net.sf.saxon.functions

Class IntegratedFunctionCall

java.lang.Object

net.sf.saxon.expr.Expression

net.sf.saxon.expr.FunctionCall

net.sf.saxon.functions.IntegratedFunctionCall

All Implemented Interfaces:

Callable, IdentityComparable

public class IntegratedFunctionCall
extends FunctionCall
implements Callable

Expression representing a call to a user-written extension function implemented as a subtype of ExtensionFunctionCall

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
IntegratedFunctionCall(StructuredQName name, ExtensionFunctionCall function)

Method Summary

Methods

Modifier and Type	Method and Description
Sequence	call(XPathContext context, Sequence[] arguments) Call the Callable.
void	checkArguments(ExpressionVisitor visitor) Method supplied by each class of function to check arguments during parsing, when all the argument expressions have been read.
protected int	computeCardinality() Compute the static cardinality of this expression
protected int	computeSpecialProperties() Compute the special properties of this expression.
Expression	copy() Copy an expression.
boolean	effectiveBooleanValue(XPathContext context) Get the effective boolean value of the expression.
void	export(ExpressionPresenter out) Diagnostic print of expression structure.
ExtensionFunctionCall	getFunction() Get the ExtensionFunctionCall object supplied by the application
StructuredQName	getFunctionName() Get the qualified of the function being called
int	getIntrinsicDependencies() Determine the intrinsic dependencies of an expression, that is, those which are not derived from the dependencies of its subexpressions.
ItemType	getItemType() Determine the data type of the expression, if possible.
StreamingAdjunct	getStreamingAdjunct() Get a class that supports streamed evaluation of this extension function
Function	getTargetFunction(XPathContext context) Get the target function to be called
SequenceIterator	iterate(XPathContext context) Return an Iterator to iterate over the values of a sequence.
Expression	preEvaluate(ExpressionVisitor visitor) Pre-evaluate a function at compile time.
void	setResultType(SequenceType resultType) Set the result type of the function
Expression	typeCheck(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) Type-check the expression.

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

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

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

addToPathMap, adoptChildExpression, checkedOperands, checkForUpdatingSubexpressions, checkPermittedContents, clearStreamabilityData, computeDependencies, computeStaticProperties, doPromotion, dynamicError, evaluateAsString, evaluateItem, evaluatePendingUpdates, explain, getCardinality, getConfiguration, getConstructType, getCost, getDependencies, getEvaluationMethod, getExpressionCompiler, getHostLanguage, getIntegerBounds, getLocation, getObjectName, getPackageData, getParentExpression, getPosture, getPostureAndSweepIfKnown, getProperties, getProperty, getRetainedStaticContext, getSlotsUsed, getSpecialProperties, getStaticBaseURI, getStaticBaseURIString, getStreamability, getSweep, getSystemId, hasVariableBinding, identityHashCode, implementsStaticTypeCheck, isCallOn, isCallOnSystemFunction, 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

IntegratedFunctionCall

public IntegratedFunctionCall(StructuredQName name,
                      ExtensionFunctionCall function)

Method Detail

setResultType

public void setResultType(SequenceType resultType)

Set the result type of the function

Parameters:

resultType - the result type

getFunctionName

public StructuredQName getFunctionName()

Get the qualified of the function being called

Specified by:

getFunctionName in class FunctionCall

Returns:

the qualified name

getTargetFunction

public Function getTargetFunction(XPathContext context)
                           throws XPathException

Get the target function to be called

Specified by:

getTargetFunction in class FunctionCall

Parameters:

context - the dynamic evaluation context

Returns:

the target function

Throws:

XPathException - if the target function cannot be determined

getFunction

public ExtensionFunctionCall getFunction()

Get the ExtensionFunctionCall object supplied by the application

Returns:

the ExtensionFunctionCall object

checkArguments

public void checkArguments(ExpressionVisitor visitor)
                    throws XPathException

Method supplied by each class of function to check arguments during parsing, when all the argument expressions have been read. This implementation of the method checks the arguments of the supplied function call against the argument types declared as part of the extension function definition, and generates code to do the conversion if necessary.

Overrides:

checkArguments in class FunctionCall

Parameters:

visitor - the expression visitor

Throws:

XPathException - if the arguments are statically determined to be incompatible with the declared argument types of the function.

typeCheck

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

Type-check the expression.

Overrides:

typeCheck in class FunctionCall

Parameters:

visitor - an expression visitor

contextInfo - Information available statically about the context item: whether it is (possibly) absent; its static type; its streaming posture.

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)

preEvaluate

public Expression preEvaluate(ExpressionVisitor visitor)
                       throws XPathException

Pre-evaluate a function at compile time. Functions that do not allow pre-evaluation, or that need access to context information, can override this method.

Overrides:

preEvaluate in class FunctionCall

Parameters:

visitor - an expression visitor

Returns:

the result of the early evaluation, or the original expression, or potentially a simplified expression

Throws:

XPathException - if evaluation fails

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)

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

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".

Overrides:

getIntrinsicDependencies in class Expression

Returns:

a set of bit-significant flags identifying the "intrinsic" dependencies. The flags are documented in class net.sf.saxon.value.StaticProperty

computeSpecialProperties

protected int computeSpecialProperties()

Compute the special properties of this expression. These properties are denoted by a bit-significant integer, possible values are in class StaticProperty. The "special" properties are properties other than cardinality and dependencies, and most of them relate to properties of node sequences, for example whether the nodes are in document order.

Overrides:

computeSpecialProperties in class Expression

Returns:

the special properties, as a bit-significant integer

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

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 - the expression presenter used to display the structure

iterate

public SequenceIterator iterate(XPathContext context)
                         throws XPathException

Return an Iterator to iterate over the values of a sequence. The value of every expression can be regarded as a sequence, so this method is supported for all expressions. This default implementation handles iteration for expressions that return singleton values: for non-singleton expressions, the subclass must provide its own implementation.

Overrides:

iterate in class FunctionCall

Parameters:

context - supplies the context for evaluation

Returns:

a SequenceIterator that can be used to iterate over the result of the expression

Throws:

XPathException - if any dynamic error occurs evaluating the expression

effectiveBooleanValue

public boolean effectiveBooleanValue(XPathContext context)
                              throws XPathException

Get the effective boolean value of the expression. This returns false if the value is the empty sequence, a zero-length string, a number equal to zero, or the boolean false. Otherwise it returns true.

Overrides:

effectiveBooleanValue in class Expression

Parameters:

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

Returns:

the effective boolean value

Throws:

XPathException - if any dynamic error occurs evaluating the expression

call

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

Description copied from interface: Callable

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

getStreamingAdjunct

public StreamingAdjunct getStreamingAdjunct()

Get a class that supports streamed evaluation of this extension function

Overrides:

getStreamingAdjunct in class Expression

Returns:

the relevant StreamingAdjunct, or null if none is available