IfStmnt.java

package jp.ac.aiit.jointry.services.lang.ast;

import java.util.List;
import jp.ac.aiit.jointry.services.lang.parser.Environment;

public class IfStmnt extends ASTList {

    public IfStmnt(List<ASTree> c) {
        super(c);
    }

    public ASTree condition() {
        return child(0);
    }

    public ASTree thenBlock() {
        return child(1);
    }

    public ASTree elseBlock() {
        return numChildren() > 2 ? child(2) : null;
    }

    public String toString() {
        return "(if " + condition() + " " + thenBlock()
                + " else " + elseBlock() + ")";
    }

    public Object eval(Environment env) {
        Object c = ((ASTree) condition()).eval(env);
        if (c instanceof Integer && ((Integer) c).intValue() != FALSE) {
            return ((ASTree) thenBlock()).eval(env);
        }
        ASTree b = elseBlock();
        if (b == null) {
            return 0;
        }
        return ((ASTree) b).eval(env);
    }
}