25.15.1 Workaround with a dedicated LHS symbol

Most users will fix the second limitation (see lim2Ex) by falling back on marker symbols. For those users who for some reason prefer to avoid this, in this section we present a workaround that is based on introducing a new symbol, one dedicated to acting as the LHS of (R3) of lim2Ex.

We show the fix as another example, one which we will call fixEx. fixEx is identical to lim2Ex with the following exceptions:

• Rule (R3) in lim2Ex is replaced with the following rules:

       [ A1 ::= W X ]             (R3a)
       [ A ::= A1 ]               (R3b)
  

  In these two rules, rule (R3a) is the replacement rule for rule (R3) in lim2Ex, and A1 is the new LHS symbol, which is dedicated to serving as the LHS of rule (R3a).

• A MARPA_EVENT_SYMBOL_COMPLETED event is activated for symbol A1, instead of for symbol A.
• Rule (R3a) has the same semantics as rule (R3) in lim2Ex, the rule that it replaced.
• Rule (R3b) has pass-through semantics.
• The application code must be changed to look for a MARPA_EVENT_SYMBOL_COMPLETED event for symbol A1, instead of symbol A.

fixEx will accept the same language as lim2Ex, with the same semantics as lim2Ex. A MARPA_EVENT_SYMBOL_COMPLETED event will trigger at the end of (R3a), this time for symbol A1, but at exactly the same parse location as it did for symbol A in lim2Ex. And a MARPA_EVENT_SYMBOL_COMPLETED event will no longer trigger at the end of (R4), which is the fix we were looking for.