lib/rubocop/cop/style/if_inside_else.rb
# frozen_string_literal: true
module RuboCop
module Cop
module Style
# If the `else` branch of a conditional consists solely of an `if` node,
# it can be combined with the `else` to become an `elsif`.
# This helps to keep the nesting level from getting too deep.
#
# @example
# # bad
# if condition_a
# action_a
# else
# if condition_b
# action_b
# else
# action_c
# end
# end
#
# # good
# if condition_a
# action_a
# elsif condition_b
# action_b
# else
# action_c
# end
#
# @example AllowIfModifier: false (default)
# # bad
# if condition_a
# action_a
# else
# action_b if condition_b
# end
#
# # good
# if condition_a
# action_a
# elsif condition_b
# action_b
# end
#
# @example AllowIfModifier: true
# # good
# if condition_a
# action_a
# else
# action_b if condition_b
# end
#
# # good
# if condition_a
# action_a
# elsif condition_b
# action_b
# end
#
class IfInsideElse < Base
include IgnoredNode
include RangeHelp
extend AutoCorrector
MSG = 'Convert `if` nested inside `else` to `elsif`.'
# rubocop:disable Metrics/CyclomaticComplexity
def on_if(node)
return if node.ternary? || node.unless?
else_branch = node.else_branch
return unless else_branch&.if_type? && else_branch&.if?
return if allow_if_modifier_in_else_branch?(else_branch)
add_offense(else_branch.loc.keyword) do |corrector|
next if part_of_ignored_node?(node)
autocorrect(corrector, else_branch)
ignore_node(node)
end
end
# rubocop:enable Metrics/CyclomaticComplexity
private
def autocorrect(corrector, node)
if then?(node)
# If the nested `if` is a then node, correct it first,
# then the next pass will use `correct_to_elsif_from_if_inside_else_form`
IfThenCorrector.new(node, indentation: 0).call(corrector)
return
end
if node.modifier_form?
correct_to_elsif_from_modifier_form(corrector, node)
else
correct_to_elsif_from_if_inside_else_form(corrector, node, node.condition)
end
corrector.remove(range_by_whole_lines(find_end_range(node), include_final_newline: true))
return unless (if_branch = node.if_branch)
range = range_by_whole_lines(if_branch.source_range, include_final_newline: true)
corrector.remove(range)
end
def correct_to_elsif_from_modifier_form(corrector, node)
corrector.replace(node.parent.loc.else, <<~RUBY.chop)
elsif #{node.condition.source}
#{indent(node.if_branch)}#{node.if_branch.source}
end
RUBY
end
def correct_to_elsif_from_if_inside_else_form(corrector, node, condition)
corrector.replace(node.parent.loc.else, "elsif #{condition.source}")
if_condition_range = if_condition_range(node, condition)
if (if_branch = node.if_branch)
corrector.replace(if_condition_range, if_branch.source)
else
corrector.remove(range_by_whole_lines(if_condition_range, include_final_newline: true))
end
corrector.remove(condition)
end
def then?(node)
node.loc.begin&.source == 'then'
end
def find_end_range(node)
end_range = node.loc.end
return end_range if end_range
find_end_range(node.parent)
end
def if_condition_range(node, condition)
range_between(node.loc.keyword.begin_pos, condition.source_range.end_pos)
end
def allow_if_modifier_in_else_branch?(else_branch)
allow_if_modifier? && else_branch&.modifier_form?
end
def allow_if_modifier?
cop_config['AllowIfModifier']
end
end
end
end
end