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module Tins
# This class can create generator objects, that can produce all tuples, that
# would be created by as many for-loops as dimensions were given.
#
# The generator
# g = Tins::Generator[1..2, %w[a b c]]
# produces
# g.to_a # => [[1, "a"], [1, "b"], [1, "c"], [2, "a"], [2, "b"], [2, "c"]]
#
# The 'each' method can be used to iterate over the tuples
# g.each { |a, b| puts "#{a} #{b}" }
# and Tins::Generator includes the Enumerable module, so
# Enumerable.instance_methods can be used as well:
# g.select { |a, b| %w[a c].include? b } # => [[1, "a"], [1, "c"], [2, "a"], [2, "c"]]
#
class Generator
include Enumerable
# Create a new Generator object from the enumberables _enums_.
def self.[](*enums)
new(enums)
end
# Create a new Generator instance. Use the objects in the Array _enums_
# as dimensions. The should all respond to the :each method (see module
# Enumerable in the core ruby library).
def initialize(enums)
@enums, @iterators, @n = [], [], 0
enums.each { |e| add_dimension(e) }
end
# Iterate over all tuples produced by this generator and yield to them.
def each(&block) # :yield: tuple
recurse(&block)
self
end
def recurse(tuple = [ nil ] * @n, i = 0, &block)
if i < @n - 1 then
@enums[i].__send__(@iterators[i]) do |x|
tuple[i] = x
recurse(tuple, i + 1, &block)
end
else
@enums[i].__send__(@iterators[i]) do |x|
tuple[i] = x
yield tuple.dup
end
end
end
private :recurse
# Add another dimension to this generator. _enum_ is an object, that ought
# to respond to the _iterator_ method (defaults to :each).
def add_dimension(enum, iterator = :each)
@enums << enum
@iterators << iterator
@n += 1
end
# Return the size of this generator, that is the number of its dimensions.
def size
@enums.size
end
end
end
require 'tins/alias'
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176 entries across 158 versions & 9 rubygems