Package net.sf.saxon.expr
Class ErrorExpression
- java.lang.Object
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- net.sf.saxon.expr.ComputedExpression
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- net.sf.saxon.expr.ErrorExpression
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- All Implemented Interfaces:
java.io.Serializable
,javax.xml.transform.SourceLocator
,Container
,Expression
,InstructionInfoProvider
public class ErrorExpression extends ComputedExpression
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- See Also:
- Serialized Form
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Field Summary
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Fields inherited from class net.sf.saxon.expr.ComputedExpression
locationId, staticProperties
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Fields inherited from interface net.sf.saxon.expr.Expression
EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD
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Constructor Summary
Constructors Constructor Description ErrorExpression(XPathException exception)
Constructor
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description int
computeCardinality()
Determine the static cardinalityvoid
display(int level, java.io.PrintStream out, Configuration config)
Diagnostic print of expression structureItem
evaluateItem(XPathContext context)
Evaluate the expression.ItemType
getItemType(TypeHierarchy th)
Determine the data type of the expression, if possibleSequenceIterator
iterate(XPathContext context)
Iterate over the expression.Expression
optimize(Optimizer opt, StaticContext env, ItemType contextItemType)
Perform optimisation of an expression and its subexpressions.Expression
typeCheck(StaticContext env, ItemType contextItemType)
Type-check the expression.-
Methods inherited from class net.sf.saxon.expr.ComputedExpression
adoptChildExpression, checkPermittedContents, computeDependencies, computeSpecialProperties, computeStaticProperties, doPromotion, dynamicError, effectiveBooleanValue, evaluateAsString, getCardinality, getColumnNumber, getConstructType, getDependencies, getExecutable, getHostLanguage, getImplementationMethod, getInstructionInfo, getIntrinsicDependencies, getLineNumber, getLocationId, getLocationProvider, getParentExpression, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasBadParentPointer, iterateSubExpressions, markTailFunctionCalls, process, promote, replaceSubExpression, resetStaticProperties, setLocationId, setParentExpression, setParentExpression, simplify, suppressValidation, typeError
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Constructor Detail
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ErrorExpression
public ErrorExpression(XPathException exception)
Constructor- Parameters:
exception
- the error found when parsing this expression
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Method Detail
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typeCheck
public Expression typeCheck(StaticContext env, ItemType contextItemType) throws XPathException
Type-check the expression.- Parameters:
env
- the static context of the expressioncontextItemType
- 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 toType.ITEM_TYPE
- Returns:
- the original expression, rewritten to perform necessary run-time type checks, and to perform other type-related optimizations
- Throws:
StaticError
- if an error is discovered during this phase (typically a type error)XPathException
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optimize
public Expression optimize(Optimizer opt, StaticContext env, ItemType contextItemType) throws XPathException
Description copied from interface:Expression
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.
- Parameters:
opt
- the optimizer in use. This provides access to supporting functions; it also allows different optimization strategies to be used in different circumstances.env
- the static context of the expressioncontextItemType
- 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 toType.ITEM_TYPE
- Returns:
- the original expression, rewritten if appropriate to optimize execution
- Throws:
StaticError
- if an error is discovered during this phase (typically a type error)XPathException
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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 interfaceExpression
- Overrides:
evaluateItem
in classComputedExpression
- Parameters:
context
- The context in which the expression is to be evaluated- Returns:
- the node or atomic value that results from evaluating the expression; or null to indicate that the result is an empty sequence
- Throws:
XPathException
- if any dynamic error occurs evaluating the expression
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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 interfaceExpression
- Overrides:
iterate
in classComputedExpression
- Parameters:
context
- supplies the context for evaluation- Returns:
- a SequenceIterator that can be used to iterate over the result of the expression
- Throws:
XPathException
- if any dynamic error occurs evaluating the expression
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getItemType
public ItemType getItemType(TypeHierarchy th)
Determine the data type of the expression, if possible- Parameters:
th
-- Returns:
- Type.ITEM (meaning not known in advance)
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computeCardinality
public int computeCardinality()
Determine the static cardinality- Specified by:
computeCardinality
in classComputedExpression
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display
public void display(int level, java.io.PrintStream out, Configuration config)
Diagnostic print of expression structure- Parameters:
level
- indentation level for this expressionout
- Output destination
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