date.hpp

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#pragma once
 
/// @file userver/storages/postgres/io/date.hpp
/// @brief utils::datetime::Date I/O support
/// @ingroup userver_postgres_parse_and_format
 
#include <limits>
 
#include <userver/storages/postgres/io/buffer_io.hpp>
#include <userver/storages/postgres/io/buffer_io_base.hpp>
#include <userver/storages/postgres/io/integral_types.hpp>
#include <userver/storages/postgres/io/type_mapping.hpp>
#include <userver/utils/datetime/date.hpp>
 
USERVER_NAMESPACE_BEGIN
 
namespace storages::postgres {
 
/// Corresponds to DATE
using Date = USERVER_NAMESPACE::utils::datetime::Date;
 
/// Postgres epoch date (2000-01-01)
Date PostgresEpochDate();
 
/// Constant equivalent to PostgreSQL 'infinity'::date, a date that is later
/// than all other dates.
/// https://www.postgresql.org/docs/current/datatype-datetime.html#DATATYPE-DATETIME-SPECIAL-TABLE
inline constexpr Date kDatePositiveInfinity = Date::SysDays::max();
 
/// Constant equivalent to PostgreSQL '-infinity'::date, a date that is earlier
/// than all other dates.
/// https://www.postgresql.org/docs/current/datatype-datetime.html#DATATYPE-DATETIME-SPECIAL-TABLE
inline constexpr Date kDateNegativeInfinity = Date::SysDays::min();
 
namespace io {
 
/// @brief Binary formatter for utils::datetime::Date
template <>
struct BufferFormatter<Date> {
    const Date value;
 
    explicit BufferFormatter(Date value) : value{value} {}
 
    template <typename Buffer>
    void operator()(const UserTypes& types, Buffer& buffer) {
        static const auto kPgEpoch = PostgresEpochDate();
        if (value == kDatePositiveInfinity) {
            WriteBuffer(types, buffer, std::numeric_limits<Integer>::max());
        } else if (value == kDateNegativeInfinity) {
            WriteBuffer(types, buffer, std::numeric_limits<Integer>::min());
        } else {
            auto pg_days = static_cast<Integer>((value.GetSysDays() - kPgEpoch.GetSysDays()).count());
            WriteBuffer(types, buffer, pg_days);
        }
    }
};
 
/// @brief Binary parser for utils::datetime::Date
template <>
struct BufferParser<Date> : detail::BufferParserBase<Date> {
    using BaseType = detail::BufferParserBase<Date>;
 
    using BaseType::BaseType;
 
    void operator()(const FieldBuffer& buffer) {
        static const auto kPgEpoch = PostgresEpochDate();
        Integer pg_days{0};
        ReadBuffer(buffer, pg_days);
        if (pg_days == std::numeric_limits<Integer>::max()) {
            this->value = kDatePositiveInfinity;
        } else if (pg_days == std::numeric_limits<Integer>::min()) {
            this->value = kDateNegativeInfinity;
        } else {
            this->value = kPgEpoch.GetSysDays() + Date::Days{pg_days};
        }
    }
};
 
template <>
struct CppToSystemPg<Date> : PredefinedOid<PredefinedOids::kDate> {};
 
}  // namespace io
}  // namespace storages::postgres
 
USERVER_NAMESPACE_END