001    /*
002     * Copyright (C) 2012 eXo Platform SAS.
003     *
004     * This is free software; you can redistribute it and/or modify it
005     * under the terms of the GNU Lesser General Public License as
006     * published by the Free Software Foundation; either version 2.1 of
007     * the License, or (at your option) any later version.
008     *
009     * This software is distributed in the hope that it will be useful,
010     * but WITHOUT ANY WARRANTY; without even the implied warranty of
011     * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
012     * Lesser General Public License for more details.
013     *
014     * You should have received a copy of the GNU Lesser General Public
015     * License along with this software; if not, write to the Free
016     * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
017     * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
018     */
019    
020    package org.crsh.cli.impl.tokenizer;
021    
022    import java.util.ArrayList;
023    import java.util.Iterator;
024    import java.util.NoSuchElementException;
025    
026    public abstract class Tokenizer implements Iterator<Token> {
027    
028      /** . */
029      private ArrayList<Token> stack;
030    
031      /** . */
032      private int ptr;
033    
034      /** . */
035      private int index = 0;
036    
037      protected Tokenizer() {
038        this.stack = new ArrayList<Token>();
039        this.ptr = 0;
040      }
041    
042      public final boolean hasNext() {
043        if (ptr < stack.size()) {
044          return true;
045        } else {
046          Token next = parse();
047          if (next != null) {
048            stack.add(next);
049          }
050          return next != null;
051        }
052      }
053    
054      public final void pushBack(int count) {
055        if (count < 0) {
056          throw new IllegalArgumentException();
057        }
058        if (ptr - count < 0) {
059          throw new IllegalStateException("Trying to push back too many tokens");
060        } else {
061          while (count > 0) {
062            index -= stack.get(--ptr).raw.length();
063            count--;
064          }
065        }
066      }
067    
068      public final Token peek() {
069        if (hasNext()) {
070          return stack.get(ptr);
071        } else {
072          return null;
073        }
074      }
075    
076      public final Token next() {
077        if (hasNext()) {
078          Token token = stack.get(ptr++);
079          index += token.raw.length();
080          return token;
081        } else {
082          throw new NoSuchElementException();
083        }
084      }
085    
086      public final void remove() {
087        throw new UnsupportedOperationException();
088      }
089    
090      public final void pushBack() {
091        pushBack(1);
092      }
093    
094      protected abstract Token parse();
095    
096      public final int getIndex() {
097        return index;
098      }
099    
100    }