ClickHouse/dbms/src/Functions/intExp2.cpp
2020-02-25 21:10:48 +03:00

61 lines
1.8 KiB
C++

#include <Functions/FunctionFactory.h>
#include <Functions/FunctionUnaryArithmetic.h>
#include <Common/FieldVisitors.h>
#include <Common/intExp.h>
namespace DB
{
namespace ErrorCodes
{
extern const int LOGICAL_ERROR;
}
template <typename A>
struct IntExp2Impl
{
using ResultType = UInt64;
static constexpr const bool allow_fixed_string = false;
static inline ResultType apply(A a)
{
return intExp2(a);
}
#if USE_EMBEDDED_COMPILER
static constexpr bool compilable = true;
static inline llvm::Value * compile(llvm::IRBuilder<> & b, llvm::Value * arg, bool)
{
if (!arg->getType()->isIntegerTy())
throw Exception("IntExp2Impl expected an integral type", ErrorCodes::LOGICAL_ERROR);
return b.CreateShl(llvm::ConstantInt::get(arg->getType(), 1), arg);
}
#endif
};
/// Assumed to be injective for the purpose of query optimization, but in fact it is not injective because of possible overflow.
struct NameIntExp2 { static constexpr auto name = "intExp2"; };
using FunctionIntExp2 = FunctionUnaryArithmetic<IntExp2Impl, NameIntExp2, true>;
template <> struct FunctionUnaryArithmeticMonotonicity<NameIntExp2>
{
static bool has() { return true; }
static IFunction::Monotonicity get(const Field & left, const Field & right)
{
Float64 left_float = left.isNull() ? -std::numeric_limits<Float64>::infinity() : applyVisitor(FieldVisitorConvertToNumber<Float64>(), left);
Float64 right_float = right.isNull() ? std::numeric_limits<Float64>::infinity() : applyVisitor(FieldVisitorConvertToNumber<Float64>(), right);
if (left_float < 0 || right_float > 63)
return {};
return { true };
}
};
void registerFunctionIntExp2(FunctionFactory & factory)
{
factory.registerFunction<FunctionIntExp2>();
}
}