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Rio parser and writer implementation for the RDF/JSON file format.
/*
* Licensed to Aduna under one or more contributor license agreements.
* See the NOTICE.txt file distributed with this work for additional
* information regarding copyright ownership.
*
* Aduna licenses this file to you under the terms of the Aduna BSD
* License (the "License"); you may not use this file except in compliance
* with the License. See the LICENSE.txt file distributed with this work
* for the full License.
*
* 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.openrdf.rio.rdfjson;
import java.io.IOException;
import java.io.InputStream;
import java.io.Reader;
import java.util.HashSet;
import java.util.Set;
import com.fasterxml.jackson.core.JsonLocation;
import com.fasterxml.jackson.core.JsonParseException;
import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.core.JsonToken;
import org.apache.commons.io.input.BOMInputStream;
import org.openrdf.model.Literal;
import org.openrdf.model.Resource;
import org.openrdf.model.Statement;
import org.openrdf.model.URI;
import org.openrdf.model.Value;
import org.openrdf.model.ValueFactory;
import org.openrdf.rio.RDFFormat;
import org.openrdf.rio.RDFHandler;
import org.openrdf.rio.RDFHandlerException;
import org.openrdf.rio.RDFParseException;
import org.openrdf.rio.RDFParser;
import org.openrdf.rio.RioSetting;
import org.openrdf.rio.helpers.RDFJSONParserSettings;
import org.openrdf.rio.helpers.RDFParserBase;
/**
* {@link RDFParser} implementation for the RDF/JSON format
*
* @author Peter Ansell
* @since 2.7.0
*/
public class RDFJSONParser extends RDFParserBase implements RDFParser {
private final RDFFormat actualFormat;
/**
* Creates a parser using {@link RDFFormat#RDFJSON} to identify the parser.
*/
public RDFJSONParser() {
this(RDFFormat.RDFJSON);
}
/**
* Creates a parser using the given RDFFormat to self identify.
*
* @param actualFormat
*/
public RDFJSONParser(final RDFFormat actualFormat) {
this.actualFormat = actualFormat;
}
@Override
public RDFFormat getRDFFormat() {
return this.actualFormat;
}
@Override
public void parse(final InputStream inputStream, final String baseUri)
throws IOException, RDFParseException, RDFHandlerException
{
if (this.rdfHandler != null) {
this.rdfHandler.startRDF();
}
JsonParser jp = null;
try {
jp = RDFJSONUtility.JSON_FACTORY.createParser(new BOMInputStream(inputStream, false));
rdfJsonToHandlerInternal(this.rdfHandler, this.valueFactory, jp);
}
catch (final IOException e) {
if (jp != null) {
reportFatalError("Found IOException during parsing", e, jp.getCurrentLocation());
}
else {
reportFatalError(e);
}
}
finally {
if (jp != null) {
try {
jp.close();
}
catch (final IOException e) {
reportFatalError("Found exception while closing JSON parser", e, jp.getCurrentLocation());
}
}
}
if (this.rdfHandler != null) {
this.rdfHandler.endRDF();
}
}
/**
* Creates a literal, using the current value, language, and datatype, and
* additionally using the given {@link JsonLocation} to provide information
* about the line and column numbers in the event of a warning, error or
* exception being generated by the creation of the literal.
*
* @param nextValue
* @param nextLanguage
* @param object
* @param currentLocation
* @return
* @throws RDFParseException
* @since 2.7.4
*/
protected Literal createLiteral(String nextValue, String nextLanguage, URI datatype,
JsonLocation currentLocation)
throws RDFParseException
{
return createLiteral(nextValue, nextLanguage, datatype, currentLocation.getLineNr(),
currentLocation.getColumnNr());
}
protected void reportError(String msg, Throwable e, JsonLocation location, RioSetting setting)
throws RDFParseException
{
reportError(msg, location.getLineNr(), location.getColumnNr(), setting);
}
protected void reportError(String msg, JsonLocation location, RioSetting setting)
throws RDFParseException
{
reportError(msg, location.getLineNr(), location.getColumnNr(), setting);
}
protected void reportFatalError(String msg, Throwable e, JsonLocation location)
throws RDFParseException
{
reportFatalError(msg, location.getLineNr(), location.getColumnNr());
}
protected void reportFatalError(String msg, JsonLocation location)
throws RDFParseException
{
reportFatalError(msg, location.getLineNr(), location.getColumnNr());
}
@Override
public void parse(final Reader reader, final String baseUri)
throws IOException, RDFParseException, RDFHandlerException
{
if (rdfHandler == null) {
rdfHandler.startRDF();
}
JsonParser jp = null;
try {
jp = RDFJSONUtility.JSON_FACTORY.createParser(reader);
rdfJsonToHandlerInternal(rdfHandler, valueFactory, jp);
}
catch (final IOException e) {
if (jp != null) {
reportFatalError("Found IOException during parsing", e, jp.getCurrentLocation());
}
else {
reportFatalError(e);
}
}
finally {
if (jp != null) {
try {
jp.close();
}
catch (final IOException e) {
reportFatalError("Found exception while closing JSON parser", e, jp.getCurrentLocation());
}
}
}
if(rdfHandler != null) {
rdfHandler.endRDF();
}
}
private void rdfJsonToHandlerInternal(final RDFHandler handler, final ValueFactory vf, final JsonParser jp)
throws IOException, JsonParseException, RDFParseException, RDFHandlerException
{
if (jp.nextToken() != JsonToken.START_OBJECT) {
reportFatalError("Expected RDF/JSON document to start with an Object", jp.getCurrentLocation());
}
while (jp.nextToken() != JsonToken.END_OBJECT) {
final String subjStr = jp.getCurrentName();
Resource subject = null;
subject = subjStr.startsWith("_:") ? vf.createBNode(subjStr.substring(2)) : vf.createURI(subjStr);
if (jp.nextToken() != JsonToken.START_OBJECT) {
reportFatalError("Expected subject value to start with an Object", jp.getCurrentLocation());
}
boolean foundPredicate = false;
while (jp.nextToken() != JsonToken.END_OBJECT) {
final String predStr = jp.getCurrentName();
final URI predicate = vf.createURI(predStr);
foundPredicate = true;
if (jp.nextToken() != JsonToken.START_ARRAY) {
reportFatalError("Expected predicate value to start with an array", jp.getCurrentLocation());
}
boolean foundObject = false;
while (jp.nextToken() != JsonToken.END_ARRAY) {
if (jp.getCurrentToken() != JsonToken.START_OBJECT) {
reportFatalError("Expected object value to start with an Object: subject=<" + subjStr
+ "> predicate=<" + predStr + ">", jp.getCurrentLocation());
}
String nextValue = null;
String nextType = null;
String nextDatatype = null;
String nextLanguage = null;
final Set nextContexts = new HashSet(2);
while (jp.nextToken() != JsonToken.END_OBJECT) {
final String fieldName = jp.getCurrentName();
if (RDFJSONUtility.VALUE.equals(fieldName)) {
if (nextValue != null) {
reportError("Multiple values found for a single object: subject=" + subjStr
+ " predicate=" + predStr, jp.getCurrentLocation(),
RDFJSONParserSettings.FAIL_ON_MULTIPLE_OBJECT_VALUES);
}
jp.nextToken();
nextValue = jp.getText();
}
else if (RDFJSONUtility.TYPE.equals(fieldName)) {
if (nextType != null) {
reportError("Multiple types found for a single object: subject=" + subjStr
+ " predicate=" + predStr, jp.getCurrentLocation(),
RDFJSONParserSettings.FAIL_ON_MULTIPLE_OBJECT_TYPES);
}
jp.nextToken();
nextType = jp.getText();
}
else if (RDFJSONUtility.LANG.equals(fieldName)) {
if (nextLanguage != null) {
reportError("Multiple languages found for a single object: subject=" + subjStr
+ " predicate=" + predStr, jp.getCurrentLocation(),
RDFJSONParserSettings.FAIL_ON_MULTIPLE_OBJECT_LANGUAGES);
}
jp.nextToken();
nextLanguage = jp.getText();
}
else if (RDFJSONUtility.DATATYPE.equals(fieldName)) {
if (nextDatatype != null) {
reportError("Multiple datatypes found for a single object: subject=" + subjStr
+ " predicate=" + predStr, jp.getCurrentLocation(),
RDFJSONParserSettings.FAIL_ON_MULTIPLE_OBJECT_DATATYPES);
}
jp.nextToken();
nextDatatype = jp.getText();
}
else if (RDFJSONUtility.GRAPHS.equals(fieldName)) {
if (jp.nextToken() != JsonToken.START_ARRAY) {
reportError("Expected graphs to start with an array", jp.getCurrentLocation(),
RDFJSONParserSettings.SUPPORT_GRAPHS_EXTENSION);
}
while (jp.nextToken() != JsonToken.END_ARRAY) {
final String nextGraph = jp.getText();
nextContexts.add(nextGraph);
}
}
else {
reportError("Unrecognised JSON field name for object: subject=" + subjStr
+ " predicate=" + predStr + " fieldname=" + fieldName, jp.getCurrentLocation(),
RDFJSONParserSettings.FAIL_ON_UNKNOWN_PROPERTY);
}
}
Value object = null;
if (nextType == null) {
reportFatalError("No type for object: subject=" + subjStr + " predicate=" + predStr,
jp.getCurrentLocation());
}
if (nextValue == null) {
reportFatalError("No value for object: subject=" + subjStr + " predicate=" + predStr,
jp.getCurrentLocation());
}
if (RDFJSONUtility.LITERAL.equals(nextType)) {
if (nextLanguage != null) {
object = this.createLiteral(nextValue, nextLanguage, null, jp.getCurrentLocation());
}
else if (nextDatatype != null) {
object = this.createLiteral(nextValue, null, this.createURI(nextDatatype),
jp.getCurrentLocation());
}
else {
object = this.createLiteral(nextValue, null, null, jp.getCurrentLocation());
}
}
else if (RDFJSONUtility.BNODE.equals(nextType)) {
if (nextLanguage != null) {
reportFatalError("Language was attached to a blank node object: subject=" + subjStr
+ " predicate=" + predStr, jp.getCurrentLocation());
}
if (nextDatatype != null) {
reportFatalError("Datatype was attached to a blank node object: subject=" + subjStr
+ " predicate=" + predStr, jp.getCurrentLocation());
}
object = vf.createBNode(nextValue.substring(2));
}
else if (RDFJSONUtility.URI.equals(nextType)) {
if (nextLanguage != null) {
reportFatalError("Language was attached to a uri object: subject=" + subjStr
+ " predicate=" + predStr, jp.getCurrentLocation());
}
if (nextDatatype != null) {
reportFatalError("Datatype was attached to a uri object: subject=" + subjStr
+ " predicate=" + predStr, jp.getCurrentLocation());
}
object = vf.createURI(nextValue);
}
foundObject = true;
if (!nextContexts.isEmpty()) {
for (final String nextContext : nextContexts) {
final Resource context = nextContext.equals(RDFJSONUtility.NULL) ? null
: vf.createURI(nextContext);
Statement st = vf.createStatement(subject, predicate, object, context);
if (handler != null) {
handler.handleStatement(st);
}
}
}
else {
Statement st = vf.createStatement(subject, predicate, object);
if (handler != null) {
handler.handleStatement(st);
}
}
}
if (!foundObject) {
reportFatalError("No object for predicate: subject=" + subjStr + " predicate=" + predStr,
jp.getCurrentLocation());
}
}
if (!foundPredicate) {
reportFatalError("No predicate for object: subject=" + subjStr, jp.getCurrentLocation());
}
}
}
}
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