lib/rubocop/cop/layout/line_end_string_concatenation_indentation.rb
# frozen_string_literal: true
module RuboCop
module Cop
module Layout
# Checks the indentation of the next line after a line that ends with a string
# literal and a backslash.
#
# If `EnforcedStyle: aligned` is set, the concatenated string parts shall be aligned with the
# first part. There are some exceptions, such as implicit return values, where the
# concatenated string parts shall be indented regardless of `EnforcedStyle` configuration.
#
# If `EnforcedStyle: indented` is set, it's the second line that shall be indented one step
# more than the first line. Lines 3 and forward shall be aligned with line 2.
#
# @example
# # bad
# def some_method
# 'x' \
# 'y' \
# 'z'
# end
#
# my_hash = {
# first: 'a message' \
# 'in two parts'
# }
#
# # good
# def some_method
# 'x' \
# 'y' \
# 'z'
# end
#
# @example EnforcedStyle: aligned (default)
# # bad
# puts 'x' \
# 'y'
#
# my_hash = {
# first: 'a message' \
# 'in two parts'
# }
#
# # good
# puts 'x' \
# 'y'
#
# my_hash = {
# first: 'a message' \
# 'in two parts'
# }
#
# @example EnforcedStyle: indented
# # bad
# result = 'x' \
# 'y'
#
# my_hash = {
# first: 'a message' \
# 'in two parts'
# }
#
# # good
# result = 'x' \
# 'y'
#
# my_hash = {
# first: 'a message' \
# 'in two parts'
# }
#
class LineEndStringConcatenationIndentation < Base
include ConfigurableEnforcedStyle
include Alignment
extend AutoCorrector
MSG_ALIGN = 'Align parts of a string concatenated with backslash.'
MSG_INDENT = 'Indent the first part of a string concatenated with backslash.'
PARENT_TYPES_FOR_INDENTED = [nil, :block, :begin, :def, :defs, :if].freeze
def on_dstr(node)
return unless strings_concatenated_with_backslash?(node)
children = node.children
return if children.empty?
if style == :aligned && !always_indented?(node)
check_aligned(children, 1)
else
check_indented(children)
check_aligned(children, 2)
end
end
def autocorrect(corrector, node)
AlignmentCorrector.correct(corrector, processed_source, node, @column_delta)
end
private
def strings_concatenated_with_backslash?(dstr_node)
dstr_node.multiline? &&
dstr_node.children.all? { |c| c.str_type? || c.dstr_type? } &&
dstr_node.children.none?(&:multiline?)
end
def always_indented?(dstr_node)
PARENT_TYPES_FOR_INDENTED.include?(dstr_node.parent&.type)
end
def check_aligned(children, start_index)
base_column = children[start_index - 1].loc.column
children[start_index..].each do |child|
@column_delta = base_column - child.loc.column
add_offense_and_correction(child, MSG_ALIGN) if @column_delta != 0
base_column = child.loc.column
end
end
def check_indented(children)
@column_delta = base_column(children[0]) + configured_indentation_width -
children[1].loc.column
add_offense_and_correction(children[1], MSG_INDENT) if @column_delta != 0
end
def base_column(child)
grandparent = child.parent.parent
if grandparent&.type == :pair
grandparent.loc.column
else
child.source_range.source_line =~ /\S/
end
end
def add_offense_and_correction(node, message)
add_offense(node, message: message) { |corrector| autocorrect(corrector, node) }
end
end
end
end
end