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ARQ is a SPARQL 1.1 query engine for Apache Jena
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.apache.jena.sparql.lib;
import org.apache.jena.atlas.json.*;
import org.apache.jena.datatypes.RDFDatatype;
import org.apache.jena.graph.Node;
import org.apache.jena.rdf.model.impl.Util;
import org.apache.jena.riot.system.RiotLib;
import org.apache.jena.sparql.expr.NodeValue;
import org.apache.jena.sparql.function.js.NV;
/**
* General converting of {@link Node}s to JSON.
*
* This is a one way, lossy, conversion from an RDF Term to the best available JSON value.
*
* This is not SPARQL results in JSON ({@code application/result-sets+json}).
*
*
* RDF Term JSON value URI String xsd:string String rdf:langString String (no {@literal @}lang) XSD numeric JSON number xsd:boolean boolean Literal, other datatype String, no ^^ Unbound JSON null
*
* @see NV for conversion to and from {@link NodeValue}s for function argument and results.
*/
public class RDFTerm2Json {
// Six data types that are primitives in JavaScript:
// Boolean
// Null
// Undefined
// Number
// String
// Symbol (new in ECMAScript 6; not in Nashorn/Java8).
// and Object
public static JsonValue fromNode(Node node) {
if ( node == null )
return JsonNull.instance;
if ( node.isURI() )
return new JsonString(node.getURI());
if ( node.isBlank() ) {
Node node2 = RiotLib.blankNodeToIri(node);
return new JsonString(node2.getURI());
}
if ( node.isVariable() )
return new JsonString("?"+node.getName());
// Literals.
if ( Util.isSimpleString(node) || Util.isLangString(node) )
return new JsonString(node.getLiteralLexicalForm());
// Includes well-formed testing.
RDFDatatype dt = node.getLiteralDatatype();
NodeValue nv = NodeValue.makeNode(node);
if ( nv.isNumber() ) {
// Order matters here to find the narrowest choice.
if ( nv.isInteger() ) {
try {
return JsonNumber.value(nv.getInteger().longValueExact());
} catch (ArithmeticException ex) {
// Bad in some way : scale maybe.
// Try as decimal.
}
}
if ( nv.isDecimal() )
return JsonNumber.value(nv.getDecimal());
if ( nv.isDouble() )
return JsonNumber.value(nv.getDouble());
if ( nv.isFloat() )
return JsonNumber.value(nv.getFloat());
// Drop through.
} else if ( nv.isBoolean() ) {
return new JsonBoolean(nv.getBoolean());
}
// else
return new JsonString(node.getLiteralLexicalForm());
}
}