## 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
    `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.

    `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.
    `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
    `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
    `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
    `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.

    `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).
    `XPathException`

### getFirst

    public abstract NodeInfo getFirst()
                               throws XPathException

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

  Returns:
    the first node
    `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
    `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
    `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,
    `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
    `XPathException`