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:
- a dynamic web project in an Eclipse workspace
- a JSP file in a dynamic web project
- a particular absolute offset into an IDocument
Context resolvers allow us to derive interesting information from these contexts such as:
- what is the current IProject?
- where are we in an IRegion or DOM tree?
- what JSF EL symbols are available at the current IDocument position?
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.
The following is a list of context resolvers that are available as provisional APIs:
||Resolves taglib information for the current context such
as retrieving the tag library information for the current tag.
||Resolves workspace information for the current document
context such as IFile and IProject.
||Resolves DOM information for the current context such as
current element and attribute.
||Resolves meta-data framework information for a given
context. For example, if the current
context resolves to an XML attribute, retrieves meta-data associate with that
||Determines what symbols are available or valid within the
current context. For example, if
context is an EL expression, what bean names are available?
Factories exist to create both contexts and context resolvers. These are:
Adding Factory Delegates
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.
Factory delegates are added programmatically be calling
addFactoryDelegate on the appropriate factory. See the JavaDoc
IDelegatingFactory for more details.