Class Substring

    • Constructor Detail

      • Substring

        public Substring()
    • 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)
      • evaluateItem

        public Item evaluateItem​(XPathContext context)
                          throws XPathException
        Evaluate the function
        Overrides:
        evaluateItem in class Expression
        Parameters:
        context - The context in which the expression is to be evaluated
        Returns:
        the node or atomic value that results from evaluating the expression; or null to indicate that the result is an empty sequence
        Throws:
        XPathException - if any dynamic error occurs evaluating the expression
      • substring

        public static java.lang.CharSequence substring​(StringValue sv,
                                                       NumericValue start)
        Implement the substring function with two arguments.
        Parameters:
        sv - the string value
        start - the numeric offset (1-based) of the first character to be included in the result (if not an integer, the XPath rules apply)
        Returns:
        the substring starting at this position.
      • substring

        public static java.lang.CharSequence substring​(StringValue sv,
                                                       NumericValue start,
                                                       NumericValue len,
                                                       XPathContext context)
        Implement the substring function with three arguments.
        Parameters:
        sv - the string value
        start - the numeric offset (1-based) of the first character to be included in the result (if not an integer, the XPath rules apply)
        len - the length of the required substring (again, XPath rules apply)
        context - the XPath dynamic context. Provided because some arithmetic computations require it
        Returns:
        the substring starting at this position.