org.topbraid.jenax.util.RDFLabels Maven / Gradle / Ivy
/*
* 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.
*
* See the NOTICE file distributed with this work for additional
* information regarding copyright ownership.
*/
package org.topbraid.jenax.util;
import java.util.Iterator;
import java.util.Map;
import org.apache.jena.rdf.model.Literal;
import org.apache.jena.rdf.model.RDFList;
import org.apache.jena.rdf.model.RDFNode;
import org.apache.jena.rdf.model.Resource;
import org.apache.jena.vocabulary.RDF;
import org.apache.jena.vocabulary.RDFS;
/**
* A singleton that is used to render resources into strings.
* By default this displays qnames (if possible).
* Can be changed, for example, to switch to displaying rdfs:labels
* instead of qnames etc.
*
* @author Holger Knublauch
*/
public class RDFLabels {
private static RDFLabels singleton = new RDFLabels();
/**
* Gets the singleton instance of this class.
* @return the singleton
*/
public static RDFLabels get() {
return singleton;
}
/**
* Replaces the singleton to a subclass with different behavior.
* This is used by TopBraid, which has its own rendering engine.
* @param value the new engine
*/
public static void set(RDFLabels value) {
RDFLabels.singleton = value;
}
/**
* Gets a "human-readable" label for a blank node,
* e.g. Manchester Syntax for OWL restrictions.
* The default implementation doesn't do much yet it's overloaded in TopBraid.
* @param resource the blank node resource to get the label for
* @return a label for the bnode
*/
public String getBlankNodeLabel(Resource resource) {
return "_:" + resource.getId();
}
/**
* Gets a "human-readable" label for a given Resource.
* This checks for any existing rdfs:label, otherwise falls back to
* getLabel().
* @param resource the resource to get the label for
* @return the label (never null)
*/
public String getCustomizedLabel(Resource resource) {
String label = JenaUtil.getStringProperty(resource, RDFS.label);
if(label != null) {
return label;
}
else {
return getLabel(resource);
}
}
/**
* Gets the label for a given Resource.
* @param resource the Resource to get the label of
* @return the label (never null)
*/
public String getLabel(Resource resource) {
if(resource.isURIResource() && resource.getModel() != null) {
String qname = resource.getModel().qnameFor(resource.getURI());
if(qname != null) {
return qname;
}
else {
return "<" + resource.getURI() + ">";
}
}
else if(resource.isAnon() && resource.getModel() != null && resource.hasProperty(RDF.first)) {
StringBuffer buffer = new StringBuffer("[");
Iterator members = resource.as(RDFList.class).iterator();
while(members.hasNext()) {
RDFNode member = members.next();
buffer.append(RDFLabels.get().getNodeLabel(member));
if(members.hasNext()) {
buffer.append(", ");
}
}
buffer.append("]");
return buffer.toString();
}
else if(resource.isAnon()) {
return getBlankNodeLabel(resource);
}
else {
return resource.toString();
}
}
public String getNodeLabel(RDFNode node) {
if(node.isLiteral()) {
return node.asNode().getLiteralLexicalForm();
}
else {
return getLabel((Resource)node);
}
}
/**
* Renders a template call's label template into a label by inserting the
* evaluated SPARQL expressions into appropriate spaces marked with {expression}.
* Currently only simple variables are supported, e.g. {?test }.
* @param buffer the StringBuffer to write to
* @param labelTemplate the labelTemplate
* @param args the arguments a Map of pre-bound variables (supplied arguments)
*/
public static void appendTemplateCallLabel(StringBuffer buffer, String labelTemplate, Map args) {
for(int i = 0; i < labelTemplate.length(); i++) {
if(i < labelTemplate.length() - 3 && labelTemplate.charAt(i) == '{' && labelTemplate.charAt(i + 1) == '?') {
int varEnd = i + 2;
while(varEnd < labelTemplate.length()) {
if(labelTemplate.charAt(varEnd) == '}') {
String varName = labelTemplate.substring(i + 2, varEnd);
RDFNode varValue = args.get(varName);
if(varValue instanceof Resource) {
buffer.append(get().getLabel((Resource)varValue));
}
else if(varValue instanceof Literal) {
buffer.append(varValue.asNode().getLiteralLexicalForm());
}
break;
}
else {
varEnd++;
}
}
i = varEnd;
}
else {
buffer.append(labelTemplate.charAt(i));
}
}
}
}