control structure
using group ((group-name (&group-name)*)|#implied) action
The groups used by a rule or action can be changed "temporarily" by the using group
prefix. The new groups are only in effect during the action that follows. After the action ends, the previous groups are returned to active status.
If the active set of groups is changed by next group is
while within an action prefixed by using group
, the groups activated by the next group is
action are only effective until the end of the action prefixed by using group
.
This example illustrates the use of the using group
prefix with the submit
action. This use allows a programmer to apply a different set of find rules to the submitted text than those find rules which are currently being used at this point in the program:
find "\table{" [ \ "}"]+ => file-name "}" using group table-processing submit file file-name
The #implied
group cannot be combined with other groups in using group
prefixes, because it would have no effect. The rules in the #implied
group are always active, whether or not they are mentioned. using group #implied
is a way of deactivating all of the programmer-defined groups in the program.
The following syntactic variations are permitted:
and
can be used to replace "&".