svn commit: r1355182 - /jena/trunk/jena-arq/src/main/java/com/hp/hpl/jena/sparql/algebra/optimize/TransformReorder.java

[rv...@apache.org]

Author: rvesse
Date: Thu Jun 28 22:19:55 2012
New Revision: 1355182

URL: http://svn.apache.org/viewvc?rev=1355182&view=rev
Log:
Adding a TransformReorder which is an algebra transformer that will reorder all BGPs and Quadpatterns using the provided ReorderTransformation

Added:
    jena/trunk/jena-arq/src/main/java/com/hp/hpl/jena/sparql/algebra/optimize/TransformReorder.java

Added: jena/trunk/jena-arq/src/main/java/com/hp/hpl/jena/sparql/algebra/optimize/TransformReorder.java
URL: http://svn.apache.org/viewvc/jena/trunk/jena-arq/src/main/java/com/hp/hpl/jena/sparql/algebra/optimize/TransformReorder.java?rev=1355182&view=auto
==============================================================================
--- jena/trunk/jena-arq/src/main/java/com/hp/hpl/jena/sparql/algebra/optimize/TransformReorder.java (added)
+++ jena/trunk/jena-arq/src/main/java/com/hp/hpl/jena/sparql/algebra/optimize/TransformReorder.java Thu Jun 28 22:19:55 2012
@@ -0,0 +1,75 @@
+/**
+ * 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 com.hp.hpl.jena.sparql.algebra.optimize;
+
+import com.hp.hpl.jena.sparql.algebra.Op;
+import com.hp.hpl.jena.sparql.algebra.TransformCopy;
+import com.hp.hpl.jena.sparql.algebra.op.OpBGP;
+import com.hp.hpl.jena.sparql.algebra.op.OpQuadPattern;
+import com.hp.hpl.jena.sparql.core.BasicPattern;
+import com.hp.hpl.jena.sparql.engine.optimizer.reorder.ReorderLib;
+import com.hp.hpl.jena.sparql.engine.optimizer.reorder.ReorderTransformation;
+
+/**
+ * A Transformer that applies a reordering to all BGPs and Quad Patterns present in the algebra
+ * <p>
+ * This transformer may be slightly naive in that it only leverages the {@link ReorderTransformation#reorder()} method and does not use the {@link ReorderTransformation#reorderIndexes()} method at all so may not achieve the best reordering
+ * </p>
+ */
+public class TransformReorder extends TransformCopy {
+	
+	private ReorderTransformation reorder;
+	
+	/**
+	 * Creates a Transformer that uses the fixed reordering provided by {@link ReorderLib#fixed()}
+	 */
+	public TransformReorder() {
+		this(ReorderLib.fixed());
+	}
+	
+	/**
+	 * Creates a Transformer that uses the given reordering
+	 */
+	public TransformReorder(ReorderTransformation reorder) {
+		if (reorder == null) throw new IllegalArgumentException("reorder cannot be null");
+		this.reorder = reorder;
+	}
+
+	/**
+	 * Transforms BGPs with the reordering
+	 */
+	@Override
+	public Op transform(OpBGP opBGP) {
+		BasicPattern pattern = opBGP.getPattern();
+		BasicPattern pattern2 = this.reorder.reorder(pattern);
+		return new OpBGP(pattern2);
+	}
+
+	/**
+	 * Transforms Quad Patterns with the reordering
+	 */
+	@Override
+	public Op transform(OpQuadPattern opQuadPattern) {
+		BasicPattern pattern = opQuadPattern.getBasicPattern();
+		BasicPattern pattern2 = this.reorder.reorder(pattern);
+		return new OpQuadPattern(opQuadPattern.getGraphNode(), pattern2);
+	}
+
+}
+