net.sf.saxon.functions

Class CurrentGroupCall

java.lang.Object

net.sf.saxon.expr.Expression

net.sf.saxon.functions.CurrentGroupCall

All Implemented Interfaces:

IdentityComparable

public class CurrentGroupCall
extends Expression

Implements the XSLT function current-group()

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
CurrentGroupCall()

Method Summary

Methods

Modifier and Type	Method and Description
protected int	computeCardinality() Compute the static cardinality of this expression
int	computeSpecialProperties() Determine the special properties of this expression.
Expression	copy() Copy an expression.
void	export(ExpressionPresenter out) Diagnostic print of expression structure.
ForEachGroup	getControllingInstruction() Get the innermost containing xsl:for-each-group instruction, if there is one
int	getImplementationMethod() An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process().
int	getIntrinsicDependencies() Determine the dependencies
ItemType	getItemType() Determine the item type of the value returned by the function
CurrentGroupAdjunct	getStreamingAdjunct() Get a class that supports streamed evaluation of this expression
boolean	isInLoop() Determine whether the current-group() function is executed repeatedly within a single iteration of the containing xsl:for-each-group
SequenceIterator	iterate(XPathContext c) Return an iteration over the result sequence
void	setControllingInstruction(ForEachGroup instruction, ItemType itemType, boolean isInLoop) Set the containing xsl:for-each-group instruction, if there is one
String	toShortString() Produce a short string identifying the expression for use in error messages
String	toString() The toString() method for an expression attempts to give a representation of the expression in an XPath-like form.

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

addToPathMap, adoptChildExpression, checkedOperands, checkForUpdatingSubexpressions, checkPermittedContents, clearStreamabilityData, computeDependencies, computeStaticProperties, doPromotion, dynamicError, effectiveBooleanValue, evaluateAsString, evaluateItem, evaluatePendingUpdates, explain, getCardinality, getConfiguration, getConstructType, getCost, getDependencies, getEvaluationMethod, getExpressionCompiler, getExpressionName, getHostLanguage, getIntegerBounds, getLocation, getNetCost, 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, operands, operandSparseList, optimize, optimizeChildren, optimizeForType, process, promote, promoteChildren, resetLocalStaticProperties, restoreParentPointers, setEvaluationMethod, setFiltered, setFlattened, setLocation, setParentExpression, setPostureAndSweep, setRetainedStaticContext, setRetainedStaticContextLocally, setStaticProperty, simplify, simplifyChildren, staticTypeCheck, suppressValidation, toPattern, toStreamingPattern, typeCheck, typeCheckChildren, typeError, unordered

Methods inherited from class java.lang.Object

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

Constructor Detail

CurrentGroupCall

public CurrentGroupCall()

Method Detail

setControllingInstruction

public void setControllingInstruction(ForEachGroup instruction,
                             ItemType itemType,
                             boolean isInLoop)

Set the containing xsl:for-each-group instruction, if there is one

Parameters:

instruction - the (innermost) containing xsl:for-each-group instruction

itemType - the statically inferred item type of the grouping population

isInLoop - true if the current-group() expression is evaluated more than once during evaluation of the body of the for-each-group instruction

getControllingInstruction

public ForEachGroup getControllingInstruction()

Get the innermost containing xsl:for-each-group instruction, if there is one

Returns:

the innermost containing xsl:for-each-group instruction

isInLoop

public boolean isInLoop()

Determine whether the current-group() function is executed repeatedly within a single iteration of the containing xsl:for-each-group

Returns:

true if it is evaluated repeatedly

getItemType

public ItemType getItemType()

Determine the item type of the value returned by the function

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)

getIntrinsicDependencies

public int getIntrinsicDependencies()

Determine the 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

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

export

public void export(ExpressionPresenter out)

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

computeSpecialProperties

public int computeSpecialProperties()

Determine the special properties of this expression. The properties such as document-ordering are the same as the properties of the grouping population as a whole.

Overrides:

computeSpecialProperties in class Expression

Returns:

StaticProperty.NON_CREATIVE (unless the variable is assignable using saxon:assign)

copy

public Expression copy()

Description copied from class: Expression

Copy an expression. This makes a deep copy.

Specified by:

copy in class Expression

Returns:

the copy of the original expression

iterate

public SequenceIterator iterate(XPathContext c)
                         throws XPathException

Return an iteration over the result sequence

Overrides:

iterate in class Expression

Parameters:

c - 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

toString

public String toString()

The toString() method for an expression attempts to give a representation of the expression in an XPath-like form.

For subclasses of Expression that represent XPath expressions, the result should always be a string that parses as an XPath 3.0 expression. The expression produced should be equivalent to the original making certain assumptions about the static context. In general the expansion will make no assumptions about namespace bindings, except that (a) the prefix "xs" is used to refer to the XML Schema namespace, and (b) the default funcion namespace is assumed to be the "fn" namespace.

In the case of XSLT instructions and XQuery expressions, the toString() method gives an abstracted view of the syntax that is not designed in general to be parseable.

Overrides:

toString in class Expression

Returns:

a representation of the expression as a string

toShortString

public String toShortString()

Produce a short string identifying the expression for use in error messages

Overrides:

toShortString in class Expression

Returns:

a short string, sufficient to identify the expression

getStreamingAdjunct

public CurrentGroupAdjunct getStreamingAdjunct()

Get a class that supports streamed evaluation of this expression

Overrides:

getStreamingAdjunct in class Expression

Returns:

the relevant StreamingAdjunct, or null if none is available