/*
* Copyright 2010 NCHOVY
*
* 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 org.krakenapps.bnf;
import java.nio.BufferUnderflowException;
import java.text.ParseException;
public class IdentifierPlaceholder implements Placeholder {
@Override
public Result eval(String text, int position, ParserContext ctx) throws ParseException {
int i = StringUtil.skipSpaces(text, position);
int begin = i;
if (text.length() <= begin)
throw new BufferUnderflowException();
if (!StringUtil.isAlpha(text.charAt(begin)))
throw new ParseException("initial character must be alphabet", i);
i = findEnd(text, i);
String token = text.substring(begin, i);
// remove trailing spaces
i = StringUtil.skipSpaces(text, i);
return new Result(new Binding(this, token), i);
}
private int findEnd(String text, int position) {
int i = position;
while (i < text.length() && StringUtil.isAlphaNumeric(text.charAt(i)))
i++;
return i;
}
@Override
public String toString() {
return "id_var";
}
}