Use Hash#each instead of Hash#inject

[okkez]

Because Hash#each is simpler than Hash#inject,
and 20% faster.

[okkez]

Benchmark script:

require "benchmark"

hash = {
  label00: "value00",
  label01: "value01",
  label02: "value02",
  label03: "value03",
  label04: "value04",
  label05: "value05",
  label06: "value06",
  label07: "value07",
  label08: "value08",
  label09: "value09",
  label10: "value10",
}

N = 100_000

delimiter = "\t"
label_delimiter = ":"


Benchmark.bmbm do |x|
  x.report(:inject) do
    N.times do
      hash.inject("") {|memo, (label, value)|
        memo << delimiter if memo.length.nonzero?
        memo << "#{label}#{label_delimiter}#{value}"
      }
    end
  end
  x.report(:each) do
    N.times do
      formatted = ""
      hash.each do |label, value|
        formatted << delimiter if formatted.length.nonzero?
        formatted << "#{label}#{label_delimiter}#{value}"
      end
    end
  end
end

a = hash.inject("") {|memo, (label, value)|
  memo << delimiter if memo.length.nonzero?
  memo << "#{label}#{label_delimiter}#{value}"
}

formatted = ""
hash.each do |label, value|
  formatted << delimiter if formatted.length.nonzero?
  formatted << "#{label}#{label_delimiter}#{value}"
end

p formatted == a

Result:

Rehearsal ------------------------------------------
inject   0.580000   0.000000   0.580000 (  0.584126)
each     0.470000   0.000000   0.470000 (  0.466243)
--------------------------------- total: 1.050000sec

             user     system      total        real
inject   0.570000   0.000000   0.570000 (  0.568520)
each     0.470000   0.000000   0.470000 (  0.466561)
true

[tagomoris]

LGTM.