class RuboCop::Cop::Style::InverseMethods

!(foo.class < Numeric) # Checking class hierarchy is allowed
!!(‘foo’ =~ /^w+$/)
foo == bar
foo != bar
foo.any? { |f| f.even? }
foo.blank?
foo.none?
# good
foo.reject { |f| f != 7 }
foo.select { |f| !f.even? }
!(foo == bar)
!foo.blank?
!foo.any? { |f| f.even? }
!foo.none?
# bad
@example
`InverseBlocks`
of the block that is passed to the method should be defined in
Methods that are inverted by inverting the return
in ‘InverseMethods`
Methods that can be inverted by a not (`not` or `!`) should be defined
when an inverse of that method can be used instead.
This cop check for usages of not (`not` or `!`) called on a method

def autocorrect(node) 

def autocorrect(node)
  method_call, _lhs, method, _rhs = inverse_candidate?(node)
  if method_call && method
    lambda do |corrector|
      corrector.remove(not_to_receiver(node, method_call))
      corrector.replace(method_call.loc.selector,
                        inverse_methods[method].to_s)
      if EQUALITY_METHODS.include?(method)
        corrector.remove(end_parentheses(node, method_call))
      end
    end
  else
    correct_inverse_block(node)
  end
end

def camel_case_constant?(node) 

def camel_case_constant?(node)
  node.const_type? && node.source =~ CAMEL_CASE
end

def correct_inverse_block(node) 

def correct_inverse_block(node)
  method_call, method, block = inverse_block?(node)
  lambda do |corrector|
    corrector.replace(method_call.loc.selector,
                      inverse_blocks[method].to_s)
    correct_inverse_selector(block, corrector)
  end
end

def correct_inverse_selector(block, corrector) 

def correct_inverse_selector(block, corrector)
  selector = block.loc.selector.source
  if NEGATED_EQUALITY_METHODS.include?(selector.to_sym)
    selector[0] = '='
    corrector.replace(block.loc.selector, selector)
  else
    corrector.remove(block.loc.selector)
  end
end

def end_parentheses(node, method_call) 

def end_parentheses(node, method_call)
  Parser::Source::Range.new(node.loc.expression.source_buffer,
                            method_call.loc.expression.end_pos,
                            node.loc.expression.end_pos)
end

def inverse_blocks 

def inverse_blocks
  @inverse_blocks ||= cop_config['InverseBlocks']
                      .merge(cop_config['InverseBlocks'].invert)
end

def inverse_methods 

def inverse_methods
  @inverse_methods ||= cop_config['InverseMethods']
                       .merge(cop_config['InverseMethods'].invert)
end

def negated?(node) 

def negated?(node)
  node.parent.respond_to?(:method?) && node.parent.method?(:!)
end

def not_to_receiver(node, method_call) 

def not_to_receiver(node, method_call)
  Parser::Source::Range.new(node.loc.expression.source_buffer,
                            node.loc.selector.begin_pos,
                            method_call.loc.expression.begin_pos)
end

def on_block(node) 

def on_block(node)
  inverse_block?(node) do |_method_call, method, block|
    return unless inverse_blocks.key?(method)
    return if negated?(node) && negated?(node.parent)
    # Inverse method offenses inside of the block of an inverse method
    # offense, such as `y.reject { |key, _value| !(key =~ /c\d/) }`,
    # can cause auto-correction to apply improper corrections.
    ignore_node(block)
    add_offense(node,
                message: format(MSG, method: method,
                                     inverse: inverse_blocks[method]))
  end
end

def on_send(node) 

def on_send(node)
  return if part_of_ignored_node?(node)
  inverse_candidate?(node) do |_method_call, lhs, method, rhs|
    return unless inverse_methods.key?(method)
    return if possible_class_hierarchy_check?(lhs, rhs, method)
    return if negated?(node)
    add_offense(node,
                message: format(MSG, method: method,
                                     inverse: inverse_methods[method]))
  end
end

def possible_class_hierarchy_check?(lhs, rhs, method)

`Integer > Numeric`.
When comparing classes, `!(Integer < Numeric)` is not the same as 
def possible_class_hierarchy_check?(lhs, rhs, method)
  CLASS_COMPARISON_METHODS.include?(method) &&
    (camel_case_constant?(lhs) ||
     (rhs.size == 1 &&
      camel_case_constant?(rhs.first)))
end