package soot.jimple.toolkits.callgraph;

/*-
 * #%L
 * Soot - a J*va Optimization Framework
 * %%
 * Copyright (C) 2003 Ondrej Lhotak
 * %%
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation, either version 2.1 of the
 * License, or (at your option) any later version.
 * 
 * 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 General Lesser Public License for more details.
 * 
 * You should have received a copy of the GNU General Lesser Public
 * License along with this program.  If not, see
 * <http://www.gnu.org/licenses/lgpl-2.1.html>.
 * #L%
 */

import java.util.Iterator;

/**
 * Represents a subset of the edges in a call graph satisfying an EdgePredicate predicate.
 * 
 * @author Ondrej Lhotak
 */
public class Filter implements Iterator<Edge> {

  private final EdgePredicate pred;
  private Iterator<Edge> source;
  private Edge next = null;

  public Filter(EdgePredicate pred) {
    this.pred = pred;
  }

  public Iterator<Edge> wrap(Iterator<Edge> source) {
    this.source = source;
    advance();
    return this;
  }

  private void advance() {
    while (source.hasNext()) {
      next = source.next();
      if (pred.want(next)) {
        return;
      }
    }
    next = null;
  }

  @Override
  public boolean hasNext() {
    return next != null;
  }

  @Override
  public Edge next() {
    Edge ret = next;
    advance();
    return ret;
  }

  @Override
  public void remove() {
    throw new UnsupportedOperationException();
  }
}
