/*
 * 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.charset;

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

/**
 *
 *
 * @author MORIGUCHI, Yuichiro 2011/10/10
 */
public class StringToCharSet 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) {
		ConsIterator otr = new ConsIterator(body);
		Datum c1a = SubrUtils.nextIf(otr, mesg, body);
		Datum c2a = Iterators.nextIf(otr);

		SubrUtils.checkTerminated(otr, body, mesg);
		if(c2a == null || c2a instanceof LispCharSet) {
			String s = SubrUtils.getString(c1a, mesg);
			LispCharSetBuilder b =
				new LispCharSetBuilder((LispCharSet)c2a);

			for(int i = 0; i < s.length();) {
				int c = s.codePointAt(i);

				b.add(c);
				i += (c > Character.MAX_SURROGATE) ? 2 : 1;
			}
			return b.toCharSet();
		} else {
			throw mesg.getError("err.charset.require.charset", c2a);
		}
	}

}
