class RuboCop::Cop::Layout::SpaceInLambdaLiteral

a = -> (x, y) { x + y }
# good
a = ->(x, y) { x + y }
# bad
@example EnforcedStyle: require_space
a = ->(x, y) { x + y }
# good
a = -> (x, y) { x + y }
# bad
@example EnforcedStyle: require_no_space (default)
parenthesis (‘(`) in lambda literals.
This cop checks for spaces between `->` and opening parameter

def arrow_lambda_with_args?(node) 

def arrow_lambda_with_args?(node)
  node.lambda_literal? && node.parent.arguments?
end

def lambda_arguments(node) 

def lambda_arguments(node)
  node.parent.children[1]
end

def on_send(node) 

def on_send(node)
  return unless arrow_lambda_with_args?(node)
  if style == :require_space && !space_after_arrow?(node)
    lambda_node = range_of_offense(node)
    add_offense(lambda_node, message: MSG_REQUIRE_SPACE) do |corrector|
      corrector.insert_before(lambda_arguments(node), ' ')
    end
  elsif style == :require_no_space && space_after_arrow?(node)
    space = space_after_arrow(node)
    add_offense(space, message: MSG_REQUIRE_NO_SPACE) do |corrector|
      corrector.remove(space)
    end
  end
end

def range_of_offense(node) 

def range_of_offense(node)
  range_between(
    node.parent.loc.expression.begin_pos,
    node.parent.arguments.loc.expression.end_pos
  )
end

def space_after_arrow(lambda_node) 

def space_after_arrow(lambda_node)
  arrow = lambda_node.parent.children[0].source_range
  parentheses = lambda_node.parent.children[1].source_range
  arrow.end.join(parentheses.begin)
end

def space_after_arrow?(lambda_node) 

def space_after_arrow?(lambda_node)
  !space_after_arrow(lambda_node).empty?
end