[Mulgara-svn] r809 - branches/mgr-61-sparql/src/jar/query/java/org/mulgara/query

[pag at mulgara.org]

Author: pag
Date: 2008-04-22 10:25:21 -0700 (Tue, 22 Apr 2008)
New Revision: 809

Added:
   branches/mgr-61-sparql/src/jar/query/java/org/mulgara/query/ModelVariable.java
Log:
A model expression that is a variable rather than a URI or an operation

Added: branches/mgr-61-sparql/src/jar/query/java/org/mulgara/query/ModelVariable.java
===================================================================
--- branches/mgr-61-sparql/src/jar/query/java/org/mulgara/query/ModelVariable.java	                        (rev 0)
+++ branches/mgr-61-sparql/src/jar/query/java/org/mulgara/query/ModelVariable.java	2008-04-22 17:25:21 UTC (rev 809)
@@ -0,0 +1,134 @@
+/**
+ * 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.query;
+
+// Java 2 standard packages
+import java.net.*;
+import java.util.*;
+
+// Third party packages
+import org.apache.log4j.Logger;
+
+/**
+ * A leaf expression containing a variable that is used for the model expression.
+ *
+ * @created Apr 22, 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 ModelVariable implements Model {
+
+  /** Used for serializing. */
+  static final long serialVersionUID = 5132086338306266830L;
+
+  /** Logger. */
+  @SuppressWarnings("unused")
+  private final static Logger logger = Logger.getLogger(ModelVariable.class);
+
+  /** The variable for the graph */
+  private Variable variable;
+
+  //
+  // Constructors
+  //
+
+  /**
+   * Construct a model from a {@link URL}.
+   *
+   * @param uri the {@link URI} of the model to query
+   * @throws IllegalArgumentException if <var>url</var> is <code>null</code>
+   */
+  public ModelVariable(Variable variable) {
+    if (variable == null) throw new IllegalArgumentException("Null variable parameter");
+    this.variable = variable;
+  }
+
+  //
+  // Methods implementing ModelExpression
+  //
+
+  /**
+   * Gets a set of database URIs to operate against.
+   * @return We don't know what is in the variable, so return the empty {@link Set}
+   */
+  @SuppressWarnings("unchecked")
+  public Set<URI> getDatabaseURIs() {
+    return (Set<URI>)Collections.EMPTY_SET;
+  }
+
+  //
+  // API methods
+  //
+
+  /**
+   * Accessor for the <var>variable</var> property.
+   * @return a {@link Variable} instance
+   */
+  public Variable getVariable() {
+    return variable;
+  }
+
+  //
+  // Methods extending Object
+  //
+
+  /**
+   * The text representation of the URI.
+   * @return the text representation of the URI.
+   */
+  public String toString() {
+    return variable.toString();
+  }
+
+  //
+  // Methods overriding Object
+  //
+
+  /**
+   * Return true if the variables of a ModelVariable are equal.
+   * @param object ModelVariable to test equality.
+   * @return true if the variables of a ModelVariable are equal.
+   */
+  public boolean equals(Object object) {
+    if (object == null) return false;
+    if (object == this) return true;
+
+    if (!(object instanceof ModelVariable)) return false;
+    ModelVariable modelVar = (ModelVariable)object;
+    return variable.equals(modelVar.variable);
+  }
+
+  /**
+   * Returns the hashCode of a Variable.
+   * @return the hashCode of a Variable.
+   */
+  public int hashCode() {
+    return variable.hashCode();
+  }
+
+  /**
+   * Returns just the default Object clone.
+   * @return just the default Object clone.
+   */
+  public Object clone() {
+    try {
+      ModelVariable cloned = (ModelVariable)super.clone();
+      cloned.variable = variable;
+      return cloned;
+    } catch (CloneNotSupportedException e) {
+      throw new RuntimeException("ModelVariable not cloneable");
+    }
+  }
+
+}