public class TraceWrapper extends Instruction
EVALUATE_METHOD, ITERATE_METHOD, locationId, PROCESS_METHOD, staticProperties
?????? |
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TraceWrapper() |
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int |
computeDependencies()
Get the static properties of this expression (other than its type).
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Expression |
copy()
Copy an expression.
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boolean |
createsNewNodes()
Determine whether this instruction creates new nodes.
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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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int |
getDependencies()
Determine which aspects of the context the expression depends on.
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InstructionInfo |
getInstructionInfo()
Get the instruction details
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int |
getInstructionNameCode()
Get the namecode of the instruction for use in diagnostics
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ItemType |
getItemType(TypeHierarchy th)
Get the item type of the items returned by evaluating this instruction
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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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TailCall |
processLeavingTail(XPathContext context)
Execute this instruction, with the possibility of returning tail calls if there are any.
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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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assembleParams, assembleTunnelParams, computeCardinality, computeSpecialProperties, dynamicError, evaluateAsString, getConstructType, getImplementationMethod, getSourceLocator, isXSLT, process, promoteInst
addToPathMap, adoptChildExpression, checkForUpdatingSubexpressions, checkPermittedContents, computeStaticProperties, display, doPromotion, dynamicError, effectiveBooleanValue, evaluatePendingUpdates, explain, findParentOf, getColumnNumber, getColumnNumber, getContainer, getExecutable, getHostLanguage, getIntrinsicDependencies, getLineNumber, getLineNumber, getLocationId, getLocationProvider, getObjectName, getProperties, getProperty, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, getSystemId, hasLoopingSubexpression, implementsStaticTypeCheck, isUpdatingExpression, iterateEvents, markTailFunctionCalls, resetLocalStaticProperties, setContainer, setFiltered, setFlattened, setLocationId, staticTypeCheck, suppressValidation, toString, typeError
public Expression simplify(ExpressionVisitor visitor) throws XPathException
simplify
??? Instruction
visitor
- an expression visitorXPathException
- if an error is discovered during expression
rewritingpublic Expression typeCheck(ExpressionVisitor visitor, ItemType contextItemType) throws XPathException
Expression
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.
If the implementation returns a value other than "this", then it is required to ensure that the parent pointer and location information in the returned expression have been set up correctly. It should not rely on the caller to do this, although for historical reasons many callers do so.
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)public Expression optimize(ExpressionVisitor visitor, ItemType contextItemType) throws XPathException
Expression
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 copy()
copy
??? Expression
public Expression promote(PromotionOffer offer) throws XPathException
promote
??? Instruction
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 TailCall processLeavingTail(XPathContext context) throws XPathException
processLeavingTail
???? TailCallReturner
processLeavingTail
??? Instruction
context
- the dynamic execution contextXPathException
public ItemType getItemType(TypeHierarchy th)
getItemType
??? Instruction
th
- the type hierarchy cachepublic int getCardinality()
getCardinality
??? Expression
public 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 final boolean createsNewNodes()
createsNewNodes
??? Instruction
public int computeDependencies()
computeDependencies
??? Expression
public Item evaluateItem(XPathContext context) throws XPathException
evaluateItem
???? EvaluableItem
evaluateItem
??? Instruction
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
??? Instruction
context
- supplies the context for evaluationXPathException
- if any dynamic error occurs evaluating the
expressionpublic java.util.Iterator iterateSubExpressions()
Expression
iterateSubExpressions
??? Expression
public boolean replaceSubExpression(Expression original, Expression replacement)
replaceSubExpression
??? Expression
original
- the original subexpressionreplacement
- the replacement subexpressionpublic InstructionInfo getInstructionInfo()
public int getInstructionNameCode()
Instruction
getInstructionNameCode
??? Instruction
public void explain(ExpressionPresenter out)
explain
??? Expression
out
- the expression presenter used to display the structure