else.java

来自「编译原理“龙书”(Compilers: Principles, Techniqu」· Java 代码 · 共 20 行

package inter;
import symbols.*;

public class Else extends Stmt {

   Expr expr; Stmt stmt1, stmt2;

   public Else(Expr x, Stmt s1, Stmt s2) {
      expr = x; stmt1 = s1; stmt2 = s2;
      if( expr.type != Type.Bool ) expr.error("boolean required in if");
   }
   public void gen(int b, int a) {
      int label1 = newlabel();   // label1 for stmt1
      int label2 = newlabel();   // label2 for stmt2
      expr.jumping(0,label2);    // fall through to stmt1 on true
      emitlabel(label1); stmt1.gen(label1, a); emit("goto L" + a);
      emitlabel(label2); stmt2.gen(label2, a);
   }
}