public final class ItemChecker extends UnaryExpression
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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ItemChecker(Expression sequence,
ItemType itemType,
RoleDiagnostic role)
Constructor
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Modifier and Type | Method and Description |
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int |
computeHashCode()
get HashCode for comparing two expressions.
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Expression |
copy(RebindingMap rebindings)
Copy an expression.
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boolean |
equals(java.lang.Object other)
Is this expression the same as another expression?
|
Item |
evaluateItem(XPathContext context)
Evaluate as an Item.
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void |
export(ExpressionPresenter out)
Diagnostic print of expression structure.
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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
/*@NotNull
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ItemMappingFunction |
getMappingFunction(XPathContext context)
Get the mapping function used to implement this item check.
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protected OperandRole |
getOperandRole()
Get the usage (in terms of streamability analysis) of the single operand
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ItemType |
getRequiredType()
Get the required type
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RoleDiagnostic |
getRoleLocator()
Get the RoleLocator (used to construct error messages)
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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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java.lang.String |
getStreamerName()
Get the (partial) name of a class that supports streaming of this kind of expression
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SequenceIterator |
iterate(XPathContext context)
Iterate over the sequence of values
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Expression |
optimize(ExpressionVisitor visitor,
ContextItemStaticInfo contextInfo)
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 |
simplify()
Simplify an expression
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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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computeCardinality, computeSpecialProperties, displayOperator, getBaseExpression, getOperand, operands, setBaseExpression
addToPathMap, adoptChildExpression, allowExtractingCommonSubexpressions, checkedOperands, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeStaticProperties, dynamicError, effectiveBooleanValue, evaluateAsString, evaluatePendingUpdates, explain, getCardinality, getConfiguration, getConstructType, getCost, getDependencies, getEvaluationMethod, getExtraProperty, getInterpretedExpression, getIntrinsicDependencies, getLocalRetainedStaticContext, getLocation, getNetCost, getObjectName, getPackageData, getParentExpression, getProperties, getProperty, getRetainedStaticContext, getScopingExpression, getSlotsUsed, getSpecialProperties, getStaticBaseURI, getStaticBaseURIString, getStaticType, hasCompatibleStaticContext, hashCode, hasVariableBinding, identityHashCode, implementsStaticTypeCheck, isCallOn, isCallOnSystemFunction, isIdentical, isInstruction, isLiftable, isMultiThreaded, isSameExpression, isStaticPropertiesKnown, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, markTailFunctionCalls, operandList, operandSparseList, optimizeChildren, resetLocalStaticProperties, restoreParentPointers, setEvaluationMethod, setExtraProperty, setFiltered, setFlattened, setLocation, setParentExpression, setRetainedStaticContext, setRetainedStaticContextLocally, setRetainedStaticContextThoroughly, setStaticProperty, simplifyChildren, staticTypeCheck, suppressValidation, toPattern, typeCheckChildren, typeError, unordered, verifyParentPointers, verifyParentPointers
public ItemChecker(Expression sequence, ItemType itemType, RoleDiagnostic role)
sequence
- the expression whose value we are checkingitemType
- the required type of the items in the sequencerole
- information used in constructing an error messagepublic ItemType getRequiredType()
protected OperandRole getOperandRole()
UnaryExpression
getOperandRole
in class UnaryExpression
public RoleDiagnostic getRoleLocator()
public Expression simplify() throws XPathException
simplify
in class Expression
XPathException
- if an error is discovered during expression
rewritingpublic Expression typeCheck(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) throws XPathException
typeCheck
in class UnaryExpression
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 Expression optimize(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) 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 UnaryExpression
visitor
- an expression visitorcontextInfo
- 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 getImplementationMethod()
getImplementationMethod
in class Expression
Expression.ITERATE_METHOD
or Expression.EVALUATE_METHOD
or
Expression.PROCESS_METHOD
public java.lang.String getStreamerName()
getStreamerName
in class Expression
public IntegerValue[] getIntegerBounds()
getIntegerBounds
in class Expression
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 ItemMappingFunction getMappingFunction(XPathContext context)
context
- The dynamic context used to evaluate the mapping functionpublic 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 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 Expression copy(RebindingMap rebindings)
copy
in class Expression
rebindings
- public ItemType getItemType()
getItemType
in class UnaryExpression
public UType getStaticUType(UType contextItemType)
getStaticUType
in class Expression
contextItemType
- public boolean equals(java.lang.Object other)
equals
in class UnaryExpression
public int computeHashCode()
computeHashCode
in class UnaryExpression
public void export(ExpressionPresenter out) throws XPathException
export
in interface ExportAgent
export
in class UnaryExpression
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 java.lang.String getExpressionName()
getExpressionName
in class Expression
public java.lang.String toString()
toString
in class UnaryExpression
public java.lang.String toShortString()
Expression
toShortString
in class UnaryExpression
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