1/*
2 * Copyright (C) 2006 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 android.database.sqlite;
18
19import android.database.CursorWindow;
20import android.os.CancellationSignal;
21import android.os.OperationCanceledException;
22import android.util.Log;
23
24/**
25 * Represents a query that reads the resulting rows into a {@link SQLiteQuery}.
26 * This class is used by {@link SQLiteCursor} and isn't useful itself.
27 * <p>
28 * This class is not thread-safe.
29 * </p>
30 */
31public final class SQLiteQuery extends SQLiteProgram {
32    private static final String TAG = "SQLiteQuery";
33
34    private final CancellationSignal mCancellationSignal;
35
36    SQLiteQuery(SQLiteDatabase db, String query, CancellationSignal cancellationSignal) {
37        super(db, query, null, cancellationSignal);
38
39        mCancellationSignal = cancellationSignal;
40    }
41
42    /**
43     * Reads rows into a buffer.
44     *
45     * @param window The window to fill into
46     * @param startPos The start position for filling the window.
47     * @param requiredPos The position of a row that MUST be in the window.
48     * If it won't fit, then the query should discard part of what it filled.
49     * @param countAllRows True to count all rows that the query would
50     * return regardless of whether they fit in the window.
51     * @return Number of rows that were enumerated.  Might not be all rows
52     * unless countAllRows is true.
53     *
54     * @throws SQLiteException if an error occurs.
55     * @throws OperationCanceledException if the operation was canceled.
56     */
57    int fillWindow(CursorWindow window, int startPos, int requiredPos, boolean countAllRows) {
58        acquireReference();
59        try {
60            window.acquireReference();
61            try {
62                int numRows = getSession().executeForCursorWindow(getSql(), getBindArgs(),
63                        window, startPos, requiredPos, countAllRows, getConnectionFlags(),
64                        mCancellationSignal);
65                return numRows;
66            } catch (SQLiteDatabaseCorruptException ex) {
67                onCorruption();
68                throw ex;
69            } catch (SQLiteException ex) {
70                Log.e(TAG, "exception: " + ex.getMessage() + "; query: " + getSql());
71                throw ex;
72            } finally {
73                window.releaseReference();
74            }
75        } finally {
76            releaseReference();
77        }
78    }
79
80    @Override
81    public String toString() {
82        return "SQLiteQuery: " + getSql();
83    }
84}
85