class RuboCop::Cop::Style::IfUnlessModifier

Checks for ‘if` and `unless` statements that would fit on one line if written as modifier `if`/`unless`. The cop also checks for modifier `if`/`unless` lines that exceed the maximum line length.

The maximum line length is configured in the ‘Layout/LineLength` cop. The tab size is configured in the `IndentationWidth` of the `Layout/IndentationStyle` cop.

One-line pattern matching is always allowed. To ensure that there are few cases where the match variable is not used, and to prevent oversights. The variable ‘x` becomes undefined and raises `NameError` when the following example is changed to the modifier form:

source,ruby

if [42] in [x]

x # `x` is undefined when using modifier form.

end


NOTE: It is allowed when ‘defined?` argument has an undefined value, because using the modifier form causes the following incompatibility:

source,ruby

unless defined?(undefined_foo)

undefined_foo = 'default_value'

end undefined_foo # => ‘default_value’

undefined_bar = ‘default_value’ unless defined?(undefined_bar) undefined_bar # => nil


@example

# bad
if condition
  do_stuff(bar)
end

unless qux.empty?
  Foo.do_something
end

do_something_with_a_long_name(arg) if long_condition_that_prevents_code_fit_on_single_line

# good
do_stuff(bar) if condition
Foo.do_something unless qux.empty?

if long_condition_that_prevents_code_fit_on_single_line
  do_something_with_a_long_name(arg)
end

if short_condition # a long comment that makes it too long if it were just a single line
  do_something
end

Constants

MSG_USE_MODIFIER
MSG_USE_NORMAL

Public Class Methods

autocorrect_incompatible_with() click to toggle source
# File lib/rubocop/cop/style/if_unless_modifier.rb, line 76
def self.autocorrect_incompatible_with
  [Style::SoleNestedConditional]
end

Public Instance Methods

on_if(node) click to toggle source
# File lib/rubocop/cop/style/if_unless_modifier.rb, line 80
def on_if(node)
  condition = node.condition
  return if defined_nodes(condition).any? { |n| defined_argument_is_undefined?(node, n) } ||
            pattern_matching_nodes(condition).any?
  return unless (msg = message(node))

  add_offense(node.loc.keyword, message: format(msg, keyword: node.keyword)) do |corrector|
    next if part_of_ignored_node?(node)

    autocorrect(corrector, node)
    ignore_node(node)
  end
end

Private Instance Methods

allowed_patterns() click to toggle source
# File lib/rubocop/cop/style/if_unless_modifier.rb, line 171
def allowed_patterns
  line_length_config = config.for_cop('Layout/LineLength')
  line_length_config['AllowedPatterns'] || line_length_config['IgnoredPatterns'] || []
end
another_statement_on_same_line?(node) click to toggle source
# File lib/rubocop/cop/style/if_unless_modifier.rb, line 231
def another_statement_on_same_line?(node)
  line_no = node.source_range.last_line

  # traverse the AST upwards until we find a 'begin' node
  # we want to look at the following child and see if it is on the
  #   same line as this 'if' node
  while node && !node.begin_type?
    index = node.sibling_index
    node  = node.parent
  end

  node && (sibling = node.children[index + 1]) && sibling.source_range.first_line == line_no
end
autocorrect(corrector, node) click to toggle source
# File lib/rubocop/cop/style/if_unless_modifier.rb, line 132
def autocorrect(corrector, node)
  replacement = if node.modifier_form?
                  replacement_for_modifier_form(corrector, node)
                else
                  to_modifier_form(node)
                end
  corrector.replace(node, replacement)
end
comment_on_node_line(node) click to toggle source
# File lib/rubocop/cop/style/if_unless_modifier.rb, line 285
def comment_on_node_line(node)
  processed_source.comments.find { |c| same_line?(c, node) }
end
defined_argument_is_undefined?(if_node, defined_node) click to toggle source
# File lib/rubocop/cop/style/if_unless_modifier.rb, line 104
def defined_argument_is_undefined?(if_node, defined_node)
  defined_argument = defined_node.first_argument
  return false unless defined_argument.lvar_type? || defined_argument.send_type?

  if_node.left_siblings.none? do |sibling|
    sibling.respond_to?(:lvasgn_type?) && sibling.lvasgn_type? &&
      sibling.name == defined_argument.node_parts[0]
  end
end
defined_nodes(condition) click to toggle source
# File lib/rubocop/cop/style/if_unless_modifier.rb, line 96
def defined_nodes(condition)
  if condition.defined_type?
    [condition]
  else
    condition.each_descendant.select(&:defined_type?)
  end
end
extract_heredoc_from(last_argument) click to toggle source
# File lib/rubocop/cop/style/if_unless_modifier.rb, line 272
def extract_heredoc_from(last_argument)
  heredoc_body = last_argument.loc.heredoc_body
  heredoc_end = last_argument.loc.heredoc_end

  [heredoc_body, heredoc_end]
end
line_length_enabled_at_line?(line) click to toggle source
# File lib/rubocop/cop/style/if_unless_modifier.rb, line 215
def line_length_enabled_at_line?(line)
  processed_source.comment_config.cop_enabled_at_line?('Layout/LineLength', line)
end
message(node) click to toggle source
# File lib/rubocop/cop/style/if_unless_modifier.rb, line 124
def message(node)
  if single_line_as_modifier?(node) && !named_capture_in_condition?(node)
    MSG_USE_MODIFIER
  elsif too_long_due_to_modifier?(node)
    MSG_USE_NORMAL
  end
end
named_capture_in_condition?(node) click to toggle source
# File lib/rubocop/cop/style/if_unless_modifier.rb, line 219
def named_capture_in_condition?(node)
  node.condition.match_with_lvasgn_type?
end
non_eligible_node?(node) click to toggle source
# File lib/rubocop/cop/style/if_unless_modifier.rb, line 223
def non_eligible_node?(node)
  non_simple_if_unless?(node) || node.chained? || node.nested_conditional? || super
end
non_simple_if_unless?(node) click to toggle source
# File lib/rubocop/cop/style/if_unless_modifier.rb, line 227
def non_simple_if_unless?(node)
  node.ternary? || node.elsif? || node.else?
end
pattern_matching_nodes(condition) click to toggle source
# File lib/rubocop/cop/style/if_unless_modifier.rb, line 114
def pattern_matching_nodes(condition)
  if condition.match_pattern_type? || condition.match_pattern_p_type?
    [condition]
  else
    condition.each_descendant.select do |node|
      node.match_pattern_type? || node.match_pattern_p_type?
    end
  end
end
remove_comment(corrector, _node, comment) click to toggle source
# File lib/rubocop/cop/style/if_unless_modifier.rb, line 289
def remove_comment(corrector, _node, comment)
  corrector.remove(range_with_surrounding_space(range: comment.source_range, side: :left))
end
remove_heredoc(corrector, heredoc) click to toggle source
# File lib/rubocop/cop/style/if_unless_modifier.rb, line 279
def remove_heredoc(corrector, heredoc)
  heredoc.each do |range|
    corrector.remove(range_by_whole_lines(range, include_final_newline: true))
  end
end
replacement_for_modifier_form(corrector, node) click to toggle source
# File lib/rubocop/cop/style/if_unless_modifier.rb, line 141
def replacement_for_modifier_form(corrector, node) # rubocop:disable Metrics/AbcSize
  comment = comment_on_node_line(node)
  if comment && too_long_due_to_comment_after_modifier?(node, comment)
    remove_comment(corrector, node, comment)

    return to_modifier_form_with_move_comment(node, indent(node), comment)
  end

  last_argument = node.if_branch.last_argument if node.if_branch.send_type?
  if last_argument.respond_to?(:heredoc?) && last_argument.heredoc?
    heredoc = extract_heredoc_from(last_argument)
    remove_heredoc(corrector, heredoc)

    return to_normal_form_with_heredoc(node, indent(node), heredoc)
  end

  to_normal_form(node, indent(node))
end
to_modifier_form_with_move_comment(node, indentation, comment) click to toggle source
# File lib/rubocop/cop/style/if_unless_modifier.rb, line 265
        def to_modifier_form_with_move_comment(node, indentation, comment)
          <<~RUBY.chomp
            #{comment.source}
            #{indentation}#{node.body.source} #{node.keyword} #{node.condition.source}
          RUBY
        end
to_normal_form(node, indentation) click to toggle source
# File lib/rubocop/cop/style/if_unless_modifier.rb, line 245
        def to_normal_form(node, indentation)
          <<~RUBY.chomp
            #{node.keyword} #{node.condition.source}
            #{indentation}  #{node.body.source}
            #{indentation}end
          RUBY
        end
to_normal_form_with_heredoc(node, indentation, heredoc) click to toggle source
# File lib/rubocop/cop/style/if_unless_modifier.rb, line 253
        def to_normal_form_with_heredoc(node, indentation, heredoc)
          heredoc_body, heredoc_end = heredoc

          <<~RUBY.chomp
            #{node.keyword} #{node.condition.source}
            #{indentation}  #{node.body.source}
            #{indentation}  #{heredoc_body.source.chomp}
            #{indentation}  #{heredoc_end.source.chomp}
            #{indentation}end
          RUBY
        end
too_long_due_to_comment_after_modifier?(node, comment) click to toggle source
# File lib/rubocop/cop/style/if_unless_modifier.rb, line 165
def too_long_due_to_comment_after_modifier?(node, comment)
  source_length = processed_source.lines[node.first_line - 1].length
  source_length >= max_line_length &&
    source_length - comment.source_range.length <= max_line_length
end
too_long_due_to_modifier?(node) click to toggle source
# File lib/rubocop/cop/style/if_unless_modifier.rb, line 160
def too_long_due_to_modifier?(node)
  node.modifier_form? && too_long_single_line?(node) &&
    !another_statement_on_same_line?(node)
end
too_long_line_based_on_allow_uri?(line) click to toggle source
# File lib/rubocop/cop/style/if_unless_modifier.rb, line 206
def too_long_line_based_on_allow_uri?(line)
  if allow_uri?
    uri_range = find_excessive_uri_range(line)
    return false if uri_range && allowed_uri_position?(line, uri_range)
  end

  true
end
too_long_line_based_on_config?(range, line) click to toggle source
# File lib/rubocop/cop/style/if_unless_modifier.rb, line 189
def too_long_line_based_on_config?(range, line)
  return false if matches_allowed_pattern?(line)

  too_long = too_long_line_based_on_ignore_cop_directives?(range, line)
  return too_long unless too_long == :undetermined

  too_long_line_based_on_allow_uri?(line)
end
too_long_line_based_on_ignore_cop_directives?(range, line) click to toggle source
# File lib/rubocop/cop/style/if_unless_modifier.rb, line 198
def too_long_line_based_on_ignore_cop_directives?(range, line)
  if ignore_cop_directives? && directive_on_source_line?(range.line - 1)
    return line_length_without_directive(line) > max_line_length
  end

  :undetermined
end
too_long_single_line?(node) click to toggle source
# File lib/rubocop/cop/style/if_unless_modifier.rb, line 176
def too_long_single_line?(node)
  return false unless max_line_length

  range = node.source_range
  return false unless range.single_line?
  return false unless line_length_enabled_at_line?(range.first_line)

  line = range.source_line
  return false if line_length(line) <= max_line_length

  too_long_line_based_on_config?(range, line)
end