forked from rubocop/rubocop-performance
/
sum.rb
186 lines (154 loc) · 5.93 KB
/
sum.rb
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
# frozen_string_literal: true
module RuboCop
module Cop
module Performance
# This cop identifies places where custom code finding the sum of elements
# in some Enumerable object can be replaced by `Enumerable#sum` method.
#
# @example
# # bad
# [1, 2, 3].inject(:+)
# [1, 2, 3].reduce(10, :+)
# [1, 2, 3].inject(&:+)
# [1, 2, 3].reduce { |acc, elem| acc + elem }
# [1, 2, 3].map { |elem| elem ** 2 }.sum
# [1, 2, 3].collect(&:count).sum(10)
#
# # good
# [1, 2, 3].sum
# [1, 2, 3].sum(10)
# [1, 2, 3].sum { |elem| elem ** 2 }
# [1, 2, 3].sum(10, &:count)
#
class Sum < Base
include RangeHelp
extend AutoCorrector
MSG = 'Use `%<good_method>s` instead of `%<bad_method>s`.'
RESTRICT_ON_SEND = %i[inject reduce sum].freeze
def_node_matcher :sum_candidate?, <<~PATTERN
(send _ ${:inject :reduce} $_init ? ${(sym :+) (block_pass (sym :+))})
PATTERN
def_node_matcher :sum_map_candidate?, <<~PATTERN
(send
{
(block $(send _ {:map :collect}) ...)
$(send _ {:map :collect} (block_pass _))
}
:sum $_init ?)
PATTERN
def_node_matcher :sum_with_block_candidate?, <<~PATTERN
(block
$(send _ {:inject :reduce} $_init ?)
(args (arg $_acc) (arg $_elem))
$send)
PATTERN
def_node_matcher :acc_plus_elem?, <<~PATTERN
(send (lvar %1) :+ (lvar %2))
PATTERN
alias elem_plus_acc? acc_plus_elem?
def on_send(node)
sum_candidate?(node) do |method, init, operation|
range = sum_method_range(node)
message = build_method_message(method, init, operation)
add_offense(range, message: message) do |corrector|
autocorrect(corrector, init, range)
end
end
sum_map_candidate?(node) do |map, init|
next if node.block_literal? || node.block_argument?
message = build_sum_map_message(map.method_name, init)
add_offense(sum_map_range(map, node), message: message) do |corrector|
autocorrect_sum_map(corrector, node, map, init)
end
end
end
def on_block(node)
sum_with_block_candidate?(node) do |send, init, var_acc, var_elem, body|
if acc_plus_elem?(body, var_acc, var_elem) || elem_plus_acc?(body, var_elem, var_acc)
range = sum_block_range(send, node)
message = build_block_message(send, init, var_acc, var_elem, body)
add_offense(range, message: message) do |corrector|
autocorrect(corrector, init, range)
end
end
end
end
private
def autocorrect(corrector, init, range)
return if init.empty?
replacement = build_good_method(init)
corrector.replace(range, replacement)
end
def autocorrect_sum_map(corrector, sum, map, init)
sum_range = method_call_with_args_range(sum)
map_range = method_call_with_args_range(map)
block_pass = map.last_argument if map.last_argument&.block_pass_type?
replacement = build_good_method(init, block_pass)
corrector.remove(sum_range)
corrector.replace(map_range, ".#{replacement}")
end
def sum_method_range(node)
range_between(node.loc.selector.begin_pos, node.loc.end.end_pos)
end
def sum_map_range(map, sum)
range_between(map.loc.selector.begin_pos, sum.source_range.end.end_pos)
end
def sum_block_range(send, node)
range_between(send.loc.selector.begin_pos, node.loc.end.end_pos)
end
def build_method_message(method, init, operation)
good_method = build_good_method(init)
bad_method = build_method_bad_method(init, method, operation)
format(MSG, good_method: good_method, bad_method: bad_method)
end
def build_sum_map_message(method, init)
sum_method = build_good_method(init)
good_method = "#{sum_method} { ... }"
bad_method = "#{method} { ... }.#{sum_method}"
format(MSG, good_method: good_method, bad_method: bad_method)
end
def build_block_message(send, init, var_acc, var_elem, body)
good_method = build_good_method(init)
bad_method = build_block_bad_method(send.method_name, init, var_acc, var_elem, body)
format(MSG, good_method: good_method, bad_method: bad_method)
end
def build_good_method(init, block_pass = nil)
good_method = 'sum'
args = []
unless init.empty?
init = init.first
args << init.source unless init.int_type? && init.value.zero?
end
args << block_pass.source if block_pass
good_method += "(#{args.join(', ')})" unless args.empty?
good_method
end
def build_method_bad_method(init, method, operation)
bad_method = "#{method}("
unless init.empty?
init = init.first
bad_method += "#{init.source}, "
end
bad_method += if operation.block_pass_type?
'&:+)'
else
':+)'
end
bad_method
end
def build_block_bad_method(method, init, var_acc, var_elem, body)
bad_method = method.to_s
unless init.empty?
init = init.first
bad_method += "(#{init.source})"
end
bad_method += " { |#{var_acc}, #{var_elem}| #{body.source} }"
bad_method
end
def method_call_with_args_range(node)
node.receiver.source_range.end.join(node.source_range.end)
end
end
end
end
end