雄也の?日坊主日記

_ [Ruby] Hash#to_struct

YAMLから読み込んだ設定値（ハッシュ）をメソッドでアクセスするような目的で再帰的にした．

ちょっと思いついたので書いてみたが...ハッシュのインスタンスメソッドである必要はないかも...

Hash#structuralizeも考えたが，打鍵数が短いこともあってHash#to_structにした．

module CoreExtensions
  module Hash
    module Conversions
      def to_struct(recursively = true)
        if recursively
          return inject({}) { |result, (key, value)|
            if value.respond_to?(:to_struct)
              value = value.to_struct
            end
            result[key] = value
            result
          }.to_struct(false)
        else
          k = keys
          result_class = Struct.new(nil, *k.collect { |key| key.to_sym })
          return result_class.new(*k.collect { |key| self[key] })
        end
      end
    end
  end
end

class Hash
  include CoreExtensions::Hash::Conversions
end

if __FILE__ == $0
  require "test/unit"

  class HashToStructTest < Test::Unit::TestCase
    def test_to_struct__recursive
      o = {
        "abc" => 10,
        :def => "ghi",
        "jkl" => {
          :mno => true,
          "10" => false,
        },
      }.to_struct
      assert_equal(10, o.abc)
      assert_equal("ghi", o.def)
      assert_equal(true, o.jkl.mno)
      assert_equal(false, o.jkl["10"])
    end

    def test_to_struct__not_recursive
      base = {
        "abc" => 10,
        :def => "ghi",
        "jkl" => {
          :mno => true,
          "10" => false,
        },
      }
      o = base.to_struct(false)
      assert_equal(10, o.abc)
      assert_equal("ghi", o.def)
      assert_raise(NoMethodError) do
        assert_equal(true, o.jkl.mno)
      end
      assert_equal(base["jkl"], o.jkl)
    end
  end
end