lib/rubocop/cop/style/multiline_ternary_operator.rb
# frozen_string_literal: true
module RuboCop
module Cop
module Style
# Checks for multi-line ternary op expressions.
#
# NOTE: `return if ... else ... end` is syntax error. If `return` is used before
# multiline ternary operator expression, it will be autocorrected to single-line
# ternary operator. The same is true for `break`, `next`, and method call.
#
# @example
# # bad
# a = cond ?
# b : c
# a = cond ? b :
# c
# a = cond ?
# b :
# c
#
# return cond ?
# b :
# c
#
# # good
# a = cond ? b : c
# a = if cond
# b
# else
# c
# end
#
# return cond ? b : c
#
class MultilineTernaryOperator < Base
include CommentsHelp
extend AutoCorrector
MSG_IF = 'Avoid multi-line ternary operators, use `if` or `unless` instead.'
MSG_SINGLE_LINE = 'Avoid multi-line ternary operators, use single-line instead.'
SINGLE_LINE_TYPES = %i[return break next send csend].freeze
def on_if(node)
return unless offense?(node)
message = enforce_single_line_ternary_operator?(node) ? MSG_SINGLE_LINE : MSG_IF
add_offense(node, message: message) do |corrector|
next if part_of_ignored_node?(node)
autocorrect(corrector, node)
ignore_node(node)
end
end
private
def offense?(node)
node.ternary? && node.multiline? && node.source != replacement(node)
end
def autocorrect(corrector, node)
corrector.replace(node, replacement(node))
return unless (parent = node.parent)
return unless (comments_in_condition = comments_in_condition(node))
corrector.insert_before(parent, comments_in_condition)
end
def replacement(node)
if enforce_single_line_ternary_operator?(node)
"#{node.condition.source} ? #{node.if_branch.source} : #{node.else_branch.source}"
else
<<~RUBY.chop
if #{node.condition.source}
#{node.if_branch.source}
else
#{node.else_branch.source}
end
RUBY
end
end
def comments_in_condition(node)
comments_in_range(node).map do |comment|
"#{comment.source}\n"
end.join
end
def enforce_single_line_ternary_operator?(node)
SINGLE_LINE_TYPES.include?(node.parent&.type) && !use_assignment_method?(node.parent)
end
def use_assignment_method?(node)
node.send_type? && node.assignment_method?
end
end
end
end
end