lib/rubocop/cop/style/next.rb
# frozen_string_literal: true
module RuboCop
module Cop
module Style
# Use `next` to skip iteration instead of a condition at the end.
#
# @example EnforcedStyle: skip_modifier_ifs (default)
# # bad
# [1, 2].each do |a|
# if a == 1
# puts a
# end
# end
#
# # good
# [1, 2].each do |a|
# next unless a == 1
# puts a
# end
#
# # good
# [1, 2].each do |a|
# puts a if a == 1
# end
#
# @example EnforcedStyle: always
# # With `always` all conditions at the end of an iteration needs to be
# # replaced by next - with `skip_modifier_ifs` the modifier if like
# # this one are ignored: `[1, 2].each { |a| puts a if a == 1 }`
#
# # bad
# [1, 2].each do |a|
# puts a if a == 1
# end
#
# # bad
# [1, 2].each do |a|
# if a == 1
# puts a
# end
# end
#
# # good
# [1, 2].each do |a|
# next unless a == 1
# puts a
# end
class Next < Base
include ConfigurableEnforcedStyle
include MinBodyLength
include RangeHelp
extend AutoCorrector
MSG = 'Use `next` to skip iteration.'
EXIT_TYPES = %i[break return].freeze
def self.autocorrect_incompatible_with
[Style::SafeNavigation]
end
def on_new_investigation
# When correcting nested offenses, we need to keep track of how much
# we have adjusted the indentation of each line
@reindented_lines = Hash.new(0)
end
def on_block(node)
return unless node.send_node.call_type? && node.send_node.enumerator_method?
check(node)
end
alias on_numblock on_block
def on_while(node)
check(node)
end
alias on_until on_while
alias on_for on_while
private
def check(node)
return unless node.body && ends_with_condition?(node.body)
offending_node = offense_node(node.body)
add_offense(offense_location(offending_node)) do |corrector|
if offending_node.modifier_form?
autocorrect_modifier(corrector, offending_node)
else
autocorrect_block(corrector, offending_node)
end
end
end
def ends_with_condition?(body)
return true if simple_if_without_break?(body)
body.begin_type? && simple_if_without_break?(body.children.last)
end
def simple_if_without_break?(node)
return false unless if_without_else?(node)
return false if if_else_children?(node)
return false if allowed_modifier_if?(node)
!exit_body_type?(node)
end
def allowed_modifier_if?(node)
if node.modifier_form?
style == :skip_modifier_ifs
else
!min_body_length?(node)
end
end
def if_else_children?(node)
node.each_child_node(:if).any?(&:else?)
end
def if_without_else?(node)
node&.if_type? && !node.ternary? && !node.else?
end
def exit_body_type?(node)
return false unless node.if_branch
EXIT_TYPES.include?(node.if_branch.type)
end
def offense_node(body)
*_, condition = *body
condition&.if_type? ? condition : body
end
def offense_location(offense_node)
offense_begin_pos = offense_node.source_range.begin
offense_begin_pos.join(offense_node.condition.source_range)
end
def autocorrect_modifier(corrector, node)
body = node.if_branch || node.else_branch
replacement =
"next #{node.inverse_keyword} #{node.condition.source}\n" \
"#{' ' * node.source_range.column}#{body.source}"
corrector.replace(node, replacement)
end
def autocorrect_block(corrector, node)
next_code = "next #{node.inverse_keyword} #{node.condition.source}"
corrector.insert_before(node, next_code)
corrector.remove(cond_range(node, node.condition))
corrector.remove(end_range(node))
lines = reindentable_lines(node)
return if lines.empty?
reindent(lines, node.condition, corrector)
end
def cond_range(node, cond)
end_pos = if node.loc.begin
node.loc.begin.end_pos # after "then"
else
cond.source_range.end_pos
end
range_between(node.source_range.begin_pos, end_pos)
end
def end_range(node)
source_buffer = node.source_range.source_buffer
end_pos = node.loc.end.end_pos
begin_pos = node.loc.end.begin_pos - node.loc.end.column
begin_pos -= 1 if end_followed_by_whitespace_only?(source_buffer, end_pos)
range_between(begin_pos, end_pos)
end
def end_followed_by_whitespace_only?(source_buffer, end_pos)
/\A\s*$/.match?(source_buffer.source[end_pos..])
end
def reindentable_lines(node)
buffer = node.source_range.source_buffer
# end_range starts with the final newline of the if body
lines = (node.source_range.line + 1)...node.loc.end.line
lines = lines.to_a - heredoc_lines(node)
# Skip blank lines
lines.reject { |lineno| /\A\s*\z/.match?(buffer.source_line(lineno)) }
end
# Adjust indentation of `lines` to match `node`
def reindent(lines, node, corrector)
range = node.source_range
buffer = range.source_buffer
target_indent = range.source_line =~ /\S/
delta = actual_indent(lines, buffer) - target_indent
lines.each { |lineno| reindent_line(corrector, lineno, delta, buffer) }
end
def actual_indent(lines, buffer)
lines.map { |lineno| buffer.source_line(lineno) =~ /\S/ }.min
end
def heredoc_lines(node)
node.each_node(:dstr)
.select(&:heredoc?)
.map { |n| n.loc.heredoc_body }
.flat_map { |b| (b.line...b.last_line).to_a }
end
def reindent_line(corrector, lineno, delta, buffer)
adjustment = delta + @reindented_lines[lineno]
@reindented_lines[lineno] = adjustment
corrector.remove_leading(buffer.line_range(lineno), adjustment) if adjustment.positive?
end
end
end
end
end