Sha256: 07639f15c638fa3c535f242121c1cbd46ae4087583e85da67b9fbbcb808c0dab
Contents?: true
Size: 918 Bytes
Versions: 5
Compression:
Stored size: 918 Bytes
Contents
module Alf
module Engine
#
# Filters operand using a tuple predicate.
#
# Example
#
# rel = [
# {:name => "Smith"},
# {:name => "Jones"}
# ]
# Filter.new(rel, TuplePredicate["name =~ /^J/"]).to_a
# # => [
# # {:name => "Jones"}
# # ]
#
class Filter < Cog
# @return [Enumerable] The operand
attr_reader :operand
# @return [TuplePredicate] Filtering predicate
attr_reader :predicate
# Creates a Filter instance
def initialize(operand, predicate)
@operand = operand
@predicate = predicate
end
# (see Cog#each)
def each
handle = Tools::TupleHandle.new
operand.each do |tuple|
yield(tuple) if @predicate.evaluate(handle.set(tuple))
end
end
end # class Filter
end # module Engine
end # module Alf
Version data entries
5 entries across 5 versions & 1 rubygems