while.java

用java实现的编译器. 包括语法分析

package inter;
import symbols.*;
public class While extends Stmt {
	Expr expr;
	Stmt stmt;
	public While() {
		expr = null;
		stmt = null;
	}
	public void init(Expr x, Stmt s) {
		expr = x;
		stmt = s;
		if(expr.type != Type.Bool)
			expr.error("boolean required in while");
	}
	public void gen(int b, int a) {
		after = a;
		expr.jumping(0, a);	
		int label = newlabel();
		emitlabel(label);
		stmt.gen(label, b);
		emit("goto L" + b);
	}

}