public class UnboundFunctionLibrary extends Object implements FunctionLibrary
|Constructor and Description|
Create an UnboundFunctionLibrary
|Modifier and Type||Method and Description|
Identify a (namespace-prefixed) function appearing in the expression.
Bind function calls that could not be bound when first encountered.
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.
Test whether a function with a given name and arity is available; if so, return a function item that can be dynamically called.
Test whether a function with a given name and arity is available
public Expression bind(StructuredQName functionName, int arity, Expression arguments, StaticContext env, Container container) throws XPathException
Note that a function call may appear earlier in the query than the definition of the function to which it is bound. Unlike XSLT, we cannot search forwards to find the function definition. Binding of function calls is therefore a two-stage process; at the time the function call is parsed, we simply register it as pending; subsequently at the end of query parsing all the pending function calls are resolved. Another consequence of this is that we cannot tell at the time a function call is parsed whether it is a call to an internal (XSLT or XQuery) function or to an extension function written in Java.
functionName- the QName of the function being called
arity- The number of arguments supplied in the function call
arguments- May be null; if present, the length of the array must match the value of arity. Contains the expressions supplied statically in arguments to 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. 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).
env- The static context of the function call
container- The container for the newly created Expression
XPathException- if the function call is invalid, either because it is an unprefixed call to a non-system function, or because it is calling a system function that is available in XSLT only. A prefixed function call that cannot be recognized at this stage is assumed to be a forwards reference, and is bound later when bindUnboundFunctionCalls() is called.
public FunctionItem getFunctionItem(StructuredQName functionName, int arity, StaticContext staticContext) throws XPathException
This supports the function-lookup() function in XPath 3.0.
functionName- the qualified name of the function being called
arity- The number of arguments.
staticContext- the static context to be used by the function, in the event that it is a system function with dependencies on the static context
XPathException- in the event of certain errors, for example attempting to get a function that is private
public boolean isAvailable(StructuredQName functionName, int arity)
This supports the function-available() function in XSLT.
public void bindUnboundFunctionReferences(XQueryFunctionBinder lib, Configuration config) throws XPathException
lib- A library containing all the XQuery functions that have been declared; the method searches this library for this missing function call
config- The Saxon configuration
XPathException- if a function call refers to a function that has not been declared
public FunctionLibrary copy()
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