tskv_parser_read.hpp

Go to the documentation of this file.

#pragma once
 
/// @file userver/utils/encoding/tskv_parser_read.hpp
/// @brief @copybrief utils::encoding::TskvReadKeysValues
 
#include <utility>
 
#include <userver/compiler/thread_local.hpp>
#include <userver/utils/encoding/tskv_parser.hpp>
 
USERVER_NAMESPACE_BEGIN
 
namespace utils::encoding {
 
namespace impl {
 
struct TskvParserKvStorage {
  std::string key{};
  std::string value{};
};
 
inline compiler::ThreadLocal tskv_parser_kv_storage = [] {
  return TskvParserKvStorage{};
};
 
}  // namespace impl
 
/// @brief Read all keys-values for 1 TSKV record.
///
/// @param parser parser that should have already found the start of the TSKV
/// record using TskvParser::SkipToRecordBegin
/// @param consumer a lambda with the signature
/// `(const std::string&, const std::string&) -> bool`;
/// the strings are temporaries, references to them should not be stored;
/// can return `false` to skip the record and return immediately
///
/// Usage example:
/// @snippet utils/encoding/tskv_parser_test.cpp  sample
template <typename TagConsumer>
TskvParser::RecordStatus TskvReadRecord(TskvParser& parser,
                                        TagConsumer consumer) {
  using RecordStatus = TskvParser::RecordStatus;
 
  auto kv_storage = impl::tskv_parser_kv_storage.Use();
 
  while (true) {
    if (const auto key_status = parser.ReadKey(kv_storage->key)) {
      return *key_status;
    }
 
    const auto value_status = parser.ReadValue(kv_storage->value);
    if (value_status == RecordStatus::kIncomplete) {
      return RecordStatus::kIncomplete;
    }
 
    const bool record_ok = consumer(std::as_const(kv_storage->key),
                                    std::as_const(kv_storage->value));
    if (value_status == RecordStatus::kReachedEnd) {
      return RecordStatus::kReachedEnd;
    }
    if (!record_ok) {
      return parser.SkipToRecordEnd();
    }
  }
}
 
}  // namespace utils::encoding
 
USERVER_NAMESPACE_END