Class Id

  • All Implemented Interfaces:
    java.io.Serializable, javax.xml.transform.SourceLocator, LocationProvider, SaxonLocator, CallableExpression, InstructionInfo, org.xml.sax.Locator

    public class Id
    extends SystemFunction
    implements CallableExpression
    The XPath id() or element-with-id() function XPath 2.0 version: accepts any sequence as the first parameter; each item in the sequence is taken as an IDREFS value, that is, a space-separated list of ID values. Also accepts an optional second argument to identify the target document, this defaults to the context node.
    See Also:
    Serialized Form
    • Constructor Detail

      • Id

        public Id()
    • Method Detail

      • typeCheck

        public Expression typeCheck​(ExpressionVisitor visitor,
                                    ExpressionVisitor.ContextItemType contextItemType)
                             throws XPathException
        Type-check the expression. This also calls preEvaluate() to evaluate the function if all the arguments are constant; functions that do not require this behavior can override the preEvaluate method.
        Overrides:
        typeCheck in class FunctionCall
        Parameters:
        visitor - an expression visitor
        contextItemType - the static type of "." at the point where this expression is invoked. The parameter is set to null if it is known statically that the context item will be undefined. If the type of the context item is not known statically, the argument is set to Type.ITEM_TYPE
        Returns:
        the original expression, rewritten to perform necessary run-time type checks, and to perform other type-related optimizations
        Throws:
        XPathException - if an error is discovered during this phase (typically a type error)
      • preEvaluate

        public Expression preEvaluate​(ExpressionVisitor visitor)
        preEvaluate: this method suppresses compile-time evaluation by doing nothing
        Overrides:
        preEvaluate in class FunctionCall
        Parameters:
        visitor - an expression visitor
        Returns:
        the result of the early evaluation, or the original expression, or potentially a simplified expression
      • computeSpecialProperties

        public int computeSpecialProperties()
        Get the static properties of this expression (other than its type). The result is bit-signficant. These properties are used for optimizations. In general, if property bit is set, it is true, but if it is unset, the value is unknown.
        Overrides:
        computeSpecialProperties in class SystemFunction
        Returns:
        the special properties, as a bit-significant integer
      • addToPathMap

        public PathMap.PathMapNodeSet addToPathMap​(PathMap pathMap,
                                                   PathMap.PathMapNodeSet pathMapNodeSet)
        Add a representation of a doc() call or similar function to a PathMap. This is a convenience method called by the addToPathMap() methods for doc(), document(), collection() and similar functions. These all create a new root expression in the path map.
        Overrides:
        addToPathMap in class Expression
        Parameters:
        pathMap - the PathMap to which the expression should be added
        pathMapNodeSet -
        Returns:
        the pathMapNode representing the focus established by this expression, in the case where this expression is the first operand of a path expression or filter expression
      • iterate

        public SequenceIterator iterate​(XPathContext context)
                                 throws XPathException
        Evaluate the function to return an iteration of selected nodes.
        Overrides:
        iterate in class Expression
        Parameters:
        context - supplies the context for evaluation
        Returns:
        a SequenceIterator that can be used to iterate over the result of the expression
        Throws:
        XPathException - if any dynamic error occurs evaluating the expression
      • getIdSingle

        public static SequenceIterator getIdSingle​(DocumentInfo doc,
                                                   java.lang.String idrefs,
                                                   int operation)
                                            throws XPathException
        Get an iterator over the nodes that have an id equal to one of the values is a whitespace separated string
        Parameters:
        doc - The document to be searched
        idrefs - a string containing zero or more whitespace-separated ID values to be found in the document
        operation - either ID or ELEMENT_WITH_ID
        Returns:
        an iterator over the nodes whose ID is one of the specified values
        Throws:
        XPathException
      • getIdMultiple

        public static SequenceIterator getIdMultiple​(DocumentInfo doc,
                                                     SequenceIterator idrefs,
                                                     int operation)
                                              throws XPathException
        Get an iterator over the nodes that have an id equal to one of the values is a set of whitespace separated strings
        Parameters:
        doc - The document to be searched
        idrefs - an iterator over a set of strings each of which is a string containing zero or more whitespace-separated ID values to be found in the document
        Returns:
        an iterator over the nodes whose ID is one of the specified values
        Throws:
        XPathException
      • call

        public SequenceIterator call​(SequenceIterator[] arguments,
                                     XPathContext context)
                              throws XPathException
        Evaluate the expression
        Specified by:
        call in interface CallableExpression
        Parameters:
        arguments - the values of the arguments, supplied as SequenceIterators
        context - the dynamic evaluation context
        Returns:
        the result of the evaluation, in the form of a SequenceIterator
        Throws:
        XPathException - if a dynamic error occurs during the evaluation of the expression