Rdf API Improvements (toString, equals, hashCode)

src/main/java/com/apicatalog/jsonld/serialization/RdfToJsonld.java

@@ -333,8 +333,8 @@ private void step5(final String graphName, final RdfGraph graph) throws JsonLdEr
         // 5.7.
         for (final RdfTriple triple : graph.toList()) {
 
-            final String subject = triple.getSubject().toString();
-            final String predicate = triple.getPredicate().toString();
+            final String subject = triple.getSubject().getValue();
+            final String predicate = triple.getPredicate().getValue();
 
             // 5.7.1.
             if (!graphMap.contains(graphName, subject)) {
@@ -350,9 +350,9 @@ private void step5(final String graphName, final RdfGraph graph) throws JsonLdEr
 
             // 5.7.4.
             if ((triple.getObject().isBlankNode() || triple.getObject().isIRI())
-                    && !graphMap.contains(graphName, triple.getObject().toString())) {
+                    && !graphMap.contains(graphName, triple.getObject().getValue())) {
 
-                graphMap.set(graphName, triple.getObject().toString(), Keywords.ID, JsonProvider.instance().createValue(triple.getObject().toString()));
+                graphMap.set(graphName, triple.getObject().getValue(), Keywords.ID, JsonProvider.instance().createValue(triple.getObject().getValue()));
             }
 
             // 5.7.5.
@@ -364,11 +364,11 @@ private void step5(final String graphName, final RdfGraph graph) throws JsonLdEr
 
                     JsonArray types = type.get().asJsonArray();
 
-                    graphMap.set(graphName, subject, Keywords.TYPE, JsonProvider.instance().createArrayBuilder(types).add(triple.getObject().toString()).build());
+                    graphMap.set(graphName, subject, Keywords.TYPE, JsonProvider.instance().createArrayBuilder(types).add(triple.getObject().getValue()).build());
 
                 } else {
 
-                    graphMap.set(graphName, subject, Keywords.TYPE, JsonProvider.instance().createArrayBuilder().add(triple.getObject().toString()).build());
+                    graphMap.set(graphName, subject, Keywords.TYPE, JsonProvider.instance().createArrayBuilder().add(triple.getObject().getValue()).build());
                 }
 
                 continue;
@@ -398,20 +398,20 @@ private void step5(final String graphName, final RdfGraph graph) throws JsonLdEr
             }
 
             // 5.7.9.
-            if (triple.getObject().isIRI() && RdfConstants.NIL.equals(triple.getObject().toString())) {
+            if (triple.getObject().isIRI() && RdfConstants.NIL.equals(triple.getObject().getValue())) {
 
                 Reference reference = new Reference();
                 reference.graphName = graphName;
                 reference.subject = subject;
                 reference.property = predicate;
                 reference.value = value;
 
-                graphMap.addUsage(graphName, triple.getObject().toString(), reference);
+                graphMap.addUsage(graphName, triple.getObject().getValue(), reference);
 
             // 5.7.10.
-            } else if (referenceOnce.containsKey(triple.getObject().toString())) {
+            } else if (referenceOnce.containsKey(triple.getObject().getValue())) {
 
-                referenceOnce.put(triple.getObject().toString(), null);
+                referenceOnce.put(triple.getObject().getValue(), null);
 
             // 5.7.11.
             } else if (triple.getObject().isBlankNode()) {
@@ -422,7 +422,7 @@ private void step5(final String graphName, final RdfGraph graph) throws JsonLdEr
                 reference.property = predicate;
                 reference.value = value;
 
-                referenceOnce.put(triple.getObject().toString(), reference);
+                referenceOnce.put(triple.getObject().getValue(), reference);
             }
         }
     }

src/main/java/com/apicatalog/rdf/RdfTriple.java

@@ -28,18 +28,17 @@ public interface RdfTriple {
     RdfResource getSubject();
 
     /**
-     * An absolute IRI or blank node identifier denoting the predicate of the triple.
+     * An absolute IRI or blank node identifier denoting the predicate of the
+     * triple.
      *
      * @return an absolute URI or blank node
      */
     RdfResource getPredicate();
 
-
     /**
      * An absolute IRI or blank node identifier or {@link RdfLiteral}.
      *
      * @return {@link RdfValue}
      */
     RdfValue getObject();
-
 }

src/main/java/com/apicatalog/rdf/impl/RdfLiteralImpl.java

@@ -19,6 +19,7 @@
 import java.util.Optional;
 
 import com.apicatalog.rdf.RdfLiteral;
+import com.apicatalog.rdf.io.nquad.NQuadsWriter;
 import com.apicatalog.rdf.lang.RdfConstants;
 import com.apicatalog.rdf.lang.XsdConstants;
 
@@ -85,15 +86,18 @@ public boolean equals(Object obj) {
     public String toString() {
         StringBuilder builder = new StringBuilder();
 
-        builder.append(value);
+        builder.append('"');
+        builder.append(NQuadsWriter.escape(value));
+        builder.append('"');
 
         if (langTag != null) {
             builder.append('@');
             builder.append(langTag);
 
-        } else if (dataType != null) {
-            builder.append("^^");
+        } else if (dataType != null && !XsdConstants.STRING.equals(dataType)) {
+            builder.append("^^<");
             builder.append(dataType);
+            builder.append('>');
         }
 
         return builder.toString();

src/main/java/com/apicatalog/rdf/impl/RdfNQuadImpl.java

@@ -15,6 +15,7 @@
  */
 package com.apicatalog.rdf.impl;
 
+import java.util.Objects;
 import java.util.Optional;
 
 import com.apicatalog.rdf.RdfNQuad;
@@ -37,10 +38,39 @@ public Optional<RdfResource> getGraphName() {
 
     @Override
     public String toString() {
-        return  "RdfNQuadImpl[subject=" + getSubject()
-                    + ", predicate=" + getPredicate()
-                    + ", object=" + getObject()
-                    + ", graph=" + graphName
-                    + "]";
+        final StringBuilder builder = new StringBuilder()
+                .append(getSubject())
+                .append(' ')
+                .append(getPredicate())
+                .append(' ')
+                .append(getObject())
+                .append(' ');
+
+        if (graphName != null) {
+            builder.append(graphName).append(' ');
+        }
+
+        return builder.append('.').toString();
+    }
+
+    @Override
+    public int hashCode() {
+        final int prime = 31;
+        int result = super.hashCode();
+        result = prime * result + Objects.hash(graphName);
+        return result;
     }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj)
+            return true;
+        if (!super.equals(obj))
+            return false;
+        if (getClass() != obj.getClass())
+            return false;
+        RdfNQuadImpl other = (RdfNQuadImpl) obj;
+        return Objects.equals(graphName, other.graphName);
+    }
+
 }

src/main/java/com/apicatalog/rdf/impl/RdfResourceImpl.java

@@ -66,6 +66,9 @@ public boolean equals(Object obj) {
 
     @Override
     public String toString() {
-        return Objects.toString(value);
+        if (blankNode) {
+            return Objects.toString(value);
+        }
+        return '<' + Objects.toString(value) + '>';
     }
 }

src/main/java/com/apicatalog/rdf/impl/RdfTripleImpl.java

@@ -15,6 +15,8 @@
  */
 package com.apicatalog.rdf.impl;
 
+import java.util.Objects;
+
 import com.apicatalog.rdf.RdfResource;
 import com.apicatalog.rdf.RdfTriple;
 import com.apicatalog.rdf.RdfValue;
@@ -50,9 +52,24 @@ public RdfValue getObject() {
 
     @Override
     public String toString() {
-        return  "RdfTripleImpl[subject=" + subject
-                    + ", predicate=" + predicate
-                    + ", object=" + object
-                    + "]";
+        return subject + " " + predicate + " " + object + " .";
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(object, predicate, subject);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj)
+            return true;
+        if (obj == null)
+            return false;
+        if (getClass() != obj.getClass())
+            return false;
+        RdfTripleImpl other = (RdfTripleImpl) obj;
+        return Objects.equals(object, other.object) && Objects.equals(predicate, other.predicate) && Objects.equals(subject, other.subject);
     }
+
 }

src/main/java/com/apicatalog/rdf/io/nquad/NQuadsWriter.java

@@ -77,7 +77,7 @@ public void writeValue(RdfValue object) throws IOException {
         }
 
         if (object.isIRI()) {
-            writeIri(object.toString());
+            writeIri(object.getValue());
             return;
         }
 
@@ -87,7 +87,7 @@ public void writeValue(RdfValue object) throws IOException {
         }
 
         if (object.isBlankNode()) {
-            writer.write(object.toString());
+            writer.write(object.getValue());
             return;
         }