Meta rules (recurse and enumerate)

The transformation processor supports two kinds of meta rules: recurse and enumerate. The meta rules are processed by the transformation compiler and transformed to a set of rules.

recurse

The recurse meta rule enables you to copy sub trees exactly as they are from the data template to the runtime data instance. Note that only template nodes that match the data source are copied.

When recurse is used in a transformation rule, then the rule starts to behave like a meta rule that automatically generates rules for the entire sub-tree. The usage of recurse is illustrated by the following example:

<tdt:rule path="/data/employee"> <tdt:value key=".">/data/message/employee</tdt:value> <tdt:value key="recurse">.</tdt:value> </tdt:rule>

This meta rule is design driven, i.e. it respects the template order of the elements.

See also Example of recurse.

enumerate

This meta rule is similar to recurse meta rule with the only difference that enumerate is data driven, i.e. it respects the element order in the input data. This meta rule is a bit more complicated, and thus slower, than recurse.