class ActiveRecord::Associations::JoinDependency::Aliases

def initialize(tables)
  @tables = tables
  @alias_cache = tables.each_with_object({}) { |table,h|
    h[table.node] = table.columns.each_with_object({}) { |column,i|
      i[column.name] = column.alias
    }
  }
  @name_and_alias_cache = tables.each_with_object({}) { |table,h|
    h[table.node] = table.columns.map { |column|
      [column.name, column.alias]
    }
  }
end