com.saxonica.deploy
Class Tail

java.lang.Object
  extended by net.sf.saxon.value.Value
      extended by com.saxonica.deploy.Tail
All Implemented Interfaces:
Serializable, SequenceIterable, ValueRepresentation

public final class Tail
extends Value

A sequence value implemented as the trailing part of an underlying value

This class is currently used only in compiled queries

See Also:
Serialized Form

Field Summary
 
Fields inherited from class net.sf.saxon.value.Value
INDETERMINATE_ORDERING
 
Fields inherited from interface net.sf.saxon.om.ValueRepresentation
EMPTY_VALUE_ARRAY
 
Method Summary
 int getCardinality()
          Determine the cardinality
 ItemType getItemType(TypeHierarchy th)
          Get the (lowest common) item type.
 int getLength()
          Get the number of items in the sequence
 Comparable getSchemaComparable()
          Get a Comparable value that implements the XML Schema ordering comparison semantics for this value.
 Item itemAt(int n)
          Get the n'th item in the sequence (starting with 0 as the first item)
 SequenceIterator iterate()
          Return an iterator over this sequence.
static Value make(Value value, int start)
          Static factory method
 Value reduce()
          Reduce a value to its simplest form.
 
Methods inherited from class net.sf.saxon.value.Value
asItem, asItem, asIterator, asValue, checkPermittedContents, convertToJava, effectiveBooleanValue, equals, fromItem, getCanonicalLexicalRepresentation, getIterator, getStringValue, getStringValueCS, hashCode, isIdentical, iterate, process
 
Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait
 

Method Detail

make

public static Value make(Value value,
                         int start)
Static factory method

Parameters:
value - The underlying value
start - zero-based offset of the first item to be included
Returns:
the constructed value

reduce

public Value reduce()
             throws XPathException
Reduce a value to its simplest form. If the value is a closure or some other form of deferred value such as a FunctionCallPackage, then it is reduced to a SequenceExtent. If it is a SequenceExtent containing a single item, then it is reduced to that item. One consequence that is exploited by class FilterExpression is that if the value is a singleton numeric value, then the result will be an instance of NumericValue

Overrides:
reduce in class Value
Returns:
the value in simplified form
Throws:
XPathException

getLength

public int getLength()
              throws XPathException
Get the number of items in the sequence

Overrides:
getLength in class Value
Returns:
the number of items in the sequence
Throws:
XPathException

getCardinality

public int getCardinality()
Determine the cardinality

Overrides:
getCardinality in class Value
Returns:
the cardinality of the sequence, using the constants defined in net.sf.saxon.value.Cardinality
See Also:
Cardinality

getItemType

public ItemType getItemType(TypeHierarchy th)
Get the (lowest common) item type. This implementation simply returns the ItemType of the underlying sequence, even though the items included in the tail might belong to a narrower type

Overrides:
getItemType in class Value
Parameters:
th - the type hierarchy cache
Returns:
ItemType identifying an item type to which all the items in this sequence conform

itemAt

public Item itemAt(int n)
            throws XPathException
Get the n'th item in the sequence (starting with 0 as the first item)

Overrides:
itemAt in class Value
Parameters:
n - the position of the required item
Returns:
the n'th item in the sequence
Throws:
XPathException

iterate

public SequenceIterator iterate()
                         throws XPathException
Return an iterator over this sequence.

Specified by:
iterate in class Value
Returns:
the required SequenceIterator, positioned at the start of the sequence
Throws:
XPathException - if a dynamic error occurs. This is possible only in the case of values that are materialized lazily, that is, where the iterate() method leads to computation of an expression that delivers the values.

getSchemaComparable

public Comparable getSchemaComparable()
Get a Comparable value that implements the XML Schema ordering comparison semantics for this value. The default implementation returns "this", which ensures that comparisons between list values are handled by the equals() and compareTo() methods on this class itself. This is overridden for atomic values.

In the case of data types that are partially ordered, the returned Comparable extends the standard semantics of the compareTo() method by returning the value Value.INDETERMINATE_ORDERING when there is no defined order relationship between two given values.

Overrides:
getSchemaComparable in class Value
Returns:
a Comparable that follows XML Schema comparison rules


Copyright (c) 2004-2010 Saxonica Limited. All rights reserved.