/*
 * 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;

import java.util.ArrayList;
import java.util.List;


public class SubrAppend extends Subr {

	@Override
	public Datum eval(
			Datum body, Environment env, LispMessage mesg) {
		List<Datum> lst1 = LispUtils.consToList(body, mesg);
		List<Datum> res  = new ArrayList<Datum>();
		
		int i = 0;
		for(; i < lst1.size() - 1; i++) {
			res.addAll(LispUtils.consToList(lst1.get(i), mesg));
		}
		
		// 最後の要素を追加する
		Datum lsc = LispUtils.listToCons(res);
		if(lst1.size() == 0) {
			return Nil.NIL;
		} else if(lsc == Nil.NIL) {
			return lst1.get(i);
		} else {
			Datum lpt = lsc;
			while(((Cons)lpt).getCdr() != Nil.NIL) {
				lpt = ((Cons)lpt).getCdr();
			}
			((Cons)lpt).setCdr(lst1.get(i));
			return lsc;
		}
	}

}
