Package net.sf.saxon.value

Class SequenceExtent<T extends Item<?>>

java.lang.Object
net.sf.saxon.value.SequenceExtent<T>
All Implemented Interfaces:
Iterable<T>, GroundedValue<T>, Sequence<T>
Direct Known Subclasses:
OneOrMore
public class SequenceExtent<T extends Item<?>> extends Object 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(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<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 remaining items in a SequenceIterator.
      Parameters:
      iter - The supplied sequence of items. The returned sequence will contain all items delivered by repeated calls on next() on this iterator, and the iterator will be consumed by calling the method.
      Throws:
      XPathException - if reading the items using the SequenceIterator raises an error

  • Method Details

    • makeSequenceExtent

      public static <T extends Item<?>> GroundedValue<? extends T> makeSequenceExtent(SequenceIterator<T> iter) throws XPathException
      Deprecated.
      since 9.9: use SequenceIterator.materialize()
      Factory method to make a GroundedValue holding the contents of any SequenceIterator.
      Parameters:
      iter - a Sequence iterator that may or may not be consumed to deliver the items in the sequence. The iterator must be positioned at the start.
      Returns:
      a GroundedValue 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.

    • fromIterator

      public static <T extends Item<?>> GroundedValue<T> fromIterator(SequenceIterator<T> iter) throws XPathException
      Deprecated.
      since 9.9: use SequenceIterator.materialize()
      Factory method to make a GroundedValue holding the contents of any SequenceIterator.
      Parameters:
      iter - a Sequence iterator that may or may not be consumed to deliver the items in the sequence. The iterator must be positioned at the start.
      Returns:
      a GroundedValue 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 other cases, the actual implementation class is not defined.

      This method is intended primarily for internal use. For external applications, calling SequenceIterator.materialize() is preferable, because it recognizes cases that can be optimized (notably, cases where the iterator is already backed by an array or list in memory).

      Throws:
      XPathException - if an error occurs processing the values from the iterator.

    • makeResidue

      public static <T extends Item<?>> GroundedValue<T> makeResidue(SequenceIterator<T> iter) throws XPathException
      Factory method to make a GroundedValue holding the remaining contents of any SequenceIterator, that is, the contents that have not yet been read
      Parameters:
      iter - a Sequence iterator that may or may not be consumed to deliver the items in the sequence. The iterator need not be positioned at the start.
      Returns:
      a GroundedValue 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<?>> GroundedValue<T> 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.

    • getStringValue

      public String getStringValue() throws XPathException
      Description copied from interface: GroundedValue
      Get the string value of this sequence. The string value of an item is the result of applying the string() function. The string value of a sequence is the space-separated result of applying the string-join() function using a single space as the separator
      Specified by:
      getStringValue in interface GroundedValue<T extends Item<?>>
      Returns:
      the string value of the sequence.
      Throws:
      XPathException - if the sequence contains items that have no string value (for example, function items)

    • getStringValueCS

      public CharSequence getStringValueCS() throws XPathException
      Description copied from interface: GroundedValue
      Get the string value of this sequence. The string value of an item is the result of applying the string() function. The string value of a sequence is the space-separated result of applying the string-join() function using a single space as the separator
      Specified by:
      getStringValueCS in interface GroundedValue<T extends Item<?>>
      Returns:
      the string value of the sequence.
      Throws:
      XPathException - if the sequence contains items that have no string value (for example, function items)

    • head

      public T head()
      Get the first item in the sequence.
      Specified by:
      head in interface GroundedValue<T extends Item<?>>
      Specified by:
      head in interface Sequence<T extends Item<?>>
      Returns:
      the first item in the sequence if there is one, or null if the sequence is empty

    • getLength

      public int getLength()
      Get the number of items in the sequence
      Specified by:
      getLength in interface GroundedValue<T extends Item<?>>
      Returns:
      the number of items in the sequence

    • getCardinality

      public int getCardinality()
      Determine the cardinality
      Returns:
      the cardinality of the sequence, using the constants defined in net.sf.saxon.value.Cardinality
      See Also:

    • 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<?>>
      Parameters:
      n - the position of the required item
      Returns:
      the n'th item in the sequence, or null if the position is out of range

    • iterate

      public ListIterator<T> iterate()
      Return an iterator over this sequence.
      Specified by:
      iterate in interface GroundedValue<T extends Item<?>>
      Specified by:
      iterate in interface Sequence<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
      Specified by:
      effectiveBooleanValue in interface GroundedValue<T extends Item<?>>
      Returns:
      the effective boolean value
      Throws:
      XPathException - if the sequence has no effective boolean value (for example a sequence of two integers)

    • 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

    • reduce

      public GroundedValue<T> reduce()
      Reduce the sequence to its simplest form. If the value is an empty sequence, the result will be EmptySequence.getInstance(). If the value is a single atomic value, the result will be an instance of AtomicValue. If the value is a single item of any other kind, the result will be an instance of One. Otherwise, the result will typically be unchanged.
      Specified by:
      reduce in interface GroundedValue<T extends Item<?>>
      Returns:
      the simplified sequence

    • asIterable

      public Iterable<T> asIterable()
      Get the contents of this value in the form of a Java Iterable, so that it can be used in a for-each expression
      Specified by:
      asIterable in interface GroundedValue<T extends Item<?>>
      Specified by:
      asIterable in interface Sequence<T extends Item<?>>
      Returns:
      an Iterable containing the same sequence of items

    • iterator

      public Iterator<T> iterator()
      Get an iterator (a Java Iterator) over the items in this sequence.
      Specified by:
      iterator in interface GroundedValue<T extends Item<?>>
      Specified by:
      iterator in interface Iterable<T extends Item<?>>
      Returns:
      an iterator over the items in this sequence.