Package com.icl.saxon.expr
Class UnionExpression
java.lang.Object
com.icl.saxon.expr.Expression
com.icl.saxon.expr.NodeSetExpression
com.icl.saxon.expr.UnionExpression
An expression representing a nodeset that is a union of two other NodeSets
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Field Summary
FieldsFields inherited from class com.icl.saxon.expr.Expression
staticContext
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionvoid
display
(int level) Diagnostic print of expression structureEvaluate the union expression.int
Determine which aspects of the context the expression depends on.boolean
Determine, in the case of an expression whose data type is Value.NODESET, whether all the nodes in the node-set are guaranteed to come from the same document as the context node.Perform a partial evaluation of the expression, by eliminating specified dependencies on the context.simplify()
Simplify an expressionMethods inherited from class com.icl.saxon.expr.NodeSetExpression
evaluate, evaluateAsBoolean, evaluateAsNodeSet, evaluateAsString, getDataType, outputStringValue, selectFirst
Methods inherited from class com.icl.saxon.expr.Expression
containsReferences, evaluateAsNumber, getStaticContext, indent, make, setStaticContext, usesCurrent
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Field Details
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p1
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p2
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Constructor Details
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UnionExpression
Constructor- Parameters:
p1
- the left-hand operandp2
- the right-hand operand
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Method Details
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simplify
Simplify an expression- Overrides:
simplify
in classExpression
- Returns:
- the simplified expression
- Throws:
XPathException
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enumerate
Evaluate the union expression. The result will always be sorted in document order, with duplicates eliminated- Specified by:
enumerate
in classNodeSetExpression
- Parameters:
c
- The context for evaluationsort
- Request the nodes in document order (they will be, regardless)- Returns:
- a NodeSetValue representing the union of the two operands
- Throws:
XPathException
- when the expression does not return a nodeset.
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getDependencies
public int getDependencies()Determine which aspects of the context the expression depends on. The result is a bitwise-or'ed value composed from constants such as Context.VARIABLES and Context.CURRENT_NODE- Specified by:
getDependencies
in classExpression
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isContextDocumentNodeSet
public boolean isContextDocumentNodeSet()Determine, in the case of an expression whose data type is Value.NODESET, whether all the nodes in the node-set are guaranteed to come from the same document as the context node. Used for optimization.- Overrides:
isContextDocumentNodeSet
in classExpression
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reduce
Perform a partial evaluation of the expression, by eliminating specified dependencies on the context.- Specified by:
reduce
in classExpression
- Parameters:
dependencies
- The dependencies to be removedcontext
- The context to be used for the partial evaluation- Returns:
- a new expression that does not have any of the specified dependencies
- Throws:
XPathException
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display
public void display(int level) Diagnostic print of expression structure- Specified by:
display
in classExpression
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