absl::Status CompressorOptions::FromString()

in riegeli/chunk_encoding/compressor_options.cc [45:146]
100 lines of code
7 McCabe index (conditional complexity)

absl::Status CompressorOptions::FromString(absl::string_view text) {
  // Set just `compression_type_` first because other parsers depend on
  // `compression_type_`.
  {
    OptionsParser options_parser;
    options_parser.AddOption(
        "uncompressed",
        ValueParser::And(ValueParser::FailIfSeen("brotli", "zstd", "snappy"),
                         [this](ValueParser& value_parser) {
                           compression_type_ = CompressionType::kNone;
                           return true;
                         }));
    options_parser.AddOption(
        "brotli", ValueParser::And(
                      ValueParser::FailIfSeen("uncompressed", "zstd", "snappy"),
                      [this](ValueParser& value_parser) {
                        compression_type_ = CompressionType::kBrotli;
                        return true;
                      }));
    options_parser.AddOption(
        "zstd", ValueParser::And(
                    ValueParser::FailIfSeen("uncompressed", "brotli", "snappy"),
                    [this](ValueParser& value_parser) {
                      compression_type_ = CompressionType::kZstd;
                      return true;
                    }));
    options_parser.AddOption(
        "snappy", ValueParser::And(
                      ValueParser::FailIfSeen("uncompressed", "brotli", "zstd"),
                      [this](ValueParser& value_parser) {
                        compression_type_ = CompressionType::kSnappy;
                        return true;
                      }));
    options_parser.AddOption("window_log",
                             [](ValueParser& value_parser) { return true; });
    if (ABSL_PREDICT_FALSE(!options_parser.FromString(text))) {
      return options_parser.status();
    }
  }
  int window_log;
  OptionsParser options_parser;
  options_parser.AddOption(
      "uncompressed",
      ValueParser::And(ValueParser::FailIfSeen("window_log"),
                       ValueParser::Empty(0, &compression_level_)));
  options_parser.AddOption(
      "brotli",
      ValueParser::Or(
          ValueParser::Empty(
              BrotliWriterBase::Options::kDefaultCompressionLevel,
              &compression_level_),
          ValueParser::Int(BrotliWriterBase::Options::kMinCompressionLevel,
                           BrotliWriterBase::Options::kMaxCompressionLevel,
                           &compression_level_)));
  options_parser.AddOption(
      "zstd",
      ValueParser::Or(
          ValueParser::Empty(ZstdWriterBase::Options::kDefaultCompressionLevel,
                             &compression_level_),
          ValueParser::Int(ZstdWriterBase::Options::kMinCompressionLevel,
                           ZstdWriterBase::Options::kMaxCompressionLevel,
                           &compression_level_)));
  options_parser.AddOption(
      "snappy", ValueParser::And(ValueParser::FailIfSeen("window_log"),
                                 ValueParser::Empty(0, &compression_level_)));
  options_parser.AddOption("window_log", [&] {
    switch (compression_type_) {
      case CompressionType::kNone:
        return ValueParser::FailIfSeen("uncompressed");
      case CompressionType::kBrotli:
        return ValueParser::Or(
            ValueParser::Enum({{"auto", absl::nullopt}}, &window_log_),
            ValueParser::And(
                ValueParser::Int(BrotliWriterBase::Options::kMinWindowLog,
                                 BrotliWriterBase::Options::kMaxWindowLog,
                                 &window_log),
                [this, &window_log](ValueParser& value_parser) {
                  window_log_ = window_log;
                  return true;
                }));
      case CompressionType::kZstd:
        return ValueParser::Or(
            ValueParser::Enum({{"auto", absl::nullopt}}, &window_log_),
            ValueParser::And(
                ValueParser::Int(ZstdWriterBase::Options::kMinWindowLog,
                                 ZstdWriterBase::Options::kMaxWindowLog,
                                 &window_log),
                [this, &window_log](ValueParser& value_parser) {
                  window_log_ = window_log;
                  return true;
                }));
      case CompressionType::kSnappy:
        return ValueParser::FailIfSeen("snappy");
    }
    RIEGELI_ASSERT_UNREACHABLE() << "Unknown compression type: "
                                 << static_cast<unsigned>(compression_type_);
  }());
  if (ABSL_PREDICT_FALSE(!options_parser.FromString(text))) {
    return options_parser.status();
  }
  return absl::OkStatus();
}