CursorBackedSuggestionExtras.java revision 27691bfcdcf3d2918b45bfadd57b08547c317ce5 
1/*
2 * Copyright (C) 2010 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 */
16package com.android.quicksearchbox;
17
18import android.database.Cursor;
19import android.util.Log;
20
21import java.util.ArrayList;
22import java.util.Arrays;
23import java.util.HashSet;
24import java.util.List;
25
26/**
27 * SuggestionExtras taking values from the extra columns in a suggestion cursor.
28 */
29public class CursorBackedSuggestionExtras extends AbstractSuggestionExtras {
30    private static final String TAG = "QSB.CursorBackedSuggestionExtras";
31
32    private static final HashSet<String> DEFAULT_COLUMNS = new HashSet<String>();
33    static {
34        DEFAULT_COLUMNS.addAll(Arrays.asList(SuggestionCursorBackedCursor.COLUMNS));
35    }
36
37    private final Cursor mCursor;
38    private final int mCursorPosition;
39    private final List<String> mExtraColumns;
40
41    static CursorBackedSuggestionExtras createExtrasIfNecessary(Cursor cursor, int position) {
42        List<String> extraColumns = getExtraColumns(cursor);
43        if (extraColumns != null) {
44            return new CursorBackedSuggestionExtras(cursor, position, extraColumns);
45        } else {
46            return null;
47        }
48    }
49
50    static String[] getCursorColumns(Cursor cursor) {
51        try {
52            return cursor.getColumnNames();
53        } catch (RuntimeException ex) {
54            // all operations on cross-process cursors can throw random exceptions
55            Log.e(TAG, "getColumnNames() failed, ", ex);
56            return null;
57        }
58    }
59
60    static boolean cursorContainsExtras(Cursor cursor) {
61        String[] columns = getCursorColumns(cursor);
62        for (String cursorColumn : columns) {
63            if (!DEFAULT_COLUMNS.contains(cursorColumn)) {
64                return true;
65            }
66        }
67        return false;
68    }
69
70    static List<String> getExtraColumns(Cursor cursor) {
71        String[] columns = getCursorColumns(cursor);
72        if (columns == null) return null;
73        List<String> extraColumns = null;
74        for (String cursorColumn : columns) {
75            if (!DEFAULT_COLUMNS.contains(cursorColumn)) {
76                if (extraColumns == null) {
77                    extraColumns = new ArrayList<String>();
78                }
79                extraColumns.add(cursorColumn);
80            }
81        }
82        return extraColumns;
83    }
84
85    private CursorBackedSuggestionExtras(Cursor cursor, int position, List<String> extraColumns) {
86        super(null);
87        mCursor = cursor;
88        mCursorPosition = position;
89        mExtraColumns = extraColumns;
90    }
91
92    @Override
93    public String doGetExtra(String columnName) {
94        try {
95            mCursor.moveToPosition(mCursorPosition);
96            int columnIdx = mCursor.getColumnIndex(columnName);
97            if (columnIdx < 0) return null;
98            return mCursor.getString(columnIdx);
99        } catch (RuntimeException ex) {
100            // all operations on cross-process cursors can throw random exceptions
101            Log.e(TAG, "getExtra(" + columnName + ") failed, ", ex);
102            return null;
103        }
104    }
105
106    @Override
107    public List<String> doGetExtraColumnNames() {
108        return mExtraColumns;
109    }
110
111}
112