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Contents
# encoding: utf-8
module RuboCop
module Cop
module Style
# This cop looks for inject / reduce calls where the passed in object is
# returned at the end and so could be replace by each_with_object without
# the need to return the object at the end.
#
# @example
# # bad
# [1, 2].inject({}) { |a, e| a[e] = e; a }
#
# # good
# [1, 2].each_with_object({}) { |e, a| a[e] = e }
class EachWithObject < Cop
MSG = 'Use `each_with_object` instead of `%s`.'
METHODS = [:inject, :reduce]
def on_block(node)
method, args, body = *node
# filter out super and zsuper nodes
return unless method.type == :send
_, method_name, method_args = *method
return unless METHODS.include? method_name
return if method_args && method_args.type == :sym
return_value = return_value(body)
return unless return_value
return unless first_argument_returned?(args, return_value)
add_offense(method, :selector, format(MSG, method_name))
end
private
def return_value(body)
return unless body
return_value = body.type == :begin ? body.children.last : body
return_value if return_value && return_value.type == :lvar
end
def first_argument_returned?(args, return_value)
first_arg, = *args
accumulator_var = *first_arg
return_var = *return_value
accumulator_var == return_var
end
end
end
end
end
Version data entries
21 entries across 21 versions & 2 rubygems