module Erubis::CGenerator

def add_expr_debug(src, code)
  code.strip!
  s = nil
  if code =~ /\A\".*?\"\s*,\s*(.*)/
    s = $1.gsub(/[%"]/, '\\\1') + '='
  end
  src << @indent if src.empty? || src[-1] == ?\n
  src << " fprintf(stderr, \"*** debug: #{s}\" #{code});"
end