Do not change visibility when sorting

[mwudka]

Hopefully fixes #141 . Updates the SortNodes visitor to preserve visibility of nodes. So, a file that looks like

class MyClass
def zethod2; end
def zethod1; end
private
def c; end
def b; end
end

will get sorted as

class MyClass
def zethod1; end
def zethod2; end
private
def b; end
def c; end
end

rather than as

class MyClass
def b; end
def c; end
private
def zethod1; end
def zethod2; end
end

[KaanOzkan]

Thanks!

I like the 2 pass solution. Although it was hard to understand at first, it may be useful to extract the core sorting logic to its own method (L37-L46). What do you think?

[paracycle]

I think there is a better way to do this by using partition and sorting each of the partitions independently. If we did that, we wouldn't have to do all the manual offset calculations that are present in this PR.

[mwudka]

After looking into partition, I realized that my original approach was wrong: visibility modifiers can be repeated, so there can be an arbitrary number of chunks. The helpful partition suggestion from @paracycle got me looking into other ruby array methods I don't know, and I found chunk which I think makes things much clearer.

It does increase allocations, but perhaps that is a good tradeoff here, since this isn't runtime code?

@KaanOzkan the code is now much shorter, so perhaps the helper method is not needed? I am on the fence, but leaned towards keeping it inline so that the flow is clear and matches the existing structure more closely.

[KaanOzkan]

This is definitely simpler thank you!