net.sf.saxon.expr

Class StaticFunctionCall

java.lang.Object

net.sf.saxon.expr.Expression

net.sf.saxon.expr.FunctionCall

net.sf.saxon.expr.StaticFunctionCall

All Implemented Interfaces:

Callable, IdentityComparable

Direct Known Subclasses:

SystemFunctionCall

public class StaticFunctionCall
extends FunctionCall
implements Callable

A call to a function that is known statically. This is a stricter definition than "static function call" in the XPath grammar, because it excludes calls that might be re-bound to a different function as a result of XSLT overrides in a different package, calls to functions that hold dynamic context information in their closure, and so on.

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
StaticFunctionCall(Function target, Expression[] arguments)

Method Summary

Methods

Modifier and Type	Method and Description
Sequence	call(XPathContext context, Sequence[] arguments) Call the Callable.
protected int	computeCardinality() Compute the static cardinality of this expression
Expression	copy() Copy an expression.
void	export(ExpressionPresenter out) Diagnostic print of expression structure.
ExpressionCompiler	getExpressionCompiler() Return the bytecode compiler for this system function call.
StructuredQName	getFunctionName() Get the qualified of the function being called
ItemType	getItemType() Determine the data type of the expression, if possible.
Function	getTargetFunction() Get the target function to be called
Function	getTargetFunction(XPathContext context) Get the target function to be called
boolean	isCallOn(Class<? extends SystemFunction> function) Ask whether this expression is a call on a particular function
boolean	isCallOnSystemFunction(String localName)
Expression	typeCheck(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) Type-check the expression.

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

addExternalFunctionCallToPathMap, adjustRequiredType, checkArgumentCount, checkArguments, checkFunctionCall, equals, evaluateArguments, getArg, getArguments, getArity, getDisplayName, getExpressionName, getImplementationMethod, getNetCost, getOperanda, hashCode, iterate, operands, optimize, pluralArguments, preEvaluate, preEvaluateIfConstant, setArg, setArguments, setOperanda, setOperanda, simplifyArguments, toShortString, toString

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

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

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

StaticFunctionCall

public StaticFunctionCall(Function target,
                  Expression[] arguments)

Method Detail

getTargetFunction

public Function getTargetFunction()

Get the target function to be called

Returns:

the target function

getTargetFunction

public Function getTargetFunction(XPathContext context)

Get the target function to be called

Specified by:

getTargetFunction in class FunctionCall

Parameters:

context - the dynamic evaluation context (not used in this implementation)

Returns:

the target function

getFunctionName

public StructuredQName getFunctionName()

Get the qualified of the function being called

Specified by:

getFunctionName in class FunctionCall

Returns:

the qualified name

isCallOn

public boolean isCallOn(Class<? extends SystemFunction> function)

Ask whether this expression is a call on a particular function

Overrides:

isCallOn in class Expression

Parameters:

function - the implementation class of the function in question

isCallOnSystemFunction

public boolean isCallOnSystemFunction(String localName)

Overrides:

isCallOnSystemFunction in class Expression

typeCheck

public Expression typeCheck(ExpressionVisitor visitor,
                   ContextItemStaticInfo contextInfo)
                     throws XPathException

Type-check the expression. This also calls preEvaluate() to evaluate the function if all the arguments are constant; functions that do not require this behavior can override the preEvaluate method.

Overrides:

typeCheck in class FunctionCall

Parameters:

visitor - the expression visitor

contextInfo - information about the type of the context item

Returns:

the original expression, rewritten to perform necessary run-time type checks, and to perform other type-related optimizations

Throws:

XPathException - if an error is discovered during this phase (typically a type error)

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

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

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)

call

public Sequence call(XPathContext context,
            Sequence[] arguments)
              throws XPathException

Call the Callable.

Specified by:

call in interface Callable

Parameters:

context - the dynamic evaluation context

arguments - the values of the arguments, supplied as Sequences.

Generally it is advisable, if calling iterate() to process a supplied sequence, to call it only once; if the value is required more than once, it should first be converted to a GroundedValue by calling the utility methd SequenceTool.toGroundedValue().

If the expected value is a single item, the item should be obtained by calling Sequence.head(): it cannot be assumed that the item will be passed as an instance of Item or AtomicValue.

It is the caller's responsibility to perform any type conversions required to convert arguments to the type expected by the callee. An exception is where this Callable is explicitly an argument-converting wrapper around the original Callable.

Returns:

the result of the evaluation, in the form of a Sequence. It is the responsibility of the callee to ensure that the type of result conforms to the expected result type.

Throws:

XPathException - if a dynamic error occurs during the evaluation of the expression

export

public void export(ExpressionPresenter out)

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

Overrides:

export in class FunctionCall

Parameters:

out -

getExpressionCompiler

public ExpressionCompiler getExpressionCompiler()
                                         throws CannotCompileException

Return the bytecode compiler for this system function call.

Overrides:

getExpressionCompiler in class Expression

Returns:

the relevant ExpressionCompiler

Throws:

CannotCompileException - if it is not possible to generate bytecode for this expression