EXPath Extensions

EXPath is a more recent initiative to define a standardized set of extension functions and extension elements that can be used across different XSLT and XQuery processors.

Saxon (since 9.5) currently supports the EXPath file and zip modules.

Details of the functions supported (with some additional information about the Saxon implementation) can be found in the main function library chapter.

The EXPath file module

For the specification of the file module: see EXPath File Module.

As with other extensions, this requires Saxon-PE or Saxon-EE.

Implementations of other EXPath modules may be available from third parties.

All functions in the File module are implemented.

The variables $file:dir.separator and $file:path.separator are not implemented.

Note that many of the functions in this module have side-effects, and therefore need to be used with care to ensure that they are called the right number of times, and in the right order. The best way of achieving this is to imagine that a function like file:write() produces an invisible result, and that this invisible result needs to be inserted into the final result of the query or stylesheet. So, for example, if <body>...</body> is an element being written to the result tree, then the function call <body>{file:write(...)}</body> will always be evaluated exactly once. By contrast, a call appearing as the initializer of a variable (for example in let $x := file:write(...) return ... might be evaluated multiple times or not at all, depending on how the variable is actually used.

Functions in the EXPath file module use file paths that by default are relative to the current working directory. However, if the Java system property expath.base.directory is set, this will be used in preference to the current working directory.

The EXPath file module

Saxon also implements the EXPath ZIP Module.

The implementation is usable but has not been thoroughly tested, and aspects of the specification are not fully stable. It should therefore be used with caution.