public final class ValueComparison extends BinaryExpression
operand0, operand1, operator
locationId, staticProperties
EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD
Constructor and Description |
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ValueComparison(Expression p1,
int op,
Expression p2)
Create a relational expression identifying the two operands and the operator
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Modifier and Type | Method and Description |
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(package private) static boolean |
compare(AtomicValue v1,
int op,
AtomicValue v2,
AtomicComparer collator)
Compare two atomic values, using a specified operator and collation
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int |
computeCardinality()
Determine the static cardinality.
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protected String |
displayOperator() |
boolean |
effectiveBooleanValue(XPathContext context)
Evaluate the effective boolean value of the expression
|
Item |
evaluateItem(XPathContext context)
Evaluate the expression in a given context
|
ItemType |
getItemType(TypeHierarchy th)
Determine the data type of the expression
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BooleanValue |
getResultWhenEmpty()
Get the result to be returned if one of the operands is an empty sequence
|
ValueComparison |
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(Optimizer opt,
StaticContext env,
ItemType contextItemType)
Perform optimisation of an expression and its subexpressions.
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void |
setResultWhenEmpty(BooleanValue value)
Set the result to be returned if one of the operands is an empty sequence
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Expression |
typeCheck(StaticContext env,
ItemType contextItemType)
Type-check the expression
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computeSpecialProperties, display, equals, getOperands, getOperator, hashCode, isAssociative, isCommutative, isInverse, iterateSubExpressions, promote, simplify
adoptChildExpression, checkPermittedContents, computeDependencies, computeStaticProperties, doPromotion, dynamicError, dynamicError, evaluateAsString, getCardinality, getColumnNumber, getConstructType, getDependencies, getExecutable, getHostLanguage, getImplementationMethod, getInstructionInfo, getIntrinsicDependencies, getLineNumber, getLocationId, getLocationProvider, getParentExpression, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasBadParentPointer, iterate, markTailFunctionCalls, process, resetStaticProperties, setLocationId, setParentExpression, suppressValidation, typeError, typeError
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 void setResultWhenEmpty(BooleanValue value)
public BooleanValue getResultWhenEmpty()
public Expression typeCheck(StaticContext env, ItemType contextItemType) throws XPathException
typeCheck
in interface Expression
typeCheck
in class BinaryExpression
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
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 interface Expression
optimize
in class BinaryExpression
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 ValueComparison negate()
public boolean effectiveBooleanValue(XPathContext context) throws XPathException
effectiveBooleanValue
in interface Expression
effectiveBooleanValue
in class ComputedExpression
context
- the given context for evaluationXPathException
- if any dynamic error occurs evaluating the
expressionstatic boolean compare(AtomicValue v1, int op, AtomicValue v2, AtomicComparer collator) throws DynamicError
v1
- the first operandop
- the operator, as defined by constants such as Token.FEQ
or
Token.FLT
v2
- the second operandcollator
- the Collator to be used when comparing stringsDynamicError
- if the values are not comparablepublic Item evaluateItem(XPathContext context) throws XPathException
evaluateItem
in interface Expression
evaluateItem
in class ComputedExpression
context
- the given context for evaluationXPathException
- if any dynamic error occurs evaluating the
expressionpublic ItemType getItemType(TypeHierarchy th)
th
- public int computeCardinality()
computeCardinality
in class BinaryExpression
protected String displayOperator()
displayOperator
in class BinaryExpression