mirror of
https://github.com/simdjson/simdjson
synced 2026-06-08 17:27:07 +00:00
Daniel Lemire
121 lines
4.3 KiB
C++
121 lines
4.3 KiB
C++
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#ifndef SIMDJSON_CONVERT_H
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#define SIMDJSON_CONVERT_H
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#include "simdjson/ondemand.h"
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#include <optional>
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#if SIMDJSON_SUPPORTS_CONCEPTS
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namespace simdjson {
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namespace convert {
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namespace internal {
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/**
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* A utility class for automatically parsing JSON documents.
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* This template is NOT part of our public API.
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* It is subject to changes.
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* @private
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*/
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template <typename parser_type = ondemand::parser*>
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struct auto_parser {
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private:
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parser_type m_parser;
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ondemand::document m_doc;
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error_code m_error{SUCCESS};
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template <typename T>
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static constexpr bool is_nothrow_gettable = requires(ondemand::document doc) {
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{ doc.get<T>() } noexcept;
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};
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public:
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explicit auto_parser(parser_type &&parser, ondemand::document &&doc) noexcept requires(!std::is_pointer_v<parser_type>);
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explicit auto_parser(parser_type &&parser, padded_string_view const str) noexcept requires(!std::is_pointer_v<parser_type>);
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explicit auto_parser(std::remove_pointer_t<parser_type> &parser, ondemand::document &&doc) noexcept requires(std::is_pointer_v<parser_type>);
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explicit auto_parser(std::remove_pointer_t<parser_type> &parser, padded_string_view const str) noexcept requires(std::is_pointer_v<parser_type>);
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explicit auto_parser(padded_string_view const str) noexcept requires(std::is_pointer_v<parser_type>);
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explicit auto_parser(parser_type parser, ondemand::document &&doc) noexcept requires(std::is_pointer_v<parser_type>);
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auto_parser(auto_parser const &) = delete;
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auto_parser &operator=(auto_parser const &) = delete;
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~auto_parser() = default;
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// Prevent moving
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auto_parser(auto_parser&&) = delete;
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auto_parser &operator=(auto_parser &&) noexcept = delete;
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simdjson_warn_unused std::remove_pointer_t<parser_type> &parser() noexcept;
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template <typename T>
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simdjson_warn_unused simdjson_inline simdjson_result<T> result() noexcept(is_nothrow_gettable<T>);
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template <typename T>
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simdjson_warn_unused simdjson_inline error_code get(T &value) && noexcept(is_nothrow_gettable<T>);
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simdjson_warn_unused simdjson_inline simdjson_result<ondemand::array> array() noexcept;
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simdjson_warn_unused simdjson_inline simdjson_result<ondemand::object> object() noexcept;
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simdjson_warn_unused simdjson_inline simdjson_result<ondemand::number> number() noexcept;
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#if SIMDJSON_EXCEPTIONS
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template <typename T>
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simdjson_warn_unused simdjson_inline explicit(false) operator T() noexcept(false);
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#endif // SIMDJSON_EXCEPTIONS
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template <typename T>
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simdjson_warn_unused simdjson_inline std::optional<T> optional() noexcept(is_nothrow_gettable<T>);
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};
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/**
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* A utility class for adapting values for the `auto_parser`.
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* This template is not part of our public API. It is subject to changes.
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* @private
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*/
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template <typename T = void>
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struct to_adaptor {
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T operator()(simdjson_result<ondemand::value> &val) const noexcept;
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auto operator()(padded_string_view const str) const noexcept;
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auto operator()(ondemand::parser &parser, padded_string_view const str) const noexcept;
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};
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// deduction guide
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auto_parser(padded_string_view const str) -> auto_parser<ondemand::parser*>;
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} // namespace internal
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} // namespace convert
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/**
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* The simdjson::from instance is EXPERIMENTAL AND SUBJECT TO CHANGES.
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*
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* The `from` instance is a utility adaptor for parsing JSON strings into objects.
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*
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* The string must be a simdjson::padded_string_view, which can be created from a std::string
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* with simdjson::pad(), from a simdjson::padded_string, or string literal using the `_padded`
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* user-defined literal.
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*
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* The `from` instance provides a convenient way to convert JSON data into C++ objects using the `auto_parser`.
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*
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* Example usage:
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*
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* ```cpp
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* std::map<std::string, std::string> obj =
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* simdjson::from(R"({"key": "value"})"_padded);
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* ```
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*
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* This will parse the JSON string and return an object representation. By default, we
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* use the simdjson::ondemand::parser::get_parser() instance. A parser instance should
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* be used for just one document at a time.
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*
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* You can also pass you own parser instance:
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* ```cpp
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* simdjson::ondemand::parser parser;
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* std::map<std::string, std::string> obj =
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* simdjson::from(parser, R"({"key": "value"})"_padded);
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* ```
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* The parser instance can be reused.
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*
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* This functionality requires C++20 or better.
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*/
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static constexpr convert::internal::to_adaptor<> from{};
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} // namespace simdjson
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#endif // SIMDJSON_SUPPORTS_CONCEPTS
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#endif // SIMDJSON_CONVERT_H
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