A utility class for recursive search in cyclic graph

[simantics/platform.git] / bundles / org.simantics.db.common / src / org / simantics / db / common / recursive / FindParentsWithType.java

diff --git a/bundles/org.simantics.db.common/src/org/simantics/db/common/recursive/FindParentsWithType.java b/bundles/org.simantics.db.common/src/org/simantics/db/common/recursive/FindParentsWithType.java
new file mode 100644 (file)
index 0000000..afdf766
--- /dev/null
+++ b/bundles/org.simantics.db.common/src/org/simantics/db/common/recursive/FindParentsWithType.java
@@ -0,0 +1,59 @@
+package org.simantics.db.common.recursive;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+import java.util.Set;
+
+import org.simantics.db.ReadGraph;
+import org.simantics.db.Resource;
+import org.simantics.db.Statement;
+import org.simantics.db.exception.DatabaseException;
+import org.simantics.layer0.Layer0;
+
+public class FindParentsWithType extends FindRoots {
+    private final ReadGraph graph;
+    private final Resource rootType;
+    private final Layer0 L0;
+    
+    public FindParentsWithType(ReadGraph graph, Resource rootType) {
+        this.graph = graph;
+        this.rootType = rootType;
+        this.L0 = Layer0.getInstance(graph);
+    }
+
+    @Override
+    protected boolean isRoot(Resource resource) throws DatabaseException {
+        return graph.isInstanceOf(resource, rootType);
+    }
+
+    @Override
+    protected Collection<Resource> children(Resource resource) throws DatabaseException {
+        Resource parent = graph.getPossibleObject(resource, L0.PartOf);
+        if(parent != null)
+            return Collections.singletonList(parent);
+        
+        ArrayList<Resource> result = new ArrayList<Resource>(4); 
+        for(Statement s : graph.getStatements(resource, L0.IsWeaklyRelatedTo)) {
+            if(!s.getSubject().equals(resource))
+                continue;
+            Resource inverse = graph.getPossibleInverse(s.getPredicate());
+            if(inverse != null && graph.isSubrelationOf(inverse, L0.IsRelatedTo))
+                result.add(s.getObject());
+        }
+        return result;
+    }
+
+    /**
+     * Makes a query for just one resource. If you want to make multiple queries with the same type, 
+     * instantiate this class and call the {@code get} method.
+     */
+    public static List<Resource> findParentsWithType(ReadGraph graph, Resource r, Resource type) throws DatabaseException {
+        Set<Resource> set = new FindParentsWithType(graph, type).get(r);
+        if(set == null)
+            return Collections.emptyList();
+        else
+            return new ArrayList<Resource>(set);
+    }
+}