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dbms: harness the power of libdouble-conversion. [#METR-13363]

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This commit is contained in:
Andrey Mironov 2014-12-09 14:33:34 +03:00
parent 3be8b25ed2
commit 00db574116
2 changed files with 16 additions and 18 deletions
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23
dbms/include/DB/Core/Field.h
View File

@ -17,6 +17,8 @@
#include <DB/IO/WriteHelpers.h>
#include <DB/IO/WriteBufferFromString.h>
#include <DB/IO/DoubleConverter.h>
namespace DB
{
@ -590,24 +592,17 @@ private:
*
* NOTE: При таком roundtrip-е, точность может теряться.
*/
static inline String formatFloat(Float64 x)
static String formatFloat(const Float64 x)
{
char tmp[24];
int res = std::snprintf(tmp, 23, "%.*g", WRITE_HELPERS_DEFAULT_FLOAT_PRECISION, x);
char tmp[25];
double_conversion::StringBuilder builder{tmp, sizeof(tmp)};
if (res >= 23 || res <= 0)
const auto result = getDoubleToStringConverter().ToShortest(x, &builder);
if (!result)
throw Exception("Cannot print float or double number", ErrorCodes::CANNOT_PRINT_FLOAT_OR_DOUBLE_NUMBER);
size_t string_size = res;
tmp[23] = '\0';
if (string_size == strspn(tmp, "-0123456789"))
{
tmp[string_size] = '.';
++string_size;
}
return {tmp, string_size};
return { tmp, tmp + builder.position() };
}
public:

11
dbms/include/DB/IO/WriteHelpers.h
View File

@ -19,6 +19,7 @@
#include <DB/IO/WriteIntText.h>
#include <DB/IO/VarInt.h>
#include <DB/IO/WriteBufferFromString.h>
#include <DB/IO/DoubleConverter.h>
#include <city.h>
#define WRITE_HELPERS_DEFAULT_FLOAT_PRECISION 6U
@ -89,13 +90,15 @@ inline void writeBoolText(bool x, WriteBuffer & buf)
template <typename T>
void writeFloatText(T x, WriteBuffer & buf, unsigned precision = WRITE_HELPERS_DEFAULT_FLOAT_PRECISION)
{
char tmp[24];
int res = std::snprintf(tmp, 24, "%.*g", precision, x);
char tmp[25];
double_conversion::StringBuilder builder{tmp, sizeof(tmp)};
if (res >= 24 || res <= 0)
const auto result = getDoubleToStringConverter<false>().ToShortest(x, &builder);
if (!result)
throw Exception("Cannot print float or double number", ErrorCodes::CANNOT_PRINT_FLOAT_OR_DOUBLE_NUMBER);
buf.write(tmp, res);
buf.write(tmp, builder.position());
}