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module Gecode::Constraints::SetEnum
class Expression
# Adds a constraint on the sets that specifies that they must have at most
# one element in common. The "option" :size must be specified, the sets
# will be constrained to that size.
def at_most_share_one_element(options = {})
unless options.has_key? :size
raise ArgumentError, 'Option :size has to be specified.'
end
unless options.size == 1
raise ArgumentError, 'Only the option :size is accepted, got ' +
"#{options.keys.join(', ')}."
end
if @params[:negate]
raise Gecode::MissingConstraintError, 'A negated atmost one ' +
'constrain is not implemented.'
end
@model.add_constraint Distinct::AtMostOneConstraint.new(
@model, @params.update(options))
end
end
# A module that gathers the classes and modules used in distinct constraints.
module Distinct #:nodoc:
# Describes an at most one constraint, which constrains all pairs of set
# variables in the enumeration to at most have one element in common and be
# of a specified size. Providing a size is not optional.
#
# Neither negation nor reification is supported.
#
# == Examples
#
# # All set variables in +sets+ must have cardinality 17 and no pair may
# # have more than one element in common.
# sets.must.at_most_share_one_element(:size => 17)
class AtMostOneConstraint < Gecode::Constraints::Constraint
def post
sets, size = @params.values_at(:lhs, :size)
Gecode::Raw::atmostOne(@model.active_space, sets.to_set_var_array, size)
end
end
end
end
Version data entries
12 entries across 12 versions & 2 rubygems