CatIterator.java :  » Template-Engine » stringtemplate » org » antlr » stringtemplate » language » Java Open Source

package org.antlr.stringtemplate.language;

import java.util.Iterator;
import java.util.List;

/** Given a list of iterators, return the combined elements one by one. */
public class CatIterator implements Iterator {
  /** List of iterators to cat together */
  protected List iterators;

  public CatIterator(List iterators) {
    this.iterators = iterators;
  }

  public boolean hasNext() {
    for (int i = 0; i < iterators.size(); i++) {
      Iterator it = (Iterator) iterators.get(i);
      if ( it.hasNext() ) {
        return true;
      }
    }
    return false;
  }

  public Object next() {
    for (int i = 0; i < iterators.size(); i++) {
      Iterator it = (Iterator) iterators.get(i);
      if ( it.hasNext() ) {
        return it.next();
      }
    }
    return null;
  }

  public void remove() {
    throw new RuntimeException("unimplemented method: CatIterator remove()");
  }

  /** The result of asking for the string of an iterator is the list of elements
   *  and so this is just the cat'd list of both elements.  This is destructive
   *  in that the iterator cursors have moved to the end after printing.
   */
  public String toString() {
    StringBuffer buf = new StringBuffer();
    while ( this.hasNext() ) {
      buf.append(this.next());
    }
    return buf.toString();
  }
}