1 /*
2 * Copyright (C) 2008, Shawn O. Pearce <spearce@spearce.org>
3 * and other copyright owners as documented in the project's IP log.
4 *
5 * This program and the accompanying materials are made available
6 * under the terms of the Eclipse Distribution License v1.0 which
7 * accompanies this distribution, is reproduced below, and is
8 * available at http://www.eclipse.org/org/documents/edl-v10.php
9 *
10 * All rights reserved.
11 *
12 * Redistribution and use in source and binary forms, with or
13 * without modification, are permitted provided that the following
14 * conditions are met:
15 *
16 * - Redistributions of source code must retain the above copyright
17 * notice, this list of conditions and the following disclaimer.
18 *
19 * - Redistributions in binary form must reproduce the above
20 * copyright notice, this list of conditions and the following
21 * disclaimer in the documentation and/or other materials provided
22 * with the distribution.
23 *
24 * - Neither the name of the Eclipse Foundation, Inc. nor the
25 * names of its contributors may be used to endorse or promote
26 * products derived from this software without specific prior
27 * written permission.
28 *
29 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
30 * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
31 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
32 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
33 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
34 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
35 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
36 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
37 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
38 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
39 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
40 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
41 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
42 */
43
44 package org.eclipse.jgit.revwalk;
45
46 import java.io.IOException;
47
48 import org.eclipse.jgit.errors.IncorrectObjectTypeException;
49 import org.eclipse.jgit.errors.MissingObjectException;
50
51 /**
52 * Produces commits for RevWalk to return to applications.
53 * <p>
54 * Implementations of this basic class provide the real work behind RevWalk.
55 * Conceptually a Generator is an iterator or a queue, it returns commits until
56 * there are no more relevant. Generators may be piped/stacked together to
57 * create a more complex set of operations.
58 *
59 * @see PendingGenerator
60 * @see StartGenerator
61 */
62 abstract class Generator {
63 /** Commits are sorted by commit date and time, descending. */
64 static final int SORT_COMMIT_TIME_DESC = 1 << 0;
65
66 /** Output may have {@link RevWalk#REWRITE} marked on it. */
67 static final int HAS_REWRITE = 1 << 1;
68
69 /** Output needs {@link RewriteGenerator}. */
70 static final int NEEDS_REWRITE = 1 << 2;
71
72 /** Topological ordering is enforced (all children before parents). */
73 static final int SORT_TOPO = 1 << 3;
74
75 /** Output may have {@link RevWalk#UNINTERESTING} marked on it. */
76 static final int HAS_UNINTERESTING = 1 << 4;
77
78 /**
79 * Connect the supplied queue to this generator's own free list (if any).
80 *
81 * @param q
82 * another FIFO queue that wants to share our queue's free list.
83 */
84 void shareFreeList(final BlockRevQueue q) {
85 // Do nothing by default.
86 }
87
88 /**
89 * Obtain flags describing the output behavior of this generator.
90 *
91 * @return one or more of the constants declared in this class, describing
92 * how this generator produces its results.
93 */
94 abstract int outputType();
95
96 /**
97 * Return the next commit to the application, or the next generator.
98 *
99 * @return next available commit; null if no more are to be returned.
100 * @throws MissingObjectException
101 * @throws IncorrectObjectTypeException
102 * @throws IOException
103 */
104 abstract RevCommit next() throws MissingObjectException,
105 IncorrectObjectTypeException, IOException;
106 }