Class SequenceExtent<T extends Item>

java.lang.Object
net.sf.saxon.value.Value<T>
net.sf.saxon.value.SequenceExtent<T>
All Implemented Interfaces:
GroundedValue<T>, ValueRepresentation<T>

public final class SequenceExtent<T extends Item> extends Value<T> implements GroundedValue<T>
A sequence value implemented extensionally. That is, this class represents a sequence by allocating memory to each item in the sequence.
  • Constructor Details

    • SequenceExtent

      public SequenceExtent(T[] items)
      Construct an sequence from an array of items. Note, the array of items is used as is, which means the caller must not subsequently change its contents.
      Parameters:
      items - the array of items to be included in the sequence
    • SequenceExtent

      public SequenceExtent(T[] value, int start, int length)
      Construct a SequenceExtent from part of an array of items
      Parameters:
      value - The array
      start - zero-based offset of the first item in the array that is to be included in the new SequenceExtent
      length - The number of items in the new SequenceExtent
    • SequenceExtent

      public SequenceExtent(SequenceExtent<T> ext, int start, int length)
      Construct a SequenceExtent as a view of another SequenceExtent
      Parameters:
      ext - The existing SequenceExtent
      start - zero-based offset of the first item in the existing SequenceExtent that is to be included in the new SequenceExtent
      length - The number of items in the new SequenceExtent
    • SequenceExtent

      public SequenceExtent(List<? extends T> list)
      Construct a SequenceExtent from a List. The members of the list must all be Items
      Parameters:
      list - the list of items to be included in the sequence
    • SequenceExtent

      public SequenceExtent(SequenceIterator<T> iter) throws XPathException
      Construct a sequence containing all the items in a SequenceIterator.
      Parameters:
      iter - The supplied sequence of items. This must be positioned at the start, so that hasNext() returns true if there are any nodes in the node-set, and next() returns the first node.
      Throws:
      XPathException - if reading the items using the SequenceIterator raises an error
  • Method Details

    • makeSequenceExtent

      public static <T extends Item> ValueRepresentation<T> makeSequenceExtent(SequenceIterator<T> iter) throws XPathException
      Factory method to make a Value holding the contents of any SequenceIterator
      Parameters:
      iter - a Sequence iterator that will be consumed to deliver the items in the sequence
      Returns:
      a ValueRepresentation holding the items delivered by the SequenceIterator. If the sequence is empty the result will be an instance of EmptySequence. If it is of length one, the result will be an Item. In all other cases, it will be an instance of SequenceExtent.
      Throws:
      XPathException - if an error occurs processing the values from the iterator.
    • makeSequenceExtent

      public static <T extends Item> ValueRepresentation makeSequenceExtent(List<T> input)
      Factory method to make a Value holding the contents of any List of items
      Parameters:
      input - a List containing the items in the sequence
      Returns:
      a ValueRepresentation holding the items in the list. If the sequence is empty the result will be an instance of EmptySequence. If it is of length one, the result will be an Item. In all other cases, it will be an instance of SequenceExtent.
    • simplify

      public Value<T> simplify()
      Simplify this SequenceExtent
      Returns:
      a Value holding the items delivered by the SequenceIterator. If the sequence is empty the result will be an instance of EmptySequence. If it is of length one, the result will be an AtomicValue or a SingletonItem. In all other cases, the SequenceExtent will be returned unchanged.
    • reduce

      public Value<T> reduce()
      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<T extends Item>
      Returns:
      the value in simplified form
    • getLength

      public int getLength()
      Get the number of items in the sequence
      Specified by:
      getLength in interface GroundedValue<T extends Item>
      Overrides:
      getLength in class Value<T extends Item>
      Returns:
      the number of items in the sequence
    • getCardinality

      public int getCardinality()
      Determine the cardinality
      Overrides:
      getCardinality in class Value<T extends Item>
      Returns:
      the cardinality of the sequence, using the constants defined in net.sf.saxon.value.Cardinality
      See Also:
    • getItemType

      public ItemType getItemType(TypeHierarchy th)
      Get the (lowest common) item type
      Overrides:
      getItemType in class Value<T extends Item>
      Parameters:
      th - the type hierarchy cache. If null, the returned value may be less precise
      Returns:
      integer identifying an item type to which all the items in this sequence conform
    • itemAt

      public T itemAt(int n)
      Get the n'th item in the sequence (starting with 0 as the first item)
      Specified by:
      itemAt in interface GroundedValue<T extends Item>
      Overrides:
      itemAt in class Value<T extends Item>
      Parameters:
      n - the position of the required item
      Returns:
      the n'th item in the sequence
    • swap

      public void swap(int a, int b)
      Swap two items (needed to support sorting)
      Parameters:
      a - the position of the first item to be swapped
      b - the position of the second item to be swapped
    • iterate

      public ArrayIterator<T> iterate()
      Return an iterator over this sequence.
      Specified by:
      iterate in class Value<T extends Item>
      Returns:
      the required SequenceIterator, positioned at the start of the sequence
    • reverseIterate

      public UnfailingIterator<T> reverseIterate()
      Return an enumeration of this sequence in reverse order (used for reverse axes)
      Returns:
      an AxisIterator that processes the items in reverse order
    • effectiveBooleanValue

      public boolean effectiveBooleanValue() throws XPathException
      Get the effective boolean value
      Overrides:
      effectiveBooleanValue in class Value<T extends Item>
      Returns:
      the effective boolean value
      Throws:
      XPathException - if any dynamic error occurs evaluating the expression
    • subsequence

      public GroundedValue<T> subsequence(int start, int length)
      Get a subsequence of the value
      Specified by:
      subsequence in interface GroundedValue<T extends Item>
      Parameters:
      start - the index of the first item to be included in the result, counting from zero. A negative value is taken as zero. If the value is beyond the end of the sequence, an empty sequence is returned
      length - the number of items to be included in the result. Specify Integer.MAX_VALUE to get the subsequence up to the end of the base sequence. If the value is negative, an empty sequence is returned. If the value goes off the end of the sequence, the result returns items up to the end of the sequence
      Returns:
      the required subsequence. If min is
    • toString

      public String toString()
      Overrides:
      toString in class Object