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# TODO:
#
# - Remove require 'enumerator' for Ruby 1.9.
# - Suggest Enumerator's #each_slice use block arity if no parameter is given.
require 'enumerator' # for each_slice
module Enumerable
# Iterators over each element pairing.
#
# [:a,:b,:c,:d].each_pair { |a,b| puts "#{a} -> #{b}" }
#
# _produces_
#
# a -> b
# c -> d
#
# CREDIT: Martin DeMello
def each_pair #:yield:
e1 = nil
each_with_index do |e,i|
if i % 2 == 0
e1 = e
next
else
yield(e1,e)
end
end
end
# Iterate over each n items based on arity.
#
# [1,2,3,4].eachn do |x, y|
# p [x,y]
# end
#
# _produces_
#
# [1,2]
# [3,4]
#
# CREDIT: Martin DeMello
def eachn(&block)
n = block.arity.abs
each_slice(n) {|i| block.call(*i)}
end
# DEPRECATED
#
# # Why the term counter? There may be a change in Ruby 2.0
# # to use this word instead of index. Index will
# # still be used for Array, since that is the proper meaning
# # in that context. In the mean time, aliases are provided.
#
# # More appropriate naming since an enumerable is not
# # neccesarily "indexed", as is an Array or Hash.
# alias_method :each_with_counter, :each_with_index
end
=begin test
def test_each_pair
r = []
a = [1,2,3,4]
a.each_pair{ |a,b| r << [a,b] }
assert_equal( [[1,2],[3,4]], r )
end
def test_eachn
x = []
[1,2,3,4].eachn{ |a,b| x << [a,b] }
o = [[1,2],[3,4]]
assert_equal( o, x )
x = []
[1,2,3,4,5].eachn{ |a,b,c| x << [a,b,c] }
o = [[1,2,3],[4,5,nil]]
assert_equal( o, x )
end
=end
|
