Fixing Wrong Generated First Set

[MammarDr]

Issue #138
Hi this is my first github contribution and i feel honored to be help to you as you were to me in your amazing courses.

1-
I fixed the wrong generated first sets from productions that have the nullable LHS(derive ε) appear in firstOf(rhs).

Grammar:
B -> B "a" | ε

Without fix:
First(B) = { ε }

With fix:
First(B) = { "a", ε }

the solution is to register the Non-Terminals that derive epsilon directly (A->ε) before calculating the first sets.

added test case for this issue.

2-
i also spotted a function typo 'getOrignialSymbol' -> 'getOriginalSymbol'

[DmitrySoshnikov]

MammarDr, thanks for the contribution - glad we have this bug finally caught! Please see comments on the formatting (use tools which should be in this repo for auto-format the code to single style).

[MammarDr]

@DmitrySoshnikov
Hi demitry, if you don't like this approach i can look for another solution.

[DmitrySoshnikov]

Thanks @MammarDr - let's stick commit only to logical change and keep formatting for cobase refactorings.

[DmitrySoshnikov]

I'm not against of any formatting styles (and we can reformat this whole codebase to the latest standard or AI-generated coding), but let's make a separate commit for formatting, and keep this change to its semantics.

[MammarDr]

@DmitrySoshnikov
I have implemented a new way to calculate first and follow sets -- it solves all the opened issues :)
In my approach, I call a single function that computes all the sets at once (build first -> build follow) then when you demand a set of a symbol it will be ready.
In your method, the sets are calculated on demand one by one
Should I follow your pattern or is it acceptable to compute everything in one go?

(not doing it all in one go will complicate the code and maybe become less efficient)