net.sf.saxon.expr

Class EagerLetExpression

Implemented Interfaces:
Binding, EvaluableItem, InstructionInfoProvider, SequenceIterable, Serializable, SourceLocator, TailCallReturner

public class EagerLetExpression
extends LetExpression

An EagerLetExpression is the same as a LetExpression except that the variable is evaluated using eager evaluation rather than lazy evaluation. This is used when performing diagnostic tracing.

Field Summary

Fields inherited from class net.sf.saxon.expr.Assignation

action, requiredType, sequence, slotNumber, variableName

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

EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD, locationId, staticProperties

Constructor Summary

EagerLetExpression()

Method Summary

Expression
optimize(ExpressionVisitor visitor, ItemType contextItemType)
Perform optimisation of an expression and its subexpressions.

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

addReference, checkPermittedContents, computeCardinality, computeSpecialProperties, copy, eval, evaluateItem, explain, getItemType, getNominalReferenceCount, implementsStaticTypeCheck, isIndexedVariable, iterate, iterateEvents, markTailFunctionCalls, optimize, process, processLeavingTail, promote, setIndexedVariable, staticTypeCheck, typeCheck

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

addToPathMap, evaluateVariable, extendBindingList, getAction, getLocalSlotNumber, getRequiredSlots, getRequiredType, getSequence, getVariableName, getVariableQName, isAssignable, isGlobal, iterateSubExpressions, promote, promoteWhereClause, refineTypeInformation, replaceSubExpression, setAction, setRequiredType, setSequence, setSlotNumber, setVariableQName, simplify, suppressValidation

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

addToPathMap, adoptChildExpression, checkPermittedContents, computeCardinality, computeDependencies, computeSpecialProperties, computeStaticProperties, copy, display, doPromotion, dynamicError, effectiveBooleanValue, evaluateAsString, evaluateItem, explain, explain, findParentOf, getCardinality, getColumnNumber, getConstructType, getContainer, getDependencies, getExecutable, getHostLanguage, getImplementationMethod, getInstructionInfo, getIntrinsicDependencies, getItemType, getLineNumber, getLocationId, getLocationProvider, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasLoopingSubexpression, implementsStaticTypeCheck, iterate, iterateEvents, iterateSubExpressions, markTailFunctionCalls, optimize, process, promote, replaceSubExpression, resetLocalStaticProperties, setContainer, setFiltered, setFlattened, setLocationId, simplify, staticTypeCheck, suppressValidation, toString, typeCheck, typeError

Constructor Details

EagerLetExpression

public EagerLetExpression()

Method Details

optimize

public Expression optimize(ExpressionVisitor visitor,
                           ItemType contextItemType)
            throws XPathException
Perform optimisation of an expression and its subexpressions. This is the third and final phase of static optimization.

This method is called after all references to functions and variables have been resolved to the declaration of the function or variable, and after all type checking has been done.

Overrides:
optimize in interface LetExpression
Parameters:
visitor - an expression visitor
contextItemType - the static type of "." at the point where this expression is invoked. The parameter is set to null if it is known statically that the context item will be undefined. If the type of the context item is not known statically, the argument is set to Type.ITEM_TYPE
Returns:
the original expression, rewritten if appropriate to optimize execution
Throws:
XPathException - if an error is discovered during this phase (typically a type error)