public class LetExpression extends Assignation implements TailCallReturner
hasLoopingReference, isIndexedVariable, references, requiredType, slotNumber, variableName
EFFECTIVE_BOOLEAN_VALUE, EVALUATE_METHOD, ITEM_FEED_METHOD, ITERATE_METHOD, MAX_SEQUENCE_LENGTH, MAX_STRING_LENGTH, PROCESS_METHOD, staticProperties, UNBOUNDED_LOWER, UNBOUNDED_UPPER, UPDATE_METHOD, WATCH_METHOD
Constructor and Description |
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LetExpression()
Create a LetExpression
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Modifier and Type | Method and Description |
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void |
checkPermittedContents(SchemaType parentType,
boolean whole)
Check that any elements and attributes constructed or returned by this expression are acceptable
in the content model of a given complex type.
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int |
computeCardinality()
Determine the static cardinality of the expression
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int |
computeSpecialProperties()
Get the static properties of this expression (other than its type).
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Expression |
copy(RebindingMap rebindings)
Copy an expression.
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boolean |
effectiveBooleanValue(XPathContext context)
Get the effective boolean value of the expression.
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Sequence |
eval(XPathContext context)
Evaluate the variable.
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Item |
evaluateItem(XPathContext context)
Evaluate the expression as a singleton
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void |
evaluatePendingUpdates(XPathContext context,
PendingUpdateList pul)
Evaluate an updating expression, adding the results to a Pending Update List.
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void |
export(ExpressionPresenter out)
Diagnostic print of expression structure.
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int |
getCost()
Return the estimated cost of evaluating an expression.
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int |
getEvaluationMode() |
java.lang.String |
getExpressionName()
Get a name identifying the kind of expression, in terms meaningful to a user.
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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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IntegerValue[] |
getIntegerBounds()
For an expression that returns an integer or a sequence of integers, get
a lower and upper bound on the values of the integers that may be returned, from
static analysis.
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ItemType |
getItemType()
Determine the data type of the items returned by the expression, if possible
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UType |
getStaticUType(UType contextItemType)
Get the static type of the expression as a UType, following precisely the type
inference rules defined in the XSLT 3.0 specification.
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boolean |
implementsStaticTypeCheck()
Determine whether this expression implements its own method for static type checking
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boolean |
isInstruction()
Ask whether this expression is an instruction.
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boolean |
isLiftable(boolean forStreaming)
Ask whether the expression can be lifted out of a loop, assuming it has no dependencies
on the controlling variable/focus of the loop
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boolean |
isNeedsLazyEvaluation() |
boolean |
isVacuousExpression()
Determine whether this is a vacuous expression as defined in the XQuery update specification
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SequenceIterator |
iterate(XPathContext context)
Iterate over the result of the expression to return a sequence of items
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int |
markTailFunctionCalls(StructuredQName qName,
int arity)
Mark tail function calls
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Expression |
optimize(ExpressionVisitor visitor,
ContextItemStaticInfo contextItemType)
Perform optimisation of an expression and its subexpressions.
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void |
process(XPathContext context)
Process this expression as an instruction, writing results to the current
outputter
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TailCall |
processLeavingTail(XPathContext context)
ProcessLeavingTail: called to do the real work of this instruction.
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void |
resetLocalStaticProperties()
Reset the static properties of the expression to -1, so that they have to be recomputed
next time they are used.
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void |
setEvaluationMode(int evaluationMode) |
void |
setInstruction(boolean inst)
Say whether this expression originates as an XSLT instruction
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void |
setNeedsEagerEvaluation(boolean req)
Say that this variable must be evaluated eagerly.
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void |
setNeedsLazyEvaluation(boolean req) |
Expression |
staticTypeCheck(SequenceType req,
boolean backwardsCompatible,
RoleDiagnostic role,
ExpressionVisitor visitor)
Static type checking for let expressions is delegated to the expression itself,
and is performed on the "action" expression, to allow further delegation to the branches
of a conditional
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java.lang.String |
toShortString()
Produce a short string identifying the expression for use in error messages
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java.lang.String |
toString()
The toString() method for an expression attempts to give a representation of the expression
in an XPath-like form, but there is no guarantee that the syntax will actually be true XPath.
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Expression |
typeCheck(ExpressionVisitor visitor,
ContextItemStaticInfo contextInfo)
Type-check the expression.
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addReference, addToPathMap, checkForUpdatingSubexpressions, computeDependencies, evaluateVariable, getAction, getActionOp, getIntegerBoundsForVariable, getLocalSlotNumber, getNominalReferenceCount, getObjectName, getRequiredSlots, getRequiredType, getSequence, getSequenceOp, getVariableEQName, getVariableName, getVariableQName, hasVariableBinding, isAssignable, isGlobal, isIndexedVariable, isUpdatingExpression, operands, rebuildReferenceList, refineTypeInformation, removeDeadReferences, replaceVariable, setAction, setIndexedVariable, setRequiredType, setSequence, setSlotNumber, setVariableQName, suppressValidation, unordered, verifyReferences
adoptChildExpression, allowExtractingCommonSubexpressions, checkedOperands, computeHashCode, computeStaticProperties, dynamicError, evaluateAsString, explain, getCardinality, getConfiguration, getConstructType, getDependencies, getEvaluationMethod, getExtraProperty, getInterpretedExpression, getIntrinsicDependencies, getLocalRetainedStaticContext, getLocation, getNetCost, getPackageData, getParentExpression, getProperties, getProperty, getRetainedStaticContext, getScopingExpression, getSlotsUsed, getSpecialProperties, getStaticBaseURI, getStaticBaseURIString, getStaticType, getStreamerName, hasCompatibleStaticContext, hashCode, identityHashCode, isCallOn, isCallOnSystemFunction, isIdentical, isMultiThreaded, isSameExpression, isStaticPropertiesKnown, isSubtreeExpression, operandList, operandSparseList, optimizeChildren, restoreParentPointers, setEvaluationMethod, setExtraProperty, setFiltered, setFlattened, setLocation, setParentExpression, setRetainedStaticContext, setRetainedStaticContextLocally, setRetainedStaticContextThoroughly, setStaticProperty, simplify, simplifyChildren, toPattern, typeCheckChildren, typeError, verifyParentPointers, verifyParentPointers
public void setInstruction(boolean inst)
inst
- true if this is an xsl:variable instructionpublic boolean isInstruction()
isInstruction
in class Expression
public java.lang.String getExpressionName()
getExpressionName
in class Expression
public void setNeedsEagerEvaluation(boolean req)
req
- set to true if eager evaluation is requiredpublic void setNeedsLazyEvaluation(boolean req)
public boolean isNeedsLazyEvaluation()
public boolean isLiftable(boolean forStreaming)
isLiftable
in class Expression
forStreaming
- public void resetLocalStaticProperties()
Expression
resetLocalStaticProperties
in class Expression
public Expression typeCheck(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) throws XPathException
typeCheck
in class Expression
visitor
- an expression visitorcontextInfo
- Information available statically about the context item: whether it is (possibly)
absent; its static type; its streaming posture.XPathException
- if an error is discovered during this phase
(typically a type error)public boolean implementsStaticTypeCheck()
implementsStaticTypeCheck
in class Expression
public Expression staticTypeCheck(SequenceType req, boolean backwardsCompatible, RoleDiagnostic role, ExpressionVisitor visitor) throws XPathException
staticTypeCheck
in class Expression
req
- the required typebackwardsCompatible
- true if backwards compatibility mode appliesrole
- the role of the expression in relation to the required typevisitor
- an expression visitorXPathException
- if failures occur, for example if the static type of one branch of the conditional
is incompatible with the required typepublic Expression optimize(ExpressionVisitor visitor, ContextItemStaticInfo 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
in class 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 int getCost()
getCost
in class Assignation
public boolean isVacuousExpression()
isVacuousExpression
in class Expression
public void checkPermittedContents(SchemaType parentType, boolean whole) throws XPathException
checkPermittedContents
in class Expression
parentType
- the "given complex type": the method is checking that the nodes returned by this
expression are acceptable members of the content model of this typewhole
- if true, we want to check that the value of this expression satisfies the content model
as a whole; if false we want to check that the value of the expression is acceptable as one part
of the contentXPathException
- if the value delivered by this expression cannot be part of the content model
of the given typepublic IntegerValue[] getIntegerBounds()
getIntegerBounds
in class Expression
public int getImplementationMethod()
getImplementationMethod
in class Expression
Expression.ITERATE_METHOD
or Expression.EVALUATE_METHOD
or
Expression.PROCESS_METHOD
public SequenceIterator iterate(XPathContext context) throws XPathException
iterate
in class Expression
context
- supplies the context for evaluationXPathException
- if any dynamic error occurs evaluating the
expressionpublic Sequence eval(XPathContext context) throws XPathException
context
- the dynamic evaluation contextXPathException
public Item evaluateItem(XPathContext context) throws XPathException
evaluateItem
in class Expression
context
- The context in which the expression is to be evaluatedXPathException
- if any dynamic error occurs evaluating the
expressionpublic boolean effectiveBooleanValue(XPathContext context) throws XPathException
effectiveBooleanValue
in class Expression
context
- The context in which the expression is to be evaluatedXPathException
- if any dynamic error occurs evaluating the
expressionpublic void process(XPathContext context) throws XPathException
process
in class Expression
context
- The dynamic context, giving access to the current node,
the current variables, etc.XPathException
- if a dynamic error occurspublic ItemType getItemType()
getItemType
in class Expression
public UType getStaticUType(UType contextItemType)
getStaticUType
in class Expression
contextItemType
- public int computeCardinality()
computeCardinality
in class Expression
StaticProperty.ALLOWS_ZERO_OR_ONE
,
StaticProperty.EXACTLY_ONE
, StaticProperty.ALLOWS_ONE_OR_MORE
,
StaticProperty.ALLOWS_ZERO_OR_MORE
public int computeSpecialProperties()
computeSpecialProperties
in class Expression
public int markTailFunctionCalls(StructuredQName qName, int arity)
markTailFunctionCalls
in class Expression
qName
- the name of the functionarity
- the arity (number of parameters) of the functionUserFunctionCall.NOT_TAIL_CALL
if no tail call was found;
UserFunctionCall.FOREIGN_TAIL_CALL
if a tail call on a different function was found;public Expression copy(RebindingMap rebindings)
copy
in class Expression
rebindings
- public TailCall processLeavingTail(XPathContext context) throws XPathException
processLeavingTail
in interface TailCallReturner
context
- The dynamic context of the transformation, giving access to the current node,
the current variables, etc.XPathException
- if a dynamic error occurs during the evaluation
of the instructionpublic void evaluatePendingUpdates(XPathContext context, PendingUpdateList pul) throws XPathException
evaluatePendingUpdates
in class Expression
context
- the XPath dynamic evaluation contextpul
- the pending update list to which the results should be writtenXPathException
- if evaluation failspublic java.lang.String toString()
toString
in class Expression
public java.lang.String toShortString()
toShortString
in class Expression
public void export(ExpressionPresenter out) throws XPathException
export
in interface ExportAgent
export
in class Expression
out
- the expression presenter used to display the structureXPathException
- if the export fails, for example if an expression is found that won't work
in the target environment.public void setEvaluationMode(int evaluationMode)
public int getEvaluationMode()
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