use struct instead of class, overloading operators

[nmn]

1. Updated Class to be a Struct instead. This makes the whole thing immutable, and get value semantics. A regular expression is clearly 'data' and should have value semantics.
2. Added two more functions for the custom operators, which just allow you to reverse the arguments.
   if a =~ b is true, b =~ a should also be true. This can be done because string matching is commutative.

[nmn]

Note: as far as I can tell, the current version doesn't allow you to use VerEx in a .then method, but it should. I'll think about it and fix it when possible.

[nmn]

Ping! @jehna

[jehna]

What's this?

[nmn]

Sorry, was using a playground to type and test it out. Will get rid of it in a new commit.

[jehna]

@nmn seems that there are some tests that are failing. Can you check those out?

[nmn]

Sure thing. Get back to you with updates soon

[nmn]

The tests should be fixed now. But I'll confirm later today.

[nubbel]

I think self. is discouraged when not necessarily needed.

[nmn]

Not seen it mentioned either way. self. just feels a little more explicit to me. I don't have any strong feeling about that however, I'll clean them up.

[nubbel]

Thanks for working on that!
I've posted my comments inline.

[nmn]

Instead of going with full fledged Lenses, I've defined an overloaded set method that lets you change one property at a time. I've then used that method in all other methods to reduce boilerplate. I think this works better than Lenses would.

Also, I've gotten rid of self. from the code.

[Danappelxx]

Good call - I think that's a better approach.

[nubbel]

@nmn Great idea, much simpler!

Final nitpicks, then I'm happy to merge:

1. The set function should be private. There's no need to expose that to clients, given that the variables it sets are also private.
2. One set function should be enough. You could make use of optionals.

[nubbel]

Regarding my second point, I was thinking about something like this:

public struct A {
    private let x: String
    private let y: String
    private let z: String
}

private extension A {
    func set(x x: String? = nil, y: String? = nil, z: String? = nil) -> A {
        return A(
            x: x ?? self.x,
            y: y ?? self.y,
            z: z ?? self.z
        )
    }
}

let a = A(x: "Hello", y: "world", z: "!")
String(a) // => "A(x: "Hello", y: "world", z: "!")"
let b = a.set(y: "nubbel")
String(b) // => "A(x: "Hello", y: "nubbel", z: "!")"
let c = b.set(x: "Bonjour")
String(c) // => "A(x: "Bonjour", y: "nubbel", z: "!")"

What would you say?

[Danappelxx]

@nubbel that's a better approach - can't believe I didn't spot it myself.

[nmn]

@nubbel that looks great. Didn't know I could combine optionals and default values like that. I'll make the update.

[nubbel]

A should probably be VerbalExpressions ;)

[nubbel]

Looks good to me now!
Kindly squash the commits into one single commit for merge. Thanks!

[nmn]

DONE

[nubbel]

Thanks!