class RuboCop::Cop::Style::YodaCondition

This cop can either enforce or forbid Yoda conditions, i.e. comparison operations where the order of expression is reversed. eg. `5 == x`

@example EnforcedStyle: forbid_for_all_comparison_operators (default)

# bad
99 == foo
"bar" != foo
42 >= foo
10 < bar

# good
foo == 99
foo == "bar"
foo <= 42
bar > 10

@example EnforcedStyle: forbid_for_equality_operators_only

# bad
99 == foo
"bar" != foo

# good
99 >= foo
3 < a && a < 5

@example EnforcedStyle: require_for_all_comparison_operators

# bad
foo == 99
foo == "bar"
foo <= 42
bar > 10

# good
99 == foo
"bar" != foo
42 >= foo
10 < bar

@example EnforcedStyle: require_for_equality_operators_only

# bad
99 >= foo
3 < a && a < 5

# good
99 == foo
"bar" != foo

Constants

EQUALITY_OPERATORS
MSG
NONCOMMUTATIVE_OPERATORS
REVERSE_COMPARISON

Public Instance Methods

autocorrect(node) click to toggle source
# File lib/rubocop/cop/style/yoda_condition.rb, line 77
def autocorrect(node)
  lambda do |corrector|
    corrector.replace(actual_code_range(node), corrected_code(node))
  end
end
on_send(node) click to toggle source
# File lib/rubocop/cop/style/yoda_condition.rb, line 70
def on_send(node)
  return unless yoda_compatible_condition?(node)
  return if equality_only? && non_equality_operator?(node)

  valid_yoda?(node) || add_offense(node)
end

Private Instance Methods

actual_code_range(node) click to toggle source
# File lib/rubocop/cop/style/yoda_condition.rb, line 121
def actual_code_range(node)
  range_between(
    node.loc.expression.begin_pos, node.loc.expression.end_pos
  )
end
corrected_code(node) click to toggle source
# File lib/rubocop/cop/style/yoda_condition.rb, line 114
def corrected_code(node)
  lhs = node.receiver
  rhs = node.first_argument

  "#{rhs.source} #{reverse_comparison(node.method_name)} #{lhs.source}"
end
enforce_yoda?() click to toggle source
# File lib/rubocop/cop/style/yoda_condition.rb, line 85
def enforce_yoda?
  style == :require_for_all_comparison_operators ||
    style == :require_for_equality_operators_only
end
equality_only?() click to toggle source
# File lib/rubocop/cop/style/yoda_condition.rb, line 90
def equality_only?
  style == :forbid_for_equality_operators_only ||
    style == :require_for_equality_operators_only
end
message(node) click to toggle source
# File lib/rubocop/cop/style/yoda_condition.rb, line 110
def message(node)
  format(MSG, source: node.source)
end
non_equality_operator?(node) click to toggle source
# File lib/rubocop/cop/style/yoda_condition.rb, line 131
def non_equality_operator?(node)
  !EQUALITY_OPERATORS.include?(node.method_name)
end
noncommutative_operator?(node) click to toggle source
# File lib/rubocop/cop/style/yoda_condition.rb, line 135
def noncommutative_operator?(node)
  NONCOMMUTATIVE_OPERATORS.include?(node.method_name)
end
reverse_comparison(operator) click to toggle source
# File lib/rubocop/cop/style/yoda_condition.rb, line 127
def reverse_comparison(operator)
  REVERSE_COMPARISON.fetch(operator.to_s, operator)
end
valid_yoda?(node) click to toggle source
# File lib/rubocop/cop/style/yoda_condition.rb, line 100
def valid_yoda?(node)
  lhs = node.receiver
  rhs = node.first_argument

  return true if lhs.literal? && rhs.literal? ||
                 !lhs.literal? && !rhs.literal?

  enforce_yoda? ? lhs.literal? : rhs.literal?
end
yoda_compatible_condition?(node) click to toggle source
# File lib/rubocop/cop/style/yoda_condition.rb, line 95
def yoda_compatible_condition?(node)
  node.comparison_method? &&
    !noncommutative_operator?(node)
end