src/plugin/parse-html/src/java/org/apache/nutch/parse/html/XMLCharacterRecognizer.java

/*
 * 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.
 */

/*
 * XXX ab@apache.org: This class is copied verbatim from Xalan-J 2.6.0
 * XXX distribution, org.apache.xml.utils.XMLCharacterRecognizer,
 * XXX in order to avoid dependency on Xalan.
 */
/*
 * $Id$
 */
package org.apache.nutch.parse.html;

/**
 * Class used to verify whether the specified <var>ch</var> conforms to the XML
 * 1.0 definition of whitespace.
 */
public class XMLCharacterRecognizer {

  /**
   * Returns whether the specified <var>ch</var> conforms to the XML 1.0
   * definition of whitespace. Refer to <A
   * href="http://www.w3.org/TR/1998/REC-xml-19980210#NT-S"> the definition of
   * <CODE>S</CODE></A> for details.
   * 
   * @param ch
   *          Character to check as XML whitespace.
   * @return =true if <var>ch</var> is XML whitespace; otherwise =false.
   */
  public static boolean isWhiteSpace(char ch) {
    return (ch == 0x20) || (ch == 0x09) || (ch == 0xD) || (ch == 0xA);
  }

  /**
   * Tell if the string is whitespace.
   * 
   * @param ch
   *          Character array to check as XML whitespace.
   * @param start
   *          Start index of characters in the array
   * @param length
   *          Number of characters in the array
   * @return True if the characters in the array are XML whitespace; otherwise,
   *         false.
   */
  public static boolean isWhiteSpace(char ch[], int start, int length) {

    int end = start + length;

    for (int s = start; s < end; s++) {
      if (!isWhiteSpace(ch[s]))
        return false;
    }

    return true;
  }

  /**
   * Tell if the string is whitespace.
   * 
   * @param buf
   *          StringBuffer to check as XML whitespace.
   * @return True if characters in buffer are XML whitespace, false otherwise
   */
  public static boolean isWhiteSpace(StringBuffer buf) {

    int n = buf.length();

    for (int i = 0; i < n; i++) {
      if (!isWhiteSpace(buf.charAt(i)))
        return false;
    }

    return true;
  }

  /**
   * Tell if the string is whitespace.
   * 
   * @param s
   *          String to check as XML whitespace.
   * @return True if characters in buffer are XML whitespace, false otherwise
   */
  public static boolean isWhiteSpace(String s) {

    if (null != s) {
      int n = s.length();

      for (int i = 0; i < n; i++) {
        if (!isWhiteSpace(s.charAt(i)))
          return false;
      }
    }

    return true;
  }

}