Classes in this File | Line Coverage | Branch Coverage | Complexity | ||||
Block |
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| 1.0;1 |
1 | // Copyright 2004, 2005 The Apache Software Foundation | |
2 | // | |
3 | // Licensed under the Apache License, Version 2.0 (the "License"); | |
4 | // you may not use this file except in compliance with the License. | |
5 | // 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 | |
10 | // distributed under the License is distributed on an "AS IS" BASIS, | |
11 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
12 | // See the License for the specific language governing permissions and | |
13 | // limitations under the License. | |
14 | ||
15 | package org.apache.tapestry.components; | |
16 | ||
17 | import org.apache.hivemind.util.Defense; | |
18 | import org.apache.tapestry.AbstractComponent; | |
19 | import org.apache.tapestry.IComponent; | |
20 | import org.apache.tapestry.IMarkupWriter; | |
21 | import org.apache.tapestry.IRequestCycle; | |
22 | ||
23 | /** | |
24 | * Prevents its contents from being rendered until triggered by an {@link RenderBlock} component. [<a | |
25 | * href="../../../../../components/general/block.html">Component Reference</a>] | |
26 | * <p> | |
27 | * Block and {@link RenderBlock} are used to build a certain class of complicated component that | |
28 | * can't be assembled using the normal wrapping containment. Such a super component would have two | |
29 | * or more sections that need to be supplied by the containing page (or component). | |
30 | * <p> | |
31 | * Using Blocks, the blocks can be provided as parameters to the super component. | |
32 | * <p> | |
33 | * The invoker property gives the components inside the block access to the component (typically an | |
34 | * {@link RenderBlock}) that rendered the block. More often, the {@link #getParameter(String)} | |
35 | * method is used to get parameters <em>of the invoking component</em>. | |
36 | * | |
37 | * @author Howard Lewis Ship | |
38 | * @since 0.2.9 | |
39 | */ | |
40 | ||
41 | 0 | public abstract class Block extends AbstractComponent |
42 | { | |
43 | private IComponent _invoker; | |
44 | ||
45 | /** | |
46 | * Provides access to the invoking component's parameters. | |
47 | * | |
48 | * @since 4.0 | |
49 | */ | |
50 | ||
51 | public Object getParameter(String name) | |
52 | { | |
53 | 0 | return _invoker.getBinding(name).getObject(); |
54 | } | |
55 | ||
56 | public void renderForComponent(IMarkupWriter writer, IRequestCycle cycle, IComponent invoker) | |
57 | { | |
58 | 0 | Defense.notNull(invoker, "invoker"); |
59 | ||
60 | 0 | IComponent oldInvoker = _invoker; |
61 | ||
62 | try | |
63 | { | |
64 | 0 | _invoker = invoker; |
65 | 0 | renderBody(writer, cycle); |
66 | } | |
67 | finally | |
68 | { | |
69 | 0 | _invoker = oldInvoker; |
70 | ||
71 | 0 | } |
72 | 0 | } |
73 | ||
74 | /** | |
75 | * Does nothing; the idea of a Block is to defer the rendering of the body of the block until an | |
76 | * {@link RenderBlock} forces it out. | |
77 | */ | |
78 | ||
79 | protected void renderComponent(IMarkupWriter writer, IRequestCycle cycle) | |
80 | { | |
81 | // Nothing! | |
82 | 0 | } |
83 | ||
84 | /** | |
85 | * Returns the object which invoked this Block's | |
86 | * {@link #renderForComponent(IMarkupWriter, IRequestCycle, IComponent)} method. This is often | |
87 | * used to access the informal parameters of a {@link RenderBlock} component. | |
88 | * | |
89 | * @since 4.0 | |
90 | */ | |
91 | public IComponent getInvoker() | |
92 | { | |
93 | 0 | return _invoker; |
94 | } | |
95 | ||
96 | /** | |
97 | * Used for testing only. | |
98 | * | |
99 | * @since 4.0 | |
100 | */ | |
101 | ||
102 | void setInvoker(IComponent invoker) | |
103 | { | |
104 | 0 | _invoker = invoker; |
105 | 0 | } |
106 | } |