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283 lines
10 KiB
C++
283 lines
10 KiB
C++
#pragma once
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#include <string.h>
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#include <stdio.h>
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#include <time.h>
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#include <math.h>
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#include <string>
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#include <limits>
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#include <common/preciseExp10.h>
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#include <common/types.h>
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#include <common/DateLUT.h>
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#include <mysqlxx/Types.h>
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#include <common/LocalDateTime.h>
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namespace mysqlxx
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{
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class ResultBase;
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/** Represents a single value read from MySQL.
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* It doesn't owns the value. It's just a wrapper of a pair (const char *, size_t).
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* If the UseQueryResult/StoreQueryResult or Connection is destroyed,
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* or you have read the next Row while using UseQueryResult, then the object is invalidated.
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* Allows to transform (parse) the value to various data types:
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* - with getUInt(), getString(), ... (recommended);
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* - with template function get<Type>() that is specialized for multiple data types;
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* - the template function get<Type> also works for all types that can be constructed from Value
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* (it is an extension point);
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* - with operator Type() - this is done for compatibility and not recommended because ambiguities possible.
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*
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* On parsing error, exception is thrown.
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* When trying to extract a value that is nullptr, exception is thrown
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* - use isNull() method to check.
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*
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* As time_t is just an alias for integer data type
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* to allow to write row[0].get<time_t>(), and expect that the values like '2011-01-01 00:00:00'
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* will be successfully parsed according to the current time zone,
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* the getUInt method and the corresponding get<>() methods
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* are capable of parsing Date and DateTime.
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*/
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class Value
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{
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public:
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/** Параметр res_ используется только для генерации подробной информации в исключениях.
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* Можно передать NULL - тогда подробной информации в исключениях не будет.
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*/
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Value(const char * data_, size_t length_, const ResultBase * res_) : m_data(data_), m_length(length_), res(res_)
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{
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}
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/// Получить значение bool.
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bool getBool() const
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{
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if (unlikely(isNull()))
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throwException("Value is NULL");
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return m_length > 0 && m_data[0] != '0';
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}
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/// Получить беззнаковое целое.
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UInt64 getUInt() const
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{
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if (unlikely(isNull()))
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throwException("Value is NULL");
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return readUIntText(m_data, m_length);
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}
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/// Получить целое со знаком или дату или дату-время (в unix timestamp согласно текущей тайм-зоне).
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Int64 getInt() const
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{
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return getIntOrDateTime();
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}
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/// Получить число с плавающей запятой.
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double getDouble() const
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{
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if (unlikely(isNull()))
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throwException("Value is NULL");
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return readFloatText(m_data, m_length);
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}
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/// Получить дату-время (из значения вида '2011-01-01 00:00:00').
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LocalDateTime getDateTime() const
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{
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return LocalDateTime(data(), size());
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}
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/// Получить дату (из значения вида '2011-01-01' или '2011-01-01 00:00:00').
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LocalDate getDate() const
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{
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return LocalDate(data(), size());
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}
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/// Получить строку.
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std::string getString() const
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{
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if (unlikely(isNull()))
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throwException("Value is NULL");
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return std::string(m_data, m_length);
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}
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/// Является ли NULL.
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bool isNull() const
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{
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return m_data == nullptr;
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}
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/// Для совместимости (используйте вместо этого метод isNull())
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bool is_null() const { return isNull(); }
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/** Получить любой поддерживаемый тип (для шаблонного кода).
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* Поддерживаются основные типы, а также любые типы с конструктором от Value (для удобства расширения).
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*/
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template <typename T> T get() const;
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/// Для совместимости. Не рекомендуется к использованию, так как неудобен (часто возникают неоднозначности).
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template <typename T> operator T() const { return get<T>(); }
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const char * data() const { return m_data; }
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size_t length() const { return m_length; }
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size_t size() const { return m_length; }
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bool empty() const { return 0 == m_length; }
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private:
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const char * m_data;
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size_t m_length;
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const ResultBase * res;
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bool checkDateTime() const
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{
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return (m_length == 10 || m_length == 19) && m_data[4] == '-' && m_data[7] == '-';
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}
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time_t getDateTimeImpl() const
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{
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const auto & date_lut = DateLUT::instance();
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if (m_length == 10)
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{
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return date_lut.makeDate(
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(m_data[0] - '0') * 1000 + (m_data[1] - '0') * 100 + (m_data[2] - '0') * 10 + (m_data[3] - '0'),
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(m_data[5] - '0') * 10 + (m_data[6] - '0'),
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(m_data[8] - '0') * 10 + (m_data[9] - '0'));
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}
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else if (m_length == 19)
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{
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return date_lut.makeDateTime(
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(m_data[0] - '0') * 1000 + (m_data[1] - '0') * 100 + (m_data[2] - '0') * 10 + (m_data[3] - '0'),
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(m_data[5] - '0') * 10 + (m_data[6] - '0'),
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(m_data[8] - '0') * 10 + (m_data[9] - '0'),
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(m_data[11] - '0') * 10 + (m_data[12] - '0'),
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(m_data[14] - '0') * 10 + (m_data[15] - '0'),
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(m_data[17] - '0') * 10 + (m_data[18] - '0'));
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}
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else
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throwException("Cannot parse DateTime");
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return 0; /// avoid warning.
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}
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time_t getDateImpl() const
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{
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const auto & date_lut = DateLUT::instance();
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if (m_length == 10 || m_length == 19)
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{
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return date_lut.makeDate(
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(m_data[0] - '0') * 1000 + (m_data[1] - '0') * 100 + (m_data[2] - '0') * 10 + (m_data[3] - '0'),
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(m_data[5] - '0') * 10 + (m_data[6] - '0'),
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(m_data[8] - '0') * 10 + (m_data[9] - '0'));
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}
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else
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throwException("Cannot parse Date");
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return 0; /// avoid warning.
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}
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Int64 getIntImpl() const
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{
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return readIntText(m_data, m_length);
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}
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Int64 getIntOrDateTime() const
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{
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if (unlikely(isNull()))
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throwException("Value is NULL");
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if (checkDateTime())
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return getDateTimeImpl();
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else
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return getIntImpl();
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}
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Int64 getIntOrDate() const
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{
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if (unlikely(isNull()))
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throwException("Value is NULL");
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if (checkDateTime())
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return getDateImpl();
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else
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{
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const auto & date_lut = DateLUT::instance();
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return date_lut.toDate(getIntImpl());
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}
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}
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/// Прочитать беззнаковое целое в простом формате из не-0-terminated строки.
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UInt64 readUIntText(const char * buf, size_t length) const;
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/// Прочитать знаковое целое в простом формате из не-0-terminated строки.
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Int64 readIntText(const char * buf, size_t length) const;
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/// Прочитать число с плавающей запятой в простом формате, с грубым округлением, из не-0-terminated строки.
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double readFloatText(const char * buf, size_t length) const;
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/// Выкинуть исключение с подробной информацией
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[[noreturn]] void throwException(const char * text) const;
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};
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template <> inline bool Value::get<bool >() const { return getBool(); }
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template <> inline char Value::get<char >() const { return getInt(); }
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template <> inline signed char Value::get<signed char >() const { return getInt(); }
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template <> inline unsigned char Value::get<unsigned char >() const { return getUInt(); }
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template <> inline char8_t Value::get<char8_t >() const { return getUInt(); }
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template <> inline short Value::get<short >() const { return getInt(); }
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template <> inline unsigned short Value::get<unsigned short >() const { return getUInt(); }
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template <> inline int Value::get<int >() const { return getInt(); }
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template <> inline unsigned int Value::get<unsigned int >() const { return getUInt(); }
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template <> inline long Value::get<long >() const { return getInt(); }
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template <> inline unsigned long Value::get<unsigned long >() const { return getUInt(); }
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template <> inline long long Value::get<long long >() const { return getInt(); }
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template <> inline unsigned long long Value::get<unsigned long long >() const { return getUInt(); }
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template <> inline float Value::get<float >() const { return getDouble(); }
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template <> inline double Value::get<double >() const { return getDouble(); }
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template <> inline std::string Value::get<std::string >() const { return getString(); }
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template <> inline LocalDate Value::get<LocalDate >() const { return getDate(); }
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template <> inline LocalDateTime Value::get<LocalDateTime >() const { return getDateTime(); }
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namespace details
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{
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// To avoid stack overflow when converting to type with no appropriate c-tor,
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// resulting in endless recursive calls from `Value::get<T>()` to `Value::operator T()` to `Value::get<T>()` to ...
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template <typename T, typename std::enable_if_t<std::is_constructible_v<T, Value>>>
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inline T contructFromValue(const Value & val)
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{
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return T(val);
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}
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}
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template <typename T>
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inline T Value::get() const
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{
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return details::contructFromValue<T>(*this);
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}
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inline std::ostream & operator<< (std::ostream & ostr, const Value & x)
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{
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return ostr.write(x.data(), x.size());
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}
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}
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