/**
* Copyright (C) 2001-2017 by RapidMiner and the contributors
*
* Complete list of developers available at our web site:
*
* http://rapidminer.com
*
* This program is free software: you can redistribute it and/or modify it under the terms of the
* GNU Affero General Public License as published by the Free Software Foundation, either version 3
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without
* even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License along with this program.
* If not, see http://www.gnu.org/licenses/.
*/
package com.rapidminer.tools.expression.internal.function.text;
import com.rapidminer.tools.expression.Function;
/**
* A {@link Function} which computes the prefix of a given length from a nominal value
*
* @author Thilo Kamradt
*
*/
public class Prefix extends AbstractStringIntegerInputStringOutputFunction {
/**
* Creates a function which computes the prefix of a given length from a nominal value
*/
public Prefix() {
super("text_transformation.prefix", 2);
}
/**
* Computes the result.
*
* @param text
* @param index
* @return the result of the computation.
*/
@Override
protected String compute(String text, double index) {
if (text == null) {
return null;
} else if (Double.isNaN(index)) {
// for compatibility reasons
index = 0;
} else if (index < 0 || index >= text.length()) {
return text;
}
return text.substring(0, Math.min(text.length(), (int) index));
}
}