[prototype runtime] Optimize performance

[ksss]

Problem

When the number of modules/classes is large and the path is deep, there is a problem that the performance of rbs prototype runtime is extremely degraded.
This is due to the loop of calling const_name for all modules to find their names each time the paths are nested.
This situation can easily occur in Rails applications and is worth addressing.

Solution

To suppress this loop, I modified @modules to be Hash to suppress the search cost.

Comparison Code

$ cat t.rb
module Root
  10.times do |i|
    const_set("A_#{i}", Module.new{
      10.times do |j|
        const_set("B_#{i}_#{j}", Module.new{
          10.times do |k|
            const_set("C_#{i}_#{j}_#{k}", Module.new{
              10.times do |l|
                const_set("D_#{i}_#{j}_#{k}_#{l}", Class.new)
              end
            })
          end
        })
      end
    })
  end
end

$ time bundle exec rbs prototype runtime -R t.rb "Root*" > /dev/null

# before
101.24s user 1.69s system 99% cpu 1:43.11 total

# after
1.05s user 0.14s system 89% cpu 1.330 total

[soutaro]

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