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Feature implementation. [#METR-15210]

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This commit is contained in:
Alexey Arno 2015-05-08 18:15:52 +03:00
parent 51711df1c0
commit e981b66ef8
2 changed files with 68 additions and 1 deletions
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68
dbms/include/DB/Functions/FunctionsRound.h
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@ -3,6 +3,54 @@
#include <DB/Functions/FunctionsArithmetic.h>
#include <cmath> // log2()
namespace
{
template <size_t N>
struct PowerOf10
{
static const size_t value = 10 * PowerOf10<N - 1>::value;
};
template<>
struct PowerOf10<0>
{
static const size_t value = 1;
};
template <size_t... TArgs>
struct TablePowersOf10
{
static const size_t value[sizeof...(TArgs)];
};
template <size_t... TArgs>
const size_t TablePowersOf10<TArgs...>::value[sizeof...(TArgs)] = { TArgs... };
// Compute powers from 0 to N - 1.
template <size_t N, size_t... TArgs>
struct FillArrayImpl
{
using result = typename FillArrayImpl<N - 1, PowerOf10<N>::value, TArgs...>::result;
};
// Fill array with computed powers.
template <size_t... TArgs>
struct FillArrayImpl<0, TArgs...>
{
using result = TablePowersOf10<PowerOf10<0>::value, TArgs...>;
};
// Bootstrap.
template <size_t N>
struct FillArray
{
using result = typename FillArrayImpl<N-1>::result;
};
using powers_of_10 = FillArray<16>::result;
}
namespace DB
{
@ -87,13 +135,31 @@ namespace DB
}
};
template<typename A, typename B>
struct RoundImpl
{
typedef A ResultType;
template <typename Result = ResultType>
static inline Result apply(A a, B b)
{
auto vb = typename NumberTraits::ToInteger<B>::Type(b);
if (vb < 0)
vb = 0;
size_t scale = (vb < 16) ? powers_of_10::value[vb] : pow(10, vb);
return static_cast<Result>(round(a * scale) / scale);
}
};
struct NameRoundToExp2 { static constexpr auto name = "roundToExp2"; };
struct NameRoundDuration { static constexpr auto name = "roundDuration"; };
struct NameRoundAge { static constexpr auto name = "roundAge"; };
struct NameRound { static constexpr auto name = "round"; };
typedef FunctionUnaryArithmetic<RoundToExp2Impl, NameRoundToExp2> FunctionRoundToExp2;
typedef FunctionUnaryArithmetic<RoundDurationImpl, NameRoundDuration> FunctionRoundDuration;
typedef FunctionUnaryArithmetic<RoundAgeImpl, NameRoundAge> FunctionRoundAge;
typedef FunctionBinaryArithmetic<RoundImpl, NameRound> FunctionRound;
}

1
dbms/src/Functions/FunctionsRound.cpp
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@ -9,6 +9,7 @@ void registerFunctionsRound(FunctionFactory & factory)
factory.registerFunction<FunctionRoundToExp2>();
factory.registerFunction<FunctionRoundDuration>();
factory.registerFunction<FunctionRoundAge>();
factory.registerFunction<FunctionRound>();
}
}