/*
 * 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.iterator;

import net.morilib.lisp.Datum;
import net.morilib.lisp.Environment;
import net.morilib.lisp.LispMessage;
import net.morilib.lisp.LispReal;
import net.morilib.lisp.subr.SubrUtils;
import net.morilib.lisp.subr.TernaryArgs;

/**
 *
 *
 * @author MORIGUCHI, Yuichiro 2012/01/29
 */
public class MakeRealNumberIterator extends TernaryArgs {

	/* (non-Javadoc)
	 * @see net.morilib.lisp.subr.TernaryArgs#execute(net.morilib.lisp.Datum, net.morilib.lisp.Datum, net.morilib.lisp.Datum, net.morilib.lisp.Environment, net.morilib.lisp.LispMessage)
	 */
	@Override
	protected Datum execute(Datum c1a, Datum c2a, Datum c3a,
			Environment env, LispMessage mesg) {
		final LispReal[] c = new LispReal[1];
		final LispReal rb, re, st;

		rb = SubrUtils.getReal(c1a, mesg);
		re = SubrUtils.getReal(c2a, mesg);
		st = SubrUtils.getReal(c3a, mesg);
		if((st.signum() * rb.compareTo(re)) > 0) {
			throw mesg.getError("err.range.invalid");
		}

		c[0] = rb;
		return new LispIteratorDatum() {

			public boolean isTerminated() {
				return (st.signum() * c[0].compareTo(re)) > 0;
			}

			public ILispIterator next() {
				c[0] = c[0].add(st);
				return this;
			}

			public Datum getCurrentDatum() {
				return c[0];
			}

			@Override
			public void toDisplayString(StringBuilder buf) {
				buf.append("#<real-number-iterator>");
			}

		};
	}

}
