XPath 3.0 changes

Support for XPath 3.0 (previously known as XPath 2.1) is provided. To enable this, call setLanguageVersion("2.1") on the s9api XPathCompiler, or equivalent calls on the net.sf.saxon.sxpath.XPathEvaluator. Within XSLT, XPath 3.0 syntax is supported if the version attribute on the principal stylesheet module is set to "3.0". From JAXP XPath interfaces, support for XPath 3.0 is supported by casting the XPath object to net.sf.saxon.xpath.XPathEvaluator and calling xpath.getStaticContext().setXPathLanguageLevel(new DecimalValue("2.1")).

The following features are available when XPath 3.0 is enabled:

• The let expression (let $x := expr, $y := expr return expr).

• The new context-independent QName syntax ("uri":local, also "uri":*)

• Facilities associated with higher-order functions: function literals, partial function application, dynamic function invocation, inline functions, plus associated functions such as map(), filter(), fold-left(), and fold-right().

• New functions and operators: see Changes to functions and operators

• Enhancements to regular expressions (non-capturing groups (?:xxxx)) and flags (the q flag)

The s9api API, together with lower-level APIs for running XPath (including the StaticContext interface) have been enhanced to allow the required type of the context item to be supplied as a property of the static context.