class Prism::LibRubyParser::PrismString

def self.with_file(filepath)
  raise TypeError unless filepath.is_a?(String)
  # On Windows and Mac, it's expected that filepaths will be encoded in
  # UTF-8. If they are not, we need to convert them to UTF-8 before
  # passing them into pm_string_mapped_init.
  if RbConfig::CONFIG["host_os"].match?(/bccwin|cygwin|djgpp|mingw|mswin|wince|darwin/i) &&
     (encoding = filepath.encoding) != Encoding::ASCII_8BIT && encoding != Encoding::UTF_8
    filepath = filepath.encode(Encoding::UTF_8)
  end
  FFI::MemoryPointer.new(SIZEOF) do |pm_string|
    case (result = LibRubyParser.pm_string_mapped_init(pm_string, filepath))
    when :PM_STRING_INIT_SUCCESS
      pointer = LibRubyParser.pm_string_source(pm_string)
      length = LibRubyParser.pm_string_length(pm_string)
      return yield new(pointer, length, false)
    when :PM_STRING_INIT_ERROR_GENERIC
      raise SystemCallError.new(filepath, FFI.errno)
    when :PM_STRING_INIT_ERROR_DIRECTORY
      raise Errno::EISDIR.new(filepath)
    else
      raise "Unknown error initializing pm_string_t: #{result.inspect}"
    end
  ensure
    LibRubyParser.pm_string_free(pm_string)
  end
end