/**
* This file is part of the Goobi Application - a Workflow tool for the support
* of mass digitization.
*
* (c) 2014 Goobi. Digitalisieren im Verein e.V. <contact@goobi.org>
*
* Visit the websites for more information.
* - http://www.goobi.org/en/
* - https://github.com/goobi
*
* This program is free software; you can redistribute it and/or modify it under
* the terms of the GNU General Public License as published by the Free Software
* Foundation; either version 2 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 General Public License for more
* details.
*
* You should have received a copy of the GNU General Public License along with
* this program; if not, write to the Free Software Foundation, Inc., 59 Temple
* Place, Suite 330, Boston, MA 02111-1307 USA
*
* Linking this library statically or dynamically with other modules is making a
* combined work based on this library. Thus, the terms and conditions of the
* GNU General Public License cover the whole combination. As a special
* exception, the copyright holders of this library give you permission to link
* this library with independent modules to produce an executable, regardless of
* the license terms of these independent modules, and to copy and distribute
* the resulting executable under terms of your choice, provided that you also
* meet, for each linked independent module, the terms and conditions of the
* license of that module. An independent module is a module which is not
* derived from or based on this library. If you modify this library, you may
* extend this exception to your version of the library, but you are not obliged
* to do so. If you do not wish to do so, delete this exception statement from
* your version.
*/
package de.sub.goobi.metadaten.copier;
import org.apache.commons.configuration.ConfigurationException;
/**
* A DataSelector is useful to access a data object. There are different
* DataSelectors available to access metadata and program variables.
*
* The factory method {{@link #create(String)} can be used to retrieve a
* DataSelector instance for a given path.
*
* @author Matthias Ronge <matthias.ronge@zeutschel.de>
*/
public abstract class DataSelector {
/**
* Symbol indicating that the element of several to choose shall be the last
* one
*/
protected final static String LAST_CHILD_QUANTIFIER = ">";
/**
* Symbol indicating that the next segment of the path is a document
* structure hierarchy level
*/
protected final static String METADATA_PATH_SEPARATOR = "/";
/**
* Symbol indicating that the next segment of the path is a metadatum
*/
protected final static String METADATA_SEPARATOR = "@";
/**
* Symbol indicating that the next segment of the path is a reference to the
* node of the logical document structure that the metadata will be written
* to.
*/
protected static final String RESPECTIVE_DESTINATION_REFERENCE = "#";
/**
* Symbol indicating that the value is a static string
*/
private static final String STRING_MARK = "\"";
/**
* Symbol indicating that the selector is to select a variable
*/
protected final static String VARIABLE_REFERENCE = "$";
/**
* Factory method to create a DataSelector.
*
* @param path
* path to the data object to access
* @return a subclass implementing the data selector required for the given
* path
* @throws ConfigurationException
* if the path cannot be evaluated
*/
public static DataSelector create(String path) throws ConfigurationException {
if (path.startsWith(METADATA_PATH_SEPARATOR) || path.startsWith(METADATA_SEPARATOR)) {
return MetadataSelector.create(path);
}
if (path.startsWith(VARIABLE_REFERENCE)) {
return new VariableSelector(path);
}
if (path.startsWith(STRING_MARK)) {
return new StringSelector(path);
}
if (path.startsWith(RESPECTIVE_DESTINATION_REFERENCE)) {
return new DestinationReferenceSelector(path);
}
throw new ConfigurationException(
"Cannot create data selector: Path must start with \"@\", \"/\" or \"$\", but is: " + path);
}
/**
* Calling findIn() on the implementing instance should return the value of
* the metadatum named by the path used to construct the metadata selector.
* Should return null if either the path or the metadatum at the end of the
* path aren’t available.
*
* @param data
* data collection to locate the metadatum in
* @return the value the path points to, or null if absent
* @throws RuntimeException
* if the path cannot be resolved
*/
public abstract String findIn(CopierData data);
}