OptionalityFieldValidator.java

/**
 * VStar: a statistical analysis tool for variable star data.
 * Copyright (C) 2009  AAVSO (http://www.aavso.org/)
 *
 * 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 org.aavso.tools.vstar.data.validation;

import org.aavso.tools.vstar.exception.ObservationValidationError;

/**
 * This class validates fields as optional or non-optional, returning 
 * the field or null.
 */
public class OptionalityFieldValidator extends AbstractStringValidator<String> {

	public static final boolean CAN_BE_EMPTY = true;
	public static final boolean CANNOT_BE_EMPTY = false;

	private boolean canBeEmpty;
	
	/**
	 * Constructor.
	 * 
	 * @param kind
	 *            The kind of entity (e.g. field name) we are validating.
	 * 
	 * @param canBeEmpty Can fields validated by this class be empty?  
	 */
	public OptionalityFieldValidator(String kind, boolean canBeEmpty) {
		super(kind);
		this.canBeEmpty = canBeEmpty;
	}
	
	/**
	 * Constructor.
	 * 
	 * @param canBeEmpty Can fields validated by this class be empty?  
	 */
	public OptionalityFieldValidator(boolean canBeEmpty) {
		this.canBeEmpty = canBeEmpty;
	}

	public String validate(String str)
			throws ObservationValidationError {
		if (this.isLegallyEmpty(str)) return null;

		return str;
	}

	protected boolean canBeEmpty() {
		return this.canBeEmpty;
	}
}