Arel::Project

    # File lib/arel/algebra/relations/operations/project.rb, line 5
 5:     def initialize(relation, projections)
 6:       super(relation)
 7:       @projections = projections.map { |p| p.bind(relation) }
 8:       @christener = Sql::Christener.new
 9:       @attributes = Header.new(projections.map { |x| x.bind(self) })
10:     end

    # File lib/arel/algebra/relations/operations/project.rb, line 16
16:     def eval
17:       unoperated_rows.collect { |r| r.slice(*projections) }
18:     end

    # File lib/arel/algebra/relations/operations/project.rb, line 12
12:     def externalizable?
13:       attributes.any? { |a| a.respond_to?(:aggregation?) && a.aggregation? } || relation.externalizable?
14:     end