1/*
2 * Copyright (C) 2014 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
5 * in compliance with the License. You may obtain a copy of the License at
6 *
7 * http://www.apache.org/licenses/LICENSE-2.0
8 *
9 * Unless required by applicable law or agreed to in writing, software distributed under the License
10 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
11 * or implied. See the License for the specific language governing permissions and limitations under
12 * the License.
13 */
14package android.support.v17.leanback.database;
15
16import android.database.Cursor;
17
18/**
19 * Abstract class used to convert the current {@link Cursor} row to a single
20 * object.
21 */
22public abstract class CursorMapper {
23
24    private Cursor mCursor;
25
26    /**
27     * Called once when the associated {@link Cursor} is changed. A subclass
28     * should bind column indexes to column names in this method. This method is
29     * not intended to be called outside of CursorMapper.
30     */
31    protected abstract void bindColumns(Cursor cursor);
32
33    /**
34     * A subclass should implement this method to create a single object using
35     * binding information. This method is not intended to be called
36     * outside of CursorMapper.
37     */
38    protected abstract Object bind(Cursor cursor);
39
40    /**
41     * Convert a {@link Cursor} at its current position to an Object.
42     */
43    public Object convert(Cursor cursor) {
44        if (cursor != mCursor) {
45            mCursor = cursor;
46            bindColumns(mCursor);
47        }
48        return bind(mCursor);
49    }
50}
51