Package com.saxonica.ee.optim

Class SearchableValue

  • All Implemented Interfaces:
    GroundedValue, Sequence
    Direct Known Subclasses:
    IndexedValue
    public abstract class SearchableValue
extends java.lang.Object
implements GroundedValue
    A sequence that is held in a form that permits rapid searching, typically by use of indexes. This is an abstract class with several implementations

    • Field Detail

      • value

        protected Item[] value

      • end

        protected int end

    • Constructor Detail

      • SearchableValue

        public SearchableValue()

    • Method Detail

      • iterate

        public SequenceIterator iterate()
        Return an Iterator to iterate over the values of a sequence. The value of every expression can be regarded as a sequence, so this method is supported for all expressions. This default implementation handles iteration for expressions that return singleton values: for non-singleton expressions, the subclass must provide its own implementation.
        Specified by:
        iterate in interface GroundedValue
        Specified by:
        iterate in interface Sequence
        Returns:
        a SequenceIterator that can be used to iterate over the result of the expression

      • itemAt

        public Item itemAt​(int n)
        Get the n'th item in the sequence (starting from 0). This is defined for all Values, but its real benefits come for a sequence Value stored extensionally (or for a MemoClosure, once all the values have been read)
        Specified by:
        itemAt in interface GroundedValue
        Parameters:
        n - position of the required item, counting from zero.
        Returns:
        the n'th item in the sequence, where the first item in the sequence is numbered zero. If n is negative or >= the length of the sequence, returns null.

      • getLength

        public int getLength()
        Get the length of the sequence
        Specified by:
        getLength in interface GroundedValue
        Returns:
        the number of items in the sequence. Note that for a single item, including a map or array, the result is always 1 (one).

      • findItems

        public abstract SequenceIterator findItems​(Expression use,
                                           SequenceIterator values,
                                           boolean convertUntypedToOther,
                                           AtomicComparer comparer,
                                           XPathContext context)
                                    throws XPathException
        Retrieve items that match a given index value
        Parameters:
        use - the expression whose value is to be matched
        values - the set of values to be found
        convertUntypedToOther - true if untypedAtomic values are to be converted to the type of the other operand
        comparer - AtomicComparer used to compare values for equality (encapsulates a collation if necessary)
        context - the dynamic evaluation context @return an iterator over the items that match the specified values
        Returns:
        an iterator over the items that matched
        Throws:
        XPathException - if an error occurs

      • subsequence

        public GroundedValue 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()
                              throws XPathException
        Description copied from interface: GroundedValue
        Get the effective boolean value of this sequence
        Specified by:
        effectiveBooleanValue in interface GroundedValue
        Returns:
        the effective boolean value
        Throws:
        XPathException - if the sequence has no effective boolean value (for example a sequence of two integers)

      • getUnicodeStringValue

        public UnicodeString getUnicodeStringValue()
                                    throws XPathException
        Description copied from interface: GroundedValue
        Get the string value of this sequence, as an instance of UnicodeString. 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.getStringValue() method. Use this method in preference either (a) if you need to use the value in a context where a UnicodeString is required, or (b) if the underlying value is held as a UnicodeString, or in a form that is readily converted to a UnicodeString. This is typically the case (i) when the value is a text or element node in a TinyTree, and (ii) when the value is a StringItem: that is, an atomic value of type xs:string.

        Specified by:
        getUnicodeStringValue in interface GroundedValue
        Returns:
        the string value of the sequence.
        Throws:
        XPathException - if the sequence contains items that have no string value (for example, function items)

      • getStringValue

        public java.lang.String getStringValue()
                                throws XPathException
        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.
        Throws:
        XPathException - if the sequence contains items that have no string value (for example, function items)

      • head

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

      • reduce

        public GroundedValue 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