com.icl.saxon.expr
Class NodeSetValue

java.lang.Object
  com.icl.saxon.expr.Expression
      com.icl.saxon.expr.Value
          com.icl.saxon.expr.NodeSetValue

Direct Known Subclasses:

EmptyNodeSet, NodeSetExtent, NodeSetIntent, SingletonNodeSet

public abstract class NodeSetValue

extends Value

A node-set value. We use this both for node-sets and node-lists. The node set will only be sorted into document order when requested (using sort() or evaluate()). This is an abstract class with a number of concrete implementations including NodeSetExtent (for extensional node-sets) and NodeSetIntent (for intensional node-sets).

Field Summary

Fields inherited from class com.icl.saxon.expr.Value

ANY, BOOLEAN, NODESET, NUMBER, OBJECT, STRING

Fields inherited from class com.icl.saxon.expr.Expression

staticContext

Constructor Summary

NodeSetValue()

Method Summary

abstract boolean	asBoolean() Evaluate as a boolean.
double	asNumber() Evaluate as a number.
abstract java.lang.String	asString() Convert to string value
boolean	compare(int operator, Value other) Test how a nodeset compares to another Value under a relational comparison
int	conversionPreference(java.lang.Class required) Get conversion preference for this value to a Java class.
java.lang.Object	convertToJava(java.lang.Class target) Convert to Java object (for passing to external functions)
void	display(int level) Diagnostic print of expression structure
abstract NodeEnumeration	enumerate() Return an enumeration of this nodeset value.
NodeEnumeration	enumerate(Context c, boolean sorted) Return an enumeration of this nodeset value.
boolean	equals(Value other) Test whether a nodeset "equals" another Value
Value	evaluate(Context context) Evaluate the Node Set.
NodeSetValue	evaluateAsNodeSet(Context context) Evaluate an expression as a NodeSet.
abstract int	getCount() Count the nodes in the node-set.
int	getDataType() Determine the data type of the expression
abstract NodeInfo	getFirst() Get the first node in the nodeset (in document order)
abstract boolean	isSorted() Test whether the value is known to be sorted
boolean	notEquals(Value other) Test whether a nodeset "not-equals" another Value
abstract void	setSorted(boolean isSorted) Set a flag to indicate whether the nodes are sorted.
abstract NodeSetValue	sort() Sort the nodes into document order.

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, isContextDocumentNodeSet, make, outputStringValue, setStaticContext, usesCurrent

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

NodeSetValue

public NodeSetValue()

Method Detail

getDataType

public int getDataType()

Determine the data type of the expression

Specified by:

getDataType in class Expression

Returns:

Value.NODESET

evaluate

public Value evaluate(Context context)
               throws XPathException

Evaluate the Node Set. This guarantees to return the result in sorted order.

Overrides:

evaluate in class Value

Parameters:

context - The context for evaluation (not used)

Returns:

the value, unchanged

Throws:

XPathException

evaluateAsNodeSet

public NodeSetValue evaluateAsNodeSet(Context context)
                               throws XPathException

Evaluate an expression as a NodeSet.

Overrides:

evaluateAsNodeSet in class Expression

Parameters:

context - The context in which the expression is to be evaluated

Returns:

the value of the expression, evaluated in the current context

Throws:

XPathException - when the expression does not return a nodeset.

enumerate

public abstract NodeEnumeration enumerate()
                                   throws XPathException

Return an enumeration of this nodeset value. Unless sort() has been called the nodes can be in any order.

Throws:

XPathException

enumerate

public NodeEnumeration enumerate(Context c,
                                 boolean sorted)
                          throws XPathException

Return an enumeration of this nodeset value. This is to satisfy the interface for Expression.

Overrides:

enumerate in class Expression

Parameters:

sorted - Indicates that the result must be in document order

c - The context in which the expression is to be evaluated

Throws:

XPathException - when the expression does not return a nodeset.

setSorted

public abstract 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.

Parameters:

isSorted - true if the caller wishes to assert that the nodes are in document order and do not need to be further sorted

isSorted

public abstract boolean isSorted()
                          throws XPathException

Test whether the value is known to be sorted

Returns:

true if the value is known to be sorted in document order, false if it is not known whether it is sorted.

Throws:

XPathException

asString

public abstract java.lang.String asString()
                                   throws XPathException

Convert to string value

Specified by:

asString in class Value

Returns:

the value of the first node in the node-set if there is one, otherwise an empty string

Throws:

XPathException

asNumber

public double asNumber()
                throws XPathException

Evaluate as a number.

Specified by:

asNumber in class Value

Returns:

the number obtained by evaluating as a String and converting the string to a number

Throws:

XPathException

asBoolean

public abstract boolean asBoolean()
                           throws XPathException

Evaluate as a boolean.

Specified by:

asBoolean in class Value

Returns:

true if the node set is not empty

Throws:

XPathException

getCount

public abstract int getCount()
                      throws XPathException

Count the nodes in the node-set. Note this will sort the node set if necessary, to make sure there are no duplicates.

Throws:

XPathException

sort

public abstract NodeSetValue sort()
                           throws XPathException

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)

Returns:

the same NodeSetValue, after sorting. (The reason for returning this is that it makes life easier for the XSL compiler).

Throws:

XPathException

getFirst

public abstract NodeInfo getFirst()
                           throws XPathException

Get the first node in the nodeset (in document order)

Returns:

the first node

Throws:

XPathException

equals

public boolean equals(Value other)
               throws XPathException

Test whether a nodeset "equals" another Value

Overrides:

equals in class Value

Returns:

a boolean giving the value of the expression, evaluated in the current context

Throws:

XPathException

notEquals

public boolean notEquals(Value other)
                  throws XPathException

Test whether a nodeset "not-equals" another Value

Overrides:

notEquals in class Value

Returns:

a boolean giving the value of the expression, evaluated in the current context

Throws:

XPathException

compare

public boolean compare(int operator,
                       Value other)
                throws XPathException

Test how a nodeset compares to another Value under a relational comparison

Overrides:

compare in class Value

Parameters:

operator - The comparison operator, one of Tokenizer.LE, Tokenizer.LT, Tokenizer.GE, Tokenizer.GT,

Throws:

XPathException

display

public void display(int level)

Diagnostic print of expression structure

Specified by:

display in class Expression

conversionPreference

public int conversionPreference(java.lang.Class required)

Get conversion preference for this value to a Java class. A low result indicates higher preference.

Specified by:

conversionPreference in class Value

convertToJava

public java.lang.Object convertToJava(java.lang.Class target)
                               throws XPathException

Convert to Java object (for passing to external functions)

Specified by:

convertToJava in class Value

Parameters:

target - The class required by the external function

Returns:

an object of the target class

Throws:

XPathException