Package net.sf.saxon.expr
Class BooleanExpression
java.lang.Object
net.sf.saxon.expr.ComputedExpression
net.sf.saxon.expr.BinaryExpression
net.sf.saxon.expr.BooleanExpression
- All Implemented Interfaces:
Serializable
,SourceLocator
,Container
,Expression
,InstructionInfoProvider
Boolean expression: two truth values combined using AND or OR.
- See Also:
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Field Summary
Fields inherited from class net.sf.saxon.expr.BinaryExpression
operand0, operand1, operator
Fields inherited from class net.sf.saxon.expr.ComputedExpression
locationId, staticProperties
Fields inherited from interface net.sf.saxon.expr.Expression
EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionint
Determine the static cardinality.boolean
Evaluate as a boolean.evaluateItem
(XPathContext context) Evaluate the expressionDetermine the data type of the expressionstatic void
listAndComponents
(Expression exp, List list) Construct a list containing the "anded" subexpressions of an expression: if the expression is (A and B and C), this returns (A, B, C).negate
(StaticContext env) Return the negation of this boolean expression, that is, an expression that returns true when this expression returns false, and vice versaoptimize
(Optimizer opt, StaticContext env, ItemType contextItemType) Perform optimisation of an expression and its subexpressions.Methods inherited from class net.sf.saxon.expr.BinaryExpression
computeSpecialProperties, display, displayOperator, equals, getOperands, getOperator, hashCode, isAssociative, isCommutative, isInverse, iterateSubExpressions, promote, replaceSubExpression, simplify, typeCheck
Methods inherited from class net.sf.saxon.expr.ComputedExpression
adoptChildExpression, checkPermittedContents, computeDependencies, computeStaticProperties, doPromotion, 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, setParentExpression, suppressValidation, typeError
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Constructor Details
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BooleanExpression
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Method Details
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computeCardinality
public int computeCardinality()Determine the static cardinality. Returns [1..1]- Overrides:
computeCardinality
in classBinaryExpression
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optimize
public Expression optimize(Optimizer opt, StaticContext env, ItemType contextItemType) throws XPathException Perform optimisation of an expression and its subexpressions.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.
- Specified by:
optimize
in interfaceExpression
- Overrides:
optimize
in classBinaryExpression
- Parameters:
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 toType.ITEM_TYPE
- Returns:
- the original expression, rewritten if appropriate to optimize execution
- Throws:
StaticError
- if an error is discovered during this phase (typically a type error)XPathException
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negate
Return the negation of this boolean expression, that is, an expression that returns true when this expression returns false, and vice versa -
evaluateItem
Evaluate the expression- Specified by:
evaluateItem
in interfaceExpression
- Overrides:
evaluateItem
in classComputedExpression
- Parameters:
context
- The context in which the expression is to be evaluated- Returns:
- the node or atomic value that results from evaluating the expression; or null to indicate that the result is an empty sequence
- Throws:
XPathException
- if any dynamic error occurs evaluating the expression
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effectiveBooleanValue
Evaluate as a boolean.- Specified by:
effectiveBooleanValue
in interfaceExpression
- Overrides:
effectiveBooleanValue
in classComputedExpression
- Parameters:
c
- The context in which the expression is to be evaluated- Returns:
- the effective boolean value
- Throws:
XPathException
- if any dynamic error occurs evaluating the expression
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getItemType
Determine the data type of the expression- Parameters:
th
-- Returns:
- Type.BOOLEAN
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listAndComponents
Construct a list containing the "anded" subexpressions of an expression: if the expression is (A and B and C), this returns (A, B, C).- Parameters:
exp
- the expression to be decomposedlist
- the list to which the subexpressions are to be added.
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