StringUtil.java

/*
 * This program is free software; you can redistribute it and/or modify it under the 
 * terms of the GNU Lesser General Public License, version 2.1 as published by the Free Software 
 * Foundation.
 *
 * You should have received a copy of the GNU Lesser General Public License along with this 
 * program; if not, you can obtain a copy at http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html 
 * or from the Free Software Foundation, Inc., 
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; 
 * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU Lesser General Public License for more details.
 *
 * Copyright 2005 - 2008 Pentaho Corporation.  All rights reserved.
 *
 * @created Jun 21, 2005 
 * @author James Dixon
 * 
 */

package org.pentaho.platform.util;

import java.util.ArrayList;
import java.util.List;
import java.util.StringTokenizer;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class StringUtil {

  private StringUtil() {
    super();
    // No need for a constructor since it should be all static utils
  }

  // match "../stuff", "stuff/../stuff", "stuff/..", and same string with "\" instead of "/"
  // Also, fail if it contains a %00 which gets interpreted as a null when thrown at the
  // file system. 
  private static final String RE_CONTAINS_PARENT_PATH = "(^.*[/\\\\]|^)\\.\\.([/\\\\].*$|$)|(^.*\0.*$)"; //$NON-NLS-1$

  private static final Pattern CONTAINS_PARENT_PATH_PATTERN = Pattern.compile(StringUtil.RE_CONTAINS_PARENT_PATH);

  /**
   * Tokenize a string and return a String Array of the values seperated by the passed in token.
   * 
   * @param tokenizedString The string to parse.  If this is null, null will be returned.
   * @param token The token used as a seperator. if this is null, the fill string will be returned in a 1 element array
   * @return Array of Strings that were seperated by the token. 
   */
  public static String[] tokenStringToArray(final String tokenizedString, final String token) {
    if (tokenizedString == null) {
      return (null);
    }
    if (token == null) {
      return (new String[] { tokenizedString });
    }

    StringTokenizer st = new StringTokenizer(tokenizedString, token);
    List<String> strList = new ArrayList<String>();
    while (st.hasMoreTokens()) {
      String tok = st.nextToken();
      strList.add(tok);
    }

    String[] rtnArray = new String[strList.size()];
    return strList.toArray(rtnArray);
  }

  /**
   * Does the path contain a path-segment that is "..".
   * @param path String
   * @return boolean return true if path contains "..", else false.
   */
  public static boolean doesPathContainParentPathSegment(final String path) {
    Matcher m = StringUtil.CONTAINS_PARENT_PATH_PATTERN.matcher(path);
    return m.matches();
  }

  public static void main(final String[] args) {
    String[] testStrings = { "../bart/maggie.xml", "/bart/..", "/bart/../maggie/homer.xml", "..//bart/maggie.xml",  //$NON-NLS-1$//$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-4$
        "/bart//..", "/bart//../maggie/homer.xml", "/../", "/..", "../", "..\\bart\\maggie.xml", "\\bart\\..",  //$NON-NLS-1$//$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-4$ //$NON-NLS-5$ //$NON-NLS-6$ //$NON-NLS-7$
        "\\bart\\..\\maggie\\homer.xml", "I am clean", "/go/not/parent.xml", "\\go\\not\\parent.xml", "..",  //$NON-NLS-1$//$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-4$ //$NON-NLS-5$
        "should/not..not/match", "..should/not/match.xml", "should/not..", "..." };  //$NON-NLS-1$//$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-4$

    for (String testString : testStrings) {
      boolean matches = StringUtil.doesPathContainParentPathSegment(testString);
      if (matches) {
        System.out.println(testString + " matches."); //$NON-NLS-1$
      } else {
        System.out.println("--------" + testString + " DOES NOT MATCH.");  //$NON-NLS-1$//$NON-NLS-2$
      }
    }
  }

  public static boolean isEmpty(final String str) {
    return (str == null) || (str.length() == 0);
  }

}