lib/arel/visitors/visitor.rb


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# frozen_string_literal: true
module Arel
  module Visitors
    class Visitor
      def initialize
        @dispatch = get_dispatch_cache
      end

      def accept object, *args
        visit object, *args
      end

      private

      attr_reader :dispatch

      def self.dispatch_cache
        Hash.new do |hash, klass|
          hash[klass] = "visit_#{(klass.name || '').gsub('::', '_')}"
        end
      end

      def get_dispatch_cache
        self.class.dispatch_cache
      end

      def visit object, *args
        dispatch_method = dispatch[object.class]
        send dispatch_method, object, *args
      rescue NoMethodError => e
        raise e if respond_to?(dispatch_method, true)
        superklass = object.class.ancestors.find { |klass|
          respond_to?(dispatch[klass], true)
        }
        raise(TypeError, "Cannot visit #{object.class}") unless superklass
        dispatch[object.class] = dispatch[superklass]
        retry
      end
    end
  end
end