[Mulgara-svn] r1796 - trunk/src/jar/query/java/org/mulgara/query

[pag at mulgara.org]

Author: pag
Date: 2009-10-05 23:28:57 -0700 (Mon, 05 Oct 2009)
New Revision: 1796

Added:
   trunk/src/jar/query/java/org/mulgara/query/FunctionResolverRegistry.java
Log:
Added a central registry for loading XPathFunctionResolvers

Added: trunk/src/jar/query/java/org/mulgara/query/FunctionResolverRegistry.java
===================================================================
--- trunk/src/jar/query/java/org/mulgara/query/FunctionResolverRegistry.java	                        (rev 0)
+++ trunk/src/jar/query/java/org/mulgara/query/FunctionResolverRegistry.java	2009-10-06 06:28:57 UTC (rev 1796)
@@ -0,0 +1,86 @@
+/*
+ * Copyright 2009 DuraSpace.
+ *
+ * Licensed 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.mulgara.query;
+
+import org.mulgara.util.Reflect;
+
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.Set;
+
+import javax.xml.xpath.XPathFunctionResolver;
+
+/**
+ * A singleton registry for XPathFunctionResolvers.
+ *
+ * @created Sep 27, 2009
+ * @author Paul Gearon
+ * @copyright &copy; 2009 <a href="http://www.duraspace.org/">DuraSpace</a>
+ */
+public class FunctionResolverRegistry implements Iterable<XPathFunctionResolver> {
+
+  /** The singleton of this object */
+  static private FunctionResolverRegistry registry = new FunctionResolverRegistry();
+
+  /** The set of registered resolvers */
+  private Set<XPathFunctionResolver> registered;
+
+  /**
+   * Constructs the singleton resolver.
+   */
+  private FunctionResolverRegistry() {
+    registered = new HashSet<XPathFunctionResolver>();
+  }
+
+  /**
+   * Gets the singleton registry.
+   * @return The registry for resolvers.
+   */
+  public static FunctionResolverRegistry getFunctionResolverRegistry() {
+    return registry;
+  }
+
+  /**
+   * Registered a resolver instance.
+   * @param resolver The resolver instance to register.
+   */
+  public void register(XPathFunctionResolver resolver) {
+    registered.add(resolver);
+  }
+
+  /**
+   * Registered a resolver by name.
+   * @param resolver The name of a resolver type to register.
+   * @throws ClassNotFoundException Unable to find the specified class.
+   * @throws RuntimeException If the class could not be instantiated for any reason.
+   */
+  @SuppressWarnings("unchecked")
+  public void register(String resolverName) throws ClassNotFoundException {
+    Class<XPathFunctionResolver> resolverType = (Class<XPathFunctionResolver>)Class.forName(resolverName);
+    registered.add(Reflect.newInstance(resolverType));
+  }
+
+  /**
+   * Get an iterator for all the registered resolvers.
+   * @see java.lang.Iterable#iterator()
+   * @return an Iterator for the registry.
+   */
+  public Iterator<XPathFunctionResolver> iterator() {
+    return Collections.unmodifiableSet(registered).iterator();
+  }
+}