conversions.hxx

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#ifndef PQXX_INTERNAL_CONVERSIONS_HXX
#define PQXX_INTERNAL_CONVERSIONS_HXX
 
#include <array>
#include <concepts>
#include <cstring>
#include <map>
#include <memory>
#include <numeric>
#include <optional>
#include <span>
#include <type_traits>
#include <variant>
 
#include "pqxx/encoding_group.hxx"
#include "pqxx/strconv.hxx"
 
 
/* Internal helpers for string conversion, and conversion implementations.
 *
 * Do not include this header directly.  The libpqxx headers do it for you.
 */
namespace pqxx::internal
{
PQXX_PURE PQXX_HOT inline constexpr char number_to_digit(int i) noexcept
{
  PQXX_ASSUME(i >= 0);
  PQXX_ASSUME(i <= 9);
  return static_cast<char>(i + '0');
}
 
 
 
PQXX_PURE PQXX_HOT inline constexpr int digit_to_number(char c) noexcept
{
  PQXX_ASSUME(c >= '0');
  PQXX_ASSUME(c <= '9');
  return c - '0';
}
 
 
 
PQXX_LIBEXPORT PQXX_COLD std::string
state_buffer_overrun(int have_bytes, int need_bytes);
 
 
template<typename HAVE, typename NEED>
PQXX_INLINE_COV PQXX_COLD inline std::string
state_buffer_overrun(HAVE have_bytes, NEED need_bytes)
{
  return state_buffer_overrun(
    static_cast<int>(have_bytes), static_cast<int>(need_bytes));
}
 
 
[[noreturn]] PQXX_COLD PQXX_LIBEXPORT void
throw_null_conversion(std::string const &type, sl);
 
 
[[noreturn]] PQXX_COLD PQXX_LIBEXPORT void
throw_null_conversion(std::string_view type, sl);
 
 
 
template<pqxx::internal::char_type CHAR_TYPE>
struct disallowed_ambiguous_char_conversion
{
  static constexpr std::size_t
  size_buffer(CHAR_TYPE const &) noexcept = delete;
 
  static constexpr std::string_view
  to_buf(std::span<char>, CHAR_TYPE const &, ctx = {}) noexcept = delete;
 
  static CHAR_TYPE from_string(std::string_view, ctx = {}) = delete;
};
 
 
template<std::floating_point T>
PQXX_LIBEXPORT extern std::string to_string_float(T, ctx = {});
 
 
template<typename T>
[[deprecated("into_buf() is no longer part of the string conversion API.")]]
inline char *
generic_into_buf(char *begin, char *end, T const &value, ctx c = {})
{
  zview text{to_buf({begin, end}, value, c)};
  auto const space{end - begin};
  // Include the trailing zero.
  auto const len = std::size(text) + 1;
  if (std::cmp_greater(len, space))
    throw conversion_overrun{
      std::format("Not enough buffer space to insert {}.", name_type<T>()) +
        state_buffer_overrun(space, len),
      c.loc};
  std::memmove(begin, std::data(text), len);
  return begin + len;
}
 
 
template<typename T>
[[deprecated("into_buf() is no longer part of the string conversion API.")]]
inline std::size_t
generic_into_buf(std::span<char> buf, T const &value, ctx c = {})
{
  auto const begin{std::data(buf)};
  zview text{to_buf(buf, value, c)};
  auto const space{std::size(buf)};
  // Include the trailing zero.
  auto const len = std::size(text) + 1;
  if (std::cmp_greater(len, space))
    throw conversion_overrun{
      std::format("Not enough buffer space to insert {}.  ", name_type<T>()) +
        state_buffer_overrun(space, len),
      c.loc};
  std::memmove(begin, std::data(text), len);
  return len;
}
 
 
 
template<std::floating_point T> struct float_string_traits
{
  PQXX_LIBEXPORT PQXX_HOT static T
  from_string(std::string_view text, ctx = {});
 
  PQXX_LIBEXPORT PQXX_HOT static std::string_view
  to_buf(std::span<char> buf, T const &value, ctx c = {});
 
  // Return a nonnegative integral value's number of decimal digits.
  PQXX_HOT static constexpr std::size_t digits10(std::size_t value) noexcept
  {
    if (value < 10)
      return 1;
    else
      return 1 + digits10(value / 10);
  }
 
  PQXX_HOT PQXX_INLINE_COV static constexpr std::size_t
  size_buffer(T const &) noexcept
  {
    using lims = std::numeric_limits<T>;
    // See #328 for a detailed discussion on the maximum number of digits.
    //
    // In a nutshell: for the big cases, the scientific notation is always
    // the shortest one, and therefore the one that to_chars will pick.
    //
    // So... How long can the scientific notation get?  1 (for sign) + 1 (for
    // decimal point) + 1 (for 'e') + 1 (for exponent sign) + max_digits10 +
    // max number of digits in the exponent + 1 (terminating zero).
    //
    // What's the max number of digits in the exponent?  It's the max number of
    // digits out of the most negative exponent and the most positive one.
    //
    // The longest positive exponent is easy: 1 + ceil(log10(max_exponent10)).
    // (The extra 1 is because 10^n takes up 1 + n digits, not n.)
    //
    // The longest negative exponent is a bit harder: min_exponent10 gives us
    // the smallest power of 10 which a normalised version of T can represent.
    // But the smallest denormalised power of 10 that T can represent is
    // another max_digits10 powers of 10 below that.  It also needs room for a
    // a minus sign.
    //
    // All this stuff messes with my head a bit because it's on the order of
    // log10(log10(n)).  It's easy to get the number of logs wrong.
    auto const max_pos_exp{digits10(lims::max_exponent10)};
    // Really want std::abs(lims::min_exponent10), but MSVC 2017 apparently has
    // problems with std::abs.  So we use -lims::min_exponent10 instead.
    auto const max_neg_exp{
      digits10(lims::max_digits10 - lims::min_exponent10)};
    return 1 +                                    // Sign.
           1 +                                    // Decimal point.
           std::numeric_limits<T>::max_digits10 + // Mantissa digits.
           1 +                                    // Exponent "e".
           1 +                                    // Exponent sign.
           // Spell this weirdly to stop Windows compilers from reading this as
           // a call to their "max" macro when NOMINMAX is not defined.
           (std::max)(max_pos_exp, max_neg_exp); // Exponent digits.
  }
};
 
 
template<pqxx::internal::integer T> struct integer_string_traits
{
  PQXX_LIBEXPORT PQXX_HOT static T
  from_string(std::string_view text, ctx = {});
  PQXX_LIBEXPORT PQXX_HOT static std::string_view
  to_buf(std::span<char> buf, T const &value, ctx c = {});
 
  PQXX_INLINE_ONLY PQXX_HOT static constexpr std::size_t
  size_buffer(T const &) noexcept
  {
    return std::is_signed_v<T> + std::numeric_limits<T>::digits10 + 1;
  }
};
} // namespace pqxx::internal
 
namespace pqxx
{
 
template<typename T>
  requires std::is_arithmetic_v<T>
struct nullness<T> final : no_null<T>
{};
 
 
template<pqxx::internal::integer T>
inline constexpr bool is_unquoted_safe<T>{true};
template<std::floating_point T>
inline constexpr bool is_unquoted_safe<T>{true};
 
#define PQXX_SPECIALIZE_INT_TRAIT(typ)                                        \
  template<>                                                                  \
  struct string_traits<typ> final                                             \
          : pqxx::internal::integer_string_traits<typ>                        \
  {}
 
PQXX_SPECIALIZE_INT_TRAIT(short);
PQXX_SPECIALIZE_INT_TRAIT(unsigned short);
PQXX_SPECIALIZE_INT_TRAIT(int);
PQXX_SPECIALIZE_INT_TRAIT(unsigned);
PQXX_SPECIALIZE_INT_TRAIT(long);
PQXX_SPECIALIZE_INT_TRAIT(unsigned long);
PQXX_SPECIALIZE_INT_TRAIT(long long);
PQXX_SPECIALIZE_INT_TRAIT(unsigned long long);
 
#undef PQXX_SPECIALIZE_INT_TRAIT
 
template<>
struct string_traits<float> final : pqxx::internal::float_string_traits<float>
{};
template<>
struct string_traits<double> final
        : pqxx::internal::float_string_traits<double>
{};
template<>
struct string_traits<long double> final
        : pqxx::internal::float_string_traits<long double>
{};
 
 
template<> struct string_traits<bool> final
{
  PQXX_LIBEXPORT PQXX_HOT static bool
  from_string(std::string_view text, ctx c = {});
 
  PQXX_PURE PQXX_HOT static constexpr std::string_view
  to_buf(std::span<char>, bool const &value, ctx = {}) noexcept
  {
    return value ? "true" : "false";
  }
 
  PQXX_PURE PQXX_HOT static constexpr std::size_t
  size_buffer(bool const &) noexcept
  {
    return 6;
  }
};
 
 
template<> inline constexpr bool is_unquoted_safe<bool>{true};
 
 
template<typename T> struct nullness<std::optional<T>> final
{
  static constexpr bool has_null = true;
  static constexpr bool always_null = pqxx::always_null<T>();
  [[nodiscard]] PQXX_PURE PQXX_HOT static constexpr bool
  is_null(std::optional<T> const &v) noexcept
  {
    return ((not v.has_value()) or pqxx::is_null(*v));
  }
  [[nodiscard]] PQXX_PURE PQXX_HOT static constexpr std::optional<T>
  null() noexcept
  {
    return {};
  }
};
 
 
template<typename T>
inline constexpr format param_format(std::optional<T> const &value)
{
  return param_format(*value);
}
 
 
template<typename T> struct string_traits<std::optional<T>> final
{
  static std::string_view
  to_buf(std::span<char> buf, std::optional<T> const &value, ctx c = {})
  {
    if (pqxx::is_null(value))
      return {};
    else
      // (No need to check: if the optional were empty, it'd be null.)
      // NOLINTNEXTLINE(bugprone-unchecked-optional-access)
      return pqxx::to_buf(buf, *value, c);
  }
 
  static std::optional<T> from_string(std::string_view text, ctx c = {})
  {
    return std::optional<T>{std::in_place, pqxx::from_string<T>(text, c)};
  }
 
  static std::size_t size_buffer(std::optional<T> const &value) noexcept
  {
    if (pqxx::is_null(value))
      return 0;
    else
      // (No need to check: if the optional were empty, it'd be null.)
      // NOLINTNEXTLINE(bugprone-unchecked-optional-access)
      return pqxx::size_buffer(value.value());
  }
};
 
 
template<typename T>
inline constexpr bool is_unquoted_safe<std::optional<T>>{is_unquoted_safe<T>};
 
 
template<typename... T> struct nullness<std::variant<T...>> final
{
  static constexpr bool has_null = (pqxx::has_null<T>() or ...);
  static constexpr bool always_null = (pqxx::always_null<T>() and ...);
  [[nodiscard]] PQXX_PURE static constexpr bool
  is_null(std::variant<T...> const &value) noexcept
  {
    return value.valueless_by_exception() or
           std::visit(
             [](auto const &i) noexcept {
               return nullness<std::remove_cvref_t<decltype(i)>>::is_null(i);
             },
             value);
  }
 
  // We don't support `null()` for `std::variant`.
  static constexpr std::variant<T...> null() = delete;
};
 
 
template<typename... T> struct string_traits<std::variant<T...>> final
{
  static std::string_view
  to_buf(std::span<char> buf, std::variant<T...> const &value, ctx c = {})
  {
    return std::visit(
      [buf, c](auto const &i) {
        using field_t = std::remove_cvref_t<decltype(i)>;
        return pqxx::to_buf<field_t>(buf, i, c);
      },
      value);
  }
  static std::size_t size_buffer(std::variant<T...> const &value) noexcept
  {
    if (pqxx::is_null(value))
      return 0;
    else
      return std::visit(
        [](auto const &i) noexcept { return pqxx::size_buffer(i); }, value);
  }
 
  static std::variant<T...> from_string(std::string_view, ctx = {}) = delete;
};
 
 
template<typename... Args>
inline constexpr format param_format(std::variant<Args...> const &value)
{
  return std::visit([](auto &v) { return param_format(v); }, value);
}
 
 
template<typename... T>
inline constexpr bool is_unquoted_safe<std::variant<T...>>{
  (is_unquoted_safe<T> and ...)};
 
 
template<typename T>
inline T from_string(std::stringstream const &text, ctx c = {})
{
  return from_string<T>(text.str(), c);
}
 
 
template<> struct string_traits<std::nullptr_t> final
{
  [[deprecated("Do not convert nulls.")]] static constexpr zview
  to_buf(std::span<char>, std::nullptr_t const &, ctx = {}) noexcept
  {
    return {};
  }
 
  [[deprecated("Do not convert nulls.")]] static constexpr std::size_t
  size_buffer(std::nullptr_t = nullptr) noexcept
  {
    return 0;
  }
  static std::nullptr_t from_string(std::string_view, ctx = {}) = delete;
};
 
 
template<> struct string_traits<std::nullopt_t> final
{
  [[deprecated("Do not convert nulls.")]] static constexpr zview
  to_buf(char *, char *, std::nullopt_t const &) noexcept
  {
    return {};
  }
 
  [[deprecated("Do not convert nulls.")]] static constexpr std::size_t
  size_buffer(std::nullopt_t) noexcept
  {
    return 0;
  }
  static std::nullopt_t from_string(std::string_view, ctx = {}) = delete;
};
 
 
template<> struct string_traits<std::monostate> final
{
  [[deprecated("Do not convert nulls.")]] static constexpr zview
  to_buf(char *, char *, std::monostate const &) noexcept
  {
    return {};
  }
 
  [[deprecated("Do not convert nulls.")]] static constexpr std::size_t
  size_buffer(std::monostate) noexcept
  {
    return 0;
  }
  [[deprecated("Do not convert nulls.")]] static std::monostate
    from_string(std::string_view, ctx = {}) = delete;
};
 
 
template<> inline constexpr bool is_unquoted_safe<std::nullptr_t>{true};
 
 
template<> struct nullness<char const *> final
{
  static constexpr bool has_null = true;
  static constexpr bool always_null = false;
  [[nodiscard]] PQXX_PURE PQXX_ZARGS static constexpr bool
  is_null(char const *t) noexcept
  {
    return t == nullptr;
  }
  [[nodiscard]] PQXX_PURE static constexpr char const *null() noexcept
  {
    return nullptr;
  }
};
 
 
 
template<> struct string_traits<char const *> final
{
  static char const *from_string(std::string_view text, ctx = {}) = delete;
 
  constexpr PQXX_ZARGS static std::string_view
  to_buf(std::span<char>, char const *const &value, ctx = {}) noexcept
  {
    return value;
  }
 
  PQXX_ZARGS static constexpr std::size_t
  size_buffer(char const *value) noexcept
  {
    if (pqxx::is_null(value))
      return 0;
    else
      // std::char_traits::length() is like std::strlen(), but constexpr.
      return std::char_traits<char>::length(value);
  }
};
 
 
template<> struct nullness<char *> final
{
  static constexpr bool has_null = true;
  static constexpr bool always_null = false;
  [[nodiscard]] PQXX_PURE static constexpr bool is_null(char const *t) noexcept
  {
    return t == nullptr;
  }
  [[nodiscard]] PQXX_PURE static constexpr char *null() { return nullptr; }
};
 
 
 
template<> struct string_traits<char *> final
{
  static std::string_view
  to_buf(std::span<char> buf, char *const &value, ctx c = {})
  {
    return pqxx::to_buf<char const *>(buf, value, c);
  }
  static std::size_t size_buffer(char *const &value) noexcept
  {
    if (pqxx::is_null(value))
      return 0;
    else
      return pqxx::size_buffer(const_cast<char const *>(value));
  }
 
  static char *from_string(std::string_view, ctx = {}) = delete;
};
 
 
template<std::size_t N> struct nullness<char[N]> final : no_null<char[N]>
{};
 
 
 
template<std::size_t N> struct string_traits<char[N]> final
{
  static constexpr zview
  to_buf(std::span<char>, char const (&value)[N], ctx = {}) noexcept
  {
    return zview{value, N - 1};
  }
 
  static constexpr std::size_t size_buffer(char const (&)[N]) noexcept
  {
    return N;
  }
 
  static void from_string(std::string_view, ctx = {}) = delete;
};
 
 
template<> struct nullness<std::string> final : no_null<std::string>
{};
 
 
template<> struct string_traits<std::string> final
{
  PQXX_INLINE_ONLY static std::string
  from_string(std::string_view text, ctx = {})
  {
    return std::string{text};
  }
 
  PQXX_INLINE_ONLY static std::string_view
  to_buf(std::span<char>, std::string const &value, ctx = {})
  {
    return {std::data(value), std::size(value)};
  }
 
  PQXX_INLINE_ONLY static constexpr std::size_t
  size_buffer(std::string const &value) noexcept
  {
    return std::size(value);
  }
};
 
 
 
template<> struct nullness<std::string_view> final : no_null<std::string_view>
{};
 
 
 
template<> struct string_traits<std::string_view> final
{
  PQXX_INLINE_ONLY static constexpr std::size_t
  size_buffer(std::string_view const &value) noexcept
  {
    return std::size(value);
  }
 
  PQXX_INLINE_ONLY static std::string_view
  to_buf(std::span<char>, std::string_view const &value, ctx = {})
  {
    return value;
  }
 
  PQXX_INLINE_ONLY static std::string_view
  from_string(std::string_view value, ctx = {})
  {
    return value;
  }
};
 
 
template<> struct nullness<zview> final : no_null<zview>
{};
 
 
template<> struct string_traits<zview> final
{
  PQXX_INLINE_ONLY static constexpr std::size_t
  size_buffer(std::string_view const &value) noexcept
  {
    return std::size(value);
  }
 
  static constexpr zview to_buf(std::span<char>, zview const &value, ctx = {})
  {
    return value;
  }
 
 
  static zview from_string(std::string_view, ctx = {}) = delete;
};
 
 
template<>
struct nullness<std::stringstream> final : no_null<std::stringstream>
{};
 
 
template<> struct string_traits<std::stringstream> final
{
  static std::size_t size_buffer(std::stringstream const &) = delete;
 
  static std::stringstream from_string(std::string_view text, ctx = {})
  {
    std::stringstream stream;
    stream.write(text.data(), std::streamsize(std::size(text)));
    return stream;
  }
 
  static std::string_view
  to_buf(std::span<char>, std::stringstream const &, ctx = {}) = delete;
};
 
 
template<>
struct nullness<std::nullptr_t> final : all_null<std::nullptr_t, nullptr>
{};
 
template<>
struct nullness<std::nullopt_t> final : all_null<std::nullopt_t, std::nullopt>
{};
 
template<>
struct nullness<std::monostate> final
        : all_null<std::monostate, std::monostate{}>
{};
 
 
template<typename T> struct nullness<std::unique_ptr<T>> final
{
  static constexpr bool has_null = true;
  static constexpr bool always_null = false;
  [[nodiscard]] PQXX_PURE static constexpr bool
  is_null(std::unique_ptr<T> const &t) noexcept
  {
    return not t or pqxx::is_null(*t);
  }
  [[nodiscard]] PQXX_PURE static constexpr std::unique_ptr<T> null() noexcept
  {
    return {};
  }
};
 
 
template<typename T, typename... Args>
struct string_traits<std::unique_ptr<T, Args...>> final
{
  static std::unique_ptr<T> from_string(std::string_view text, ctx c = {})
  {
    return std::make_unique<T>(pqxx::from_string<T>(text, c));
  }
 
  static std::string_view to_buf(
    std::span<char> buf, std::unique_ptr<T, Args...> const &value, ctx c = {})
  {
    if (not value)
      internal::throw_null_conversion(name_type<std::unique_ptr<T>>(), c.loc);
    return pqxx::to_buf(buf, *value, c);
  }
 
  static std::size_t
  size_buffer(std::unique_ptr<T, Args...> const &value) noexcept
  {
    if (pqxx::is_null(value))
      return 0;
    else
      return pqxx::size_buffer(*value.get());
  }
};
 
 
template<typename T, typename... Args>
inline format param_format(std::unique_ptr<T, Args...> const &value)
{
  return param_format(*value);
}
 
 
template<typename T, typename... Args>
inline constexpr bool is_unquoted_safe<std::unique_ptr<T, Args...>>{
  is_unquoted_safe<T>};
 
 
template<typename T> struct nullness<std::shared_ptr<T>> final
{
  static constexpr bool has_null = true;
  static constexpr bool always_null = false;
  [[nodiscard]] PQXX_PURE static constexpr bool
  is_null(std::shared_ptr<T> const &t) noexcept
  {
    return not t or pqxx::is_null(*t);
  }
  [[nodiscard]] PQXX_PURE static constexpr std::shared_ptr<T> null() noexcept
  {
    return {};
  }
};
 
 
template<typename T> struct string_traits<std::shared_ptr<T>> final
{
  static std::shared_ptr<T> from_string(std::string_view text, ctx c = {})
  {
    return std::make_shared<T>(pqxx::from_string<T>(text, c));
  }
 
  static std::string_view
  to_buf(std::span<char> buf, std::shared_ptr<T> const &value, ctx c = {})
  {
    if (not value)
      internal::throw_null_conversion(name_type<std::shared_ptr<T>>(), c.loc);
    return pqxx::to_buf(buf, *value, c);
  }
  static std::size_t size_buffer(std::shared_ptr<T> const &value) noexcept
  {
    if (pqxx::is_null(value))
      return 0;
    else
      return pqxx::size_buffer(*value);
  }
};
 
 
template<typename T> format param_format(std::shared_ptr<T> const &value)
{
  return param_format(*value);
}
 
 
template<typename T>
inline constexpr bool is_unquoted_safe<std::shared_ptr<T>>{
  is_unquoted_safe<T>};
 
 
template<binary DATA> struct nullness<DATA> final : no_null<DATA>
{};
 
 
template<binary DATA> struct string_traits<DATA> final
{
  static std::size_t size_buffer(DATA const &value) noexcept
  {
    return internal::size_esc_bin(std::size(value));
  }
 
  static std::string_view
  to_buf(std::span<char> buf, DATA const &value, ctx c = {})
  {
    // Budget for this type is precise.
    auto const budget{size_buffer(value)};
    if (std::cmp_less(std::size(buf), budget))
      throw conversion_overrun{
        "Not enough buffer space to escape binary data.", c.loc};
    internal::esc_bin(value, buf);
    // The budget included a terminating zero, which we do not include in the
    // view.
    return {std::data(buf), budget - 1};
  }
 
  static DATA from_string(std::string_view text, ctx c = {})
  {
    auto const size{pqxx::internal::size_unesc_bin(std::size(text))};
    DATA buf{};
    if constexpr (requires { buf.resize(std::size_t{}); })
    {
      // Make `buf` allocate the number of bytes we need to store.
      buf.resize(size);
    }
    else
    {
      // There's no suitable `DATA::resize()`.  But perhaps the caller has
      // ensured that `DATA` is a type that inherently has the right size.
      // Might a `std::array<std::byte, ...>` for instance.
      if (std::size(buf) != size)
        throw conversion_error{
          std::format(
            "Can't convert binary data from SQL text to {}: I don't know how "
            "to "
            "resize that type.",
            name_type<DATA>()),
          c.loc};
    }
 
    pqxx::internal::unesc_bin(text, buf, c.loc);
    return buf;
  }
};
} // namespace pqxx
 
 
namespace pqxx::internal
{
template<nonbinary_range TYPE>
inline std::size_t array_into_buf(
  std::span<char> buf, TYPE const &value, std::size_t budget, ctx c = {});
 
 
 
template<typename T> struct nonbinary_range_traits
{
  using elt_type = std::remove_cvref_t<value_type<T>>;
  using elt_traits = string_traits<elt_type>;
  static constexpr zview s_null{"NULL"};
 
  static std::size_t size_buffer(T const &value) noexcept
  {
    if constexpr (is_unquoted_safe<elt_type>)
      return 3 + std::accumulate(
                   std::begin(value), std::end(value), std::size_t{},
                   [](std::size_t acc, elt_type const &elt) {
                     // Add one extra byte for the separator
                     return acc + (pqxx::is_null(elt) ?
                                     std::size(s_null) :
                                     elt_traits::size_buffer(elt)) + 1;
                   });
    else
      return 3 + std::accumulate(
                   std::begin(value), std::end(value), std::size_t{},
                   [](std::size_t acc, elt_type const &elt) {
                     // Opening and closing quotes, plus worst-case escaping,
                     // plus one byte for the separator.
                     std::size_t const elt_size{
                       pqxx::is_null(elt) ? std::size(s_null) :
                                            elt_traits::size_buffer(elt)};
                     return acc + 2 * elt_size + 3;
                   });
  }
 
  static std::string_view
  to_buf(std::span<char> buf, T const &value, ctx c = {})
  {
    auto const sz{
      pqxx::internal::array_into_buf(buf, value, size_buffer(value), c)};
    return {std::data(buf), sz};
  }
};
} // namespace pqxx::internal
 
 
namespace pqxx
{
template<nonbinary_range T> struct nullness<T> final : no_null<T>
{};
 
 
 
template<nonbinary_range T>
struct string_traits<T> final : pqxx::internal::nonbinary_range_traits<T>
{};
 
 
template<nonbinary_range T> inline constexpr format param_format(T const &)
{
  return format::text;
}
 
 
template<binary T> inline constexpr format param_format(T const &)
{
  return format::binary;
}
 
 
template<nonbinary_range T> inline constexpr bool is_sql_array<T>{true};
 
 
template<typename TYPE>
PQXX_INLINE_COV inline std::string to_string(TYPE const &value, ctx c)
{
  if (is_null(value))
    throw conversion_error{
      std::format("Attempt to convert null to a string.", name_type<TYPE>()),
      c.loc};
 
  if constexpr (pqxx::always_null<TYPE>())
  {
    // Have to separate out this case: some functions in the "regular" code
    // may not exist in the "always null" case.
    PQXX_UNREACHABLE;
    // C++23: The return may not be needed when std::unreachable is available.
    return {};
  }
  else
  {
    std::string buf;
    // We can't just reserve() space; modifying the terminating zero leads to
    // undefined behaviour.
    buf.resize(pqxx::size_buffer(value));
    std::size_t const stop{pqxx::into_buf(buf, value, c)};
    buf.resize(stop);
    return buf;
  }
}
 
 
template<> inline std::string to_string(float const &value, ctx c)
{
  return pqxx::internal::to_string_float(value, c);
}
template<> inline std::string to_string(double const &value, ctx c)
{
  return pqxx::internal::to_string_float(value, c);
}
template<> inline std::string to_string(long double const &value, ctx c)
{
  return pqxx::internal::to_string_float(value, c);
}
 
// clang-tidy rule bug:
// NOLINTNEXTLINE(misc-unused-parameters)
template<> inline std::string to_string(std::stringstream const &value, ctx)
{
  return value.str();
}
 
 
template<typename T>
inline void into_string(T const &value, std::string &out, ctx c = {})
{
  if (is_null(value))
    throw conversion_error{
      std::format("Attempt to convert null {} to a string.", name_type<T>()),
      c.loc};
 
  // We can't just reserve() data; modifying the terminating zero leads to
  // undefined behaviour.
  out.resize(size_buffer(value));
  auto const data{out.data()};
  auto const end{into_buf({data, std::size(out)}, value, c)};
  out.resize(static_cast<std::size_t>(end - data));
}
} // namespace pqxx
#endif