
    52
    53          this.inner = inner;
    54          this.start = start;
    55          this.end = end;
    56      }
    57
    58      /*
    59       *  (non-Javadoc)
    60       * @see java.lang.CharSequence#length()
    61       */
    62      public int length() {
    63          return this.end - this.start;
    64      }
    65
    66      /*
    67       *  (non-Javadoc)
    68       * @see java.lang.CharSequence#charAt(int)
    69       */
    70      public char charAt(int index) {
    71          return this.inner.charAt(this.start + index);
    72      }
    73
    74      /*
    75       *  (non-Javadoc)
    76       * @see java.lang.CharSequence#subSequence(int, int)
    77       */
    78      public CharSequence subSequence(int begin, int finish) {
    79          return new CharSubSequence(this, begin, finish);
    80      }
    81
    82      /*
    83       *  (non-Javadoc)
    84       * @see java.lang.CharSequence#toString()
    85       */
    86      public String toString() {
    87          StringBuffer sb = new StringBuffer(length());
    88          // could use StringBuffer.append(CharSequence) if willing to do 1.5 & up
    89          for (int i = 0;i<length();i++) {
    90              sb.append(charAt(i));
    91          }
    92          return sb.toString();
    93      }
    94  }