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 |
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2 | // |
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3 | // Licensed under the Apache License, Version 2.0 (the "License"); |
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4 | // you may not use this file except in compliance with the License. |
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5 | // You may obtain a copy of the License at |
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6 | // |
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7 | // http://www.apache.org/licenses/LICENSE-2.0 |
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8 | // |
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9 | // Unless required by applicable law or agreed to in writing, software |
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10 | // distributed under the License is distributed on an "AS IS" BASIS, |
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11 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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12 | // See the License for the specific language governing permissions and |
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13 | // limitations under the License. |
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14 | ||
15 | package org.apache.tapestry.components; |
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16 | ||
17 | import org.apache.hivemind.util.Defense; |
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18 | import org.apache.tapestry.AbstractComponent; |
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19 | import org.apache.tapestry.IComponent; |
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20 | import org.apache.tapestry.IMarkupWriter; |
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21 | import org.apache.tapestry.IRequestCycle; |
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22 | ||
23 | /** |
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24 | * Prevents its contents from being rendered until triggered by an {@link RenderBlock} component. [<a |
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25 | * href="../../../../../ComponentReference/Block.html">Component Reference</a>] |
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26 | * <p> |
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27 | * Block and {@link RenderBlock} are used to build a certain class of complicated component that |
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28 | * can't be assembled using the normal wrapping containment. Such a super component would have two |
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29 | * or more sections that need to be supplied by the containing page (or component). |
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30 | * <p> |
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31 | * Using Blocks, the blocks can be provided as parameters to the super component. |
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32 | * <p> |
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33 | * The invoker property gives the components inside the block access to the component (typically an |
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34 | * {@link RenderBlock}) that rendered the block. More often, the {@link #getParameter(String)} |
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35 | * method is used to get parameters <em>of the invoking component</em>. |
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36 | * |
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37 | * @author Howard Lewis Ship |
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38 | * @since 0.2.9 |
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39 | */ |
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40 | ||
41 | 3 | public abstract class Block extends AbstractComponent |
42 | { |
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43 | private IComponent _invoker; |
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44 | ||
45 | /** |
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46 | * Provides access to the invoking component's parameters. |
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47 | * |
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48 | * @since 4.0 |
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49 | */ |
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50 | ||
51 | public Object getParameter(String name) |
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52 | { |
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53 | 1 | return _invoker.getBinding(name).getObject(); |
54 | } |
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55 | ||
56 | public void renderForComponent(IMarkupWriter writer, IRequestCycle cycle, IComponent invoker) |
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57 | { |
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58 | 3 | Defense.notNull(invoker, "invoker"); |
59 | ||
60 | 3 | IComponent oldInvoker = _invoker; |
61 | ||
62 | try |
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63 | { |
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64 | 3 | _invoker = invoker; |
65 | 3 | renderBody(writer, cycle); |
66 | } |
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67 | finally |
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68 | { |
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69 | 3 | _invoker = oldInvoker; |
70 | ||
71 | 3 | } |
72 | 3 | } |
73 | ||
74 | /** |
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75 | * Does nothing; the idea of a Block is to defer the rendering of the body of the block until an |
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76 | * {@link RenderBlock} forces it out. |
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77 | */ |
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78 | ||
79 | protected void renderComponent(IMarkupWriter writer, IRequestCycle cycle) |
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80 | { |
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81 | // Nothing! |
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82 | 0 | } |
83 | ||
84 | /** |
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85 | * Returns the object which invoked this Block's |
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86 | * {@link #renderForComponent(IMarkupWriter, IRequestCycle, IComponent)} method. This is often |
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87 | * used to access the informal parameters of a {@link RenderBlock} component. |
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88 | * |
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89 | * @since 4.0 |
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90 | */ |
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91 | public IComponent getInvoker() |
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92 | { |
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93 | 3 | return _invoker; |
94 | } |
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95 | ||
96 | /** |
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97 | * Used for testing only. |
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98 | * |
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99 | * @since 4.0 |
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100 | */ |
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101 | ||
102 | void setInvoker(IComponent invoker) |
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103 | { |
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104 | 1 | _invoker = invoker; |
105 | 1 | } |
106 | } |