selection.java

myassembler（大学作业）

public class Selection extends Statement {
   private Expression condition;
   private Statement ifStatement, elseStatement;

   public Selection(Expression c, Statement ts, Statement fs) {
      condition = (Expression)c.clone();
      ifStatement = (Statement)ts.clone();
      elseStatement = (Statement)fs.clone();
   }

   public void run() throws ExecutionException {
      if (condition.eval() == 1) ifStatement.run();
      else elseStatement.run();
   }

   public Object clone() {
      return new Selection(condition, ifStatement, elseStatement);
   }

   /* --------------------------------------- 
    *    condition
    *    jzero li
    *    ifstatement
    *    jump lj
    * li:elsestatement
    * lj:...   
    * @see java.lang.Object#toString()
    */
   public String toString() {
      String result = condition.toString();
      int truelabel = ++labels, falselabel = ++labels;
      result += labelling()+"JZERO L"+falselabel+"\n"+ifStatement.toString()+labelling()+"JUMP L"+truelabel+"\n";
      toLabel = falselabel;
      result += elseStatement.toString();
      toLabel = truelabel;
      return result;
   }
}