ClickHouse/src/IO/WriteIntText.h

#pragma once

#include <Core/Defines.h>
#include <IO/WriteBuffer.h>
#include <base/itoa.h>


namespace
{
    template <typename T> constexpr size_t max_int_width = 20;
    template <> inline constexpr size_t max_int_width<UInt8> = 3;    /// 255
    template <> inline constexpr size_t max_int_width<Int8> = 4;     /// -128
    template <> inline constexpr size_t max_int_width<UInt16> = 5;   /// 65535
    template <> inline constexpr size_t max_int_width<Int16> = 6;    /// -32768
    template <> inline constexpr size_t max_int_width<UInt32> = 10;  /// 4294967295
    template <> inline constexpr size_t max_int_width<Int32> = 11;   /// -2147483648
    template <> inline constexpr size_t max_int_width<UInt64> = 20;  /// 18446744073709551615
    template <> inline constexpr size_t max_int_width<Int64> = 20;   /// -9223372036854775808
    template <> inline constexpr size_t max_int_width<UInt128> = 39; /// 340282366920938463463374607431768211455
    template <> inline constexpr size_t max_int_width<Int128> = 40;  /// -170141183460469231731687303715884105728
    template <> inline constexpr size_t max_int_width<UInt256> = 78; /// 115792089237316195423570985008687907853269984665640564039457584007913129639935
    template <> inline constexpr size_t max_int_width<Int256> = 78;  /// -57896044618658097711785492504343953926634992332820282019728792003956564819968
}


namespace DB
{

namespace detail
{
    template <typename T>
    void NO_INLINE writeUIntTextFallback(T x, WriteBuffer & buf)
    {
        char tmp[max_int_width<T>];
        char * end = itoa(x, tmp);
        buf.write(tmp, end - tmp);
    }
}

template <typename T>
void writeIntText(T x, WriteBuffer & buf)
{
    if (likely(reinterpret_cast<uintptr_t>(buf.position()) + max_int_width<T> < reinterpret_cast<uintptr_t>(buf.buffer().end())))
        buf.position() = itoa(x, buf.position());
    else
        detail::writeUIntTextFallback(x, buf);
}

}