public class PatternSponsor extends Expression
This class implements the Expression interface, so that an Expression can have a PatternSponsor as a subexpression; it wraps a Pattern.
A Pattern is treated as a boolean expression that returns true if the pattern matches the context node. However, it is not currently evaluated in that way.
EVALUATE_METHOD, ITERATE_METHOD, locationId, PROCESS_METHOD, staticProperties
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PatternSponsor(Pattern pattern)
Create a sponsor expression for a pattern
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void |
checkPermittedContents(SchemaType parentType,
StaticContext env,
boolean whole)
Check statically that the results of the expression are capable of constructing the content
of a given schema type.
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protected int |
computeCardinality()
Compute the static cardinality of this expression
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Expression |
copy()
Copy an expression.
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boolean |
effectiveBooleanValue(XPathContext context)
Get the effective boolean value of the expression.
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java.lang.CharSequence |
evaluateAsString(XPathContext context)
Evaluate an expression as a String.
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Item |
evaluateItem(XPathContext context)
Evaluate an expression as a single item.
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void |
explain(ExpressionPresenter out)
Diagnostic print of expression structure.
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int |
getCardinality()
Determine the static cardinality of the expression.
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Container |
getContainer()
Get the container that immediately contains this expression.
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int |
getDependencies()
Determine which aspects of the context the expression depends on.
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int |
getImplementationMethod()
An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process().
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ItemType |
getItemType(TypeHierarchy th)
Determine the data type of the expression, if possible.
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Pattern |
getPattern()
Get the wrapped pattern
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boolean |
hasLoopingSubexpression(Expression child)
Treat all subexpressions as being evaluated repeatedly
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SequenceIterator |
iterate(XPathContext context)
Return an Iterator to iterate over the values of a sequence.
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java.util.Iterator |
iterateSubExpressions()
Get the immediate sub-expressions of this expression.
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Expression |
optimize(ExpressionVisitor visitor,
ItemType contextItemType)
Perform optimisation of an expression and its subexpressions.
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void |
process(XPathContext context)
Process the instruction, without returning any tail calls
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Expression |
promote(PromotionOffer offer)
Offer promotion for this subexpression.
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boolean |
replaceSubExpression(Expression original,
Expression replacement)
Replace one subexpression by a replacement subexpression
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Expression |
simplify(ExpressionVisitor visitor)
Simplify an expression.
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Expression |
typeCheck(ExpressionVisitor visitor,
ItemType contextItemType)
Perform type checking of an expression and its subexpressions.
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addToPathMap, adoptChildExpression, checkForUpdatingSubexpressions, computeDependencies, computeSpecialProperties, computeStaticProperties, display, doPromotion, dynamicError, evaluatePendingUpdates, explain, findParentOf, getColumnNumber, getColumnNumber, getConstructType, getExecutable, getHostLanguage, getIntrinsicDependencies, getLineNumber, getLineNumber, getLocationId, getLocationProvider, getObjectName, getProperties, getProperty, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, getSystemId, implementsStaticTypeCheck, isUpdatingExpression, iterateEvents, markTailFunctionCalls, resetLocalStaticProperties, setContainer, setFiltered, setFlattened, setLocationId, staticTypeCheck, suppressValidation, toString, typeError
public PatternSponsor(Pattern pattern)
pattern
- the pattern being wrappedpublic Pattern getPattern()
public int getImplementationMethod()
getImplementationMethod
??? Expression
Expression.ITERATE_METHOD
or Expression.EVALUATE_METHOD
or
Expression.PROCESS_METHOD
public Expression simplify(ExpressionVisitor visitor) throws XPathException
simplify
??? Expression
visitor
- an expression visitorXPathException
- if an error is discovered during expression
rewritingpublic Expression optimize(ExpressionVisitor visitor, ItemType contextItemType) throws XPathException
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.
optimize
??? Expression
visitor
- an expression visitorcontextItemType
- 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
XPathException
- if an error is discovered during this phase
(typically a type error)public Expression typeCheck(ExpressionVisitor visitor, ItemType contextItemType) throws XPathException
This checks statically that the operands of the expression have the correct type; if necessary it generates code to do run-time type checking or type conversion. A static type error is reported only if execution cannot possibly succeed, that is, if a run-time type error is inevitable. The call may return a modified form of the expression.
This method is called after all references to functions and variables have been resolved to the declaration of the function or variable. However, the types of such functions and variables may not be accurately known if they have not been explicitly declared.
typeCheck
??? Expression
visitor
- an expression visitorcontextItemType
- 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
XPathException
- if an error is discovered during this phase
(typically a type error)protected int computeCardinality()
Expression
computeCardinality
??? Expression
StaticProperty.ALLOWS_ZERO_OR_ONE
,
StaticProperty.EXACTLY_ONE
, StaticProperty.ALLOWS_ONE_OR_MORE
,
StaticProperty.ALLOWS_ZERO_OR_MORE
public Expression copy()
copy
??? Expression
public Expression promote(PromotionOffer offer) throws XPathException
promote
??? Expression
offer
- details of the offer, for example the offer to move
expressions that don't depend on the context to an outer level in
the containing expressionXPathException
- if any error is detectedpublic boolean hasLoopingSubexpression(Expression child)
hasLoopingSubexpression
??? Expression
child
- public int getCardinality()
Determine the static cardinality of the expression. This establishes how many items there will be in the result of the expression, at compile time (i.e., without actually evaluating the result.
This method should always return a result, though it may be the best approximation that is available at the time.
public ItemType getItemType(TypeHierarchy th)
This method should always return a result, though it may be the best approximation that is available at the time.
getItemType
??? Expression
th
- the type hierarchy cachepublic int getDependencies()
StaticProperty.DEPENDS_ON_CONTEXT_ITEM
and
StaticProperty.DEPENDS_ON_CURRENT_ITEM
. The default implementation combines the intrinsic
dependencies of this expression with the dependencies of the subexpressions,
computed recursively. This is overridden for expressions such as FilterExpression
where a subexpression's dependencies are not necessarily inherited by the parent
expression.getDependencies
??? Expression
public java.util.Iterator iterateSubExpressions()
iterateSubExpressions
??? Expression
public boolean replaceSubExpression(Expression original, Expression replacement)
replaceSubExpression
??? Expression
original
- the original subexpressionreplacement
- the replacement subexpressionpublic Container getContainer()
getContainer
??? Expression
public Item evaluateItem(XPathContext context) throws XPathException
evaluateItem
???? EvaluableItem
evaluateItem
??? Expression
context
- The context in which the expression is to be evaluatedXPathException
- if any dynamic error occurs evaluating the
expressionpublic SequenceIterator iterate(XPathContext context) throws XPathException
iterate
???? SequenceIterable
iterate
??? Expression
context
- supplies the context for evaluationXPathException
- if any dynamic error occurs evaluating the
expressionpublic boolean effectiveBooleanValue(XPathContext context) throws XPathException
effectiveBooleanValue
??? Expression
context
- The context in which the expression is to be evaluatedXPathException
- if any dynamic error occurs evaluating the
expressionpublic java.lang.CharSequence evaluateAsString(XPathContext context) throws XPathException
evaluateAsString
??? Expression
context
- The context in which the expression is to be evaluatedXPathException
- if any dynamic error occurs evaluating the
expressionjava.lang.ClassCastException
- if the result type of the
expression is not xs:string?public void process(XPathContext context) throws XPathException
process
??? Expression
context
- The dynamic context, giving access to the current node,
the current variables, etc.XPathException
public void explain(ExpressionPresenter out)
explain
??? Expression
out
- the expression presenter used to display the structurepublic void checkPermittedContents(SchemaType parentType, StaticContext env, boolean whole) throws XPathException
checkPermittedContents
??? Expression
parentType
- The schema typeenv
- the static contextwhole
- true if this expression is expected to make the whole content of the type, false
if it is expected to make up only a partXPathException
- if the expression doesn't match the required content type