ClickHouse/dbms/include/DB/Core/FieldVisitors.h

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#pragma once
#include <DB/Core/Field.h>
#include <DB/IO/ReadBuffer.h>
#include <DB/IO/WriteBuffer.h>
#include <DB/IO/ReadHelpers.h>
#include <DB/IO/WriteHelpers.h>
#include <DB/IO/ReadBufferFromString.h>
#include <DB/IO/WriteBufferFromString.h>
namespace DB
{
namespace ErrorCodes
{
extern const int CANNOT_CONVERT_TYPE;
}
/** StaticVisitor (его наследники) - класс с перегруженными для разных типов операторами ().
* Вызвать visitor для field можно с помощью функции apply_visitor.
* Также поддерживается visitor, в котором оператор () принимает два аргумента.
*/
template <typename R = void>
struct StaticVisitor
{
using ResultType = R;
};
template <typename Visitor, typename F>
typename Visitor::ResultType apply_visitor_impl(Visitor & visitor, F & field)
{
switch (field.getType())
{
case Field::Types::Null: return visitor(field.template get<Null>());
case Field::Types::UInt64: return visitor(field.template get<UInt64>());
case Field::Types::Int64: return visitor(field.template get<Int64>());
case Field::Types::Float64: return visitor(field.template get<Float64>());
case Field::Types::String: return visitor(field.template get<String>());
case Field::Types::Array: return visitor(field.template get<Array>());
case Field::Types::Tuple: return visitor(field.template get<Tuple>());
default:
throw Exception("Bad type of Field", ErrorCodes::BAD_TYPE_OF_FIELD);
}
}
/** Эти штуки нужны, чтобы принимать временный объект по константной ссылке.
* В шаблон выше, типы форвардятся уже с const-ом.
*/
template <typename Visitor>
typename Visitor::ResultType apply_visitor(const Visitor & visitor, Field & field)
{
return apply_visitor_impl(visitor, field);
}
template <typename Visitor>
typename Visitor::ResultType apply_visitor(const Visitor & visitor, const Field & field)
{
return apply_visitor_impl(visitor, field);
}
template <typename Visitor>
typename Visitor::ResultType apply_visitor(Visitor & visitor, Field & field)
{
return apply_visitor_impl(visitor, field);
}
template <typename Visitor>
typename Visitor::ResultType apply_visitor(Visitor & visitor, const Field & field)
{
return apply_visitor_impl(visitor, field);
}
template <typename Visitor, typename F1, typename F2>
typename Visitor::ResultType apply_binary_visitor_impl2(Visitor & visitor, F1 & field1, F2 & field2)
{
switch (field2.getType())
{
case Field::Types::Null: return visitor(field1, field2.template get<Null>());
case Field::Types::UInt64: return visitor(field1, field2.template get<UInt64>());
case Field::Types::Int64: return visitor(field1, field2.template get<Int64>());
case Field::Types::Float64: return visitor(field1, field2.template get<Float64>());
case Field::Types::String: return visitor(field1, field2.template get<String>());
case Field::Types::Array: return visitor(field1, field2.template get<Array>());
case Field::Types::Tuple: return visitor(field1, field2.template get<Tuple>());
default:
throw Exception("Bad type of Field", ErrorCodes::BAD_TYPE_OF_FIELD);
}
}
template <typename Visitor, typename F1, typename F2>
typename Visitor::ResultType apply_binary_visitor_impl1(Visitor & visitor, F1 & field1, F2 & field2)
{
switch (field1.getType())
{
case Field::Types::Null: return apply_binary_visitor_impl2(visitor, field1.template get<Null>(), field2);
case Field::Types::UInt64: return apply_binary_visitor_impl2(visitor, field1.template get<UInt64>(), field2);
case Field::Types::Int64: return apply_binary_visitor_impl2(visitor, field1.template get<Int64>(), field2);
case Field::Types::Float64: return apply_binary_visitor_impl2(visitor, field1.template get<Float64>(), field2);
case Field::Types::String: return apply_binary_visitor_impl2(visitor, field1.template get<String>(), field2);
case Field::Types::Array: return apply_binary_visitor_impl2(visitor, field1.template get<Array>(), field2);
case Field::Types::Tuple: return apply_binary_visitor_impl2(visitor, field1.template get<Tuple>(), field2);
default:
throw Exception("Bad type of Field", ErrorCodes::BAD_TYPE_OF_FIELD);
}
}
template <typename Visitor>
typename Visitor::ResultType apply_visitor(Visitor & visitor, Field & field1, Field & field2)
{
return apply_binary_visitor_impl1(visitor, field1, field2);
}
template <typename Visitor>
typename Visitor::ResultType apply_visitor(Visitor & visitor, Field & field1, const Field & field2)
{
return apply_binary_visitor_impl1(visitor, field1, field2);
}
template <typename Visitor>
typename Visitor::ResultType apply_visitor(Visitor & visitor, const Field & field1, Field & field2)
{
return apply_binary_visitor_impl1(visitor, field1, field2);
}
template <typename Visitor>
typename Visitor::ResultType apply_visitor(Visitor & visitor, const Field & field1, const Field & field2)
{
return apply_binary_visitor_impl1(visitor, field1, field2);
}
template <typename Visitor>
typename Visitor::ResultType apply_visitor(const Visitor & visitor, Field & field1, Field & field2)
{
return apply_binary_visitor_impl1(visitor, field1, field2);
}
template <typename Visitor>
typename Visitor::ResultType apply_visitor(const Visitor & visitor, Field & field1, const Field & field2)
{
return apply_binary_visitor_impl1(visitor, field1, field2);
}
template <typename Visitor>
typename Visitor::ResultType apply_visitor(const Visitor & visitor, const Field & field1, Field & field2)
{
return apply_binary_visitor_impl1(visitor, field1, field2);
}
template <typename Visitor>
typename Visitor::ResultType apply_visitor(const Visitor & visitor, const Field & field1, const Field & field2)
{
return apply_binary_visitor_impl1(visitor, field1, field2);
}
/** Возвращает строковый дамп типа */
class FieldVisitorDump : public StaticVisitor<String>
{
private:
template <typename T>
static inline String formatQuotedWithPrefix(T x, const char * prefix)
{
String res;
WriteBufferFromString wb(res);
wb.write(prefix, strlen(prefix));
writeQuoted(x, wb);
return res;
}
public:
String operator() (const Null & x) const { return "NULL"; }
String operator() (const UInt64 & x) const { return formatQuotedWithPrefix(x, "UInt64_"); }
String operator() (const Int64 & x) const { return formatQuotedWithPrefix(x, "Int64_"); }
String operator() (const Float64 & x) const { return formatQuotedWithPrefix(x, "Float64_"); }
String operator() (const String & x) const;
String operator() (const Array & x) const;
String operator() (const Tuple & x) const;
};
/** Выводит текстовое представление типа, как литерала в SQL запросе */
class FieldVisitorToString : public StaticVisitor<String>
{
private:
template <typename T>
static inline String formatQuoted(T x)
{
String res;
WriteBufferFromString wb(res);
writeQuoted(x, wb);
return res;
}
/** В отличие от writeFloatText (и writeQuoted), если число после форматирования выглядит целым, всё равно добавляет десятичную точку.
* - для того, чтобы это число могло обратно распарситься как Float64 парсером запроса (иначе распарсится как целое).
*
* При этом, не оставляет завершающие нули справа.
*
* NOTE: При таком roundtrip-е, точность может теряться.
*/
static String formatFloat(const Float64 x);
public:
String operator() (const Null & x) const { return "NULL"; }
String operator() (const UInt64 & x) const { return formatQuoted(x); }
String operator() (const Int64 & x) const { return formatQuoted(x); }
String operator() (const Float64 & x) const { return formatFloat(x); }
String operator() (const String & x) const { return formatQuoted(x); }
String operator() (const Array & x) const;
String operator() (const Tuple & x) const;
};
/** Числовой тип преобразует в указанный. */
template <typename T>
class FieldVisitorConvertToNumber : public StaticVisitor<T>
{
public:
T operator() (const Null & x) const
{
throw Exception("Cannot convert NULL to " + TypeName<T>::get(), ErrorCodes::CANNOT_CONVERT_TYPE);
}
T operator() (const String & x) const
{
throw Exception("Cannot convert String to " + TypeName<T>::get(), ErrorCodes::CANNOT_CONVERT_TYPE);
}
T operator() (const Array & x) const
{
throw Exception("Cannot convert Array to " + TypeName<T>::get(), ErrorCodes::CANNOT_CONVERT_TYPE);
}
T operator() (const Tuple & x) const
{
throw Exception("Cannot convert Tuple to " + TypeName<T>::get(), ErrorCodes::CANNOT_CONVERT_TYPE);
}
T operator() (const UInt64 & x) const { return x; }
T operator() (const Int64 & x) const { return x; }
T operator() (const Float64 & x) const { return x; }
};
/// Converts string with date or datetime (in format 'YYYY-MM-DD hh:mm:ss') to UInt64 containing numeric value of date (or datetime)
UInt64 stringToDateOrDateTime(const String & s);
/// Converts string with date to UInt16 (which is alias of DayNum_t) containing numeric value of date
DayNum_t stringToDate(const String & s);
/// Converts string with date to UInt64 containing numeric value of datetime
UInt64 stringToDateTime(const String & s);
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/** More precise comparison, used for index.
* Differs from Field::operator< and Field::operator== in that it also compares values of different types.
* Comparison rules are same as in FunctionsComparison (to be consistent with expression evaluation in query).
* Except in cases when comparing signed and unsigned integers, which is unspecified behavior in FunctionsComparison,
* and when comparing integers and floats. Comparison is accurate here.
*/
class FieldVisitorAccurateEquals : public StaticVisitor<bool>
{
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using Double128 = long double; /// Non portable. Must have 64 bit mantissa to provide accurate comparisons.
public:
bool operator() (const Null & l, const Null & r) const { return true; }
bool operator() (const Null & l, const UInt64 & r) const { return false; }
bool operator() (const Null & l, const Int64 & r) const { return false; }
bool operator() (const Null & l, const Float64 & r) const { return false; }
bool operator() (const Null & l, const String & r) const { return false; }
bool operator() (const Null & l, const Array & r) const { return false; }
bool operator() (const Null & l, const Tuple & r) const { return false; }
bool operator() (const UInt64 & l, const Null & r) const { return false; }
bool operator() (const UInt64 & l, const UInt64 & r) const { return l == r; }
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bool operator() (const UInt64 & l, const Int64 & r) const { return r >= 0 && l == UInt64(r); }
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bool operator() (const UInt64 & l, const Float64 & r) const { return Double128(l) == Double128(r); }
bool operator() (const UInt64 & l, const String & r) const { return l == stringToDateOrDateTime(r); }
bool operator() (const UInt64 & l, const Array & r) const { return false; }
bool operator() (const UInt64 & l, const Tuple & r) const { return false; }
bool operator() (const Int64 & l, const Null & r) const { return false; }
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bool operator() (const Int64 & l, const UInt64 & r) const { return l >= 0 && UInt64(l) == r; }
bool operator() (const Int64 & l, const Int64 & r) const { return l == r; }
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bool operator() (const Int64 & l, const Float64 & r) const { return Double128(l) == Double128(r); }
bool operator() (const Int64 & l, const String & r) const { return false; }
bool operator() (const Int64 & l, const Array & r) const { return false; }
bool operator() (const Int64 & l, const Tuple & r) const { return false; }
bool operator() (const Float64 & l, const Null & r) const { return false; }
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bool operator() (const Float64 & l, const UInt64 & r) const { return Double128(l) == Double128(r); }
bool operator() (const Float64 & l, const Int64 & r) const { return Double128(l) == Double128(r); }
bool operator() (const Float64 & l, const Float64 & r) const { return l == r; }
bool operator() (const Float64 & l, const String & r) const { return false; }
bool operator() (const Float64 & l, const Array & r) const { return false; }
bool operator() (const Float64 & l, const Tuple & r) const { return false; }
bool operator() (const String & l, const Null & r) const { return false; }
bool operator() (const String & l, const UInt64 & r) const { return stringToDateOrDateTime(l) == r; }
bool operator() (const String & l, const Int64 & r) const { return false; }
bool operator() (const String & l, const Float64 & r) const { return false; }
bool operator() (const String & l, const String & r) const { return l == r; }
bool operator() (const String & l, const Array & r) const { return false; }
bool operator() (const String & l, const Tuple & r) const { return false; }
bool operator() (const Array & l, const Null & r) const { return false; }
bool operator() (const Array & l, const UInt64 & r) const { return false; }
bool operator() (const Array & l, const Int64 & r) const { return false; }
bool operator() (const Array & l, const Float64 & r) const { return false; }
bool operator() (const Array & l, const String & r) const { return false; }
bool operator() (const Array & l, const Array & r) const { return l == r; }
bool operator() (const Array & l, const Tuple & r) const { return false; }
bool operator() (const Tuple & l, const Null & r) const { return false; }
bool operator() (const Tuple & l, const UInt64 & r) const { return false; }
bool operator() (const Tuple & l, const Int64 & r) const { return false; }
bool operator() (const Tuple & l, const Float64 & r) const { return false; }
bool operator() (const Tuple & l, const String & r) const { return false; }
bool operator() (const Tuple & l, const Array & r) const { return false; }
bool operator() (const Tuple & l, const Tuple & r) const { return l == r; }
};
class FieldVisitorAccurateLess : public StaticVisitor<bool>
{
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using Double128 = long double; /// Non portable. Must have 64 bit mantissa to provide accurate comparisons.
public:
bool operator() (const Null & l, const Null & r) const { return false; }
bool operator() (const Null & l, const UInt64 & r) const { return true; }
bool operator() (const Null & l, const Int64 & r) const { return true; }
bool operator() (const Null & l, const Float64 & r) const { return true; }
bool operator() (const Null & l, const String & r) const { return true; }
bool operator() (const Null & l, const Array & r) const { return true; }
bool operator() (const Null & l, const Tuple & r) const { return true; }
bool operator() (const UInt64 & l, const Null & r) const { return false; }
bool operator() (const UInt64 & l, const UInt64 & r) const { return l < r; }
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bool operator() (const UInt64 & l, const Int64 & r) const { return r >= 0 && l < UInt64(r); }
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bool operator() (const UInt64 & l, const Float64 & r) const { return Double128(l) < Double128(r); }
bool operator() (const UInt64 & l, const String & r) const { return l < stringToDateOrDateTime(r); }
bool operator() (const UInt64 & l, const Array & r) const { return true; }
bool operator() (const UInt64 & l, const Tuple & r) const { return true; }
bool operator() (const Int64 & l, const Null & r) const { return false; }
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bool operator() (const Int64 & l, const UInt64 & r) const { return l < 0 || UInt64(l) < r; }
bool operator() (const Int64 & l, const Int64 & r) const { return l < r; }
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bool operator() (const Int64 & l, const Float64 & r) const { return Double128(l) < Double128(r); }
bool operator() (const Int64 & l, const String & r) const { return true; }
bool operator() (const Int64 & l, const Array & r) const { return true; }
bool operator() (const Int64 & l, const Tuple & r) const { return true; }
bool operator() (const Float64 & l, const Null & r) const { return false; }
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bool operator() (const Float64 & l, const UInt64 & r) const { return Double128(l) < Double128(r); }
bool operator() (const Float64 & l, const Int64 & r) const { return Double128(l) < Double128(r); }
bool operator() (const Float64 & l, const Float64 & r) const { return l < r; }
bool operator() (const Float64 & l, const String & r) const { return true; }
bool operator() (const Float64 & l, const Array & r) const { return true; }
bool operator() (const Float64 & l, const Tuple & r) const { return true; }
bool operator() (const String & l, const Null & r) const { return false; }
bool operator() (const String & l, const UInt64 & r) const { return stringToDateOrDateTime(l) < r; }
bool operator() (const String & l, const Int64 & r) const { return false; }
bool operator() (const String & l, const Float64 & r) const { return false; }
bool operator() (const String & l, const String & r) const { return l < r; }
bool operator() (const String & l, const Array & r) const { return true; }
bool operator() (const String & l, const Tuple & r) const { return true; }
bool operator() (const Array & l, const Null & r) const { return false; }
bool operator() (const Array & l, const UInt64 & r) const { return false; }
bool operator() (const Array & l, const Int64 & r) const { return false; }
bool operator() (const Array & l, const Float64 & r) const { return false; }
bool operator() (const Array & l, const String & r) const { return false; }
bool operator() (const Array & l, const Array & r) const { return l < r; }
bool operator() (const Array & l, const Tuple & r) const { return false; }
bool operator() (const Tuple & l, const Null & r) const { return false; }
bool operator() (const Tuple & l, const UInt64 & r) const { return false; }
bool operator() (const Tuple & l, const Int64 & r) const { return false; }
bool operator() (const Tuple & l, const Float64 & r) const { return false; }
bool operator() (const Tuple & l, const String & r) const { return false; }
bool operator() (const Tuple & l, const Array & r) const { return false; }
bool operator() (const Tuple & l, const Tuple & r) const { return l < r; }
};
}