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
020package org.crsh.cli.impl.tokenizer;
021
022import java.util.ArrayList;
023import java.util.Iterator;
024import java.util.NoSuchElementException;
025
026public 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}