/*
 * Copyright 2009 Yuichiro Moriguchi
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package net.morilib.lisp.subr;

import net.morilib.lisp.ConsIterator;
import net.morilib.lisp.Datum;
import net.morilib.lisp.Environment;
import net.morilib.lisp.LispMessage;
import net.morilib.lisp.Nil;
import net.morilib.lisp.Subr;
import net.morilib.util.Iterators;

/**
 * 
 *
 *
 * @author MORIGUCHI, Yuichiro 2009
 */
public class Exit extends Subr {

	@Override
	public Datum eval(Datum body, Environment env, LispMessage mesg) {
		ConsIterator itr = new ConsIterator(body);
		Datum d1 = Iterators.nextIf(itr);

		if(d1 == null) {
			System.exit(0);
		} else if(d1.isTrue()) {
			System.exit(SubrUtils.getU8(d1, mesg));
		} else {
			System.exit(72);
		}
		return Nil.NIL;
	}

}
