net.sf.saxon.expr

Class ErrorExpression

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

public class ErrorExpression
extends Expression

Error expression: this expression is generated when the supplied expression cannot be parsed, and the containing element enables forwards-compatible processing. It defers the generation of an error message until an attempt is made to evaluate the expression

Field Summary

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

EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD, locationId, staticProperties

Constructor Summary

ErrorExpression(XPathException exception)
Constructor

Method Summary

int
computeCardinality()
Determine the static cardinality
Expression
copy()
Copy an expression.
Item
evaluateItem(XPathContext context)
Evaluate the expression.
void
explain(ExpressionPresenter destination)
Diagnostic print of expression structure.
XPathException
getException()
Get the wrapped exception
ItemType
getItemType(TypeHierarchy th)
Determine the data type of the expression, if possible
SequenceIterator
iterate(XPathContext context)
Iterate over the expression.
Expression
optimize(ExpressionVisitor visitor, ItemType contextItemType)
Perform optimisation of an expression and its subexpressions.
Expression
typeCheck(ExpressionVisitor visitor, ItemType contextItemType)
Type-check the expression.

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

ErrorExpression

public ErrorExpression(XPathException exception)
Constructor
Parameters:
exception - the error found when parsing this expression

Method Details

computeCardinality

public int computeCardinality()
Determine the static cardinality
Overrides:
computeCardinality in interface Expression

copy

public Expression copy()
Copy an expression. This makes a deep copy.
Overrides:
copy in interface Expression
Returns:
the copy of the original expression

evaluateItem

public Item evaluateItem(XPathContext context)
            throws XPathException
Evaluate the expression. This always throws the exception registered when the expression was first parsed.
Specified by:
evaluateItem in interface EvaluableItem
Overrides:
evaluateItem in interface Expression

explain

public void explain(ExpressionPresenter destination)
Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.
Overrides:
explain in interface Expression

getException

public XPathException getException()
Get the wrapped exception

getItemType

public ItemType getItemType(TypeHierarchy th)
Determine the data type of the expression, if possible
Overrides:
getItemType in interface Expression
Parameters:
th - the type hierarchy cache
Returns:
Type.ITEM (meaning not known in advance)

iterate

public SequenceIterator iterate(XPathContext context)
            throws XPathException
Iterate over the expression. This always throws the exception registered when the expression was first parsed.
Specified by:
iterate in interface SequenceIterable
Overrides:
iterate in interface Expression

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 Expression
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)

typeCheck

public Expression typeCheck(ExpressionVisitor visitor,
                            ItemType contextItemType)
            throws XPathException
Type-check the expression.
Overrides:
typeCheck in interface Expression