Package net.sf.saxon.expr

Class PlaceHolder

java.lang.Object

net.sf.saxon.expr.Expression

net.sf.saxon.expr.PseudoExpression

net.sf.saxon.expr.PlaceHolder

All Implemented Interfaces:

ExportAgent, Locatable, IdentityComparable, Traceable

public class PlaceHolder
extends PseudoExpression

A PlaceHolder corresponds to the symbol "?" in a partial function application; it is a PseudoExpression because it can appear in the expression tree in the place of an expression, but is never actually evaluated.

In 4.0, placeholders can be associated with keywords, and the mapping from arguments of the partially-applied function to arguments of the base function is therefore more complex. The PlaceHolder holds an integer indicating a 0-based offset of the placeholder in the argument list of the partially-applied function.

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, UPDATE_METHOD, WATCH_METHOD

Constructor Summary

Constructors

Constructor	Description
PlaceHolder(int placeHolderSequence)	Create a placeholder, representing a "?" in a partial function application

Method Summary

Modifier and Type	Method	Description
Expression	copy(RebindingMap rebindings)	Copy an expression.
void	export(ExpressionPresenter out)	Diagnostic print of expression structure.
int	getPlaceHolderSequence()

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

computeCardinality, effectiveBooleanValue, evaluateAsString, evaluateItem, getElaborator, getImplementationMethod, getItemType, iterate, process

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

adoptChildExpression, allowExtractingCommonSubexpressions, checkedOperands, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeHashCode, computeSpecialProperties, computeStaticProperties, dispatchTailCall, dynamicError, equals, explain, getCardinality, getConfiguration, getCost, getDependencies, getEvaluationMethod, getExpressionName, getExtraProperty, getIntrinsicDependencies, getLocalRetainedStaticContext, getLocation, getNetCost, getObjectName, getPackageData, getParentExpression, getProperties, getProperty, getRetainedStaticContext, getScopingExpression, getSlotsUsed, getSpecialProperties, getStaticBaseURI, getStaticBaseURIString, getStaticType, getStaticUType, getStreamerName, getTracingTag, hasCompatibleStaticContext, hashCode, hasSpecialProperty, hasVariableBinding, identityHashCode, implementsStaticTypeCheck, isCallOn, isEqual, isIdentical, isInstruction, isLiftable, isMultiThreaded, isStaticPropertiesKnown, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, makeElaborator, markTailFunctionCalls, operandList, operands, operandSparseList, optimize, optimizeChildren, prepareForStreaming, resetLocalStaticProperties, restoreParentPointers, setEvaluationMethod, setExtraProperty, setFiltered, setFlattened, setLocation, setParentExpression, setRetainedStaticContext, setRetainedStaticContextLocally, setRetainedStaticContextThoroughly, setStaticProperty, simplify, simplifyChildren, staticTypeCheck, supportsLazyEvaluation, suppressValidation, toPattern, toShortString, toString, typeCheck, typeCheckChildren, typeError, unordered, verifyParentPointers, warning, withLocation

Methods inherited from class java.lang.Object

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

Methods inherited from interface net.sf.saxon.trace.Traceable

gatherProperties

Constructor Details

PlaceHolder

public PlaceHolder(int placeHolderSequence)

Create a placeholder, representing a "?" in a partial function application

Parameters:

placeHolderSequence - the 0-based position of this placeholder among all the placeholders in the partial function call

Method Details

getPlaceHolderSequence

public int getPlaceHolderSequence()

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.

copy

public Expression copy(RebindingMap rebindings)

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