saxon:expression
Creates a stored expression that can be evaluated repeatedly with different argument values and a different dynamic context.
expression($string as xs:string) ➔ jt:net.sf.saxon.functions.Evaluate-PreparedExpression
Arguments | |||
| $string | xs:string | The expression to be compiled |
Result | jt:net.sf.saxon.functions.Evaluate-PreparedExpression |
expression($string as xs:string, $ns as element()) ➔ jt:net.sf.saxon.functions.Evaluate-PreparedExpression
Arguments | |||
| $string | xs:string | The expression to be compiled |
| $ns | element() | Provides the namespace context |
Result | jt:net.sf.saxon.functions.Evaluate-PreparedExpression |
Namespace
http://saxon.sf.net/
Notes on the Saxon implementation
Available since before Saxon 7.2.
Details
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 context item.
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-defined, EXSLT-defined, and EXPath-defined
functions, as well as user-defined functions 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()
.
Use of the current()
function is allowed, provided saxon:evaluate() is
called from XSLT: the value is the context item at the point where
saxon:evaluate()
or saxon:eval()
is called. Use of other
XSLT-specific functions such as key()
or format-number()
is
untested; they might work in some cases and fail in others, possibly in an obscure
way.
If the second argument is present, its value must be a single element node. The in-scope namespace bindings of this element node will 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
.