public class TraceWrapper extends Instruction
Modifier and Type | Field and Description |
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(package private) Expression |
child |
locationId, staticProperties
EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD
Constructor and Description |
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TraceWrapper() |
Modifier and Type | Method and Description |
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int |
computeDependencies()
Get the static properties of this expression (other than its type).
|
boolean |
createsNewNodes()
Determine whether this instruction creates new nodes.
|
void |
display(int level,
java.io.PrintStream out,
Configuration config)
Diagnostic print of expression structure.
|
Item |
evaluateItem(XPathContext context)
Evaluate an expression as a single item.
|
int |
getCardinality()
Determine the static cardinality of the expression.
|
int |
getDependencies()
Determine which aspects of the context the expression depends on.
|
int |
getInstructionNameCode()
Get the namecode of the instruction for use in diagnostics
|
ItemType |
getItemType(TypeHierarchy th)
Get the item type of the items returned by evaluating this instruction
|
SequenceIterator |
iterate(XPathContext context)
Return an Iterator to iterate over the values of a sequence.
|
java.util.Iterator |
iterateSubExpressions()
Get the immediate sub-expressions of this expression.
|
Expression |
optimize(Optimizer opt,
StaticContext env,
ItemType contextItemType)
Perform optimisation of an expression and its subexpressions.
|
TailCall |
processLeavingTail(XPathContext context)
Execute this instruction, with the possibility of returning tail calls if there are any.
|
Expression |
promote(PromotionOffer offer)
Offer promotion for this subexpression.
|
boolean |
replaceSubExpression(Expression original,
Expression replacement)
Replace one subexpression by a replacement subexpression
|
Expression |
simplify(StaticContext env)
Simplify an expression.
|
Expression |
typeCheck(StaticContext env,
ItemType contextItemType)
Perform type checking of an expression and its subexpressions.
|
appendItem, assembleParams, assembleTunnelParams, computeCardinality, computeSpecialProperties, dynamicError, evaluateAsString, getImplementationMethod, getInstructionInfo, getSourceLocator, isXSLT, process, promoteInst
adoptChildExpression, checkPermittedContents, computeStaticProperties, doPromotion, dynamicError, effectiveBooleanValue, getColumnNumber, getConstructType, getExecutable, getHostLanguage, getIntrinsicDependencies, getLineNumber, getLocationId, getLocationProvider, getParentExpression, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasBadParentPointer, markTailFunctionCalls, resetStaticProperties, setLocationId, setParentExpression, setParentExpression, suppressValidation, typeError
Expression child
public Expression simplify(StaticContext env) throws XPathException
simplify
in interface Expression
simplify
in class Instruction
env
- the static contextXPathException
- if an error is discovered during expression
rewritingpublic Expression typeCheck(StaticContext env, 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.
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 to
Type.ITEM_TYPE
StaticError
- if an error is discovered during this phase
(typically a type error)XPathException
public Expression optimize(Optimizer opt, StaticContext env, 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.
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 to
Type.ITEM_TYPE
StaticError
- if an error is discovered during this phase
(typically a type error)XPathException
public Expression promote(PromotionOffer offer) throws XPathException
promote
in interface Expression
promote
in class 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
in interface TailCallReturner
processLeavingTail
in class Instruction
context
- the dynamic execution contextXPathException
public ItemType getItemType(TypeHierarchy th)
getItemType
in interface Expression
getItemType
in class Instruction
th
- public int getCardinality()
getCardinality
in interface Expression
getCardinality
in class ComputedExpression
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
in interface Expression
getDependencies
in class ComputedExpression
public final boolean createsNewNodes()
createsNewNodes
in class Instruction
public int computeDependencies()
computeDependencies
in class ComputedExpression
public Item evaluateItem(XPathContext context) throws XPathException
evaluateItem
in interface Expression
evaluateItem
in class 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
in interface Expression
iterate
in class Instruction
context
- supplies the context for evaluationXPathException
- if any dynamic error occurs evaluating the
expressionpublic java.util.Iterator iterateSubExpressions()
ComputedExpression
iterateSubExpressions
in interface Expression
iterateSubExpressions
in class ComputedExpression
public boolean replaceSubExpression(Expression original, Expression replacement)
replaceSubExpression
in interface Container
replaceSubExpression
in class ComputedExpression
original
- the original subexpressionreplacement
- the replacement subexpressionpublic int getInstructionNameCode()
Instruction
getInstructionNameCode
in class Instruction
public void display(int level, java.io.PrintStream out, Configuration config)
level
- indentation level for this expressionout
- config
-