Initial checkin of AOSP Messaging app.

b/23110861

Change-Id: I11db999bd10656801e618f78ab2b2ef74136fff1

src/com/android/messaging/datamodel/binding/BindingBase.java

@@ -0,0 +1,84 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * 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 com.android.messaging.datamodel.binding;
+
+/**
+ * The binding class keeps track of a binding between a ui component and an item of BindableData
+ * It allows each side to ensure that when it communicates with the other they are still bound
+ * together.
+ * NOTE: Ensure that the UI component uses the same binding instance for it's whole lifetime
+ *  (DO NOT CREATE A NEW BINDING EACH TIME A NEW PIECE OF DATA IS BOUND)...
+ *
+ * The ui component owns the binding instance.
+ * It can use it [isBound(data)] to see if the binding still binds to the right piece of data
+ *
+ * Upon binding the data is informed of a unique binding key generated in this class and can use
+ * that to ensure that it is still issuing callbacks to the right piece of ui.
+ */
+public abstract class BindingBase<T extends BindableData> {
+    /**
+     * Creates a new exclusively owned binding for the owner object.
+     */
+    public static <T extends BindableData> Binding<T> createBinding(final Object owner) {
+        return new Binding<T>(owner);
+    }
+
+    /**
+     * Creates a new read-only binding referencing the source binding object.
+     * TODO: We may want to refcount the Binding references, so that when the binding owner
+     * calls unbind() when there's still outstanding references we can catch it.
+     */
+    public static <T extends BindableData> ImmutableBindingRef<T> createBindingReference(
+            final BindingBase<T> srcBinding) {
+        return new ImmutableBindingRef<T>(srcBinding);
+    }
+
+    /**
+     * Creates a detachable binding for the owner object. Use this if your owner object is a UI
+     * component that may undergo a "detached from window" -> "re-attached to window" transition.
+     */
+    public static <T extends BindableData> DetachableBinding<T> createDetachableBinding(
+            final Object owner) {
+        return new DetachableBinding<T>(owner);
+    }
+
+    public abstract T getData();
+
+    /**
+     * Check if binding connects to the specified data instance
+     */
+    public abstract boolean isBound();
+
+    /**
+     * Check if binding connects to the specified data instance
+     */
+    public abstract boolean isBound(final T data);
+
+    /**
+     * Throw if binding connects to the specified data instance
+     */
+    public abstract void ensureBound();
+
+    /**
+     * Throw if binding connects to the specified data instance
+     */
+    public abstract void ensureBound(final T data);
+
+    /**
+     * Return the binding id for this binding (will be null if not bound)
+     */
+    public abstract String getBindingId();
+}