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class_and_module_children.rb
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/
class_and_module_children.rb
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# frozen_string_literal: true
module RuboCop
module Cop
module Style
# Checks the style of children definitions at classes and
# modules. Basically there are two different styles:
#
# @safety
# Autocorrection is unsafe.
#
# Moving from compact to nested children requires knowledge of whether the
# outer parent is a module or a class. Moving from nested to compact requires
# verification that the outer parent is defined elsewhere. Rubocop does not
# have the knowledge to perform either operation safely and thus requires
# manual oversight.
#
# @example EnforcedStyle: nested (default)
# # good
# # have each child on its own line
# class Foo
# class Bar
# end
# end
#
# @example EnforcedStyle: compact
# # good
# # combine definitions as much as possible
# class Foo::Bar
# end
#
# The compact style is only forced for classes/modules with one child.
class ClassAndModuleChildren < Base
include ConfigurableEnforcedStyle
include RangeHelp
extend AutoCorrector
NESTED_MSG = 'Use nested module/class definitions instead of compact style.'
COMPACT_MSG = 'Use compact module/class definition instead of nested style.'
def on_class(node)
return if node.parent_class && style != :nested
check_style(node, node.body)
end
def on_module(node)
check_style(node, node.body)
end
private
def nest_or_compact(corrector, node)
if style == :nested
nest_definition(corrector, node)
else
compact_definition(corrector, node)
end
end
def nest_definition(corrector, node)
padding = ((' ' * indent_width) + leading_spaces(node)).to_s
padding_for_trailing_end = padding.sub(' ' * node.loc.end.column, '')
replace_namespace_keyword(corrector, node)
split_on_double_colon(corrector, node, padding)
add_trailing_end(corrector, node, padding_for_trailing_end)
end
def replace_namespace_keyword(corrector, node)
class_definition = node.left_sibling&.each_node(:class)&.find do |class_node|
class_node.identifier == node.identifier.namespace
end
namespace_keyword = class_definition ? 'class' : 'module'
corrector.replace(node.loc.keyword, namespace_keyword)
end
def split_on_double_colon(corrector, node, padding)
children_definition = node.children.first
range = range_between(children_definition.loc.double_colon.begin_pos,
children_definition.loc.double_colon.end_pos)
replacement = "\n#{padding}#{node.loc.keyword.source} "
corrector.replace(range, replacement)
end
def add_trailing_end(corrector, node, padding)
replacement = "#{padding}end\n#{leading_spaces(node)}end"
corrector.replace(node.loc.end, replacement)
end
def compact_definition(corrector, node)
compact_node(corrector, node)
remove_end(corrector, node.body)
unindent(corrector, node)
end
def compact_node(corrector, node)
range = range_between(node.loc.keyword.begin_pos, node.body.loc.name.end_pos)
corrector.replace(range, compact_replacement(node))
end
def compact_replacement(node)
replacement = "#{node.body.type} #{compact_identifier_name(node)}"
body_comments = processed_source.ast_with_comments[node.body]
unless body_comments.empty?
replacement = body_comments.map(&:text).push(replacement).join("\n")
end
replacement
end
def compact_identifier_name(node)
"#{node.identifier.const_name}::" \
"#{node.body.children.first.const_name}"
end
def remove_end(corrector, body)
remove_begin_pos = body.loc.end.begin_pos - leading_spaces(body).size
adjustment = processed_source.raw_source[remove_begin_pos] == ';' ? 0 : 1
range = range_between(remove_begin_pos, body.loc.end.end_pos + adjustment)
corrector.remove(range)
end
def configured_indentation_width
config.for_badge(Layout::IndentationWidth.badge).fetch('Width', 2)
end
def unindent(corrector, node)
return if node.body.children.last.nil?
column_delta = configured_indentation_width - leading_spaces(node.body.children.last).size
return if column_delta.zero?
AlignmentCorrector.correct(corrector, processed_source, node, column_delta)
end
def leading_spaces(node)
node.source_range.source_line[/\A\s*/]
end
def indent_width
@config.for_cop('Layout/IndentationWidth')['Width'] || 2
end
def check_style(node, body)
return if node.identifier.children[0]&.cbase_type?
if style == :nested
check_nested_style(node)
else
check_compact_style(node, body)
end
end
def check_nested_style(node)
return unless compact_node_name?(node)
add_offense(node.loc.name, message: NESTED_MSG) do |corrector|
autocorrect(corrector, node)
end
end
def check_compact_style(node, body)
parent = node.parent
return if parent&.class_type? || parent&.module_type?
return unless needs_compacting?(body)
add_offense(node.loc.name, message: COMPACT_MSG) do |corrector|
autocorrect(corrector, node)
end
end
def autocorrect(corrector, node)
return if node.class_type? && node.parent_class && style != :nested
nest_or_compact(corrector, node)
end
def needs_compacting?(body)
body && %i[module class].include?(body.type)
end
def compact_node_name?(node)
/::/.match?(node.identifier.source)
end
end
end
end
end