Package com.icl.saxon.expr
Class UnionExpression
- java.lang.Object
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- com.icl.saxon.expr.Expression
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- com.icl.saxon.expr.NodeSetExpression
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- com.icl.saxon.expr.UnionExpression
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class UnionExpression extends NodeSetExpression
An expression representing a nodeset that is a union of two other NodeSets
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Field Summary
Fields Modifier and Type Field Description protected Expression
p1
protected Expression
p2
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Fields inherited from class com.icl.saxon.expr.Expression
staticContext
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Constructor Summary
Constructors Constructor Description UnionExpression(Expression p1, Expression p2)
Constructor
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
display(int level)
Diagnostic print of expression structureNodeEnumeration
enumerate(Context c, boolean sort)
Evaluate the union expression.int
getDependencies()
Determine which aspects of the context the expression depends on.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.Expression
reduce(int dependencies, Context context)
Perform a partial evaluation of the expression, by eliminating specified dependencies on the context.Expression
simplify()
Simplify an expression-
Methods inherited from class com.icl.saxon.expr.NodeSetExpression
evaluate, evaluateAsBoolean, evaluateAsNodeSet, evaluateAsString, getDataType, outputStringValue, selectFirst
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Methods inherited from class com.icl.saxon.expr.Expression
containsReferences, evaluateAsNumber, getStaticContext, indent, make, setStaticContext, usesCurrent
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Field Detail
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p1
protected Expression p1
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p2
protected Expression p2
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Constructor Detail
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UnionExpression
public UnionExpression(Expression p1, Expression p2)
Constructor- Parameters:
p1
- the left-hand operandp2
- the right-hand operand
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Method Detail
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simplify
public Expression simplify() throws XPathException
Simplify an expression- Overrides:
simplify
in classExpression
- Returns:
- the simplified expression
- Throws:
XPathException
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enumerate
public NodeEnumeration enumerate(Context c, boolean sort) throws XPathException
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
public Expression reduce(int dependencies, Context context) throws XPathException
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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