primitivecommandnode.java

《深入浅出设计模式》的完整源代码

package littlecompiler;
//基元命令类,相应的文法为：<primitive command> ::= PRINT <string> | SPACE | BREAK | LINEBREAK
public class PrimitiveCommandNode implements Node {
  private String name;
  private String text;
  public void parse(Context context) {
      name = context.currentToken();
      context.skipToken(name);
      if (!name.equals("PRINT") && !name.equals("BREAK") && !name.equals("LINEBREAK") && !name.equals("SPACE")) {
          System.err.println("Undefined Command");
      }

      if (name.equals("PRINT")) {
          text = context.currentToken();
          context.nextToken();
      }
  }
  public void execute() {
      if(name.equals("PRINT"))
          System.out.print(text);
      else if(name.equals("SPACE"))
          System.out.print(" ");
      else if(name.equals("BREAK"))
          System.out.println();
      else if(name.equals("LINEBREAK"))
          System.out.println("\n------------------------------");
  }
  public String toString() {
      return name;
  }
}