net.sf.saxon.expr

Class EagerLetExpression

java.lang.Object

net.sf.saxon.expr.Expression

net.sf.saxon.expr.Assignation

net.sf.saxon.expr.LetExpression

net.sf.saxon.expr.EagerLetExpression

All Implemented Interfaces:

Binding, ExportAgent, TailCallReturner, LocalBinding, Locatable, IdentityComparable

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

hasLoopingReference, isIndexedVariable, references, requiredType, slotNumber, variableName

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
EagerLetExpression()

Method Summary

Modifier and Type	Method and Description
Expression	optimize(ExpressionVisitor visitor, ContextItemStaticInfo contextItemType) Perform optimisation of an expression and its subexpressions.

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

checkPermittedContents, computeCardinality, computeSpecialProperties, copy, effectiveBooleanValue, eval, evaluateItem, evaluatePendingUpdates, export, getCost, getEvaluator, getExpressionName, getImplementationMethod, getIntegerBounds, getItemType, getStaticUType, implementsStaticTypeCheck, isInstruction, isLiftable, isNeedsLazyEvaluation, isVacuousExpression, iterate, markTailFunctionCalls, process, processLeavingTail, resetLocalStaticProperties, setEvaluationMode, setEvaluator, setEvaluator, setInstruction, setNeedsEagerEvaluation, setNeedsLazyEvaluation, staticTypeCheck, toShortString, toString, typeCheck

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

addReference, addToPathMap, checkForUpdatingSubexpressions, computeDependencies, evaluateVariable, getAction, getActionOp, getIntegerBoundsForVariable, getLocalSlotNumber, getNominalReferenceCount, getObjectName, getRequiredSlots, getRequiredType, getSequence, getSequenceOp, getVariableEQName, getVariableName, getVariableQName, hasVariableBinding, isAssignable, isGlobal, isIndexedVariable, isUpdatingExpression, operands, rebuildReferenceList, refineTypeInformation, removeDeadReferences, replaceVariable, setAction, setIndexedVariable, setRequiredType, setSequence, setSlotNumber, setVariableQName, suppressValidation, unordered, verifyReferences

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

adoptChildExpression, allowExtractingCommonSubexpressions, checkedOperands, computeHashCode, computeStaticProperties, dynamicError, equals, evaluateAsString, explain, getCardinality, getConfiguration, getConstructType, getDependencies, getEvaluationMethod, getExtraProperty, getInterpretedExpression, getIntrinsicDependencies, getLocalRetainedStaticContext, getLocation, getNetCost, getPackageData, getParentExpression, getProperties, getProperty, getRetainedStaticContext, getScopingExpression, getSlotsUsed, getSpecialProperties, getStaticBaseURI, getStaticBaseURIString, getStaticType, getStreamerName, hasCompatibleStaticContext, hashCode, hasSpecialProperty, identityHashCode, isCallOn, isEqual, isIdentical, isMultiThreaded, isStaticPropertiesKnown, isSubtreeExpression, operandList, operandSparseList, optimizeChildren, prepareForStreaming, restoreParentPointers, setEvaluationMethod, setExtraProperty, setFiltered, setFlattened, setLocation, setParentExpression, setRetainedStaticContext, setRetainedStaticContextLocally, setRetainedStaticContextThoroughly, setStaticProperty, simplify, simplifyChildren, toPattern, typeCheckChildren, typeError, verifyParentPointers

Methods inherited from class java.lang.Object

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

Constructor Detail

EagerLetExpression

public EagerLetExpression()

Method Detail

optimize

public Expression optimize(ExpressionVisitor visitor,
                           ContextItemStaticInfo contextItemType)
                    throws XPathException

Description copied from class: LetExpression

Perform optimisation of an expression and its subexpressions.

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 class 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)