Sha256: bc19ac861c82ef57ac6540a21887cbd8e97289cbcc1dc8dc82d49b2c1b8abbc4
Contents?: true
Size: 915 Bytes
Versions: 5
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Stored size: 915 Bytes
Contents
module Alf
module Algebra
class Group
include Operator
include Relational
include Unary
signature do |s|
s.argument :attributes, AttrList, []
s.argument :as, AttrName, :group
s.option :allbut, Boolean, false, 'Group all but specified attributes?'
end
def heading
@heading ||= begin
keep, sub = operand.heading.split(attributes, !allbut)
keep.merge(as => Relation[sub])
end
end
def keys
@keys ||= operand.keys.map{|k|
proj = k.project(attributes, !allbut)
proj.empty? ? AttrList[as] : proj
}.freeze
end
private
def _type_check(options)
no_unknown!(attributes - operand.attr_list)
no_name_clash!(operand.attr_list - attributes, AttrList[as])
end
end # class Group
end # module Algebra
end # module Alf
Version data entries
5 entries across 5 versions & 1 rubygems