lib/rubocop/cop/style/and_or.rb
# frozen_string_literal: true
module RuboCop
module Cop
module Style
# Checks for uses of `and` and `or`, and suggests using `&&` and
# `||` instead. It can be configured to check only in conditions or in
# all contexts.
#
# @safety
# Autocorrection is unsafe because there is a different operator precedence
# between logical operators (`&&` and `||`) and semantic operators (`and` and `or`),
# and that might change the behavior.
#
# @example EnforcedStyle: conditionals (default)
# # bad
# if foo and bar
# end
#
# # good
# foo.save && return
#
# # good
# foo.save and return
#
# # good
# if foo && bar
# end
#
# @example EnforcedStyle: always
# # bad
# foo.save and return
#
# # bad
# if foo and bar
# end
#
# # good
# foo.save && return
#
# # good
# if foo && bar
# end
class AndOr < Base
include ConfigurableEnforcedStyle
include RangeHelp
extend AutoCorrector
MSG = 'Use `%<prefer>s` instead of `%<current>s`.'
def on_and(node)
process_logical_operator(node) if style == :always
end
alias on_or on_and
def on_if(node)
on_conditionals(node) if style == :conditionals
end
alias on_while on_if
alias on_while_post on_if
alias on_until on_if
alias on_until_post on_if
private
def process_logical_operator(node)
return if node.logical_operator?
message = message(node)
add_offense(node.loc.operator, message: message) do |corrector|
node.each_child_node do |expr|
if expr.send_type?
correct_send(expr, corrector)
elsif expr.return_type? || expr.assignment?
correct_other(expr, corrector)
end
end
corrector.replace(node.loc.operator, node.alternate_operator)
keep_operator_precedence(corrector, node)
end
end
def on_conditionals(node)
node.condition.each_node(*AST::Node::OPERATOR_KEYWORDS) do |operator|
process_logical_operator(operator)
end
end
def message(node)
format(MSG, prefer: node.alternate_operator, current: node.operator)
end
def correct_send(node, corrector)
return correct_not(node, node.receiver, corrector) if node.method?(:!)
return correct_setter(node, corrector) if node.setter_method?
return correct_other(node, corrector) if node.comparison_method?
return unless correctable_send?(node)
whitespace_before_arg_range = whitespace_before_arg(node)
corrector.remove(whitespace_before_arg_range)
corrector.insert_before(whitespace_before_arg_range, '(')
corrector.insert_after(node.last_argument, ')')
end
def correct_setter(node, corrector)
corrector.insert_before(node.receiver, '(')
corrector.insert_after(node.last_argument, ')')
end
# ! is a special case:
# 'x and !obj.method arg' can be autocorrected if we
# recurse down a level and add parens to 'obj.method arg'
# however, 'not x' also parses as (send x :!)
def correct_not(node, receiver, corrector)
if node.prefix_bang?
return unless receiver.send_type?
correct_send(receiver, corrector)
elsif node.prefix_not?
correct_other(node, corrector)
else
raise 'unrecognized unary negation operator'
end
end
def correct_other(node, corrector)
return if node.source_range.begin.is?('(')
corrector.wrap(node, '(', ')')
end
def keep_operator_precedence(corrector, node)
if node.or_type? && node.parent&.and_type?
corrector.wrap(node, '(', ')')
elsif node.and_type? && node.rhs.or_type?
corrector.wrap(node.rhs, '(', ')')
end
end
def correctable_send?(node)
!node.parenthesized? && node.arguments? && !node.method?(:[])
end
def whitespace_before_arg(node)
begin_paren = node.loc.selector.end_pos
end_paren = begin_paren
# Increment position of parenthesis, unless message is a predicate
# method followed by a non-whitespace char (e.g. is_a?String).
end_paren += 1 unless /\?\S/.match?(node.source)
range_between(begin_paren, end_paren)
end
end
end
end
end