Package net.sf.saxon.expr
Class VennExpression
java.lang.Object
net.sf.saxon.expr.Expression
net.sf.saxon.expr.BinaryExpression
net.sf.saxon.expr.VennExpression
- All Implemented Interfaces:
Serializable
,SourceLocator
,LocationProvider
,SaxonLocator
,InstructionInfo
,Locator
- Direct Known Subclasses:
SingletonIntersectExpression
An expression representing a nodeset that is a union, difference, or
intersection of two other NodeSets
- 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.Expression
EFFECTIVE_BOOLEAN_VALUE, EVALUATE_METHOD, EVENT_FEED_METHOD, ITEM_FEED_METHOD, ITERATE_METHOD, locationId, MAX_SEQUENCE_LENGTH, MAX_STRING_LENGTH, PROCESS_METHOD, PUSH_SELECTION, staticProperties, UNBOUNDED_LOWER, UNBOUNDED_UPPER, WATCH_METHOD
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionfinal int
Determine the static cardinality of the expressionint
Get the static properties of this expression (other than its type).copy()
Copy an expression.boolean
effectiveBooleanValue
(XPathContext context) Get the effective boolean value.boolean
Is this expression the same as another expression?void
gatherComponents
(int operator, Set set) Gather the component operands of a union or intersect expressionGet a name identifying the kind of expression, in terms meaningful to a user.final ItemType
Determine the data type of the items returned by this expressionint
hashCode()
Get a hashCode for comparing two expressions.Iterate over the value of the expression.optimize
(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType) Perform optimisation of an expression and its subexpressions.simplify
(ExpressionVisitor visitor) Simplify the expressiontypeCheck
(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType) Type-check the expressionMethods inherited from class net.sf.saxon.expr.BinaryExpression
displayOperator, explain, explainExtraAttributes, getArguments, getOperands, getOperator, isAssociative, isCommutative, isInverse, iterateSubExpressions, promote, replaceSubExpression, setFlattened, toString
Methods inherited from class net.sf.saxon.expr.Expression
addToPathMap, adoptChildExpression, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeStaticProperties, doPromotion, dynamicError, evaluateAsString, evaluateItem, evaluatePendingUpdates, explain, getCardinality, getColumnNumber, getColumnNumber, getConstructType, getContainer, getDependencies, getEvaluationMethod, getExecutable, getHostLanguage, getImplementationMethod, getIntegerBounds, getIntrinsicDependencies, getLineNumber, getLineNumber, getLocationId, getLocationProvider, getObjectName, getProperties, getProperty, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, getSystemId, hasLoopingSubexpression, hasVariableBinding, implementsStaticTypeCheck, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, iterateEvents, iterateSameFocusSubExpressions, markTailFunctionCalls, process, resetLocalStaticProperties, setContainer, setEvaluationMethod, setFiltered, setLocationId, staticTypeCheck, suppressValidation, typeError
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Constructor Details
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VennExpression
Constructor- Parameters:
p1
- the left-hand operandop
- the operator (union, intersection, or difference)p2
- the right-hand operand
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Method Details
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getExpressionName
Get a name identifying the kind of expression, in terms meaningful to a user.- Overrides:
getExpressionName
in classExpression
- Returns:
- a name identifying the kind of expression, in terms meaningful to a user. The name will always be in the form of a lexical XML QName, and should match the name used in explain() output displaying the expression.
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getItemType
Determine the data type of the items returned by this expression- Specified by:
getItemType
in classExpression
- Parameters:
th
- the type hierarchy cache- Returns:
- the data type
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computeCardinality
public final int computeCardinality()Determine the static cardinality of the expression- Overrides:
computeCardinality
in classBinaryExpression
- Returns:
- the computed cardinality, as one of the values
StaticProperty.ALLOWS_ZERO_OR_ONE
,StaticProperty.EXACTLY_ONE
,StaticProperty.ALLOWS_ONE_OR_MORE
,StaticProperty.ALLOWS_ZERO_OR_MORE
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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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gatherComponents
Gather the component operands of a union or intersect expression- Parameters:
operator
- union or intersectset
- the set into which the components are to be gathered. If the operator is union, this follows the tree gathering all operands of union expressions. Ditto, mutatis mutandis, for intersect expressions.
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simplify
Simplify the expression- Overrides:
simplify
in classBinaryExpression
- Parameters:
visitor
- an expression visitor- Returns:
- the simplified expression
- Throws:
XPathException
- if an error is discovered during expression rewriting
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typeCheck
public Expression typeCheck(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType) throws XPathException Type-check the expression- Overrides:
typeCheck
in classBinaryExpression
- Parameters:
visitor
- an expression visitorcontextItemType
- 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:
XPathException
- if an error is discovered during this phase (typically a type error)
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optimize
public Expression optimize(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType 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.
- Overrides:
optimize
in classBinaryExpression
- Parameters:
visitor
- an expression visitorcontextItemType
- 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:
XPathException
- if an error is discovered during this phase (typically a type error)
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copy
Copy an expression. This makes a deep copy.- Specified by:
copy
in classExpression
- Returns:
- the copy of the original expression
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equals
Is this expression the same as another expression?- Overrides:
equals
in classBinaryExpression
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hashCode
public int hashCode()Description copied from class:BinaryExpression
Get a hashCode for comparing two expressions. Note that this hashcode gives the same result for (A op B) and for (B op A), whether or not the operator is commutative.- Overrides:
hashCode
in classBinaryExpression
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iterate
Iterate over the value of the expression. The result will always be sorted in document order, with duplicates eliminated- Overrides:
iterate
in classExpression
- 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
Get the effective boolean value. In the case of a union expression, this is reduced to an OR expression, for efficiency- Overrides:
effectiveBooleanValue
in classExpression
- 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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