EBNF - Allow full repetition management with repetition-symbol "*"

Question

Hello PlantUML team,

• Could you allow full repetition management with repetition-symbol "*"?

Here is some examples (taken from the ISO EBNF standard):

@startebnf
Fortran_77_continuation_line = 5 * " ",  '[...]', 66 * [character];
@endebnf

or

@startebnf
test = 4 * '2';
@endebnf

or 

@startebnf
title Example of §5.7 Syntactic-factor of ISO EBNF
aa = "A";
bb = 3 * aa, "B";
cc = 3 * [aa], "C";
dd = {aa}, "D";
ee = aa, {aa}, "E";
ff = 3 * aa, 3 * [aa], "F";
gg = 3 * {aa}, "D";
@endebnf

Proposal 1:

A proposal will be to use above, a curly bracket as:

Proposal 2:

[New Adding 2022-10-12]: Perhaps more better solution: adding 'n times' near a loop arrow...

@startebnf
test = 4 * '2';
@endebnf

Could be equivalent at the drawing of:

@startebnf
test = {'2'}-;
@endebnf

with a `4 times` near (above) the loop arrow. 

[Then another question: how to i18n the field... 'n times', 'n fois', ... like gantt with `language <xx>`] 

But it is not so urgent!
Regards,
Th.

Answer 1

Something like this:

Comments

Hello PlantUML,
Good. 

To avoid i18n, perhaps add the times sign (U+00D7 × MULTIPLICATION SIGN (&times;)) after the factor, as:

Then, for the second form, that asks question about times or ranges...
I'm thinking...
First: perhaps add a little more space between (''before, after') the backward loop.

Regards.

---

Looks good for the base case, but what about "5 to 10 times", or "at least 10 times"?

Answer 2

Great suggestion... could also be done as a box around the items to repete like component state in state diagrams.

Comments

Borrowing from regex, we might want to add some kind of support for min and max bounds (the above would be where min=max).

Not part of the spec, so it would be an extnsion of ebnf proper, but might be useful, and non standard extensions are common in the wild.