1 /**
2 * This file Copyright (c) 2013 Magnolia International
3 * Ltd. (http://www.magnolia-cms.com). All rights reserved.
4 *
5 *
6 * This file is dual-licensed under both the Magnolia
7 * Network Agreement and the GNU General Public License.
8 * You may elect to use one or the other of these licenses.
9 *
10 * This file is distributed in the hope that it will be
11 * useful, but AS-IS and WITHOUT ANY WARRANTY; without even the
12 * implied warranty of MERCHANTABILITY or FITNESS FOR A
13 * PARTICULAR PURPOSE, TITLE, or NONINFRINGEMENT.
14 * Redistribution, except as permitted by whichever of the GPL
15 * or MNA you select, is prohibited.
16 *
17 * 1. For the GPL license (GPL), you can redistribute and/or
18 * modify this file under the terms of the GNU General
19 * Public License, Version 3, as published by the Free Software
20 * Foundation. You should have received a copy of the GNU
21 * General Public License, Version 3 along with this program;
22 * if not, write to the Free Software Foundation, Inc., 51
23 * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
24 *
25 * 2. For the Magnolia Network Agreement (MNA), this file
26 * and the accompanying materials are made available under the
27 * terms of the MNA which accompanies this distribution, and
28 * is available at http://www.magnolia-cms.com/mna.html
29 *
30 * Any modifications to this file must keep this entire header
31 * intact.
32 *
33 */
34 package info.magnolia.commands.chain;
35
36 import java.util.Collection;
37 import java.util.Collections;
38 import java.util.LinkedList;
39 import java.util.List;
40
41
42 /**
43 * Replacement for org.apache.commons.chain.impl.ChainBase. Base Chain
44 * implementation.
45 */
46 public class ChainBase implements Chain {
47
48 protected List<Command> commands = new LinkedList<Command>();
49
50 protected boolean frozen = false;
51
52 public ChainBase() {
53 }
54
55 public ChainBase(Command command) {
56 addCommand(command);
57 }
58
59 public ChainBase(Command... commands) {
60 for (Command command : commands) {
61 addCommand(command);
62 }
63 }
64
65 public ChainBase(Collection<Command> commands) {
66 this(commands.toArray(new Command[0]));
67 }
68
69 @Override
70 public void addCommand(Command command) {
71 if (command == null) {
72 throw new IllegalArgumentException();
73 }
74 if (frozen) {
75 throw new IllegalStateException();
76 }
77 commands.add(command);
78 }
79
80 @Override
81 public boolean execute(Context context) throws Exception {
82 // Verify our parameters
83 if (context == null) {
84 throw new IllegalArgumentException();
85 }
86 // Freeze the configuration of the command list
87 frozen = true;
88 // Execute the commands in this list until one returns true
89 // or throws an exception
90 boolean saveResult = false;
91 Exception saveException = null;
92 int i = 0;
93 int n = commands.size();
94 for (i = 0; i < n; i++) {
95 try {
96 saveResult = commands.get(i).execute(context);
97 if (saveResult) {
98 break;
99 }
100 } catch (Exception e) {
101 saveException = e;
102 break;
103 }
104 }
105 // Call postprocess methods on Filters in reverse order
106 if (i >= n) { // Fell off the end of the chain
107 i--;
108 }
109 boolean handled = false;
110 boolean result = false;
111 for (int j = i; j >= 0; j--) {
112 if (commands.get(j) instanceof Filter) {
113 try {
114 result = ((Filter) commands.get(j)).postprocess(context, saveException);
115 if (result) {
116 handled = true;
117 }
118 } catch (Exception e) {
119 // Silently ignore
120 }
121 }
122 }
123 // Return the exception or result state from the last execute()
124 if ((saveException != null) && !handled) {
125 throw saveException;
126 }
127 return (saveResult);
128 }
129
130 /**
131 * Returns <b>unmodifiable</b> list of commands.
132 */
133 public List<Command> getCommands() {
134 return Collections.unmodifiableList(commands);
135 }
136
137 @Override
138 public Chain copy(Command command) {
139 ChainBase master = (ChainBase) command;
140 ChainBase copy = new ChainBase();
141 for (Command c : master.commands) {
142 copy.addCommand(c.copy(c));
143 }
144 return copy;
145 }
146
147 }