Repeating section in live template Follow

Is it possible or could it be implemented to have a repeating section in a live template, similar to emmet but more intelligent in that it would keep adding the enclosed items until a tab or other shortcut is entered.

For example, something along the lines of this if you wanted an array of objects:

$array = (
     $REPEAT$'$ARR$' => '$VAL$'%IF NOT LAST%,%ENDIF%$REPEAT$
);


Which when used would produce:

$array = (
     'Key1' => 'Val1', <- Repeater key entered

     'Key1' => 'Val1', <- Repeater key entered
     'Key1' => 'Val1', <- Repeater key entered
     'Key1' => 'Val1', <- Repeater key entered
     'Key1' => 'Val1'  <- Break key entered here and thus final comma is negated...
);

I can see a huge value in having this in the templating system - how about anyone else. Or if it exists please can someone explain how to use it?

Regards,

M