On Dec 27, 2017, at 11:59 , Daryle Walker <dary...@mac.com> wrote:
>
>> guard let firstBreak = index(where: {
>> [MyConstants.cr, MyConstants.lf].contains($0)
>> }) else { return nil }
I would be inclined to code it like this:
> guard let firstBreak = index(where: {
> $0 == MyConstants.cr || MyConstants.lf == $0
> }) else { return nil }
It *should* be possible for the compiler to optimize your version to this, at
least in a release build, but after a certain amount of complexity in the
source, it might be asking too much.
Since your test result showed “contains” actually being invoked, you know you
have that overhead, and also I wonder if there’s some overhead in setting up
the array value for every byte.
> I wonder if using something like [2]
*My* [2]? I dunno exactly, the difference is that it eliminates the invocation
of “index(where:)” for each byte. It’s not clear whether the current (or the
upcoming) Swift compiler could actually inline the method, which would make it
a wash, or if the overhead is worth worrying about.
My advice is, as usual, don’t go to extraordinary lengths to optimize something
unless you know you have a performance problem, and breaking out of a pure
Swift idiom might be a little extraordinary.
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