Package net.sf.saxon.expr
Class VennExpression
- java.lang.Object
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- net.sf.saxon.expr.ComputedExpression
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- net.sf.saxon.expr.BinaryExpression
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- net.sf.saxon.expr.VennExpression
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- All Implemented Interfaces:
java.io.Serializable
,javax.xml.transform.SourceLocator
,Container
,Expression
,InstructionInfoProvider
public class VennExpression extends BinaryExpression
An expression representing a nodeset that is a union, difference, or intersection of two other NodeSets- See Also:
- Serialized Form
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Field Summary
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Fields inherited from class net.sf.saxon.expr.BinaryExpression
operand0, operand1, operator
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Fields inherited from class net.sf.saxon.expr.ComputedExpression
locationId, staticProperties
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Fields inherited from interface net.sf.saxon.expr.Expression
EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD
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Constructor Summary
Constructors Constructor Description VennExpression(Expression p1, int op, Expression p2)
Constructor
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description int
computeCardinality()
Determine the static cardinality of the expressionint
computeSpecialProperties()
Get the static properties of this expression (other than its type).boolean
effectiveBooleanValue(XPathContext context)
Get the effective boolean value.ItemType
getItemType(TypeHierarchy th)
Determine the data type of the items returned by this expressionint
hashCode()
Is this expression the same as another expression?SequenceIterator
iterate(XPathContext c)
Iterate over the value of the expression.Expression
simplify(StaticContext env)
Simplify the expressionExpression
typeCheck(StaticContext env, ItemType contextItemType)
Type-check the expression-
Methods inherited from class net.sf.saxon.expr.BinaryExpression
display, displayOperator, equals, getOperands, getOperator, isAssociative, isCommutative, isInverse, iterateSubExpressions, optimize, promote, replaceSubExpression
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Methods inherited from class net.sf.saxon.expr.ComputedExpression
adoptChildExpression, checkPermittedContents, computeDependencies, computeStaticProperties, doPromotion, dynamicError, evaluateAsString, evaluateItem, getCardinality, getColumnNumber, getConstructType, getDependencies, getExecutable, getHostLanguage, getImplementationMethod, getInstructionInfo, getIntrinsicDependencies, getLineNumber, getLocationId, getLocationProvider, getParentExpression, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasBadParentPointer, markTailFunctionCalls, process, resetStaticProperties, setLocationId, setParentExpression, setParentExpression, suppressValidation, typeError
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Constructor Detail
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VennExpression
public VennExpression(Expression p1, int op, Expression p2)
Constructor- Parameters:
p1
- the left-hand operandop
- the operator (union, intersection, or difference)p2
- the right-hand operand
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Method Detail
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getItemType
public final ItemType getItemType(TypeHierarchy th)
Determine the data type of the items returned by this expression- Parameters:
th
-- Returns:
- the data type
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computeCardinality
public final int computeCardinality()
Determine the static cardinality of the expression- Overrides:
computeCardinality
in classBinaryExpression
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computeSpecialProperties
public int computeSpecialProperties()
Get the static properties of this expression (other than its type). The result is bit-signficant. These properties are used for optimizations. In general, if property bit is set, it is true, but if it is unset, the value is unknown.- Overrides:
computeSpecialProperties
in classBinaryExpression
- Returns:
StaticProperty.NON_CREATIVE
. This is overridden for some subclasses.
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simplify
public Expression simplify(StaticContext env) throws XPathException
Simplify the expression- Specified by:
simplify
in interfaceExpression
- Overrides:
simplify
in classBinaryExpression
- Parameters:
env
- the static context- Returns:
- the simplified expression
- Throws:
XPathException
- if an error is discovered during expression rewriting
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typeCheck
public Expression typeCheck(StaticContext env, ItemType contextItemType) throws XPathException
Type-check the expression- Specified by:
typeCheck
in interfaceExpression
- Overrides:
typeCheck
in classBinaryExpression
- Parameters:
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 to perform necessary run-time type checks, and to perform other type-related optimizations
- Throws:
StaticError
- if an error is discovered during this phase (typically a type error)XPathException
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hashCode
public int hashCode()
Is this expression the same as another expression?- Overrides:
hashCode
in classBinaryExpression
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iterate
public SequenceIterator iterate(XPathContext c) throws XPathException
Iterate over the value of the expression. The result will always be sorted in document order, with duplicates eliminated- Specified by:
iterate
in interfaceExpression
- Overrides:
iterate
in classComputedExpression
- Parameters:
c
- The context for evaluation- Returns:
- a SequenceIterator representing the union of the two operands
- Throws:
XPathException
- if any dynamic error occurs evaluating the expression
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effectiveBooleanValue
public boolean effectiveBooleanValue(XPathContext context) throws XPathException
Get the effective boolean value. In the case of a union expression, this is reduced to an OR expression, for efficiency- Specified by:
effectiveBooleanValue
in interfaceExpression
- Overrides:
effectiveBooleanValue
in classComputedExpression
- Parameters:
context
- 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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