commandlistnode.java

《深入浅出设计模式》的完整源代码

package littlecompiler;
//命令列表类，相应文法为:<command list> ::= <command>* END
import java.util.*;
public class CommandListNode implements Node {
  private Vector list = new Vector ();
  public void parse (Context context) {
    while (true) {
      if (context.currentToken () == null) {
        System.err.println ("Missing 'END'");
        break;
      }
      else if (context.currentToken ().equals ("END")) {
        context.skipToken ("END");
        break;
      }
      else {
        Node commandNode = new CommandNode ();
        commandNode.parse (context);
        list.add (commandNode);
      }
    }
  }
  public void execute () {
    Iterator it = list.iterator ();
    while (it.hasNext ()) {
      ( (CommandNode) it.next ()).execute ();
    }
  }
}