Towards JENA-632: Conversion of Nodes to JsonValues.

jena-arq/src/main/java/org/apache/jena/sparql/function/js/NV.java

@@ -26,6 +26,7 @@
 import org.apache.jena.graph.NodeFactory;
 import org.apache.jena.sparql.expr.ExprEvalException;
 import org.apache.jena.sparql.expr.NodeValue;
+import org.apache.jena.sparql.lib.RDFTerm2Json;
 
 /**
  * General representation of an {@link NodeValue} for JavaScript. Conversion is to native
@@ -34,6 +35,7 @@
  * 
  * @see #fromNodeValue
  * @see #toNodeValue
+ * @see RDFTerm2Json RDFTerm2Json, for one way conversion JSON.  
  */
 
 public class NV implements RDFJS {

jena-arq/src/main/java/org/apache/jena/sparql/lib/RDFTerm2Json.java

@@ -0,0 +1,104 @@
+/*
+ * 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.
+ * <p>
+ * This is a one way, lossy, conversion from an RDF Term to the best available JSON value.
+ * <p> 
+ * This is not SPARQL results in JSON ({@locde application/result-sets+json}).
+ * 
+ * <table>
+ * <tr><th>RDF Term</th><th>JSON value</th></tr>
+ * <tr><td>URI</td><td>String</td></tr>
+ * <tr><td>xsd:string</td><td>String</td></tr>
+ * <tr><td>rdf:langString</td><td>String (no {@literal @}lang)</td></tr>
+ * <tr><td>XSD numeric</td><td>JSON number</td></tr>
+ * <tr><td>xsd:boolean</td><td>boolean</td></tr>
+ * <tr><td>Literal, other datatype</td><td>String, no ^^</td></tr>
+ * <tr><td>Unbound</td><td>JSON null</td></tr>
+ * </table>
+ * 
+ * @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(node.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());
+    }
+}

jena-arq/src/test/java/org/apache/jena/sparql/function/js/TestNV.java

@@ -32,7 +32,7 @@ public class TestNV {
 
     // No conversion to JS - becomes an NV.
     @Test public void nv_5() { test("'2018-01-06T17:56:41.293+00:00'^^xsd:dateTime"); }
-    @Test public void nv_6() { test("<http://jena/apche.org/>"); }
+    @Test public void nv_6() { test("<http://jena.apache.org/>"); }
     @Test public void nv_7() { test("_:abc123"); }
 
     @Test public void nv_10() {
@@ -44,10 +44,10 @@ public class TestNV {
     }
 
     @Test public void nv_12() {
-        NodeValue nodeValue = nv("<http://jena/apche.org/>");
+        NodeValue nodeValue = nv("<http://jena.apache.org/>");
         NV nv = new NV(nodeValue);
-        assertEquals("http://jena/apche.org/", nv.getUri());
-        assertEquals("http://jena/apche.org/", nv.getValue());
+        assertEquals("http://jena.apache.org/", nv.getUri());
+        assertEquals("http://jena.apache.org/", nv.getValue());
         assertEquals("NamedNode", nv.getTermType());
     }
 

jena-arq/src/test/java/org/apache/jena/sparql/lib/TS_Lib.java

@@ -0,0 +1,31 @@
+/*
+ * 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.junit.runner.RunWith;
+import org.junit.runners.Suite;
+import org.junit.runners.Suite.SuiteClasses;
+
+@RunWith(Suite.class)
+@SuiteClasses( {
+    TestRDFTerm2Json.class
+})
+public class TS_Lib {
+
+}

jena-arq/src/test/java/org/apache/jena/sparql/lib/TestRDFTerm2Json.java

@@ -0,0 +1,58 @@
+/*
+ * 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 static org.junit.Assert.assertEquals;
+
+import java.math.BigDecimal;
+
+import org.apache.jena.atlas.json.*;
+import org.apache.jena.graph.Node;
+import org.apache.jena.sparql.lib.RDFTerm2Json;
+import org.apache.jena.sparql.sse.SSE;
+import org.junit.Test;
+
+public class TestRDFTerm2Json {
+
+    @Test public void n2j_1() { test("'abc'", new JsonString("abc")); }
+
+    @Test public void n2j_2() { test("<http://jena.apache.org/>", new JsonString("http://jena.apache.org/")); }
+
+    @Test public void n2j_3() { test("123", JsonNumber.value(123)); }
+
+    @Test public void n2j_4() { test("123.0", JsonNumber.value(new BigDecimal("123.0"))); }
+
+    @Test public void n2j_5() { test("123e0", JsonNumber.value(/*(double)*/123e0)); }
+
+    @Test public void n2j_6() { test("'123e0'^^xsd:float", JsonNumber.value((float)123.0)); }
+
+    @Test public void n2j_7() { test("true", new JsonBoolean(true)); }
+
+    @Test public void n2j_8() { test("'text'@en", new JsonString("text")) ; }
+
+    @Test public void n2j_9() { assertEquals(JsonNull.instance, RDFTerm2Json.fromNode(null)) ; }
+
+
+    private void test(String nodeStr, JsonValue expected) {
+        Node n = SSE.parseNode(nodeStr);
+        JsonValue jv = RDFTerm2Json.fromNode(n);
+        assertEquals(expected, jv);
+    }
+
+}