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