public final class ValueComparison extends BinaryExpression implements ComparisonExpression, Negatable
operator
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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ValueComparison(Expression p1,
int op,
Expression p2)
Create a comparison expression identifying the two operands and the operator
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Modifier and Type | Method and Description |
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Sequence |
call(XPathContext context,
Sequence[] arguments)
Call the Callable.
|
static boolean |
compare(AtomicValue v0,
int op,
AtomicValue v1,
AtomicComparer comparer,
boolean checkTypes)
Compare two atomic values, using a specified operator and collation
|
int |
computeCardinality()
Determine the static cardinality.
|
boolean |
convertsUntypedToOther()
Determine whether untyped atomic values should be converted to the type of the other operand
|
Expression |
copy(RebindingMap rebindings)
Copy an expression.
|
boolean |
effectiveBooleanValue(XPathContext context)
Evaluate the effective boolean value of the expression
|
boolean |
equals(java.lang.Object other)
Is this expression the same as another expression?
|
BooleanValue |
evaluateItem(XPathContext context)
Evaluate the expression in a given context
|
protected void |
explainExtraAttributes(ExpressionPresenter out)
Add subclass-specific attributes to the expression tree explanation.
|
AtomicComparer |
getAtomicComparer()
Get the AtomicComparer used to compare atomic values.
|
java.lang.String |
getExpressionName()
Get a name identifying the kind of expression, in terms meaningful to a user.
|
ItemType |
getItemType()
Determine the data type of the expression
|
BooleanValue |
getResultWhenEmpty()
Get the result to be returned if one of the operands is an empty sequence
|
int |
getSingletonOperator()
Get the primitive (singleton) operator used: one of Token.FEQ, Token.FNE, Token.FLT, Token.FGT,
Token.FLE, Token.FGE
|
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.
|
boolean |
isNegatable(TypeHierarchy th)
Check whether this specific instance of the expression is negatable
|
boolean |
needsRuntimeComparabilityCheck()
Determine whether a run-time check is needed to check that the types of the arguments
are comparable
|
Expression |
negate()
Return the negation of this value comparison: that is, a value comparison that returns true()
if and only if the original returns false().
|
Expression |
optimize(ExpressionVisitor visitor,
ContextItemStaticInfo contextInfo)
Perform optimisation of an expression and its subexpressions.
|
void |
setAtomicComparer(AtomicComparer comparer)
Set the AtomicComparer used to compare atomic values
|
void |
setResultWhenEmpty(BooleanValue value)
Set the result to be returned if one of the operands is an empty sequence
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java.lang.String |
tag()
Get the element name used to identify this expression in exported expression format
|
Expression |
typeCheck(ExpressionVisitor visitor,
ContextItemStaticInfo contextInfo)
Type-check the expression
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computeHashCode, computeSpecialProperties, displayOperator, export, getImplementationMethod, getLhs, getLhsExpression, getOperandRole, getOperator, getRhs, getRhsExpression, isAssociative, isCommutative, isInverse, operands, setFlattened, setLhsExpression, setRhsExpression, toShortString, toString
addToPathMap, adoptChildExpression, allowExtractingCommonSubexpressions, checkedOperands, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeStaticProperties, dynamicError, evaluateAsString, evaluatePendingUpdates, explain, getCardinality, getConfiguration, getConstructType, getCost, getDependencies, getEvaluationMethod, getExtraProperty, getIntegerBounds, getInterpretedExpression, getIntrinsicDependencies, getLocalRetainedStaticContext, getLocation, getNetCost, getObjectName, getPackageData, getParentExpression, getProperties, getProperty, getRetainedStaticContext, getScopingExpression, getSlotsUsed, getSpecialProperties, getStaticBaseURI, getStaticBaseURIString, getStaticType, getStreamerName, hasCompatibleStaticContext, hashCode, hasVariableBinding, identityHashCode, implementsStaticTypeCheck, isCallOn, isCallOnSystemFunction, isIdentical, isInstruction, isLiftable, isMultiThreaded, isSameExpression, isStaticPropertiesKnown, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, iterate, markTailFunctionCalls, operandList, operandSparseList, optimizeChildren, process, resetLocalStaticProperties, restoreParentPointers, setEvaluationMethod, setExtraProperty, setFiltered, setLocation, setParentExpression, setRetainedStaticContext, setRetainedStaticContextLocally, setRetainedStaticContextThoroughly, setStaticProperty, simplify, simplifyChildren, staticTypeCheck, suppressValidation, toPattern, typeCheckChildren, typeError, unordered, verifyParentPointers, verifyParentPointers
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
getLhs, getLhsExpression, getRhs, getRhsExpression
public ValueComparison(Expression p1, int op, Expression p2)
p1
- the left-hand operandop
- the operator, as a token returned by the Tokenizer (e.g. Token.LT)p2
- the right-hand operandpublic java.lang.String getExpressionName()
getExpressionName
in class Expression
public void setAtomicComparer(AtomicComparer comparer)
comparer
- the AtomicComparerpublic AtomicComparer getAtomicComparer()
getAtomicComparer
in interface ComparisonExpression
public int getSingletonOperator()
getSingletonOperator
in interface ComparisonExpression
public boolean convertsUntypedToOther()
convertsUntypedToOther
in interface ComparisonExpression
public void setResultWhenEmpty(BooleanValue value)
value
- the result to be returned if an operand is empty. Supply null to mean the empty sequence.public BooleanValue getResultWhenEmpty()
public boolean needsRuntimeComparabilityCheck()
public Expression typeCheck(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) throws XPathException
typeCheck
in class BinaryExpression
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 BinaryExpression
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 boolean isNegatable(TypeHierarchy th)
isNegatable
in interface Negatable
th
- the type hierarchypublic Expression negate()
public boolean equals(java.lang.Object other)
BinaryExpression
equals
in class BinaryExpression
public Expression copy(RebindingMap rebindings)
copy
in class Expression
rebindings
- public boolean effectiveBooleanValue(XPathContext context) throws XPathException
effectiveBooleanValue
in class Expression
context
- the given context for evaluationXPathException
- if any dynamic error occurs evaluating the
expressionpublic static boolean compare(AtomicValue v0, int op, AtomicValue v1, AtomicComparer comparer, boolean checkTypes) throws XPathException
v0
- the first operandop
- the operator, as defined by constants such as Token.FEQ
or
Token.FLT
v1
- the second operandcomparer
- the Collator to be used when comparing stringscheckTypes
- set to true if it is necessary to check that the types of the arguments are comparableXPathException
- if the values are not comparablepublic BooleanValue evaluateItem(XPathContext context) throws XPathException
evaluateItem
in class Expression
context
- the given context for evaluationXPathException
- if any dynamic error occurs evaluating the
expressionpublic Sequence call(XPathContext context, Sequence[] arguments) throws XPathException
context
- the dynamic evaluation contextarguments
- the values of the arguments, supplied as Sequences.
Generally it is advisable, if calling iterate() to process a supplied sequence, to
call it only once; if the value is required more than once, it should first be converted
to a GroundedValue
by calling the utility methd
SequenceTool.toGroundedValue().
If the expected value is a single item, the item should be obtained by calling
Sequence.head(): it cannot be assumed that the item will be passed as an instance of
Item
or AtomicValue
.
It is the caller's responsibility to perform any type conversions required to convert arguments to the type expected by the callee. An exception is where this Callable is explicitly an argument-converting wrapper around the original Callable.
XPathException
- if a dynamic error occurs during the evaluation of the expressionpublic ItemType getItemType()
getItemType
in class Expression
public UType getStaticUType(UType contextItemType)
getStaticUType
in class Expression
contextItemType
- public int computeCardinality()
computeCardinality
in class BinaryExpression
StaticProperty.ALLOWS_ZERO_OR_ONE
,
StaticProperty.EXACTLY_ONE
, StaticProperty.ALLOWS_ONE_OR_MORE
,
StaticProperty.ALLOWS_ZERO_OR_MORE
public java.lang.String tag()
BinaryExpression
tag
in class BinaryExpression
protected void explainExtraAttributes(ExpressionPresenter out)
BinaryExpression
explainExtraAttributes
in class BinaryExpression
out
- the output destination for the displayed expression treeCopyright (c) 2004-2018 Saxonica Limited. All rights reserved.