わたしがつくりました prototype

ar_producer.rb

module ArProducer
  class CollectorProxy
    attr_accessor :preparable

    def initialize(collector)
      @collector = collector
      @last_str = nil
    end

    attr_reader :last_str

    def <<(str)
      @collector << str
      @last_str = str
      self
    end

    def add_bind(obj)
      @collector.add_bind(obj)
      self
    end

    def add_binds(binds, proc_for_binds = nil)
      @collector.add_binds(binds, proc_for_binds)
      self
    end

    def value
      @collector.value
    end
  end

  module ArelNodeExtension
    def initialize
      super
      @ar_producer_backtrace = caller
    end

    attr_reader :ar_producer_backtrace
  end

  module ArelVisitorExtension
    def accept(object, collector)
      super(object, CollectorProxy.new(collector))
    end

    private

    %i[
      visit_Arel_Nodes_Ascending
      visit_Arel_Nodes_Descending
      visit_Arel_Nodes_Equality
      visit_Arel_Nodes_InnerJoin
    ].each do |method_name|
      define_method(method_name) do |o, collector|
        comment = " /* #{format_producer(o)} */\n"
        res = super(o, collector)
        res << comment unless collector.last_str.end_with?(comment)
        res
      end
    end

    def format_producer(o)
      Rails.backtrace_cleaner.clean(o.ar_producer_backtrace).first
    end
  end
end

Arel::Nodes::Node.include ArProducer::ArelNodeExtension
Arel::Visitors::ToSql.prepend ArProducer::ArelVisitorExtension