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/* This file is part of the OWL API.
* The contents of this file are subject to the LGPL License, Version 3.0.
* Copyright 2014, The University of Manchester
*
* 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 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 General Public License for more details.
* You should have received a copy of the GNU General Public License along with this program. If not, see http://www.gnu.org/licenses/.
*
* Alternatively, the contents of this file may be used under the terms of the Apache License, Version 2.0 in which case, the provisions of the Apache License Version 2.0 are applicable instead of those above.
* 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.semanticweb.owlapi.rdf.rdfxml.parser;
import static org.semanticweb.owlapi.rdf.rdfxml.parser.RDFConstants.*;
import static org.semanticweb.owlapi.util.OWLAPIPreconditions.*;
import java.util.HashSet;
import java.util.Set;
import java.util.concurrent.atomic.AtomicLong;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import org.semanticweb.owlapi.io.XMLUtils;
import org.semanticweb.owlapi.model.NodeID;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
abstract class AbstractState {
//@formatter:off
@Nonnull static final String DATATYPE_RESOURCE = "rdf:datatype specified on a node with resource value.";
@Nonnull static final String TEXT_SEEN = "Text was seen and new node is started.";
@Nonnull static final String RDF_RDF = "Expecting rdf:RDF element.";
@Nonnull static final String OP_EXPECTED = "Cannot answer characters when object properties are expected.";
@Nonnull static final String CHARACTERS_NOT_EXPECTED = "Characters were not expected.";
@Nonnull static final String INCORRECT_START = "incorrect element start encountered.";
@Nonnull static final String EXPECTING_OBJECT = "Expecting an object element instead of character content.";
@Nonnull static final String RDF_RDF_EXPECTED = "Expecting rdf:rdf element instead of character content.";
@Nonnull static final String NODE_EXPECTED = "Cannot answer characters when node is expected.";
@Nonnull static final String NO_RDF_NODE_ID_ID_ABOUT = "Element cannot specify both rdf:nodeID and rdf:ID or rdf:about attributes.";
@Nonnull static final String NO_RDF_ID_AND_ABOUT = "Element cannot specify both rdf:ID and rdf:about attributes.";
@Nonnull static final String ABOUT_EACH_PREFIX_UNSUPPORTED = "rdf:aboutEachPrefix attribute is not supported.";
@Nonnull static final String ABOUT_EACH_UNSUPPORTED = "rdf:aboutEach attribute is not supported.";
//@formatter:on
protected static final Logger LOGGER = LoggerFactory.getLogger(AbstractState.class);
@Nonnull protected final RDFParser parser;
AbstractState(@Nonnull RDFParser parser) {
this.parser = parser;
}
/**
* Returns the reification manager for given attributes.
*
* @param atts
* the attributes
* @return the reification manager
*/
@Nonnull
ReificationManager getReificationManager(@Nonnull Attributes atts) {
String bagIDAttr = atts.getValue(RDFNS, ATTR_BAG_ID);
if (bagIDAttr == null) {
return ReificationManager.INSTANCE;
} else {
String bagID = parser.resolveIRI('#' + bagIDAttr);
return new ReifiedStatementBag(bagID, parser);
}
}
/**
* Parses the propertyAttributes production.
*
* @param subjectIRI
* IRI of the resource whose properties are being parsed
* @param atts
* attributes
* @param reificationManager
* the reification manager
*/
void propertyAttributes(@Nonnull String subjectIRI, @Nonnull Attributes atts,
@Nonnull ReificationManager reificationManager) {
int length = atts.getLength();
for (int i = 0; i < length; i++) {
String nsIRI = atts.getURI(i);
String localName = atts.getLocalName(i);
String value = atts.getValue(i);
assert value != null;
if (!XMLNS.equals(nsIRI) && !XMLLANG.equals(localName) && !(RDFNS.equals(nsIRI) && (ATTR_ID.equals(
localName) || ATTR_NODE_ID.equals(localName) || ATTR_ABOUT.equals(localName) || ELT_TYPE.equals(
localName) || ATTR_RESOURCE.equals(localName) || ATTR_PARSE_TYPE.equals(localName)
|| ATTR_ABOUT_EACH.equals(localName) || ATTR_ABOUT_EACH_PREFIX.equals(localName) || ATTR_BAG_ID.equals(
localName)))) {
String reificationID = reificationManager.getReificationID(null, parser);
parser.statementWithLiteralValue(subjectIRI, nsIRI + localName, value, null, reificationID);
} else if (RDFNS.equals(nsIRI) && ELT_TYPE.equals(localName)) {
String resolvedValue = parser.resolveIRI(value);
String reificationID = reificationManager.getReificationID(null, parser);
parser.statementWithResourceValue(subjectIRI, nsIRI + localName, resolvedValue, reificationID);
}
}
}
/**
* Extracts the IRI of the resource from rdf:resource or rdf:nodeID
* attribute. If no attribute is found, {@code null} is returned.
*
* @param atts
* the attributes
* @return the IRI of the resource or {@code null}
*/
@Nullable
String getNodeIDResourceResourceIRI(@Nonnull Attributes atts) {
String value = atts.getValue(RDFNS, ATTR_RESOURCE);
if (value != null) {
return parser.resolveIRI(value);
} else {
value = atts.getValue(RDFNS, ATTR_NODE_ID);
if (value != null) {
return NodeID.getIRIFromNodeID(value);
} else {
return null;
}
}
}
/**
* Checks whether given characters contain only whitespace.
*
* @param data
* the data being checked
* @param start
* the start index (inclusive)
* @param length
* the end index (non-inclusive)
* @return {@code true} if characters contain whitespace
*/
boolean notBlank(char[] data, int start, int length) {
int end = start + length;
for (int i = start; i < end; i++) {
if (notSpace(data[i])) {
return true;
}
}
return false;
}
/**
* @param c
* character to test
* @return true if the character is other than a space, carriage return, or
* tabulator
*/
boolean notSpace(char c) {
return c != ' ' && c != '\n' && c != '\r' && c != '\t';
}
/**
* Checks whether given characters contain only whitespace.
*
* @param buffer
* the data being checked
* @return {@code true} if characters contain whitespace
*/
boolean notBlank(@Nonnull StringBuilder buffer) {
for (int i = 0; i < buffer.length(); i++) {
if (notSpace(buffer.charAt(i))) {
return true;
}
}
return false;
}
}
/** State expecting start of RDF text. */
class StartRDF extends AbstractState implements State {
StartRDF(@Nonnull RDFParser parser) {
super(parser);
}
@Override
public void startElement(String namespaceIRI, String localName, String qName, @Nonnull Attributes atts) {
parser.verify(!RDFNS.equals(namespaceIRI) || !ELT_RDF.equals(localName), RDF_RDF);
String value = atts.getValue(XMLNS, "base");
if (value == null) {
LOGGER.info("Notice: root element does not have an xml:base. Relative IRIs will be resolved against {}",
parser.getBaseIRI());
}
// the logical IRI is the current IRI that we have as the base IRI
// at this point
parser.consumer.logicalURI(parser.getBaseIRI());
parser.pushState(new NodeElementList(parser));
}
@Override
public void endElement(String namespaceIRI, String localName, String qName) {
parser.popState();
}
@Override
public void characters(char[] data, int start, int length) {
parser.verify(notBlank(data, start, length), RDF_RDF_EXPECTED);
}
}
/** Parses emptyPropertyElt production. */
class EmptyPropertyElement extends AbstractState implements State {
@Nonnull protected final NodeElement nodeElement;
protected String pIRI;
@Nonnull
protected String propertyIRI() {
return verifyNotNull(pIRI);
}
EmptyPropertyElement(@Nonnull NodeElement nodeElement, @Nonnull RDFParser parser) {
super(parser);
this.nodeElement = nodeElement;
}
@Override
public void startElement(String namespaceIRI, String localName, String qName, @Nonnull Attributes atts) {
parser.verify(pIRI != null, INCORRECT_START);
// this is the invocation on the outer element
pIRI = nodeElement.getPropertyIRI(namespaceIRI + localName);
String reificationID = nodeElement.getReificationID(atts);
String objectIRI = getNodeIDResourceResourceIRI(atts);
if (objectIRI == null) {
objectIRI = NodeID.nextAnonymousIRI();
}
parser.statementWithResourceValue(nodeElement.subjectIRI(), propertyIRI(), objectIRI, reificationID);
propertyAttributes(objectIRI, atts, getReificationManager(atts));
}
@Override
public void endElement(String namespaceIRI, String localName, String qName) {
parser.popState();
}
@Override
public void characters(char[] data, int start, int length) {
parser.verify(true, CHARACTERS_NOT_EXPECTED);
}
}
/** Parses the nodeElement production. */
class NodeElement extends AbstractState implements State {
protected String subjectIRI;
protected ReificationManager reificationManager;
@Nonnull protected final AtomicLong nextLi = new AtomicLong(1);
NodeElement(@Nonnull RDFParser parser) {
super(parser);
}
@Nonnull
protected String subjectIRI() {
return verifyNotNull(subjectIRI);
}
void startDummyElement(@Nonnull Attributes atts) {
subjectIRI = NodeID.nextAnonymousIRI();
reificationManager = getReificationManager(atts);
}
/**
* @param atts
* the atts
* @return reification id
*/
@Nullable
String getReificationID(@Nonnull Attributes atts) {
String rdfID = atts.getValue(RDFNS, ATTR_ID);
if (rdfID != null) {
rdfID = parser.resolveIRI('#' + rdfID);
}
return reificationManager.getReificationID(rdfID, parser);
}
/** @return next list item */
@Nonnull
String getNextLi() {
return RDFNS + '_' + nextLi.getAndIncrement();
}
/**
* @param uri
* the uri
* @return property iri
*/
@Nonnull
String getPropertyIRI(@Nonnull String uri) {
if (RDF_LI.equals(uri)) {
return getNextLi();
}
return uri;
}
@Override
public void startElement(String namespaceIRI, String localName, String qName, @Nonnull Attributes atts) {
subjectIRI = getIDNodeIDAboutResourceIRI(atts);
boolean isRDFNS = RDFNS.equals(namespaceIRI);
reificationManager = getReificationManager(atts);
if (!isRDFNS || !ELT_DESCRIPTION.equals(localName)) {
parser.statementWithResourceValue(subjectIRI(), RDF_TYPE, namespaceIRI + localName, reificationManager
.getReificationID(null, parser));
}
// Checks if attribute list contains some of the unsupported attributes.
parser.verify(atts.getIndex(RDFNS, ATTR_ABOUT_EACH) != -1, ABOUT_EACH_UNSUPPORTED);
parser.verify(atts.getIndex(RDFNS, ATTR_ABOUT_EACH_PREFIX) != -1, ABOUT_EACH_PREFIX_UNSUPPORTED);
propertyAttributes(subjectIRI(), atts, verifyNotNull(reificationManager));
parser.pushState(new PropertyElementList(this, parser));
}
/**
* Extracts the IRI of the resource from rdf:ID, rdf:nodeID or rdf:about
* attribute. If no attribute is found, an IRI is generated.
*
* @param atts
* atts
* @return string for IRI
*/
@Nonnull
String getIDNodeIDAboutResourceIRI(@Nonnull Attributes atts) {
checkNotNull(atts, "atts cannot be null");
String result = null;
String value = atts.getValue(RDFNS, ATTR_ID);
if (value != null) {
result = parser.resolveIRI('#' + value);
}
value = atts.getValue(RDFNS, ATTR_ABOUT);
if (value != null) {
parser.verify(result != null, NO_RDF_ID_AND_ABOUT);
result = parser.resolveIRI(value);
}
value = atts.getValue(RDFNS, ATTR_NODE_ID);
if (value != null) {
parser.verify(result != null, NO_RDF_NODE_ID_ID_ABOUT);
result = NodeID.getIRIFromNodeID(value);
}
if (result == null) {
result = NodeID.nextAnonymousIRI();
}
return result;
}
@Override
public void endElement(String namespaceIRI, String localName, String qName) {
parser.popState();
}
@Override
public void characters(char[] data, int start, int length) {
parser.verify(notBlank(data, start, length), NODE_EXPECTED);
}
}
/** Parses the nodeElementList production. */
class NodeElementList extends AbstractState implements State {
NodeElementList(@Nonnull RDFParser parser) {
super(parser);
}
@Override
public void startElement(String namespaceIRI, String localName, String qName, Attributes atts) throws SAXException {
parser.pushState(new NodeElement(parser));
parser.state.startElement(namespaceIRI, localName, qName, atts);
}
@Override
public void endElement(String namespaceIRI, String localName, String qName) throws SAXException {
parser.popState();
parser.state.endElement(namespaceIRI, localName, qName);
}
@Override
public void characters(char[] data, int start, int length) {
parser.verify(notBlank(data, start, length), EXPECTING_OBJECT);
}
}
/** Parses parseTypeCollectionPropertyElt production. */
class ParseTypeCollectionElement extends AbstractState implements State {
protected final NodeElement nodeElement;
protected String pIRI;
@Nullable protected String reificationID;
protected String lastCellIRI;
@Nonnull
protected String lastCell() {
return verifyNotNull(lastCellIRI);
}
@Nonnull
protected String propertyIRI() {
return verifyNotNull(pIRI);
}
ParseTypeCollectionElement(NodeElement nodeElement, @Nonnull RDFParser parser) {
super(parser);
this.nodeElement = nodeElement;
}
@Override
public void startElement(String namespaceIRI, String localName, String qName, @Nonnull Attributes atts)
throws SAXException {
if (pIRI == null) {
pIRI = nodeElement.getPropertyIRI(namespaceIRI + localName);
reificationID = nodeElement.getReificationID(atts);
} else {
NodeElement collectionNode = new NodeElement(parser);
parser.pushState(collectionNode);
parser.state.startElement(namespaceIRI, localName, qName, atts);
String newListCellIRI = listCell(collectionNode.subjectIRI());
if (lastCellIRI == null) {
parser.statementWithResourceValue(nodeElement.subjectIRI(), propertyIRI(), newListCellIRI,
reificationID);
} else {
parser.statementWithResourceValue(lastCell(), RDF_REST, newListCellIRI, null);
}
lastCellIRI = newListCellIRI;
}
}
@Nonnull
String listCell(@Nonnull String valueIRI) {
String listCellIRI = NodeID.nextAnonymousIRI();
parser.statementWithResourceValue(listCellIRI, RDF_FIRST, valueIRI, null);
parser.statementWithResourceValue(listCellIRI, RDF_TYPE, RDF_LIST, null);
return listCellIRI;
}
@Override
public void endElement(String namespaceIRI, String localName, String qName) {
if (lastCellIRI == null) {
parser.statementWithResourceValue(nodeElement.subjectIRI(), propertyIRI(), RDF_NIL, reificationID);
} else {
parser.statementWithResourceValue(lastCell(), RDF_REST, RDF_NIL, null);
}
parser.popState();
}
@Override
public void characters(char[] data, int start, int length) {
parser.verify(notBlank(data, start, length), EXPECTING_OBJECT);
}
}
/**
* Parses resourcePropertyElt or literalPropertyElt productions. m_text is
* {@code null} when startElement is expected on the actual property element.
*/
class ResourceOrLiteralElement extends AbstractState implements State {
@Nonnull protected final NodeElement nodeElement;
protected String propertyIRI;
@Nullable protected String reificationID;
protected String datatype;
protected StringBuilder text;
protected NodeElement innerNode;
@Nonnull
protected String propertyIRI() {
return verifyNotNull(propertyIRI);
}
ResourceOrLiteralElement(@Nonnull NodeElement nodeElement, @Nonnull RDFParser parser) {
super(parser);
this.nodeElement = nodeElement;
}
@Override
public void startElement(String namespaceIRI, String localName, String qName, @Nonnull Attributes atts)
throws SAXException {
if (text == null) {
// this is the invocation on the outer element
propertyIRI = nodeElement.getPropertyIRI(namespaceIRI + localName);
reificationID = nodeElement.getReificationID(atts);
datatype = atts.getValue(RDFNS, ATTR_DATATYPE);
text = new StringBuilder();
} else {
parser.verify(notBlank(verifyNotNull(text)), TEXT_SEEN);
parser.verify(datatype != null, DATATYPE_RESOURCE);
innerNode = new NodeElement(parser);
parser.pushState(innerNode);
parser.state.startElement(namespaceIRI, localName, qName, atts);
}
}
@Override
public void endElement(String namespaceIRI, String localName, String qName) {
if (innerNode != null) {
parser.statementWithResourceValue(nodeElement.subjectIRI(), propertyIRI(), innerNode.subjectIRI(),
reificationID);
} else {
parser.statementWithLiteralValue(nodeElement.subjectIRI(), propertyIRI(), verifyNotNull(text.toString()),
datatype, reificationID);
}
parser.popState();
}
@Override
public void characters(char[] data, int start, int length) {
if (innerNode != null) {
parser.verify(notBlank(data, start, length), OP_EXPECTED);
} else {
text.append(data, start, length);
}
}
}
/** Parses parseTypeLiteralPropertyElt production. */
class ParseTypeLiteralElement extends AbstractState implements State {
protected final NodeElement nodeElement;
protected String pIRI;
@Nullable protected String reificationID;
protected int depth;
protected StringBuilder m_content;
// avoid multiple redeclarations of namespace abbreviations in XML Literals
protected Set declaredNamespaces = new HashSet<>(2);
@Nonnull
protected String propertyIRI() {
return verifyNotNull(pIRI);
}
ParseTypeLiteralElement(NodeElement nodeElement, @Nonnull RDFParser parser) {
super(parser);
this.nodeElement = nodeElement;
}
@Override
public void startElement(String namespaceIRI, String localName, String qName, @Nonnull Attributes atts) {
if (depth == 0) {
pIRI = nodeElement.getPropertyIRI(namespaceIRI + localName);
reificationID = nodeElement.getReificationID(atts);
m_content = new StringBuilder();
} else {
m_content.append('<');
m_content.append(qName);
// ensure namespace declarations are added at the root, and only if
// not already added in a parent node
if (!localName.equals(qName) && declaredNamespaces.add(namespaceIRI)) {
m_content.append(" xmlns:").append(qName.substring(0, qName.indexOf(':'))).append("=\"").append(
namespaceIRI).append('"');
}
int length = atts.getLength();
for (int i = 0; i < length; i++) {
m_content.append(' ');
m_content.append(atts.getQName(i));
m_content.append("=\"");
m_content.append(atts.getValue(i));
m_content.append('"');
}
m_content.append('>');
}
depth++;
}
@Override
public void endElement(String namespaceIRI, String localName, String qName) {
if (depth == 1) {
parser.statementWithLiteralValue(nodeElement.subjectIRI(), propertyIRI(), verifyNotNull(m_content
.toString()), RDF_XMLLITERAL, reificationID);
parser.popState();
} else {
m_content.append("');
}
depth--;
}
@Override
public void characters(char[] data, int start, int length) {
XMLUtils.escapeXML(data, start, length, m_content);
}
}
/** Parses parseTypeResourcePropertyElt production. */
class ParseTypeResourceElement extends AbstractState implements State {
protected final NodeElement nodeElement;
protected String mpIRI;
@Nullable protected String reificationID;
ParseTypeResourceElement(NodeElement nodeElement, @Nonnull RDFParser parser) {
super(parser);
this.nodeElement = nodeElement;
}
@Override
public void startElement(String namespaceIRI, String localName, String qName, @Nonnull Attributes atts) {
mpIRI = nodeElement.getPropertyIRI(namespaceIRI + localName);
reificationID = nodeElement.getReificationID(atts);
NodeElement anonymousNodeElement = new NodeElement(parser);
anonymousNodeElement.startDummyElement(atts);
parser.statementWithResourceValue(nodeElement.subjectIRI(), verifyNotNull(mpIRI), anonymousNodeElement
.subjectIRI(), reificationID);
parser.pushState(new PropertyElementList(anonymousNodeElement, parser));
}
@Override
public void endElement(String namespaceIRI, String localName, String qName) {
parser.popState();
}
@Override
public void characters(char[] data, int start, int length) {
parser.verify(notBlank(data, start, length), OP_EXPECTED);
}
}
/**
* Parses the propertyEltList production. The contents of the startElement
* method implements also the propertyElt production.
*/
class PropertyElementList extends AbstractState implements State {
@Nonnull protected final NodeElement node;
PropertyElementList(@Nonnull NodeElement nodeElement, @Nonnull RDFParser parser) {
super(parser);
node = nodeElement;
}
@Override
public void startElement(String namespaceIRI, String localName, String qName, @Nonnull Attributes atts)
throws SAXException {
String parseType = atts.getValue(RDFNS, ATTR_PARSE_TYPE);
// allow for xml literals with specified dataype instead of just
// parseType=Literal
if (PARSE_TYPE_LITERAL.equals(parseType) || RDF_XMLLITERAL.equals(atts.getValue(RDFNS, ATTR_DATATYPE))) {
parser.pushState(new ParseTypeLiteralElement(node, parser));
} else if (PARSE_TYPE_RESOURCE.equals(parseType)) {
parser.pushState(new ParseTypeResourceElement(node, parser));
} else if (PARSE_TYPE_COLLECTION.equals(parseType)) {
parser.pushState(new ParseTypeCollectionElement(node, parser));
} else if (parseType != null) {
parser.pushState(new ParseTypeLiteralElement(node, parser));
} else {
String objectIRI = getNodeIDResourceResourceIRI(atts);
if (objectIRI != null) {
parser.pushState(new EmptyPropertyElement(node, parser));
} else {
parser.pushState(new ResourceOrLiteralElement(node, parser));
}
}
parser.state.startElement(namespaceIRI, localName, qName, atts);
}
@Override
public void endElement(String namespaceIRI, String localName, String qName) throws SAXException {
parser.popState();
parser.state.endElement(namespaceIRI, localName, qName);
}
@Override
public void characters(char[] data, int start, int length) {
parser.verify(notBlank(data, start, length), OP_EXPECTED);
}
}
class ReificationManager {
@Nonnull public static final ReificationManager INSTANCE = new ReificationManager();
@Nullable
@SuppressWarnings("unused")
String getReificationID(String reificationID, @Nonnull RDFParser parser) {
return reificationID;
}
}
class ReifiedStatementBag extends ReificationManager {
@Nonnull protected final AtomicLong elements = new AtomicLong(1);
@Nonnull protected final String iri;
ReifiedStatementBag(@Nonnull String uri, @Nonnull RDFParser parser) {
iri = uri;
parser.statementWithResourceValue(iri, RDF_TYPE, RDF_BAG, null);
}
@Nullable
@Override
String getReificationID(@Nullable String reificationID, @Nonnull RDFParser parser) {
String resultIRI;
if (reificationID == null) {
resultIRI = NodeID.nextAnonymousIRI();
} else {
resultIRI = reificationID;
}
parser.statementWithResourceValue(iri, RDFNS + '_' + elements.getAndIncrement(), resultIRI, null);
return resultIRI;
}
}
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