Package com.icl.saxon.expr
Class EmptyNodeSet
java.lang.Object
com.icl.saxon.expr.Expression
com.icl.saxon.expr.Value
com.icl.saxon.expr.NodeSetValue
com.icl.saxon.expr.EmptyNodeSet
A node-set value no nodes
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Field Summary
Fields inherited from class com.icl.saxon.expr.Expression
staticContext
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionboolean
Evaluate as a boolean.asString()
Convert to string valueReturn an enumeration of this nodeset value.boolean
Test whether this nodeset "equals" another ValueEvaluate the Node Set.evaluateAsNodeSet
(Context context) Evaluate an expression as a NodeSet.int
getCount()
Count the nodes in the node-set.getFirst()
Get the first node in the nodeset (in document order)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.boolean
isSorted()
Test whether the value is known to be sortedboolean
Test whether this nodeset "not-equals" another Valuevoid
setSorted
(boolean isSorted) Set a flag to indicate whether the nodes are sorted.sort()
Sort the nodes into document order.Methods inherited from class com.icl.saxon.expr.NodeSetValue
asNumber, compare, conversionPreference, convertToJava, display, enumerate, getDataType
Methods inherited from class com.icl.saxon.expr.Value
getDependencies, inverse, numericCompare, reduce, simplify, stringToNumber
Methods inherited from class com.icl.saxon.expr.Expression
containsReferences, evaluateAsBoolean, evaluateAsNumber, evaluateAsString, getStaticContext, indent, make, outputStringValue, setStaticContext, usesCurrent
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Constructor Details
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EmptyNodeSet
public EmptyNodeSet()
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Method Details
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evaluate
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
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
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
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
Get the first node in the nodeset (in document order)- Specified by:
getFirst
in classNodeSetValue
- Returns:
- null
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equals
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
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
Return an enumeration of this nodeset value.- Specified by:
enumerate
in classNodeSetValue
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