How to limit array index and case number to be int terminal in grammar?

[durianwaffle]

Hi Langium community,

I found that when I change the terminal NUMBER to INT_NUMBER. The grammar will show errors.
Do you know how to fix it in grammar?

Langium playground for grammar of using int number as index in array that shows error

Langium playground for grammar of using float number as index in array that doesn't show error

[ydaveluy]

I think that you probably have a decimal number rule that match 1.. If you add a space like `array[1 .. 2] does it solve the issue ?

[durianwaffle]

Yes, it will solve this issue

[durianwaffle]

But what if users don't want to type space in array type declaration?
I want to support this array[1..2]

[msujew]

Hey @durianwaffle,

The INT_NUMBER terminal is shadowed by the NUMBER terminal since it appears first in the grammar.

[durianwaffle]

I see! Thank you @msujew, do you know how to fix this issue?

I have changed NUMBER terminal to disable a := 1. or a := .1 but it still have issues.
terminal NUMBER returns number: /[0-9]+(\.[0-9]+)?([eE][+-]?[0-9]+)?/;

Langium playground for updated grammar of using int number as index in array that still shows error

[msujew]

You should just use a single number terminal. You can later perform validations in the appropriate places that the entered number is an integer (and not some real value).

[durianwaffle]

I see! Thank you @msujew.
Since I can only use a single number terminal, can't limit the type of number in grammar.
I will do validation for that (to check it's not real)