net.sf.saxon.expr
Class EagerLetExpression

java.lang.Object
  extended by net.sf.saxon.expr.Expression
      extended by net.sf.saxon.expr.Assignation
          extended by net.sf.saxon.expr.LetExpression
              extended by net.sf.saxon.expr.EagerLetExpression
All Implemented Interfaces:
Serializable, SourceLocator, Binding, EvaluableItem, SequenceIterable, TailCallReturner, InstructionInfoProvider

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.

See Also:
Serialized Form

Field Summary
 
Fields inherited from class net.sf.saxon.expr.Expression
EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD
 
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, evaluateItem, explain, getItemType, getNominalReferenceCount, implementsStaticTypeCheck, isIndexedVariable, iterate, iterateEvents, markTailFunctionCalls, process, processLeavingTail, promote, setIndexedVariable, staticTypeCheck, typeCheck
 
Methods inherited from class net.sf.saxon.expr.Assignation
addToPathMap, evaluateVariable, getAction, getLocalSlotNumber, getRequiredSlots, getRequiredType, getSequence, getVariableName, getVariableQName, isAssignable, isGlobal, iterateSubExpressions, refineTypeInformation, replaceSubExpression, setAction, setRequiredType, setSequence, setSlotNumber, setVariableQName, simplify, suppressValidation
 
Methods inherited from class net.sf.saxon.expr.Expression
adoptChildExpression, computeDependencies, computeStaticProperties, display, doPromotion, effectiveBooleanValue, evaluateAsString, explain, findParentOf, getCardinality, getColumnNumber, getContainer, getDependencies, getExecutable, getHostLanguage, getImplementationMethod, getInstructionInfo, getIntrinsicDependencies, getLineNumber, getLocationId, getLocationProvider, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasLoopingSubexpression, setContainer, setFiltered, setFlattened, setLocationId, toString
 
Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Constructor Detail

EagerLetExpression

public EagerLetExpression()
Method Detail

optimize

public Expression optimize(ExpressionVisitor visitor,
                           ItemType 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)


Copyright (C) Michael H. Kay. All rights reserved.