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Contents
# frozen_string_literal: true
module RuboCop
module Cop
module Rails
# This cop looks for uses of `each_with_object({}) { ... }`,
# `map { ... }.to_h`, and `Hash[map { ... }]` that are transforming
# an enumerable into a hash where the values are the original elements.
# Rails provides the `index_by` method for this purpose.
#
# @example
# # bad
# [1, 2, 3].each_with_object({}) { |el, h| h[foo(el)] = el }
# [1, 2, 3].to_h { |el| [foo(el), el] }
# [1, 2, 3].map { |el| [foo(el), el] }.to_h
# Hash[[1, 2, 3].collect { |el| [foo(el), el] }]
#
# # good
# [1, 2, 3].index_by { |el| foo(el) }
class IndexBy < Base
include IndexMethod
extend AutoCorrector
def_node_matcher :on_bad_each_with_object, <<~PATTERN
(block
({send csend} _ :each_with_object (hash))
(args (arg $_el) (arg _memo))
({send csend} (lvar _memo) :[]= $!`_memo (lvar _el)))
PATTERN
def_node_matcher :on_bad_to_h, <<~PATTERN
(block
({send csend} _ :to_h)
(args (arg $_el))
(array $_ (lvar _el)))
PATTERN
def_node_matcher :on_bad_map_to_h, <<~PATTERN
({send csend}
(block
({send csend} _ {:map :collect})
(args (arg $_el))
(array $_ (lvar _el)))
:to_h)
PATTERN
def_node_matcher :on_bad_hash_brackets_map, <<~PATTERN
(send
(const _ :Hash)
:[]
(block
({send csend} _ {:map :collect})
(args (arg $_el))
(array $_ (lvar _el))))
PATTERN
private
def new_method_name
'index_by'
end
end
end
end
end
Version data entries
14 entries across 14 versions & 1 rubygems