string_builder.hpp

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#pragma once
 
/// @file userver/formats/json/string_builder.hpp
/// @brief @copybrief formats::json::StringBuilder
 
#include <string>
#include <string_view>
 
#include <userver/formats/json/string_builder_fwd.hpp>
#include <userver/formats/json/value.hpp>
#include <userver/formats/serialize/to.hpp>
#include <userver/formats/serialize/write_to_stream.hpp>
#include <userver/utils/fast_pimpl.hpp>
 
USERVER_NAMESPACE_BEGIN
 
namespace formats::json {
 
// clang-format off
 
/// @ingroup userver_universal userver_containers userver_formats userver_formats_serialize_sax
///
/// @brief SAX like builder of JSON string. Use with extreme caution and only in
/// performance critical part of your code.
///
/// Prefer using WriteToStream function to add data to the StringBuilder.
///
/// ## Example usage:
///
/// @snippet formats/json/string_builder_test.cpp  Sample formats::json::StringBuilder usage
///
/// @see @ref scripts/docs/en/userver/formats.md
 
// clang-format on
 
class StringBuilder final : public serialize::SaxStream {
 public:
  // Required by the WriteToStream fallback to Serialize
  using Value = formats::json::Value;
 
  StringBuilder();
  ~StringBuilder();
 
  /// Construct this guard on new object start and its destructor will end the
  /// object
  class ObjectGuard final {
   public:
    explicit ObjectGuard(StringBuilder& sw);
    ~ObjectGuard();
 
   private:
    StringBuilder& sw_;
  };
 
  /// Construct this guard on new array start and its destructor will end the
  /// array
  class ArrayGuard final {
   public:
    explicit ArrayGuard(StringBuilder& sw);
    ~ArrayGuard();
 
   private:
    StringBuilder& sw_;
  };
 
  /// @return JSON string
  std::string GetString() const;
  std::string_view GetStringView() const;
 
  void WriteNull();
  void WriteString(std::string_view value);
  void WriteBool(bool value);
  void WriteInt64(int64_t value);
  void WriteUInt64(uint64_t value);
  void WriteDouble(double value);
 
  /// ONLY for objects/dicts: write key
  void Key(std::string_view sw);
 
  /// Appends raw data
  void WriteRawString(std::string_view value);
 
  void WriteValue(const Value& value);
 
 private:
  struct Impl;
  utils::FastPimpl<Impl, 112, 8> impl_;
};
 
void WriteToStream(bool value, StringBuilder& sw);
void WriteToStream(long long value, StringBuilder& sw);
void WriteToStream(unsigned long long value, StringBuilder& sw);
void WriteToStream(int value, StringBuilder& sw);
void WriteToStream(unsigned value, StringBuilder& sw);
void WriteToStream(long value, StringBuilder& sw);
void WriteToStream(unsigned long value, StringBuilder& sw);
void WriteToStream(double value, StringBuilder& sw);
void WriteToStream(const char* value, StringBuilder& sw);
void WriteToStream(std::string_view value, StringBuilder& sw);
void WriteToStream(const formats::json::Value& value, StringBuilder& sw);
void WriteToStream(const std::string& value, StringBuilder& sw);
 
void WriteToStream(std::chrono::system_clock::time_point tp, StringBuilder& sw);
 
}  // namespace formats::json
 
USERVER_NAMESPACE_END