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| <h1>Using Context Resolvers</h1> |
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| <h3>Overview</h3> |
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| Context resolvers are an abstraction used by the JSF EL framework to |
| decouple sources of context information from the way that information |
| is created. Common examples of such contexts are:<br> |
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| <br> |
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| - a dynamic web project in an Eclipse workspace<br> |
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| - a JSP file in a dynamic web project<br> |
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| - a particular absolute offset into an IDocument<br> |
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| <br> |
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| Context resolvers allow us to derive interesting information from these contexts such as:<br> |
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| - what is the current IProject?<br> |
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| - where are we in an IRegion or DOM tree?<br> |
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| - what JSF EL symbols are available at the current IDocument position?<br> |
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| <h3>IStructuredDocumentContext</h3> |
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| A particularly useful context is one in an IStructuredDocument. |
| An IStructuredDocument represents an SSE document that can be |
| manipulated in a number of different ways including as a regular |
| IDocument or as a DOM. The IStructuredDocumentContext points to a |
| specific absolute offset into such a document. The context can |
| then be passed to various resolvers to determine information about this |
| position in the document.<br> |
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| <br> |
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| <h3>Context Resolvers</h3> |
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| <br> |
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| The following is a list of context resolvers that are available as provisional APIs:<br> |
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| <td style="vertical-align: top;">Resolver Type<br> |
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| <td style="vertical-align: top;">Purpose<br> |
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| <td style="vertical-align: top;">ITaglibContextResolver</td> |
| <td style="vertical-align: top;">Resolves taglib information for the current context such |
| as retrieving the tag library information for the current tag.</td> |
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| <td style="vertical-align: top;">IWorkspaceContextResolver</td> |
| <td style="vertical-align: top;">Resolves workspace information for the current document |
| context such as IFile and IProject.</td> |
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| <td style="vertical-align: top;">IDOMContextResolver</td> |
| <td style="vertical-align: top;">Resolves DOM information for the current context such as |
| current element and attribute.</td> |
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| <td style="vertical-align: top;">IMetadataContextResolver</td> |
| <td style="vertical-align: top;">Resolves meta-data framework information for a given |
| context.<span style=""> </span>For example, if the current |
| context resolves to an XML attribute, retrieves meta-data associate with that |
| attribute/element/uri.</td> |
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| <td style="vertical-align: top;">ISymbolContextResolver</td> |
| <td style="vertical-align: top;">Determines what symbols are available or valid within the |
| current context.<span style=""> </span>For example, if |
| context is an EL expression, what bean names are available?</td> |
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| <br> |
| <h3>Factories</h3> |
| Factories exist to create both contexts and context resolvers. These are:<br> |
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| <td style="vertical-align: top;">Factory Name<br> |
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| <td style="vertical-align: top;">What it does<br> |
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| <td style="vertical-align: top;">org.eclipse.jst.jsf.context.structureddocument.internal.provisional.IStructuredDocumentContextFactory<br> |
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| <td style="vertical-align: top;">Creates new IStructuredDocumentContext objects based on a document and offset.<br> |
| </td> |
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| <td style="vertical-align: top;">org.eclipse.jst.jsf.context.resolver.structureddocument.internal.provisional.IStructuredDocumentContextResolverFactory<br> |
| </td> |
| <td style="vertical-align: top;">Creates a new instances of context resolvers for an IStructuredDocumentContext.<br> |
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| <br> |
| <h3>Adding Factory Delegates</h3>The existing factories can be extended |
| using factory delegates. A delegate for |
| IStructuredDocumentContextFactory allows you to extend the existing |
| factory to create IStructuredDocumentContext's for document contexts |
| other than an IStructuredDocumentContext and offset. Similarly, |
| adding factory delegates to IStructuredDocumentContextResolverFactory |
| allows you to create context resolvers for structured documents other |
| than those already supported.<br> |
| <br> |
| Factory delegates are added programmatically be calling |
| addFactoryDelegate on the appropriate factory. See the JavaDoc |
| for IDelegatingFactory for more details.<br> |
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