public class UnboundFunctionLibrary extends java.lang.Object implements FunctionLibrary
Constructor and Description |
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UnboundFunctionLibrary()
Create an UnboundFunctionLibrary
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Modifier and Type | Method and Description |
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Expression |
bind(SymbolicName.F functionName,
Expression[] arguments,
StaticContext env)
Identify a (namespace-prefixed) function appearing in the expression.
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void |
bindUnboundFunctionReferences(XQueryFunctionBinder lib,
Configuration config)
Bind function calls that could not be bound when first encountered.
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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.
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Function |
getFunctionItem(SymbolicName.F functionName,
StaticContext staticContext)
Test whether a function with a given name and arity is available; if so, return a function
item that can be dynamically called.
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boolean |
isAvailable(SymbolicName.F functionName)
Test whether a function with a given name and arity is available
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public UnboundFunctionLibrary()
public Expression bind(SymbolicName.F functionName, Expression[] arguments, StaticContext env) 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.
bind
in interface FunctionLibrary
functionName
- the QName of the function being calledarguments
- 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 callXPathException
- 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 Function getFunctionItem(SymbolicName.F functionName, StaticContext staticContext) throws XPathException
This supports the function-lookup() function in XPath 3.0.
getFunctionItem
in interface FunctionLibrary
functionName
- the qualified name of the function being calledstaticContext
- the static context to be used by the function, in the event that
it is a system function with dependencies on the static contextXPathException
- in the event of certain errors, for example attempting to get a function
that is privatepublic boolean isAvailable(SymbolicName.F functionName)
This supports the function-available() function in XSLT.
isAvailable
in interface FunctionLibrary
functionName
- the qualified name of the function being calledpublic 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 callconfig
- The Saxon configurationXPathException
- if a function call refers to a function that has
not been declaredpublic FunctionLibrary copy()
copy
in interface FunctionLibrary
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