/*
 * 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.nano.subr;

import net.morilib.lisp.nano.Datum;
import net.morilib.lisp.nano.EOFObject;
import net.morilib.lisp.nano.Environment;
import net.morilib.lisp.nano.InputPort;
import net.morilib.lisp.nano.LispBoolean;
import net.morilib.lisp.nano.LispMessage;

/**
 * 
 *
 *
 * @author MORIGUCHI, Yuichiro 2009
 */
public class IsEofObject extends UnaryArgs {

	/* (non-Javadoc)
	 * @see net.morilib.lisp.nano.subr.UnaryArgs#execute(net.morilib.lisp.nano.Datum, net.morilib.lisp.nano.Environment, net.morilib.lisp.nano.LispMessage)
	 */
	@Override
	protected Datum execute(Datum c1a, Environment env,
			LispMessage mesg) {
		boolean r;

		if(c1a instanceof InputPort) {
			r = ((InputPort)c1a).peekChar().equals(EOFObject.EOF);
		} else {
			r = c1a == EOFObject.EOF;
		}
		return LispBoolean.getInstance(r);
	}

}
