com.saxonica.functions.hof

Class UserFunctionReference

java.lang.Object

net.sf.saxon.expr.Expression

com.saxonica.functions.hof.UserFunctionReference

All Implemented Interfaces:

ComponentInvocation, UserFunctionResolvable, IdentityComparable

public class UserFunctionReference
extends Expression
implements ComponentInvocation, UserFunctionResolvable

A UserFunctionReference is an expression in the form local:f#1 where local:f is a user-defined function. Evaluating the expression returns a function item. The reason that UserFunctionReference is treated as an expression rather than a value is that the binding to the actual function may be deferred, for example if the function is overridden in a different package.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	UserFunctionReference.BoundUserFunction

Field Summary

Fields inherited from class net.sf.saxon.expr.Expression

EFFECTIVE_BOOLEAN_VALUE, EVALUATE_METHOD, ITEM_FEED_METHOD, ITERATE_METHOD, MAX_SEQUENCE_LENGTH, MAX_STRING_LENGTH, PROCESS_METHOD, staticProperties, UNBOUNDED_LOWER, UNBOUNDED_UPPER, UPDATE_METHOD, WATCH_METHOD

Constructor Summary

Constructors

Constructor and Description
UserFunctionReference(SymbolicName name)
UserFunctionReference(UserFunction target)

Method Summary

Methods

Modifier and Type	Method and Description
protected int	computeCardinality() Compute the static cardinality of this expression
Expression	copy() Copy an expression.
Item	evaluateItem(XPathContext context) Evaluate an expression as a single item.
void	export(ExpressionPresenter out) Diagnostic print of expression structure.
int	getArity() Get the arity of the function
int	getBindingSlot() Get the binding slot to be used.
Component	getFixedTarget() Get the target component if this is known in advance, that is, if the target component is private or final.
FunctionItemType	getFunctionItemType(TypeHierarchy th) Get the item type of the function item
StructuredQName	getFunctionName() Get the name of the function, or null if it is anonymous
int	getImplementationMethod() An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process().
ItemType	getItemType() Determine the data type of the expression, if possible.
SymbolicName	getSymbolicName() Get the symbolic name of the component that this invocation references
void	setBindingSlot(int slot) Set the binding slot to be used.
void	setFunction(UserFunction function)

Methods inherited from class net.sf.saxon.expr.Expression

addToPathMap, adoptChildExpression, checkedOperands, checkForUpdatingSubexpressions, checkPermittedContents, clearStreamabilityData, computeDependencies, computeSpecialProperties, computeStaticProperties, doPromotion, dynamicError, effectiveBooleanValue, evaluateAsString, evaluatePendingUpdates, explain, getCardinality, getConfiguration, getConstructType, getCost, getDependencies, getEvaluationMethod, getExpressionCompiler, getExpressionName, getHostLanguage, getIntegerBounds, getIntrinsicDependencies, getLocation, getNetCost, getObjectName, getPackageData, getParentExpression, getPosture, getPostureAndSweepIfKnown, getProperties, getProperty, getRetainedStaticContext, getSlotsUsed, getSpecialProperties, getStaticBaseURI, getStaticBaseURIString, getStreamability, getStreamingAdjunct, getSweep, getSystemId, hasVariableBinding, identityHashCode, implementsStaticTypeCheck, isCallOn, isCallOnSystemFunction, isIdentical, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, iterate, iterateEvents, makeStreamingAdjunct, markTailFunctionCalls, operandList, operands, operandSparseList, optimize, optimizeChildren, optimizeForType, process, promote, promoteChildren, resetLocalStaticProperties, restoreParentPointers, setEvaluationMethod, setFiltered, setFlattened, setLocation, setParentExpression, setPostureAndSweep, setRetainedStaticContext, setRetainedStaticContextLocally, setStaticProperty, simplify, simplifyChildren, staticTypeCheck, suppressValidation, toPattern, toShortString, toStreamingPattern, toString, typeCheck, typeCheckChildren, typeError, unordered

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

UserFunctionReference

public UserFunctionReference(UserFunction target)

UserFunctionReference

public UserFunctionReference(SymbolicName name)

Method Detail

setFunction

public void setFunction(UserFunction function)

Specified by:

setFunction in interface UserFunctionResolvable

getBindingSlot

public int getBindingSlot()

Get the binding slot to be used. This is the offset within the binding vector of the containing component where the actual target component is to be found.

Specified by:

getBindingSlot in interface ComponentInvocation

Returns:

the offset in the binding vector of the containing package where the target component can be found.

getFixedTarget

public Component getFixedTarget()

Get the target component if this is known in advance, that is, if the target component is private or final. Otherwise, return null.

Specified by:

getFixedTarget in interface ComponentInvocation

Returns:

the bound component if the binding has been fixed

setBindingSlot

public void setBindingSlot(int slot)

Set the binding slot to be used. This is the offset within the binding vector of the containing component where the actual target component is to be found. The target template is not held directly in the invocation instruction/expression itself because it can be overridden in a using package.

Specified by:

setBindingSlot in interface ComponentInvocation

Parameters:

slot - the offset in the binding vector of the containing package where the target component can be found.

getSymbolicName

public SymbolicName getSymbolicName()

Get the symbolic name of the component that this invocation references

Specified by:

getSymbolicName in interface ComponentInvocation

Returns:

the symbolic name of the target component

getFunctionItemType

public FunctionItemType getFunctionItemType(TypeHierarchy th)

Get the item type of the function item

Parameters:

th - the type hierarchy cache

Returns:

the function item's type

getFunctionName

public StructuredQName getFunctionName()

Get the name of the function, or null if it is anonymous

Returns:

the function name, or null for an anonymous inline function

getArity

public int getArity()

Get the arity of the function

Returns:

the number of arguments in the function signature

computeCardinality

protected int computeCardinality()

Compute the static cardinality of this expression

Specified by:

computeCardinality in class Expression

Returns:

the computed cardinality, as one of the values StaticProperty.ALLOWS_ZERO_OR_ONE, StaticProperty.EXACTLY_ONE, StaticProperty.ALLOWS_ONE_OR_MORE, StaticProperty.ALLOWS_ZERO_OR_MORE

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.

Specified by:

getImplementationMethod in class Expression

Returns:

the implementation method, for example Expression.ITERATE_METHOD or Expression.EVALUATE_METHOD or Expression.PROCESS_METHOD

getItemType

public ItemType getItemType()

Determine the data type of the expression, if possible. All expression return sequences, in general; this method determines the type of the items within the sequence, assuming that (a) this is known in advance, and (b) it is the same for all items in the sequence.

This method should always return a result, though it may be the best approximation that is available at the time.

Specified by:

getItemType in class Expression

Returns:

a value such as Type.STRING, Type.BOOLEAN, Type.NUMBER, Type.NODE, or Type.ITEM (meaning not known at compile time)

copy

public Expression copy()

Copy an expression. This makes a deep copy.

Specified by:

copy in class Expression

Returns:

the copy of the original expression

evaluateItem

public Item evaluateItem(XPathContext context)
                  throws XPathException

Evaluate an expression as a single item. This always returns either a single Item or null (denoting the empty sequence). No conversion is done. This method should not be used unless the static type of the expression is a subtype of "item" or "item?": that is, it should not be called if the expression may return a sequence. There is no guarantee that this condition will be detected.

Overrides:

evaluateItem in class Expression

Parameters:

context - The context in which the expression is to be evaluated

Returns:

the node or atomic value that results from evaluating the expression; or null to indicate that the result is an empty sequence

Throws:

XPathException - if any dynamic error occurs evaluating the expression

export

public void export(ExpressionPresenter out)

Description copied from class: Expression

Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.

Specified by:

export in class Expression

Parameters:

out - the expression presenter used to display the structure