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/*
 * This file is part of the DiffX library.
 *
 * For licensing information please see the file license.txt included in the release.
 * A copy of this licence can also be found at
 *   http://www.opensource.org/licenses/artistic-license-2.0.php
 */
package com.topologi.diffx.sequence;

import java.util.Stack;

import com.topologi.diffx.event.CloseElementEvent;
import com.topologi.diffx.event.DiffXEvent;
import com.topologi.diffx.event.OpenElementEvent;

/**
 * A utility class for event sequences.
 * 
 * @author Christophe Lauret
 * @version 3 April 2005
 * 
 * @since 0.6
 */
public final class EventSequenceUtils {

  /**
   * Prevent creation of instances.
   */
  private EventSequenceUtils() {
  }

  /**
   * Indicates whether the sequence corresponds to well-formed XML.
   * 
   * @param sequence The sequence.
   * 
   * @return true if the sequence is "well-formed";
   *         false otherwise.
   */
  public static boolean isWellFormed(EventSequence sequence) {
    // TODO: if the sequence is null ??
    if (sequence == null) return false;
    Stack open = new Stack();
    DiffXEvent e = null;
    for (int i = 0; i < sequence.size(); i++) {
      e = sequence.getEvent(i);
      if (e instanceof OpenElementEvent) {
        open.push(e);
      } else if (e instanceof CloseElementEvent) {
        if (open.empty()) return false;
        OpenElementEvent o = (OpenElementEvent)open.peek();
        String lastOpenElementName = o.getName();
        String closeElementName = ((CloseElementEvent)e).getName();
        if (!closeElementName.equals(lastOpenElementName)) return false;
      }
    }
    return open.empty();
  }

  /**
   * Returns the maximum depth of the sequence.
   * 
   * 

This method assumes that the sequence is well-formed, and counts * the maximum number of open element events. * * @param sequence The sequence * * @return The maximum depth. */ public static int getMaxDepth(EventSequence sequence) { int max = 0; int depth = 0; for (int i = 0; i < sequence.size(); i++) { if (sequence.getEvent(i) instanceof OpenElementEvent) { depth++; } else if (sequence.getEvent(i) instanceof CloseElementEvent) { depth--; } if (depth > max) { max = depth; } } return max; } /** * Returns the maximum number of token inside an element tag. * *

This method assumes that the sequence is well-formed. * * @param sequence The sequence. * * @return The maximum number of tokens. */ public static int getMaxElementContent(EventSequence sequence) { int max = 0; int tmp = 0; for (int i = 0; i < sequence.size(); i++) { DiffXEvent e = sequence.getEvent(i); if (e instanceof OpenElementEvent) { tmp = 0; } else if (e instanceof CloseElementEvent) { if (tmp > max) { max = tmp; } } else { tmp++; } } return max; } }





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