net.sf.saxon.functions

Class CurrentGroupCall

java.lang.Object

net.sf.saxon.expr.Expression

net.sf.saxon.functions.CurrentGroupCall

All Implemented Interfaces:

Callable, ExportAgent, Locatable, IdentityComparable

public class CurrentGroupCall
extends Expression
implements Callable

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_COST, 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

Modifier and Type	Method and Description
Sequence<?>	call(XPathContext context, Sequence[] arguments) Call the Callable (used from generated bytecode).
protected int	computeCardinality() Compute the static cardinality of this expression
int	computeSpecialProperties() Determine the special properties of this expression.
Expression	copy(RebindingMap rebindings) Copy an expression.
void	export(ExpressionPresenter out) Diagnostic print of expression structure.
static ForEachGroup	findControllingInstruction(Expression exp)
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
Expression	getScopingExpression() Get the innermost scoping expression of this expression, for expressions that directly depend on something in the dynamic context.
java.lang.String	getStreamerName() Get the (partial) name of a class that supports streaming of this kind of 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	resetLocalStaticProperties() Reset the static properties of the expression to -1, so that they have to be recomputed next time they are used.
void	setControllingInstruction(ForEachGroup instruction, ItemType itemType, boolean isInLoop) Set the containing xsl:for-each-group instruction, if there is one
java.lang.String	toShortString() Produce a short string identifying the expression for use in error messages
java.lang.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, allowExtractingCommonSubexpressions, checkedOperands, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeHashCode, computeStaticProperties, dynamicError, effectiveBooleanValue, equals, evaluateAsString, evaluateItem, evaluatePendingUpdates, explain, getCardinality, getConfiguration, getConstructType, getCost, getDependencies, getEvaluationMethod, getExpressionName, getExtraProperty, getIntegerBounds, getInterpretedExpression, getLocalRetainedStaticContext, getLocation, getNetCost, getObjectName, getPackageData, getParentExpression, getProperties, getProperty, getRetainedStaticContext, getSlotsUsed, getSpecialProperties, getStaticBaseURI, getStaticBaseURIString, getStaticType, getStaticUType, hasCompatibleStaticContext, hashCode, hasSpecialProperty, hasVariableBinding, identityHashCode, implementsStaticTypeCheck, isCallOn, isEqual, isIdentical, isInstruction, isLiftable, isMultiThreaded, isStaticPropertiesKnown, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, markTailFunctionCalls, operandList, operands, operandSparseList, optimize, optimizeChildren, prepareForStreaming, process, restoreParentPointers, setEvaluationMethod, setExtraProperty, setFiltered, setFlattened, setLocation, setParentExpression, setRetainedStaticContext, setRetainedStaticContextLocally, setRetainedStaticContextThoroughly, setStaticProperty, simplify, simplifyChildren, staticTypeCheck, suppressValidation, toPattern, typeCheck, typeCheckChildren, typeError, unordered, verifyParentPointers

Methods inherited from class java.lang.Object

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

Constructor Detail

CurrentGroupCall

public CurrentGroupCall()

Method Detail

getScopingExpression

public Expression getScopingExpression()

Get the innermost scoping expression of this expression, for expressions that directly depend on something in the dynamic context. For example, in the case of a local variable reference this is the expression that causes the relevant variable to be bound; for a context item expression it is the innermost focus-setting container. For expressions that have no intrinsic dependency on the dynamic context, the value returned is null; the scoping container for such an expression is the innermost scoping container of its operands.

Overrides:

getScopingExpression in class Expression

Returns:

the innermost scoping container of this expression

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

resetLocalStaticProperties

public void resetLocalStaticProperties()

Description copied from class: Expression

Reset the static properties of the expression to -1, so that they have to be recomputed next time they are used.

Overrides:

resetLocalStaticProperties in class Expression

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

findControllingInstruction

public static ForEachGroup findControllingInstruction(Expression exp)

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)
            throws XPathException

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

Specified by:

export in interface ExportAgent

Specified by:

export in class Expression

Parameters:

out - the expression presenter used to display the structure

Throws:

XPathException - if the export fails, for example if an expression is found that won't work in the target environment.

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

copy

public Expression copy(RebindingMap rebindings)

Description copied from class: Expression

Copy an expression. This makes a deep copy.

Specified by:

copy in class Expression

Parameters:

rebindings - a mutable list of (old binding, new binding) pairs that is used to update the bindings held in any local variable references that are copied.

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

call

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

Call the Callable (used from generated bytecode).

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 method 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

toString

public java.lang.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 java.lang.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

getStreamerName

public java.lang.String getStreamerName()

Get the (partial) name of a class that supports streaming of this kind of expression

Overrides:

getStreamerName in class Expression

Returns:

the partial name of a class that can be instantiated to provide streaming support in Saxon-EE, or null if there is no such class