1  // HTMLParser Library $Name: v1_6_20060319 $ - A java-based parser for HTML
  2  // http://sourceforge.org/projects/htmlparser
  3  // Copyright (C) 2004 Derrick Oswald
  4  //
  5  // Revision Control Information
  6  //
  7  // $Source: /cvsroot/htmlparser/htmlparser/src/org/htmlparser/lexer/Cursor.java,v $
  8  // $Author: derrickoswald $
  9  // $Date: 2005/05/15 11:49:04 $
 10  // $Revision: 1.20 $
 11  //
 12  // This library is free software; you can redistribute it and/or
 13  // modify it under the terms of the GNU Lesser General Public
 14  // License as published by the Free Software Foundation; either
 15  // version 2.1 of the License, or (at your option) any later version.
 16  //
 17  // This library is distributed in the hope that it will be useful,
 18  // but WITHOUT ANY WARRANTY; without even the implied warranty of
 19  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 20  // Lesser General Public License for more details.
 21  //
 22  // You should have received a copy of the GNU Lesser General Public
 23  // License along with this library; if not, write to the Free Software
 24  // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 25  //
 26  
 27  package org.htmlparser.lexer;
 28  
 29  import java.io.Serializable;
 30  import org.htmlparser.util.sort.Ordered;
 31  
 32  /**
 33   * A bookmark in a page.
 34   * This class remembers the page it came from and its position within the page.
 35   */
 36  public class Cursor
 37      implements
 38          Serializable,
 39          Ordered,
 40          Cloneable
 41  {
 42      /**
 43       * This cursor's position.
 44       */
 45      protected int mPosition;
 46  
 47      /**
 48       * This cursor's page.
 49       */
 50      protected Page mPage;
 51  
 52      /**
 53       * Construct a <code>Cursor</code> from the page and position given.
 54       * @param page The page this cursor is on.
 55       * @param offset The character offset within the page.
 56       */
 57      public Cursor (Page page, int offset)
 58      {
 59          mPage = page;
 60          mPosition = offset;
 61      }
 62  
 63      /**
 64       * Get this cursor's page.
 65       * @return The page associated with this cursor.
 66       */
 67      public Page getPage ()
 68      {
 69          return (mPage);
 70      }
 71  
 72      /**
 73       * Get the position of this cursor.
 74       * @return The cursor position.
 75       */
 76      public int getPosition ()
 77      {
 78          return (mPosition);
 79      }
 80  
 81      /**
 82       * Set the position of this cursor.
 83       * @param position The new cursor position.
 84       */
 85      public void setPosition (int position)
 86      {
 87          mPosition = position;
 88      }
 89  
 90      /**
 91       * Move the cursor position ahead one character.
 92       */
 93      public void advance ()
 94      {
 95          mPosition++;
 96      }
 97  
 98      /**
 99       * Move the cursor position back one character.
100       */
101      public void retreat ()
102      {
103          mPosition--;
104          if (0 > mPosition)
105              mPosition = 0;
106      }
107  
108      /**
109       * Make a new cursor just like this one.
110       * @return The new cursor positioned where <code>this</code> one is,
111       * and referring to the same page.
112       */
113      public Cursor dup ()
114      {
115          try
116          {
117              return ((Cursor)clone ());
118          }
119          catch (CloneNotSupportedException cnse)
120          {
121              return (new Cursor (getPage (), getPosition ()));
122          }
123      }
124  
125      /**
126       * Return a string representation of this cursor
127       * @return A string of the form "n[r,c]", where n is the character position,
128       * r is the row (zero based) and c is the column (zero based) on the page.
129       */
130      public String toString ()
131      {
132          StringBuffer ret;
133  
134          ret = new StringBuffer (9 * 3 + 3); // three ints and delimiters
135          ret.append (getPosition ());
136          ret.append ("[");
137          if (null != mPage)
138              ret.append (mPage.row (this));
139          else
140              ret.append ("?");
141          ret.append (",");
142          if (null != mPage)
143              ret.append (mPage.column (this));
144          else
145              ret.append ("?");
146          ret.append ("]");
147  
148          return (ret.toString ());
149      }
150  
151      //
152      // Ordered interface
153      //
154  
155      /**
156       * Compare one reference to another.
157       * @param that The object to compare this to.
158       * @return A negative integer, zero, or a positive
159       * integer as this object is less than, equal to,
160       * or greater than that object.
161       * @see org.htmlparser.util.sort.Ordered
162       */
163      public int compare (Object that)
164      {
165          Cursor r = (Cursor)that;
166          return (getPosition () - r.getPosition ());
167      }
168  }