find and bind extension points automatically

scm-webapp/src/main/java/sonia/scm/plugin/ext/ExtensionBinder.java

@@ -0,0 +1,211 @@
+/**
+ * Copyright (c) 2010, Sebastian Sdorra All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ * this list of conditions and the following disclaimer. 2. Redistributions in
+ * binary form must reproduce the above copyright notice, this list of
+ * conditions and the following disclaimer in the documentation and/or other
+ * materials provided with the distribution. 3. Neither the name of SCM-Manager;
+ * nor the names of its contributors may be used to endorse or promote products
+ * derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR
+ * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * http://bitbucket.org/sdorra/scm-manager
+ *
+ */
+
+
+
+package sonia.scm.plugin.ext;
+
+//~--- non-JDK imports --------------------------------------------------------
+
+import com.google.common.collect.Iterables;
+import com.google.common.collect.Sets;
+import com.google.inject.Binder;
+import com.google.inject.multibindings.Multibinder;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import sonia.scm.plugin.ExtensionPoint;
+
+//~--- JDK imports ------------------------------------------------------------
+
+import java.util.Set;
+
+/**
+ *
+ * @author Sebastian Sdorra
+ */
+public class ExtensionBinder
+{
+
+  /**
+   * the logger for ExtensionBinder
+   */
+  private static final Logger logger =
+    LoggerFactory.getLogger(ExtensionBinder.class);
+
+  //~--- constructors ---------------------------------------------------------
+
+  /**
+   * Constructs ...
+   *
+   *
+   * @param binder
+   */
+  public ExtensionBinder(Binder binder)
+  {
+    this.binder = binder;
+  }
+
+  //~--- methods --------------------------------------------------------------
+
+  /**
+   * Method description
+   *
+   *
+   *
+   * @param bounds
+   * @param extensionPoints
+   * @param extensions
+   */
+  public void bind(Set<AnnotatedClass<Extension>> bounds,
+    Set<AnnotatedClass<ExtensionPoint>> extensionPoints,
+    Set<AnnotatedClass<Extension>> extensions)
+  {
+    if (logger.isInfoEnabled())
+    {
+      logger.info("bind {} extensions to {} extension points",
+        extensions.size(), extensionPoints.size());
+    }
+
+    for (AnnotatedClass<ExtensionPoint> extensionPoint : extensionPoints)
+    {
+      ExtensionPoint extensionPointAnnotation = extensionPoint.getAnnotation();
+      Class extensionPointClass = extensionPoint.getAnnotatedClass();
+
+      if (extensionPointAnnotation.multi())
+      {
+        bindMultiExtensionPoint(bounds, extensionPointClass, extensions);
+      }
+      else
+      {
+        bindExtensionPoint(bounds, extensionPointClass, extensions);
+      }
+    }
+
+    Set<AnnotatedClass<Extension>> extensionsCopy = Sets.newHashSet(extensions);
+
+    Iterables.removeAll(extensionsCopy, bounds);
+
+    for (AnnotatedClass<Extension> extension : extensionsCopy)
+    {
+      logger.info("bind {}, without extensionpoint",
+        extension.getAnnotatedClass());
+      binder.bind(extension.getAnnotatedClass());
+    }
+  }
+
+  /**
+   * Method description
+   *
+   *
+   *
+   * @param found
+   * @param extensionPointClass
+   * @param extensions
+   */
+  private void bindExtensionPoint(Set<AnnotatedClass<Extension>> found,
+    Class extensionPointClass, Set<AnnotatedClass<Extension>> extensions)
+  {
+    for (AnnotatedClass<Extension> extension : extensions)
+    {
+      Class extensionClass = extension.getAnnotatedClass();
+
+      if (extensionPointClass.isAssignableFrom(extensionClass))
+      {
+        found.add(extension);
+        bindSingleInstance(extensionPointClass, extensionClass);
+
+        break;
+      }
+    }
+  }
+
+  /**
+   * Method description
+   *
+   *
+   *
+   * @param found
+   * @param extensionPointClass
+   * @param extensions
+   */
+  private void bindMultiExtensionPoint(Set<AnnotatedClass<Extension>> found,
+    Class extensionPointClass, Set<AnnotatedClass<Extension>> extensions)
+  {
+    if (logger.isInfoEnabled())
+    {
+      logger.info("create multibinder for {}", extensionPointClass.getName());
+    }
+
+    Multibinder multibinder = Multibinder.newSetBinder(binder,
+                                extensionPointClass);
+
+    for (AnnotatedClass<Extension> extension : extensions)
+    {
+      Class extensionClass = extension.getAnnotatedClass();
+
+      if (extensionPointClass.isAssignableFrom(extensionClass))
+      {
+        if (logger.isInfoEnabled())
+        {
+          logger.info("bind {} to multibinder of {}", extensionClass.getName(),
+            extensionPointClass.getName());
+        }
+
+        found.add(extension);
+        multibinder.addBinding().to(extensionClass);
+      }
+    }
+  }
+
+  /**
+   * Method description
+   *
+   *
+   * @param extensionPointClass
+   * @param extensionClass
+   */
+  private void bindSingleInstance(Class extensionPointClass,
+    Class extensionClass)
+  {
+    if (logger.isInfoEnabled())
+    {
+      logger.info("bind {} to {}", extensionClass.getName(),
+        extensionPointClass.getName());
+    }
+
+    binder.bind(extensionPointClass).to(extensionClass);
+  }
+
+  //~--- fields ---------------------------------------------------------------
+
+  /** Field description */
+  private Binder binder;
+}