Reduce usage of regexes for performance

[tb0yd]

Some small performance enhancements.

coercible at performance branch:

Comparison:
Virtus: integer values for integer attributes        :    20948.6 i/s
Virtus: string values for integer attributes         :    18220.3 i/s - 1.15x slower
Virtus: string values for whatever attributes        :    18067.7 i/s - 1.16x slower
Virtus: without values                               :     9618.0 i/s - 2.18x slower

coercible at master branch:

Comparison:
Virtus: integer values for integer attributes        :    21541.2 i/s
Virtus: string values for whatever attributes        :    13354.4 i/s - 1.61x slower
Virtus: without values                               :    10314.2 i/s - 2.09x slower
Virtus: string values for integer attributes         :     3165.7 i/s - 6.80x slower

• [x] Specs pass

Finished in 0.28534 seconds
396 examples, 0 failures

Benchmark code at: https://gist.github.com/tb0yd/79bc56683748605cff96

This benchmark is very simple & does not represent a realistic usage of Virtus. But the numbers are encouraging

[solnic]

Thanks, I'm gonna update and cleanup devel/test setup so that build is passing in master, then could you merge master into your branch and then I could merge it, OK?

[tb0yd]

Ok

[solnic]

OK, I updated master

[solnic]

BTW you could also check out another PR (that I must've missed for some reason :() that's related to performance

[tb0yd]

I couldn't reproduce his findings