class RuboCop::Cop::Style::EmptyCaseCondition

This cop checks for case statements with an empty condition.

@example

# bad:
case
when x == 0
  puts 'x is 0'
when y == 0
  puts 'y is 0'
else
  puts 'neither is 0'
end

# good:
if x == 0
  puts 'x is 0'
elsif y == 0
  puts 'y is 0'
else
  puts 'neither is 0'
end

# good: (the case condition node is not empty)
case n
when 0
  puts 'zero'
when 1
  puts 'one'
else
  puts 'more'
end

Constants

MSG

Public Instance Methods

on_case(case_node) click to toggle source
# File lib/rubocop/cop/style/empty_case_condition.rb, line 42
def on_case(case_node)
  condition_node = case_node.children.first

  add_offense(case_node, :keyword, MSG) if condition_node.nil?
end

Private Instance Methods

autocorrect(case_node) click to toggle source
# File lib/rubocop/cop/style/empty_case_condition.rb, line 50
def autocorrect(case_node)
  lambda do |corrector|
    _cond_node, *when_nodes, _else_node = *case_node

    correct_case_whens(corrector, case_node, when_nodes)

    correct_multiple_alternative_whens(corrector, when_nodes)
  end
end
correct_case_whens(corrector, case_node, when_nodes) click to toggle source
# File lib/rubocop/cop/style/empty_case_condition.rb, line 60
def correct_case_whens(corrector, case_node, when_nodes)
  case_to_first_when =
    case_node.loc.keyword.join(when_nodes.first.loc.keyword)

  corrector.replace(case_to_first_when, 'if')

  when_nodes.drop(1).each do |when_node|
    corrector.replace(when_node.loc.keyword, 'elsif')
  end
end
correct_multiple_alternative_whens(corrector, when_nodes) click to toggle source

Since an if condition containing commas is not syntactically valid, we correct `when x, y` to `if x || y`.

# File lib/rubocop/cop/style/empty_case_condition.rb, line 73
def correct_multiple_alternative_whens(corrector, when_nodes)
  when_nodes.each do |when_node|
    # In `when a; r` we have two children: [a, r].
    # In `when a, b, c; r` we have 4.
    # In `when a, b then r` we have 3.
    *children, _ = when_node.children

    next unless children.size > 1

    first = children.first
    last = children.last
    range =
      Parser::Source::Range.new(when_node.loc.expression.source_buffer,
                                first.loc.expression.begin_pos,
                                last.loc.expression.end_pos)

    corrector.replace(range, children.map(&:source).join(' || '))
  end
end