Appendix B: XPath Function Library

Overview

This appendix lists all the standard functions in the core XPath function library.

For each function, I give: its name , a brief description of its purpose, and its signature (that is, a list of the arguments it expects and the value it returns). For expanded descriptions of these functions see Chapter 10 of XPath 2.0 Programmer's Reference.

These are not the only functions you can call from an XPath expression:

• XSLT 2.0 defines additional functions for use in XPath expressions invoked from XSLT stylesheets. These are listed in Chapter 7 of this book.

• So called constructor functions are available corresponding to built-in and user -defined atomic types. For example, there is a function called xs:float() to create values of type xs:float , xs:date() to create values of type xs:date , and so on. These functions are also available for user-defined atomic types.

• User-defined functions may be defined in the stylesheet, using an <xsl:function> declaration.

• Extension functions written in other languages may be available (see Chapter 8).

• Vendor-defined functions may be available. These will be in a namespace controlled by the vendor of the particular product.