net.sf.saxon.query

Class ImportedFunctionLibrary

public class ImportedFunctionLibrary extends Object implements FunctionLibrary, XQueryFunctionBinder

This implementation of FunctionLibrary contains all the functions imported into a Query Module. It is implemented as a view of the "global" XQueryFunctionLibrary for the whole query, selecting only those functions that are in an imported namespace.
Field Summary
XQueryFunctionLibrarybaseLibrary
HashSetnamespaces
Constructor Summary
ImportedFunctionLibrary(XQueryFunctionLibrary baseLibrary)
Method Summary
voidaddImportedNamespace(String namespace)
Expressionbind(int nameCode, String uri, 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.
FunctionLibrarycopy()
This method creates a copy of a FunctionLibrary: if the original FunctionLibrary allows new functions to be added, then additions to this copy will not affect the original, or vice versa.
XQueryFunctiongetDeclaration(int nameCode, String uri, String local, Expression[] staticArgs)
Get the function declaration corresponding to a given function name and arity
booleanisAvailable(int fingerprint, String uri, String local, int arity)
Test whether an extension function with a given name and arity is available.

Field Detail

baseLibrary

XQueryFunctionLibrary baseLibrary

namespaces

HashSet namespaces

Constructor Detail

ImportedFunctionLibrary

public ImportedFunctionLibrary(XQueryFunctionLibrary baseLibrary)

Method Detail

addImportedNamespace

public void addImportedNamespace(String namespace)

bind

public Expression bind(int nameCode, String uri, 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. This method is called at compile time.

Parameters: 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 name local The local part of the function name staticArgs The expressions supplied statically in arguments to the function call. The length of this array represents the arity of the function. The intention is that the static type of the arguments (obtainable via getItemType() and getCardinality()) may be used as part of the binding algorithm. In some cases it may be possible for the function to be pre-evaluated at compile time, for example if these expressions are all constant values.

The conventions of the XPath language demand that the results of a function depend only on the values of the expressions supplied as arguments, and not on the form of those expressions. For example, the result of f(4) is expected to be the same as f(2+2). The actual expression is supplied here to enable the binding mechanism to select the most efficient possible implementation (including compile-time pre-evaluation where appropriate).

Returns: An object representing the function to be called, if one is found; null if no function was found matching the required name and arity.

Throws: net.sf.saxon.trans.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.

copy

public FunctionLibrary copy()
This method creates a copy of a FunctionLibrary: if the original FunctionLibrary allows new functions to be added, then additions to this copy will not affect the original, or vice versa.

Returns: a copy of this function library. This must be an instance of the original class.

getDeclaration

public XQueryFunction getDeclaration(int nameCode, String uri, String local, Expression[] staticArgs)
Get the function declaration corresponding to a given function name and arity

Returns: the XQueryFunction if there is one, or null if not.

isAvailable

public boolean isAvailable(int fingerprint, String uri, String local, int arity)
Test whether an extension function with a given name and arity is available. This supports the function-available() function in XSLT. This method may be called either at compile time or at run time. If the function library is to be used only in an XQuery or free-standing XPath environment, this method may throw an UnsupportedOperationException.

Parameters: 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 name local The local part of the function name arity 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.