introducing priority annotation to order extensions

scm-annotations/src/main/java/sonia/scm/Priority.java

@@ -0,0 +1,53 @@
+/**
+ * Copyright (c) 2014, 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;
+
+//~--- JDK imports ------------------------------------------------------------
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ *
+ * @author Sebastian Sdorra
+ * @since 2.0.0
+ */
+@Documented
+@Target(ElementType.TYPE)
+@Retention(RetentionPolicy.RUNTIME)
+public @interface Priority
+{
+  public int value();
+}

scm-core/src/main/java/sonia/scm/Priorities.java

@@ -0,0 +1,142 @@
+/**
+ * Copyright (c) 2014, 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;
+
+//~--- non-JDK imports --------------------------------------------------------
+
+import com.google.common.collect.Ordering;
+import com.google.common.primitives.Ints;
+
+//~--- JDK imports ------------------------------------------------------------
+
+import java.util.List;
+
+/**
+ * Priority constants and util methods to sort classes by {@link Priority} 
+ * annotation.
+ *
+ * @author Sebastian Sdorra
+ * @since 2.0.0
+ */
+public final class Priorities
+{
+
+  /** authentication priority */
+  public static final int AUTHENTICATION = 5000;
+
+  /** base url priority */
+  public static final int BASEURL = 1000;
+
+  /** default priority */
+  public static final int DEFAULT = 9999;
+
+  /** post authentication priority */
+  public static final int POST_AUTHENTICATION = 5500;
+
+  /** post base url priority */
+  public static final int POST_BASEURL = 1500;
+
+  /** pre authentication priority */
+  public static final int PRE_AUTHENTICATION = 4500;
+
+  /** pre base url priority */
+  public static final int PRE_BASEURL = 500;
+
+  //~--- constructors ---------------------------------------------------------
+
+  /**
+   * Constructs ...
+   *
+   */
+  private Priorities() {}
+
+  //~--- methods --------------------------------------------------------------
+
+  /**
+   * Returns a list sorted by priority.
+   *
+   * @param unordered unordered classes
+   *
+   * @return sorted class list
+   */
+  public static List<Class<?>> sort(Iterable<Class<?>> unordered)
+  {
+    return new PriorityOrdering().sortedCopy(unordered);
+  }
+
+  //~--- get methods ----------------------------------------------------------
+
+  /**
+   * Returns the priority of the given class.
+   *
+   * @param clazz class
+   *
+   * @return priority of class
+   */
+  public static int getPriority(Class<?> clazz)
+  {
+    int priority = DEFAULT;
+
+    Priority annotation = clazz.getAnnotation(Priority.class);
+
+    if (annotation != null)
+    {
+      priority = annotation.value();
+    }
+
+    return priority;
+  }
+
+  //~--- inner classes --------------------------------------------------------
+
+  /**
+   * {@link Ordering} which orders classes by priority.
+   */
+  public static class PriorityOrdering extends Ordering<Class<?>>
+  {
+
+    /**
+     * Compares the left class with the right class.
+     *
+     *
+     * @param left left class
+     * @param right right class
+     *
+     * @return compare value
+     */
+    @Override
+    public int compare(Class<?> left, Class<?> right)
+    {
+      return Ints.compare(getPriority(left), getPriority(right));
+    }
+  }
+}