Package net.sf.saxon.expr
Class SingletonIntersectExpression
- java.lang.Object
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- net.sf.saxon.expr.Expression
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- net.sf.saxon.expr.BinaryExpression
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- net.sf.saxon.expr.VennExpression
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- net.sf.saxon.expr.SingletonIntersectExpression
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- All Implemented Interfaces:
ExportAgent,Locatable,IdentityComparable,Traceable
public class SingletonIntersectExpression extends VennExpression
This expression is equivalent to (A intersect B) in the case where A has cardinality zero-or-one. This is handled as a special case because the standard sort-merge algorithm involves an unnecessary sort on B.
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Field Summary
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Fields inherited from class net.sf.saxon.expr.BinaryExpression
operator
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Fields inherited from class net.sf.saxon.expr.Expression
EFFECTIVE_BOOLEAN_VALUE, EVALUATE_METHOD, ITEM_FEED_METHOD, ITERATE_METHOD, MAX_COST, MAX_SEQUENCE_LENGTH, MAX_STRING_LENGTH, PROCESS_METHOD, staticProperties, UNBOUNDED_LOWER, UNBOUNDED_UPPER, UPDATE_METHOD, WATCH_METHOD
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Constructor Summary
Constructors Constructor Description SingletonIntersectExpression(Expression p1, int op, Expression p2)Special case of an intersect expression where the first argument is a singleton
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description static booleancontainsNode(SequenceIterator iter, NodeInfo m)Ask whether the sequence supplied in the first argument contains the node supplied in the secondExpressioncopy(RebindingMap rebindings)Copy an expression.protected java.lang.StringdisplayOperator()Display the operator used by this binary expressionbooleaneffectiveBooleanValue(XPathContext c)Get the effective boolean value.java.lang.StringgetExpressionName()Get a name identifying the kind of expression, in terms meaningful to a user.SequenceIteratoriterate(XPathContext c)Iterate over the value of the expression.Expressionoptimize(ExpressionVisitor visitor, ContextItemStaticInfo contextItemType)Perform optimisation of an expression and its subexpressions.Expressionsimplify()Simplify the expressionprotected java.lang.Stringtag()Get the element name used to identify this expression in exported expression format-
Methods inherited from class net.sf.saxon.expr.VennExpression
computeCardinality, computeHashCode, computeSpecialProperties, equals, gatherComponents, getImplementationMethod, getItemType, getOperandRole, getStaticUType, getStreamerName, toPattern, typeCheck, unordered
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Methods inherited from class net.sf.saxon.expr.BinaryExpression
explainExtraAttributes, export, getLhs, getLhsExpression, getOperator, getRhs, getRhsExpression, isAssociative, isCommutative, isInverse, operands, setFlattened, setLhsExpression, setRhsExpression, toShortString, toString
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Methods inherited from class net.sf.saxon.expr.Expression
addToPathMap, adoptChildExpression, allowExtractingCommonSubexpressions, checkedOperands, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeStaticProperties, dynamicError, evaluateAsString, evaluateItem, evaluatePendingUpdates, explain, getCardinality, getConfiguration, getCost, getDependencies, getEvaluationMethod, getExtraProperty, getIntegerBounds, getInterpretedExpression, getIntrinsicDependencies, getLocalRetainedStaticContext, getLocation, getNetCost, getObjectName, getPackageData, getParentExpression, getProperties, getProperty, getRetainedStaticContext, getScopingExpression, getSlotsUsed, getSpecialProperties, getStaticBaseURI, getStaticBaseURIString, getStaticType, getTracingTag, hasCompatibleStaticContext, hashCode, hasSpecialProperty, hasVariableBinding, identityHashCode, implementsStaticTypeCheck, isCallOn, isEqual, isIdentical, isInstruction, isLiftable, isMultiThreaded, isStaticPropertiesKnown, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, markTailFunctionCalls, operandList, operandSparseList, optimizeChildren, prepareForStreaming, process, resetLocalStaticProperties, restoreParentPointers, setEvaluationMethod, setExtraProperty, setFiltered, setLocation, setParentExpression, setRetainedStaticContext, setRetainedStaticContextLocally, setRetainedStaticContextThoroughly, setStaticProperty, simplifyChildren, staticTypeCheck, suppressValidation, typeCheckChildren, typeError, verifyParentPointers
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Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
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Methods inherited from interface net.sf.saxon.trace.Traceable
gatherProperties
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Constructor Detail
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SingletonIntersectExpression
public SingletonIntersectExpression(Expression p1, int op, Expression p2)
Special case of an intersect expression where the first argument is a singleton- Parameters:
p1- the first argument, always a singletonop- the operator, always Token.INTERSECTp2- the second argument
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Method Detail
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simplify
public Expression simplify() throws XPathException
Simplify the expression- Overrides:
simplifyin classVennExpression- Returns:
- the simplified expression (or the original if unchanged, or if modified in-situ)
- Throws:
XPathException- if an error is discovered during expression rewriting
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optimize
public Expression optimize(ExpressionVisitor visitor, ContextItemStaticInfo 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:
optimizein classVennExpression- 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
public Expression copy(RebindingMap rebindings)
Copy an expression. This makes a deep copy.- Overrides:
copyin classVennExpression- Parameters:
rebindings-- Returns:
- the copy of the original expression
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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- Overrides:
iteratein classVennExpression- 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 c) throws XPathException
Get the effective boolean value. In the case of a union expression, this is reduced to an OR expression, for efficiency- Overrides:
effectiveBooleanValuein classVennExpression- 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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containsNode
public static boolean containsNode(SequenceIterator iter, NodeInfo m) throws XPathException
Ask whether the sequence supplied in the first argument contains the node supplied in the second- Parameters:
iter- an iterator over nodes. The iterator will be closed if the node is found.m- the node to be tested- Returns:
- true if (and only if) the sequence contains the node
- Throws:
XPathException- if evaluating the iterator fails
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getExpressionName
public java.lang.String getExpressionName()
Description copied from class:VennExpressionGet a name identifying the kind of expression, in terms meaningful to a user.- Overrides:
getExpressionNamein classVennExpression- 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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displayOperator
protected java.lang.String displayOperator()
Display the operator used by this binary expression- Overrides:
displayOperatorin classBinaryExpression- Returns:
- String representation of the operator (for diagnostic display only)
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tag
protected java.lang.String tag()
Get the element name used to identify this expression in exported expression format- Overrides:
tagin classVennExpression- Returns:
- the element name used to identify this expression
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