1/*
2 * Copyright (C) 2015 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.android.messaging.datamodel.binding;
18
19/**
20 * Base class for data objects that will be bound to a piece of the UI
21 */
22public abstract class BindableData {
23    /**
24     * Called by Binding during unbind to allow data to proactively unregister callbacks
25     * Data instance should release all listeners that may call back to the host UI
26     */
27    protected abstract void unregisterListeners();
28
29    /**
30     * Key used to identify the piece of UI that the data is currently bound to
31     */
32    private String mBindingId;
33
34    /**
35     * Bind this data to the ui host - checks data is currently unbound
36     */
37    public void bind(final String bindingId) {
38        if (isBound() || bindingId == null) {
39            throw new IllegalStateException();
40        }
41        mBindingId = bindingId;
42    }
43
44    /**
45     * Unbind this data from the ui host - checks that the data is currently bound to specified id
46     */
47    public void unbind(final String bindingId) {
48        if (!isBound(bindingId)) {
49            throw new IllegalStateException();
50        }
51        unregisterListeners();
52        mBindingId = null;
53    }
54
55    /**
56     * Check to see if the data is bound to anything
57     *
58     * TODO: This should be package private because it's supposed to only be used by Binding,
59     * however, several classes call this directly.  We want the classes to track what they are
60     * bound to.
61     */
62    protected boolean isBound() {
63        return (mBindingId != null);
64    }
65
66    /**
67     * Check to see if data is still bound with specified bindingId before calling over to ui
68     */
69    public boolean isBound(final String bindingId) {
70        return (bindingId.equals(mBindingId));
71    }
72}
73