class RuboCop::NodePattern::Compiler

def compile_expr_with_index(tokens, cur_node, index)
  if index.nil?
    # in 'sequence head' position; some expressions are compiled
    # differently at 'sequence head' (notably 'node type' expressions)
    # grep for seq_head to see where it makes a difference
    [compile_expr(tokens, cur_node, true), 0]
  else
    child_node = "#{cur_node}.children[#{index}]"
    [compile_expr(tokens, child_node, false), index + 1]
  end
end