`case` statement vs `Hash` lookup

case_vs_Hash_benchmark.rb

#!/usr/bin/ruby

# ruby 3.3.0 (2023-12-25 revision 5124f9ac75) [arm64-darwin23]
# Comparison:
# Memo+Freeze+Ident H : 15333385.5 i/s
# Memo+Freeze Hash    : 11604676.7 i/s - 1.32x  slower
# case                : 11026464.0 i/s - 1.39x  slower
# Memo'ed Hash        :  4516328.0 i/s - 3.40x  slower
# Hash full of Ints   :  4387124.4 i/s - 3.50x  slower

require "awesome_print"
require "active_support/all"
require "sorbet-runtime"
require "benchmark/ips"

class MyEnum < T::Enum
  enums { A = new; B = new; C = new }
end

def lookup_case(e)
  case e
  when MyEnum::A then 1
  when MyEnum::B then 2
  when MyEnum::C then 3
  end
end

def lookup_hash_full_of_ints(e)
  {
    MyEnum::A => 1,
    MyEnum::B => 2,
    MyEnum::C => 3,
  }[e]
end

MEMOED_HASH = {
  MyEnum::A => 1,
  MyEnum::B => 2,
  MyEnum::C => 3,
}

def lookup_memoed_hash_full_of_ints(e)
  MEMOED_HASH[e]
end


MEMOED_FROZEN_HASH = {
  MyEnum::A => 1,
  MyEnum::B => 2,
  MyEnum::C => 3,
}.freeze

def lookup_memoed_frozen_hash_full_of_ints(e)
  MEMOED_HASH[e]
end

MEMOED_FROZEN_IDENT_HASH = {
  MyEnum::A => 1,
  MyEnum::B => 2,
  MyEnum::C => 3,
}.compare_by_identity.freeze

def lookup_memoed_frozen_identity_hash_full_of_ints(e)
  MEMOED_FROZEN_IDENT_HASH[e]
end

a = (MyEnum.values * 100).shuffle

width = 20
Benchmark.ips do |x|
  x.config(warmup: 1, time: 5)
  
  x.report("case".ljust(width, " ")) do |times|
    i = 0
    while (i += 1) <= times
      lookup_case a[i % a.size]
    end
  end
  
  x.report("Hash full of Ints".ljust(width, " ")) do |times|
    i = 0
    while (i += 1) <= times
      lookup_hash_full_of_ints a[i % a.size]
    end
  end
  
  x.report("Memo'ed Hash".ljust(width, " ")) do |times|
    i = 0
    while (i += 1) <= times
      lookup_hash_full_of_ints a[i % a.size]
    end
  end
  
  x.report("Memo+Freeze Hash".ljust(width, " ")) do |times|
    i = 0
    while (i += 1) <= times
      lookup_memoed_frozen_hash_full_of_ints a[i % a.size]
    end
  end
  
  x.report("Memo+Freeze+Ident H".ljust(width, " ")) do |times|
    i = 0
    while (i += 1) <= times
      lookup_memoed_frozen_identity_hash_full_of_ints a[i % a.size]
    end
  end

  x.compare!
end