Package com.icl.saxon.expr
Class EmptyNodeSet
- java.lang.Object
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- com.icl.saxon.expr.Expression
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- com.icl.saxon.expr.Value
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- com.icl.saxon.expr.NodeSetValue
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- com.icl.saxon.expr.EmptyNodeSet
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public final class EmptyNodeSet extends NodeSetValue
A node-set value no nodes
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Field Summary
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Fields inherited from class com.icl.saxon.expr.Expression
staticContext
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Constructor Summary
Constructors Constructor Description EmptyNodeSet()
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description boolean
asBoolean()
Evaluate as a boolean.java.lang.String
asString()
Convert to string valueNodeEnumeration
enumerate()
Return an enumeration of this nodeset value.boolean
equals(Value other)
Test whether this nodeset "equals" another ValueValue
evaluate(Context context)
Evaluate the Node Set.NodeSetValue
evaluateAsNodeSet(Context context)
Evaluate an expression as a NodeSet.int
getCount()
Count the nodes in the node-set.NodeInfo
getFirst()
Get the first node in the nodeset (in document order)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.boolean
isSorted()
Test whether the value is known to be sortedboolean
notEquals(Value other)
Test whether this nodeset "not-equals" another Valuevoid
setSorted(boolean isSorted)
Set a flag to indicate whether the nodes are sorted.NodeSetValue
sort()
Sort the nodes into document order.-
Methods inherited from class com.icl.saxon.expr.NodeSetValue
asNumber, compare, conversionPreference, convertToJava, display, enumerate, getDataType
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Methods inherited from class com.icl.saxon.expr.Value
getDependencies, inverse, numericCompare, reduce, simplify, stringToNumber
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Methods inherited from class com.icl.saxon.expr.Expression
containsReferences, evaluateAsBoolean, evaluateAsNumber, evaluateAsString, getStaticContext, indent, make, outputStringValue, setStaticContext, usesCurrent
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Method Detail
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evaluate
public Value evaluate(Context context)
Evaluate the Node Set. This guarantees to return the result in sorted order.- Overrides:
evaluate
in classNodeSetValue
- Parameters:
context
- The context for evaluation (not used)- Returns:
- the value, unchanged
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evaluateAsNodeSet
public NodeSetValue evaluateAsNodeSet(Context context)
Evaluate an expression as a NodeSet.- Overrides:
evaluateAsNodeSet
in classNodeSetValue
- Parameters:
context
- The context in which the expression is to be evaluated- Returns:
- the value of the expression, evaluated in the current context
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setSorted
public void setSorted(boolean isSorted)
Set a flag to indicate whether the nodes are sorted. Used when the creator of the node-set knows that they are already in document order.- Specified by:
setSorted
in classNodeSetValue
- Parameters:
isSorted
- true if the caller wishes to assert that the nodes are in document order and do not need to be further sorted
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isSorted
public boolean isSorted()
Test whether the value is known to be sorted- Specified by:
isSorted
in classNodeSetValue
- Returns:
- true if the value is known to be sorted in document order, false if it is not known whether it is sorted.
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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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asString
public java.lang.String asString()
Convert to string value- Specified by:
asString
in classNodeSetValue
- Returns:
- an empty string
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asBoolean
public boolean asBoolean()
Evaluate as a boolean.- Specified by:
asBoolean
in classNodeSetValue
- Returns:
- false
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getCount
public int getCount()
Count the nodes in the node-set.- Specified by:
getCount
in classNodeSetValue
- Returns:
- zero
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sort
public NodeSetValue sort()
Sort the nodes into document order. This does nothing if the nodes are already known to be sorted; to force a sort, call setSorted(false)- Specified by:
sort
in classNodeSetValue
- Returns:
- the same NodeSetValue, after sorting. (Historic)
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getFirst
public NodeInfo getFirst()
Get the first node in the nodeset (in document order)- Specified by:
getFirst
in classNodeSetValue
- Returns:
- null
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equals
public boolean equals(Value other)
Test whether this nodeset "equals" another Value- Overrides:
equals
in classNodeSetValue
- Returns:
- a boolean giving the value of the expression, evaluated in the current context
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notEquals
public boolean notEquals(Value other)
Test whether this nodeset "not-equals" another Value- Overrides:
notEquals
in classNodeSetValue
- Returns:
- a boolean giving the value of the expression, evaluated in the current context
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enumerate
public NodeEnumeration enumerate()
Return an enumeration of this nodeset value.- Specified by:
enumerate
in classNodeSetValue
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