Extension points can be now sorted.

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@30071 71c3de6d-444a-0410-be80-ed276b4c234a

core/src/main/java/hudson/ExtensionComponent.java

@@ -0,0 +1,77 @@
+/*
+ * The MIT License
+ *
+ * Copyright (c) 2010, Kohsuke Kawaguchi
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+package hudson;
+
+/**
+ * Discovered {@link Extension} object with a bit of metadata for Hudson.
+ * This is a plain value object.
+ *
+ * @author Kohsuke Kawaguchi
+ * @since 1.356
+ */
+public class ExtensionComponent<T> implements Comparable<ExtensionComponent<T>> {
+    private final T instance;
+    private final double ordinal;
+
+    public ExtensionComponent(T instance, double ordinal) {
+        this.instance = instance;
+        this.ordinal = ordinal;
+    }
+
+    public ExtensionComponent(T instance, Extension annotation) {
+        this(instance,annotation.ordinal());
+    }
+
+    public ExtensionComponent(T instance) {
+        this(instance,0);
+    }
+
+    /**
+     * See {@link Extension#ordinal()}. Used to sort extensions.
+     */
+    public double ordinal() {
+        return ordinal;
+    }
+
+    /**
+     * The instance of the discovered extension.
+     *
+     * @return never null.
+     */
+    public T getInstance() {
+        return instance;
+    }
+
+    /**
+     * Sort {@link ExtensionComponent}s in the descending order of {@link #ordinal()}.
+     */
+    public int compareTo(ExtensionComponent<T> that) {
+        double a = this.ordinal();
+        double b = that.ordinal();
+        if (a>b)    return -1;
+        if (a<b)    return 1;
+        return 0;
+    }
+}