[Mulgara-svn] r1045 - trunk/src/jar/sparql-interpreter/java/org/mulgara/sparql

[pag at mulgara.org]

Author: pag
Date: 2008-07-02 14:39:30 -0700 (Wed, 02 Jul 2008)
New Revision: 1045

Added:
   trunk/src/jar/sparql-interpreter/java/org/mulgara/sparql/VariableRenameTransformer.java
Log:
Transformation for changing all occurances of one variable into another

Added: trunk/src/jar/sparql-interpreter/java/org/mulgara/sparql/VariableRenameTransformer.java
===================================================================
--- trunk/src/jar/sparql-interpreter/java/org/mulgara/sparql/VariableRenameTransformer.java	                        (rev 0)
+++ trunk/src/jar/sparql-interpreter/java/org/mulgara/sparql/VariableRenameTransformer.java	2008-07-02 21:39:30 UTC (rev 1045)
@@ -0,0 +1,130 @@
+/*
+ * The contents of this file are subject to the Open Software License
+ * Version 3.0 (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.opensource.org/licenses/osl-3.0.txt
+ *
+ * Software distributed under the License is distributed on an "AS IS"
+ * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
+ * the License for the specific language governing rights and limitations
+ * under the License.
+ */
+
+package org.mulgara.sparql;
+
+
+import org.jrdf.graph.URIReference;
+import org.mulgara.query.Constraint;
+import org.mulgara.query.ConstraintElement;
+import org.mulgara.query.ConstraintImpl;
+import org.mulgara.query.ConstraintIs;
+import org.mulgara.query.ConstraintNotOccurs;
+import org.mulgara.query.ConstraintOccurs;
+import org.mulgara.query.ConstraintOccursLessThan;
+import org.mulgara.query.ConstraintOccursMoreThan;
+import org.mulgara.query.Variable;
+import org.mulgara.resolver.test.TestConstraint;
+import org.mulgara.resolver.xsd.IntervalConstraint;
+
+/**
+ * Transforms constraint expressions to rename variables.
+ *
+ * @created May 19, 2008
+ * @author Paul Gearon
+ * @copyright &copy; 2008 <a href="http://www.topazproject.org/">The Topaz Project</a>
+ * @licence <a href="{@docRoot}/../../LICENCE.txt">Open Software License v3.0</a>
+ */
+public class VariableRenameTransformer extends IdentityTransformer {
+
+  /** The variable to find and change. */
+  private final Variable from;
+
+  /** The new variable to use in place of <var>from</var>. */
+  private final Variable to;
+
+  /**
+   * Creates a new transformer for mapping constraints with a replaced variable.
+   * @param from The Variable to replace.
+   * @param to The Variable to change to.
+   */
+  public VariableRenameTransformer(Variable from, Variable to) {
+    this.from = from;
+    this.to = to;
+    initialize(new CNO(), new CO(), new COLT(), new COMT(), new CI(), new CIs(), new CInt(), new CT());
+  }
+
+  // reimplement the individual construction code to replace variables
+
+  /**
+   * Updates ops when a constraint contains 4 of them.
+   * @return An array of 4 update operands.
+   */
+  private ConstraintElement[] morphOps(Constraint c) {
+    ConstraintElement[] ops = new ConstraintElement[4];
+    for (int i = 0; i < ops.length; i++) {
+      ConstraintElement e = c.getElement(i);
+      if (e instanceof Variable && ((Variable)e).equals(from)) e = to;
+      ops[i] = e;
+    }
+    return ops;
+  }
+
+  protected class CNO extends ConsNotOccurs {
+    public ConstraintNotOccurs newConstraint(Constraint c) {
+      return newHaving(morphOps(c));
+    }
+  }
+
+  protected class CO extends ConsOccurs {
+    public ConstraintOccurs newConstraint(Constraint c) {
+      return newHaving(morphOps(c));
+    }
+  }
+
+  protected class COLT extends ConsOccursLessThan {
+    public ConstraintOccursLessThan newConstraint(Constraint c) {
+      return newHaving(morphOps(c));
+    }
+  }
+
+  protected class COMT extends ConsOccursMoreThan {
+    public ConstraintOccursMoreThan newConstraint(Constraint c) {
+      return newHaving(morphOps(c));
+    }
+  }
+
+  protected class CI extends ConsImpl {
+    public ConstraintImpl newConstraint(Constraint c) {
+      ConstraintElement[] o = morphOps(c);
+      return new ConstraintImpl(o[0], o[1], o[2], o[3]);
+    }
+  }
+
+  protected class CIs extends ConsIs {
+    public ConstraintIs newConstraint(Constraint c) {
+      ConstraintElement[] o = morphOps(c);
+      return new ConstraintIs(o[0], o[2], o[3]);
+    }
+  }
+
+  protected class CInt extends ConsInterval {
+    public IntervalConstraint newConstraint(Constraint c) {
+      IntervalConstraint i = (IntervalConstraint)c;
+      Variable v = i.getVariables().iterator().next();
+      if (v.equals(from)) v = to;
+      return i.mutateTo(v, (URIReference)i.getModel());
+    }
+  }
+
+  protected class CT extends ConsTest {
+    public TestConstraint newConstraint(Constraint c) {
+      TestConstraint t = (TestConstraint)c;
+      Variable v1 = t.getVariable1();
+      Variable v2 = t.getVariable2();
+      if (v1.equals(from)) v1 = to;
+      if (v2.equals(from)) v2 = to;
+      return new TestConstraint(v1, v2, t.getTestSelection(), t.getTestParam());
+    }
+  }
+
+}