This package contains the code to map XML Schema and XPath regular expressions to a regular expression engine of the underlying Java platform.

Most of the classes implement a regular expression engine derived from Apache's Jakarta project. The code of Jakarta has been modified so that the regular expressions implement the syntax of XSD/XPath regular expressions. There have also been extensive changes for performance reasons

In addition, there are classes to provide direct access to the native JDK regular expression engine. The flags value ";j" may be used to select this engine. The resulting syntax/semantics will not be an exact match to the XPath definition.

Users should not normally need to use these classes directly.

Earlier versions of Saxon included a translator from XPath regular expressions to Java regular expressions, based on that produced by James Clark. This mechanism is no longer used.