Reduce allocations and branching in transform_code_lengths_to_code

[LilithHafner]

This is a small performance improvement. It is not visible when running end to end benchmarks (nor is there a visible regression). We can see an improvement when just benchmarking the target function, though:

julia> Random.seed!(13); for i in 1:10
           x = rand(1:i, rand(1:i))
           display(@b x Inflate.transform_code_lengths_to_code)
       end
61.461 ns (4 allocs: 272 bytes)
98.814 ns (6 allocs: 416 bytes)
137.207 ns (8 allocs: 560 bytes)
105.065 ns (6 allocs: 400 bytes)
191.794 ns (11 allocs: 768 bytes)
207.341 ns (11 allocs: 768 bytes)
164.368 ns (9 allocs: 592 bytes)
261.114 ns (14 allocs: 960 bytes)
295.660 ns (16 allocs: 1.328 KiB)
304.303 ns (16 allocs: 1.094 KiB)

shell> git stash pop
...

julia> Random.seed!(13); for i in 1:10
           x = rand(1:i, rand(1:i))
           display(@b x Inflate.transform_code_lengths_to_code)
       end
46.199 ns (3 allocs: 208 bytes)
81.508 ns (5 allocs: 352 bytes)
113.339 ns (7 allocs: 512 bytes)
86.581 ns (5 allocs: 352 bytes)
163.136 ns (10 allocs: 736 bytes)
171.270 ns (10 allocs: 736 bytes)
131.980 ns (8 allocs: 560 bytes)
220.342 ns (13 allocs: 944 bytes)
223.109 ns (14 allocs: 1.000 KiB)
254.167 ns (15 allocs: 1.078 KiB)

Looping through the input a second time is cheap compared to the additional branching and allocations within the loop. IMO this is also slightly simpler to understand, though the previous version was also quite legible.

[codecov-commenter]

⚠️ Please install the to ensure uploads and comments are reliably processed by Codecov.

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.35%. Comparing base (f16eec8) to head (166c274).
Report is 6 commits behind head on master.

❗ Your organization needs to install the Codecov GitHub app to enable full functionality.

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #27      +/-   ##
==========================================
- Coverage   99.35%   99.35%   -0.01%     
==========================================
  Files           1        1              
  Lines         468      467       -1     
==========================================
- Hits          465      464       -1     
  Misses          3        3              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[GunnarFarneback]

Looks fine, thanks.