/*
 * Copyright 2009-2010 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.exlib;

import java.util.Map;
import java.util.Properties;

import net.morilib.lisp.Cons;
import net.morilib.lisp.ConsListBuilder;
import net.morilib.lisp.Datum;
import net.morilib.lisp.Environment;
import net.morilib.lisp.LispMessage;
import net.morilib.lisp.LispString;
import net.morilib.lisp.Subr;

/**
 *
 *
 * @author MORIGUCHI, Yuichiro 2011/04/17
 */
public class GetSystemProperties extends Subr {

	/* (non-Javadoc)
	 * @see net.morilib.lisp.Subr#eval(net.morilib.lisp.Datum, net.morilib.lisp.Environment, net.morilib.lisp.LispMessage)
	 */
	@Override
	public Datum eval(Datum body, Environment env, LispMessage mesg) {
		if(body.isNil()) {
			Properties m = System.getProperties();
			ConsListBuilder r = new ConsListBuilder();

			for(Map.Entry<Object, Object> e : m.entrySet()) {
				r.append(new Cons(
						new LispString(e.getKey().toString()),
						new LispString(e.getValue().toString())));
			}
			return r.get();
		} else {
			throw mesg.getError("err.argument", body);
		}
	}

}
