build_joins

# File activerecord/lib/active_record/relation/query_methods.rb, line 181
    def build_joins(relation, joins)
      joined_associations = []
      association_joins = []

      joins = @joins_values.map {|j| j.respond_to?(:strip) ? j.strip : j}.uniq

      joins.each do |join|
        association_joins << join if [Hash, Array, Symbol].include?(join.class) && !array_of_strings?(join)
      end

      stashed_association_joins = joins.grep(ActiveRecord::Associations::ClassMethods::JoinDependency::JoinAssociation)

      non_association_joins = (joins - association_joins - stashed_association_joins)
      custom_joins = custom_join_sql(*non_association_joins)

      join_dependency = ActiveRecord::Associations::ClassMethods::JoinDependency.new(@klass, association_joins, custom_joins)

      join_dependency.graft(*stashed_association_joins)

      @implicit_readonly = true unless association_joins.empty? && stashed_association_joins.empty?

      to_join = []

      join_dependency.join_associations.each do |association|
        if (association_relation = association.relation).is_a?(Array)
          to_join << [association_relation.first, association.join_class, association.association_join.first]
          to_join << [association_relation.last, association.join_class, association.association_join.last]
        else
          to_join << [association_relation, association.join_class, association.association_join]
        end
      end

      to_join.each do |tj|
        unless joined_associations.detect {|ja| ja[0] == tj[0] && ja[1] == tj[1] && ja[2] == tj[2] }
          joined_associations << tj
          relation = relation.join(tj[0], tj[1]).on(*tj[2])
        end
      end

      relation.join(custom_joins)
    end