Package net.sf.saxon.om

Class EmptyAtomicSequence

java.lang.Object
net.sf.saxon.om.EmptyAtomicSequence
All Implemented Interfaces:
Iterable<AtomicValue>, AtomicSequence, GroundedValue, Sequence
public class EmptyAtomicSequence extends Object implements AtomicSequence
An implementation of AtomicSequence that contains no items.

  • Method Details

    • getInstance

      public static EmptyAtomicSequence getInstance()

    • head

      public AtomicValue head()
      Description copied from interface: AtomicSequence
      Get the first item in the sequence
      Specified by:
      head in interface AtomicSequence
      Specified by:
      head in interface GroundedValue
      Specified by:
      head in interface Sequence
      Returns:
      the first item in the sequence, or null if the sequence is empty

    • iterate

      public AtomicIterator iterate()
      Description copied from interface: AtomicSequence
      Make an iterator over the items in the sequence
      Specified by:
      iterate in interface AtomicSequence
      Specified by:
      iterate in interface GroundedValue
      Specified by:
      iterate in interface Sequence
      Returns:
      an iterator over the items in the sequence

    • itemAt

      public AtomicValue itemAt(int n)
      Description copied from interface: AtomicSequence
      Get the Nth item in the sequence, zero-based
      Specified by:
      itemAt in interface AtomicSequence
      Specified by:
      itemAt in interface GroundedValue
      Parameters:
      n - the index of the required item, with 0 representing the first item in the sequence
      Returns:
      the Nth item in the sequence, or null if the index is out of range

    • getLength

      public int getLength()
      Description copied from interface: AtomicSequence
      Get the length of the sequence
      Specified by:
      getLength in interface AtomicSequence
      Specified by:
      getLength in interface GroundedValue
      Returns:
      the number of items in the sequence

    • getCanonicalLexicalRepresentation

      public UnicodeString getCanonicalLexicalRepresentation()
      Get the canonical lexical representation as defined in XML Schema. This is not always the same as the result of casting to a string according to the XPath rules.
      Specified by:
      getCanonicalLexicalRepresentation in interface AtomicSequence
      Returns:
      the canonical lexical representation if defined in XML Schema; otherwise, the result of casting to string according to the XPath 2.0 rules

    • getUnicodeStringValue

      public UnicodeString getUnicodeStringValue()
      Description copied from interface: AtomicSequence
      Get a string representation of the sequence. The is the space-separated concatenation of the result of casting each of the items in the sequence to xs:string
      Specified by:
      getUnicodeStringValue in interface AtomicSequence
      Specified by:
      getUnicodeStringValue in interface GroundedValue
      Returns:
      a whitespace-separated concatenation of the string values of the items making up the sequence, as a String.

    • getStringValue

      public String getStringValue()
      Description copied from interface: GroundedValue
      Get the string value of this sequence, as an instance of String. The string value of an item is the result of applying the XPath 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.

      The result of this method is always equivalent to the result of the GroundedValue.getUnicodeStringValue() method. Use this method in preference either (a) if you need to use the value in a context where a String is required, or (b) if the underlying value is held as a String, or in a form that is readily converted to a String. This is typically the case (i) when the value is an attribute node in a TinyTree, or (ii) any kind of node in a third-party tree model such as DOM.

      Specified by:
      getStringValue in interface GroundedValue
      Returns:
      the string value of the sequence.

    • subsequence

      public EmptyAtomicSequence subsequence(int start, int length)
      Get a subsequence of the value
      Specified by:
      subsequence in interface GroundedValue
      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

    • effectiveBooleanValue

      public boolean effectiveBooleanValue()
      Description copied from interface: GroundedValue
      Get the effective boolean value of this sequence
      Specified by:
      effectiveBooleanValue in interface GroundedValue
      Returns:
      the effective boolean value

    • reduce

      public EmptyAtomicSequence 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 SingletonItem. Otherwise, the result will typically be unchanged.
      Specified by:
      reduce in interface GroundedValue
      Returns:
      the simplified sequence

    • iterator

      public Iterator<AtomicValue> iterator()
      Return a Java iterator over the atomic sequence.
      Specified by:
      iterator in interface Iterable<AtomicValue>
      Returns:
      an Iterator.