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A FunctionLibrary handles the binding of function calls in XPath (or XQuery) expressions.
There are a number of implementations of this
class to handle different kinds of function: system functions, constructor functions, vendor-defined
functions, Java extension functions, stylesheet functions, and so on. There is also an implementation
FunctionLibraryList
that allows a FunctionLibrary to be constructed by combining other
FunctionLibrary objects.
Method Summary | |
Expression |
bind(int nameCode,
java.lang.String uri,
java.lang.String local,
Expression[] staticArgs)
Bind an extension function, given the URI and local parts of the function name, and the list of expressions supplied as arguments. |
boolean |
isAvailable(int fingerprint,
java.lang.String uri,
java.lang.String local,
int arity)
Test whether an extension function with a given name and arity is available. |
Method Detail |
public boolean isAvailable(int fingerprint, java.lang.String uri, java.lang.String local, int arity)
fingerprint
- The namepool fingerprint of the function name. This must match the
uri and localName; the information is provided redundantly to avoid repeated lookups in the name pool.uri
- The URI of the function namelocal
- The local part of the function namearity
- The number of arguments. This is set to -1 in the case of the single-argument
function-available() function; in this case the method should return true if there is some
matching extension function, regardless of its arity.public Expression bind(int nameCode, java.lang.String uri, java.lang.String local, Expression[] staticArgs) throws XPathException
nameCode
- The namepool nameCode of the function name. The uri and local name are also
supplied (redundantly) to avoid fetching them from the name pool.uri
- The URI of the function namelocal
- The local part of the function namestaticArgs
- The expressions supplied statically in the function call. The intention is
that the static type of the arguments (obtainable via getItemType() and getCardinality() may
be used as part of the binding algorithm.
XPathException
- if a function is found with the required name and arity, but
the implementation of the function cannot be loaded or used; or if an error occurs
while searching for the function.
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