[GitHub] [jena] ajs6f commented on a change in pull request #804: JENA-1974: G, a library of functions for working with Graph.

[GitBox <gi...@apache.org>]

ajs6f commented on a change in pull request #804:
URL: https://github.com/apache/jena/pull/804#discussion_r498327157



##########
File path: jena-arq/src/main/java/org/apache/jena/riot/other/G.java
##########
@@ -0,0 +1,593 @@
+/*
+ * 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.riot.other;
+
+import java.util.*;
+import java.util.function.Consumer;
+
+import org.apache.jena.atlas.iterator.Iter;
+import org.apache.jena.graph.Graph;
+import org.apache.jena.graph.GraphUtil;
+import org.apache.jena.graph.Node;
+import org.apache.jena.graph.Triple;
+import org.apache.jena.riot.out.NodeFmtLib;
+//import org.apache.jena.shacl.lib.GN;
+//import org.apache.jena.shacl.lib.RDFDataException;
+//import org.apache.jena.shacl.lib.Transitive;
+//import org.apache.jena.shacl.sys.C;
+import org.apache.jena.sparql.core.Quad;
+import org.apache.jena.sparql.graph.NodeConst;
+import org.apache.jena.sparql.util.graph.GNode;
+import org.apache.jena.sparql.util.graph.GraphList;
+import org.apache.jena.util.iterator.ExtendedIterator;
+
+/** A library of functions for working with {@link Graph}. */
+public class G {
+    private G() {}
+    private static Node rdfType = NodeConst.nodeRDFType;
+
+    /** Return the subject of a triple, or null if the triple is null. */
+    public static Node subject(Triple triple) {
+        return triple == null ? null : triple.getSubject();
+    }
+
+    /** Return the predicate of a triple, or null if the triple is null. */
+    public static Node predicate(Triple triple) {
+        return triple == null ? null : triple.getPredicate();
+    }
+
+    /** Return the object of a triple, or null if the triple is null. */
+    public static Node object(Triple triple) {
+        return triple == null ? null : triple.getObject();
+    }
+
+    // ---- Node filter tests.
+    public static boolean isURI(Node n)         { return n != null && n.isURI(); }
+    public static boolean isBlank(Node n)       { return n != null && n.isBlank(); }
+    public static boolean isLiteral(Node n)     { return n != null && n.isLiteral(); }
+    public static boolean isResource(Node n)    { return n != null && (n.isURI()||n.isBlank()); }
+
+    /** Convert null to Node.ANY */
+    public static Node nullAsAny(Node x) { return nullAsDft(x, Node.ANY) ; }
+
+    /** Convert null to some default Node */
+    public static Node nullAsDft(Node x, Node dft) { return x==null ? dft : x ; }
+
+    /** Does the graph match the s/p/o pattern? */ 
+    public static boolean contains(Graph g, Node s, Node p, Node o) {
+        return g.contains(s, p, o);
+    }
+    
+    /** Does the graph use the node anywhere as a subject, predicate or object? */
+    public static boolean containsNode(Graph graph, Node node) {
+        return GraphUtil.containsNode(graph, node);
+//        return
+//            contains(graph, node, Node.ANY, Node.ANY) ||
+//            contains(graph, Node.ANY, Node.ANY, node) ||
+//            contains(graph, Node.ANY, node, Node.ANY) ;
+    }
+    
+    /** Test whether the node has the type or is rdfs:subclassOf. */
+    public static boolean isOfType(Graph graph, Node x, Node type) {
+        Objects.requireNonNull(x, "Subject");
+        Objects.requireNonNull(type, "Type");
+        List<Node> allClasses = listSubClasses(graph, type);
+        for ( Node c : allClasses ) {
+            if ( hasType(graph, x, c) )
+                return true;
+        }
+        return false;
+    }
+
+    /** Does the node x have the given type (non-RDFS - no rdfs:subclassOf considered)? */ 
+    public static boolean hasType(Graph graph, Node x, Node type) {
+        Objects.requireNonNull(x, "Subject");
+        Objects.requireNonNull(type, "Type");
+        return contains(graph, x, NodeConst.nodeRDFType, type);
+    }
+
+    //---- get/list/iter
+
+    /** Does node {@code s} have property {@code p} in graph {@code g}? */
+    public static boolean hasProperty(Graph g, Node s, Node p) {
+        return g.contains(s, p, null);
+    }
+
+    /** Contains exactly one. */
+    public static boolean containsOne(Graph g, Node s, Node p, Node o) {
+        return g.contains(s, p, o) && Iter.count(g.find(s,p,null)) == 1;

Review comment:
       See https://issues.apache.org/jira/browse/JENA-1956...




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