lib/rubocop/cop/lint/number_conversion.rb
# frozen_string_literal: true
module RuboCop
module Cop
module Lint
# Warns the usage of unsafe number conversions. Unsafe
# number conversion can cause unexpected error if auto type conversion
# fails. Cop prefer parsing with number class instead.
#
# Conversion with `Integer`, `Float`, etc. will raise an `ArgumentError`
# if given input that is not numeric (eg. an empty string), whereas
# `to_i`, etc. will try to convert regardless of input (``''.to_i => 0``).
# As such, this cop is disabled by default because it's not necessarily
# always correct to raise if a value is not numeric.
#
# NOTE: Some values cannot be converted properly using one of the `Kernel`
# method (for instance, `Time` and `DateTime` values are allowed by this
# cop by default). Similarly, Rails' duration methods do not work well
# with `Integer()` and can be allowed with `AllowedMethods`. By default,
# there are no methods to allowed.
#
# @safety
# Autocorrection is unsafe because it is not guaranteed that the
# replacement `Kernel` methods are able to properly handle the
# input if it is not a standard class.
#
# @example
#
# # bad
#
# '10'.to_i
# '10.2'.to_f
# '10'.to_c
# '1/3'.to_r
# ['1', '2', '3'].map(&:to_i)
# foo.try(:to_f)
# bar.send(:to_c)
#
# # good
#
# Integer('10', 10)
# Float('10.2')
# Complex('10')
# Rational('1/3')
# ['1', '2', '3'].map { |i| Integer(i, 10) }
# foo.try { |i| Float(i) }
# bar.send { |i| Complex(i) }
#
# @example AllowedMethods: [] (default)
#
# # bad
# 10.minutes.to_i
#
# @example AllowedMethods: [minutes]
#
# # good
# 10.minutes.to_i
#
# @example AllowedPatterns: [] (default)
#
# # bad
# 10.minutes.to_i
#
# @example AllowedPatterns: ['min*']
#
# # good
# 10.minutes.to_i
#
# @example IgnoredClasses: [Time, DateTime] (default)
#
# # good
# Time.now.to_datetime.to_i
class NumberConversion < Base
extend AutoCorrector
include AllowedMethods
include AllowedPattern
include IgnoredNode
CONVERSION_METHOD_CLASS_MAPPING = {
to_i: "#{Integer.name}(%<number_object>s, 10)",
to_f: "#{Float.name}(%<number_object>s)",
to_c: "#{Complex.name}(%<number_object>s)",
to_r: "#{Rational.name}(%<number_object>s)"
}.freeze
MSG = 'Replace unsafe number conversion with number ' \
'class parsing, instead of using ' \
'`%<current>s`, use stricter ' \
'`%<corrected_method>s`.'
CONVERSION_METHODS = %i[Integer Float Complex Rational to_i to_f to_c to_r].freeze
METHODS = CONVERSION_METHOD_CLASS_MAPPING.keys.map(&:inspect).join(' ')
# @!method to_method(node)
def_node_matcher :to_method, <<~PATTERN
(call $_ ${#{METHODS}})
PATTERN
# @!method to_method_symbol(node)
def_node_matcher :to_method_symbol, <<~PATTERN
(call _ $_ ${
{
(sym ${#{METHODS}})
(block_pass (sym ${#{METHODS}}))
}
} ...)
PATTERN
def on_send(node)
handle_conversion_method(node)
handle_as_symbol(node)
end
alias on_csend on_send
private
def handle_conversion_method(node)
to_method(node) do |receiver, to_method|
next if receiver.nil? || allow_receiver?(receiver)
message = format(
MSG,
current: "#{receiver.source}.#{to_method}",
corrected_method: correct_method(node, receiver)
)
add_offense(node, message: message) do |corrector|
next if part_of_ignored_node?(node)
corrector.replace(node, correct_method(node, node.receiver))
ignore_node(node)
end
end
end
def handle_as_symbol(node)
to_method_symbol(node) do |receiver, sym_node, to_method|
next if receiver.nil? || !node.arguments.one?
message = format(
MSG,
current: sym_node.source,
corrected_method: correct_sym_method(to_method)
)
add_offense(node, message: message) do |corrector|
remove_parentheses(corrector, node) if node.parenthesized?
corrector.replace(sym_node, correct_sym_method(to_method))
end
end
end
def correct_method(node, receiver)
format(CONVERSION_METHOD_CLASS_MAPPING[node.method_name], number_object: receiver.source)
end
def correct_sym_method(to_method)
body = format(CONVERSION_METHOD_CLASS_MAPPING[to_method], number_object: 'i')
"{ |i| #{body} }"
end
def remove_parentheses(corrector, node)
corrector.replace(node.loc.begin, ' ')
corrector.remove(node.loc.end)
end
def allow_receiver?(receiver)
if receiver.numeric_type? || (receiver.send_type? &&
(conversion_method?(receiver.method_name) ||
allowed_method_name?(receiver.method_name)))
true
elsif (receiver = top_receiver(receiver))
receiver.const_type? && ignored_class?(receiver.const_name)
else
false
end
end
def allowed_method_name?(name)
allowed_method?(name) || matches_allowed_pattern?(name)
end
def top_receiver(node)
receiver = node
receiver = receiver.receiver until receiver.receiver.nil?
receiver
end
def conversion_method?(method_name)
CONVERSION_METHODS.include?(method_name)
end
def ignored_classes
cop_config.fetch('IgnoredClasses', [])
end
def ignored_class?(name)
ignored_classes.include?(name.to_s)
end
end
end
end
end