This class represents a call to a user-defined function in the stylesheet or query.
addToPathMap
public PathMap.PathMapNodeSet addToPathMap(PathMap pathMap,
PathMap.PathMapNodeSet pathMapNodeSet)
Add a representation of this expression to a PathMap. The PathMap captures a map of the nodes visited
by an expression in a source tree.
The default implementation of this method assumes that an expression does no navigation other than
the navigation done by evaluating its subexpressions, and that the subexpressions are evaluated in the
same context as the containing expression. The method must be overridden for any expression
where these assumptions do not hold. For example, implementations exist for AxisExpression, ParentExpression,
and RootExpression (because they perform navigation), and for the doc(), document(), and collection()
functions because they create a new navigation root. Implementations also exist for PathExpression and
FilterExpression because they have subexpressions that are evaluated in a different context from the
calling expression.
- addToPathMap in interface Expression
pathMap
- the PathMap to which the expression should be addedpathMapNodeSet
-
- the pathMapNode representing the focus established by this expression, in the case where this
expression is the first operand of a path expression or filter expression. For an expression that does
navigation, it represents the end of the arc in the path map that describes the navigation route. For other
expressions, it is the same as the input pathMapNode.
checkFunctionCall
public void checkFunctionCall(UserFunction compiledFunction,
ExpressionVisitor visitor)
throws XPathException
Check the function call against the declared function signature
compiledFunction
- the function being calledvisitor
- an expression visitor
computeArgumentEvaluationModes
public void computeArgumentEvaluationModes()
Compute the evaluation mode of each argument
copy
public Expression copy()
Copy an expression. This makes a deep copy.
- copy in interface Expression
- the copy of the original expression
dynamicCall
public ValueRepresentation dynamicCall(ValueRepresentation[] suppliedArguments,
XPathContext context)
throws XPathException
Call the function dynamically. For this to be possible, the static arguments of the function call
must have been set up as SuppliedParameterReference objects. The actual arguments are placed on the
callee's stack, and the type conversion takes place "in situ".
suppliedArguments
- the values to be used for the arguments of the functioncontext
- the dynamic evaluation context
- the result of evaluating the function
explain
public void explain(ExpressionPresenter out)
Diagnostic print of expression structure. The abstract expression tree
is written to the supplied output destination.
- explain in interface FunctionCall
getArgumentEvaluationModes
public int[] getArgumentEvaluationModes()
Get the evaluation modes that have been determined for each of the arguments
- an array of integers representing the evaluation modes, one for each argument
getArguments
public Expression[] getArguments()
Get the arguments (the expressions supplied in the function call)
- getArguments in interface FunctionCall
- the actual expressions used as arguments in the function call
getFunction
public UserFunction getFunction()
Get the function that is being called by this function call
- the function being called
getImplementationMethod
public int getImplementationMethod()
An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process().
This method indicates which of these methods is provided directly. The other methods will always be available
indirectly, using an implementation that relies on one of the other methods.
- getImplementationMethod in interface Expression
getIntrinsicDependencies
public int getIntrinsicDependencies()
Determine the intrinsic dependencies of an expression, that is, those which are not derived
from the dependencies of its subexpressions. For example, position() has an intrinsic dependency
on the context position, while (position()+1) does not. The default implementation
of the method returns 0, indicating "no dependencies".
- getIntrinsicDependencies in interface Expression
- a set of bit-significant flags identifying the "intrinsic"
dependencies. The flags are documented in class net.sf.saxon.value.StaticProperty
getItemType
public ItemType getItemType(TypeHierarchy th)
Determine the data type of the expression, if possible
- getItemType in interface Expression
th
- the type hierarchy cache
- Type.ITEM (meaning not known in advance)
isConfirmed
public boolean isConfirmed()
Determine whether this function call is confirmed
- true if the function being called is known to exist
isRecursiveTailCall
public boolean isRecursiveTailCall()
Determine whether this is a recursive tail call
- true if this function call is a recursive tail call
isTailCall
public boolean isTailCall()
Determine whether this is a tail call (not necessarily a recursive tail call)
- true if this function call is a tail call
markTailFunctionCalls
public int markTailFunctionCalls(StructuredQName qName,
int arity)
Mark tail-recursive calls on stylesheet functions. This marks the function call as tailRecursive if
if is a call to the containing function, and in this case it also returns "true" to the caller to indicate
that a tail call was found.
- markTailFunctionCalls in interface Expression
optimize
public Expression optimize(ExpressionVisitor visitor,
ItemType contextItemType)
throws XPathException
Perform optimisation of an expression and its subexpressions. This is the third and final
phase of static optimization.
This method is called after all references to functions and variables have been resolved
to the declaration of the function or variable, and after all type checking has been done.
- optimize in interface FunctionCall
visitor
- an expression visitorcontextItemType
- the static type of "." at the point where this expression is invoked.
The parameter is set to null if it is known statically that the context item will be undefined.
If the type of the context item is not known statically, the argument is set to
Type.ITEM_TYPE
- the original expression, rewritten if appropriate to optimize execution
XPathException
- if an error is discovered during this phase
(typically a type error)
preEvaluate
public Expression preEvaluate(ExpressionVisitor visitor)
Pre-evaluate a function at compile time. This version of the method suppresses
early evaluation by doing nothing.
- preEvaluate in interface FunctionCall
visitor
- an expression visitor
setConfirmed
public void setConfirmed(boolean conf)
Set this function as confirmed (the function being called is known to exist) or not
conf
- true if the function being called is known to exist
setFunction
public void setFunction(UserFunction compiledFunction)
Create the reference to the function to be called
compiledFunction
- the function being called
setStaticType
public void setStaticType(SequenceType type)
Set the static type
typeCheck
public Expression typeCheck(ExpressionVisitor visitor,
ItemType contextItemType)
throws XPathException
Perform type checking of an expression and its subexpressions. This is the second phase of
static optimization.
This checks statically that the operands of the expression have
the correct type; if necessary it generates code to do run-time type checking or type
conversion. A static type error is reported only if execution cannot possibly succeed, that
is, if a run-time type error is inevitable. The call may return a modified form of the expression.
This method is called after all references to functions and variables have been resolved
to the declaration of the function or variable. However, the types of such functions and
variables may not be accurately known if they have not been explicitly declared.
If the implementation returns a value other than "this", then it is required to ensure that
the parent pointer and location information in the returned expression have been set up correctly.
It should not rely on the caller to do this, although for historical reasons many callers do so.
- typeCheck in interface FunctionCall
visitor
- an expression visitorcontextItemType
- the static type of "." at the point where this expression is invoked.
The parameter is set to null if it is known statically that the context item will be undefined.
If the type of the context item is not known statically, the argument is set to
Type.ITEM_TYPE
- the original expression, rewritten to perform necessary run-time type checks,
and to perform other type-related optimizations
XPathException
- if an error is discovered during this phase
(typically a type error)