feature: add current and next state matches to on_enter and on_exit

[lotus128]

Implements #18.

[Seldom-SE]

Hm, this makes the API a bit more confusing. Would a default type work here (ex fn on_enter<NextState: EntityState, CurrentState: EntityState = AnyState>) and would it allow the previous usage (omitting the second type param like on_enter::<MyState>) to still work?

[lotus128]

I'm not super familiar with rust, but I did try this and found that Rust does not support default type params for functions: rust-lang/rust#36887.

New methods could be introduced (like on_enter_from and on_exit_to) and the old methods could call those instead.

[Seldom-SE]

Good idea. I'll give a proper review soon.

[Seldom-SE]

Change on_enter and on_exit back and add on_enter_from and on_exit_to (as you suggested). Same for command_on_enter et al.

Someday, I'll add a feature that makes all the command_on_* functions unnecessary, so all this duplication is temporary.

Thanks!

[Seldom-SE]

NextState should be called Next and CurrentState should be called Prev to match other methods.

[lotus128]

Done.

[Seldom-SE]

Put CurrentState before NextState. Both ways have ways they can be confusing, but putting CurrentState first feels to me more consistent with the rest of the API.

[lotus128]

Done.

[Seldom-SE]

Aside from this, it looks good

[Seldom-SE]

Whoops forgot to add the comment

[Seldom-SE]

Thank you