Class Id

All Implemented Interfaces:
Serializable, SourceLocator, LocationProvider, SaxonLocator, CallableExpression, InstructionInfo, 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:
  • Field Details

  • Constructor Details

    • Id

      public Id()
  • Method Details

    • simplify

      public Expression simplify(ExpressionVisitor visitor) throws XPathException
      Simplify: add a second implicit argument, the context document
      Overrides:
      simplify in class FunctionCall
      Parameters:
      visitor - an expression visitor
      Returns:
      the simplified expression
      Throws:
      XPathException - if an error is discovered during expression rewriting
    • 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)
    • checkArguments

      public void checkArguments(ExpressionVisitor visitor) throws XPathException
      Static analysis: prevent sorting of the argument
      Overrides:
      checkArguments in class SystemFunction
      Parameters:
      visitor - the expression visitor
      Throws:
      XPathException - if the arguments are incorrect
    • 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, 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