XML templates are specified for a grammar element by placing one of the following tags within it:
Tag | Purpose |
|---|---|
| Encloses an XML fragment that is associated with the grammar element. If the grammar element has children with their own XML templates, then an embedded |
| Specifies that the grammar element is associated with the absence of any parsed or emitted XML. This is only meaningful when other alternative constructs in a choice have non-empty XML templates. |
| Specifies that the grammar element is associated with an XML attribute. |
Here is an example to clarify the use of XML templates. Suppose you have a custom scenario action whose expression grammar takes the following form:
Perform action in ( this way | that way ) on [literal]
This action will be represented as a sequence beginning with the token Perform MyAction in, followed by a choice of tokens this way and that way, followed by the on token, and finally a literal for the user to supply a value. In the case where the token this way is chosen, the expression will correspond to the following PDL fragment (all of which would be automatically enclosed in an <action> element by the scenario editor):
<action-name>MyAction</action-name> <action-param name="mode"> <constant>this</constant> </action-param> <action-param name="value"> <constant type="java.lang.Integer">value</constant> </action-param>
(In the case where that way is chosen, the PDL would be identical but the value of the mode argument would be that.)
The expression grammar for such a custom action could look like this:
<sequence id="action-MyAction"> <!-- XML template specifying the action name. Child elements' XML will be processed following the <action-name> element. --> <xml-template> <action-name>myAction</action-name> <apply-xml-templates/> </xml-template> <!-- "noise" token that simply acts as a choice handle in the UI; it is not associated with any PDL. --> <token><description>Perform action</description></token> <!-- further "noise" token providing connective to choice. We separate it because "Perform action" is nicer in a dropdown list than "Perform action in". --> <token><description>in</description></token> <!-- choice of mode arguments --> <choice> <!-- XML template specifying the "mode" parameter. This XML template is processed where the <apply-xml-templates/> element occurred in the parent sequence's template, so the parameter will follow the <action-name> element. --> <xml-template> <action-param name="mode"> <constant><apply-xml-templates/></constant> </action-param> </xml-template> <!-- mode tokens. Because these have values, the tokens are associated with XML text nodes at the point where the <apply-xml-templates/> element occurred in the parent choice's template, i.e. within the <constant> element. --> <token value="this"><description>this way</description></token> <token value="that"><description>that way</description></token> </choice> <token><description>on</description></token> <literal> <!-- XML template for the "value" parameter. Note that the value of the literal will be associated with an XML text node processed at the point of <apply-xml-templates/>. --> <xml-template> <action-param name="value"> <constant><apply-xml-templates/></constant> </action-param> </xml-template> <required/> <default><value type="java.lang.Integer">1</value></default> </literal> </sequence>
