Saxon Documentation

Full Contents

About Saxon

Changes in this Release

Notices

Using XSLT 2.0

Using XQuery

Handling Source Documents

XML Schema Processing

XPath API for Java

Saxon on .NET

Extensibility

Saxon Extensions
	Introduction
	EXSLT Extensions
	Extension attributes (XSLT only)
	Additional serialization parameters
»	Extension functions
	Extension instructions

Sample Saxon Applications

The Saxon SQL Extension

XSLT Elements

XPath 2.0 Expression Syntax

Function Library

Standards Conformance

saxon:expression()

saxon:expression($expr as xs:string) ==> jt:net.sf.saxon.functions.Evaluate-PreparedExpression

saxon:expression($expr as xs:string, $ns as element()) ==> jt:net.sf.saxon.functions.Evaluate-PreparedExpression

This function creates a stored expression that can be evaluated repeatedly with different argument values and a different dynamic context.

The supplied string must contain an XPath expression. The result of the function is a stored expression, which may be supplied as an argument to other extension functions such as saxon:eval. The result of the expression will usually depend on the current node. The context for the expression includes the namespaces in scope at this point in the stylesheet. The expression may contain references to the nine variables $p1, $p2, ... $p9 only. It may contain calls on Java extension functions, including Saxon and EXSLT-defined functions (other than those which are restricted to use within stylesheets, for example the saxon:evaluate() function itself), as well as user-defined function declared within the containing query or stylesheet. But it does not allow access to stylesheet variables, or functions defined in the XSLT specification such as key() or format-number().

If the second argument is present, its value must be a single element node. The in-scope namespace bindings of this element node be used to resolve any namespace prefixes present in the XPath expression. The default namespace for the element is also used as the default namespace for elements and types within the XPath expression. In addition, standard namespace bindings are automatically available for the prefixes xml, xs, xsi, fn, and saxon.

If the second argument is omitted, then the namespace context for the expression is taken from the stylesheet. (This is also the rule used by saxon:evaluate().) If the expression contains namespace prefixes, these are interpreted in terms of the namespace declarations in scope at the point where the saxon:expression() function is called, not those in scope where the stored expression is evaluated.

The stored expression (if it is to be evaluated using saxon:eval()) may contain references to variables named $p1, $p2, ... $p9. The values of these variables can be supplied when the expression is evaluated using saxon:eval. The second argument of saxon:eval supplies the value of $p1, the third argument supplies the value of $p2, and so on.

For example, following <xsl:variable name="add" select="saxon:expression('$p1 + $p2')"/>, the instruction <xsl:value-of select="saxon:eval($add, 6, 7)"/> will output 13.