ClickHouse/dbms/include/DB/IO/ReadHelpers.h
2011-08-19 18:31:14 +00:00

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#ifndef DBMS_COMMON_READHELPERS_H
#define DBMS_COMMON_READHELPERS_H
#include <cstring>
#include <limits>
#include <algorithm>
#include <Yandex/DateLUT.h>
#include <DB/Core/Types.h>
#include <DB/Core/Exception.h>
#include <DB/Core/ErrorCodes.h>
#include <DB/IO/ReadBuffer.h>
#include <DB/IO/VarInt.h>
#define DEFAULT_MAX_STRING_SIZE 0x00FFFFFFULL
namespace DB
{
/// Функции-помошники для форматированного чтения
static inline char parseEscapeSequence(char c)
{
switch(c)
{
case 'b':
return '\b';
case 'f':
return '\f';
case 'n':
return '\n';
case 'r':
return '\r';
case 't':
return '\t';
case '0':
return '\0';
default:
return c;
}
}
static inline void throwReadAfterEOF()
{
throw Exception("Attempt to read after eof", ErrorCodes::ATTEMPT_TO_READ_AFTER_EOF);
}
/// Чтение числа в native формате
template <typename T>
inline void readBinary(T & x, ReadBuffer & buf)
{
buf.readStrict(reinterpret_cast<char *>(&x), sizeof(x));
}
template <typename T>
inline void readIntBinary(T & x, ReadBuffer & buf)
{
readBinary(x, buf);
}
template <typename T>
inline void readFloatBinary(T & x, ReadBuffer & buf)
{
readBinary(x, buf);
}
inline void readStringBinary(std::string & s, DB::ReadBuffer & buf, size_t MAX_STRING_SIZE = DEFAULT_MAX_STRING_SIZE)
{
size_t size = 0;
DB::readVarUInt(size, buf);
if (size > MAX_STRING_SIZE)
throw Poco::Exception("Too large string size.");
s.resize(size);
buf.readStrict(const_cast<char *>(s.data()), size);
}
inline void readChar(char & x, ReadBuffer & buf)
{
if (!buf.eof())
{
x = *buf.position();
++buf.position();
}
else
throwReadAfterEOF();
}
void assertString(const char * s, ReadBuffer & buf);
/// грубо
template <typename T>
void readIntText(T & x, ReadBuffer & buf)
{
bool negative = false;
x = 0;
if (buf.eof())
throwReadAfterEOF();
while (!buf.eof())
{
switch (*buf.position())
{
case '+':
break;
case '-':
negative = true;
break;
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
case '8':
case '9':
x *= 10;
x += *buf.position() - '0';
break;
default:
if (negative)
x = -x;
return;
}
++buf.position();
}
if (negative)
x = -x;
}
/// грубо
template <typename T>
void readFloatText(T & x, ReadBuffer & buf)
{
bool negative = false;
x = 0;
bool after_point = false;
double power_of_ten = 1;
if (buf.eof())
throwReadAfterEOF();
while (!buf.eof())
{
switch (*buf.position())
{
case '+':
break;
case '-':
negative = true;
break;
case '.':
after_point = true;
break;
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
case '8':
case '9':
if (after_point)
{
power_of_ten /= 10;
x += (*buf.position() - '0') * power_of_ten;
}
else
{
x *= 10;
x += *buf.position() - '0';
}
break;
case 'e':
case 'E':
{
++buf.position();
Int32 exponent = 0;
readIntText(exponent, buf);
if (exponent == 0)
{
if (negative)
x = -x;
return;
}
else if (exponent > 0)
{
for (Int32 i = 0; i < exponent; ++i)
x *= 10;
if (negative)
x = -x;
return;
}
else
{
for (Int32 i = 0; i < exponent; ++i)
x /= 10;
if (negative)
x = -x;
return;
}
}
case 'i':
++buf.position();
assertString("nf", buf);
x = std::numeric_limits<T>::infinity();
if (negative)
x = -x;
return;
case 'I':
++buf.position();
assertString("NF", buf);
x = std::numeric_limits<T>::infinity();
if (negative)
x = -x;
return;
case 'n':
++buf.position();
assertString("an", buf);
x = std::numeric_limits<T>::quiet_NaN();
return;
case 'N':
++buf.position();
assertString("AN", buf);
x = std::numeric_limits<T>::quiet_NaN();
return;
default:
if (negative)
x = -x;
return;
}
++buf.position();
}
if (negative)
x = -x;
}
template <typename T>
void readText(T & x, ReadBuffer & buf);
template <> inline void readText<UInt8> (UInt8 & x, ReadBuffer & buf) { readIntText(x, buf); }
template <> inline void readText<UInt16> (UInt16 & x, ReadBuffer & buf) { readIntText(x, buf); }
template <> inline void readText<UInt32> (UInt32 & x, ReadBuffer & buf) { readIntText(x, buf); }
template <> inline void readText<UInt64> (UInt64 & x, ReadBuffer & buf) { readIntText(x, buf); }
template <> inline void readText<Int8> (Int8 & x, ReadBuffer & buf) { readIntText(x, buf); }
template <> inline void readText<Int16> (Int16 & x, ReadBuffer & buf) { readIntText(x, buf); }
template <> inline void readText<Int32> (Int32 & x, ReadBuffer & buf) { readIntText(x, buf); }
template <> inline void readText<Int64> (Int64 & x, ReadBuffer & buf) { readIntText(x, buf); }
template <> inline void readText<Float32> (Float32 & x, ReadBuffer & buf) { readFloatText(x, buf); }
template <> inline void readText<Float64> (Float64 & x, ReadBuffer & buf) { readFloatText(x, buf); }
/// грубо; всё до '\n' или '\t'
void readString(String & s, ReadBuffer & buf);
void readEscapedString(String & s, ReadBuffer & buf);
void readQuotedString(String & s, ReadBuffer & buf);
void readDoubleQuotedString(String & s, ReadBuffer & buf);
/// в формате YYYY-MM-DD
inline void readDateText(Yandex::DayNum_t & date, ReadBuffer & buf)
{
char s[10];
size_t size = buf.read(s, 10);
if (10 != size)
{
s[size] = 0;
throw Exception(std::string("Cannot parse date ") + s, ErrorCodes::CANNOT_PARSE_DATE);
}
UInt16 year = (s[0] - '0') * 1000 + (s[1] - '0') * 100 + (s[2] - '0') * 10 + (s[3] - '0');
UInt8 month = (s[5] - '0') * 10 + (s[6] - '0');
UInt8 day = (s[8] - '0') * 10 + (s[9] - '0');
date = Yandex::DateLUTSingleton::instance().makeDayNum(year, month, day);
}
/// в формате YYYY-MM-DD HH:MM:SS, согласно текущему часовому поясу
inline void readDateTimeText(time_t & datetime, ReadBuffer & buf)
{
char s[19];
size_t size = buf.read(s, 19);
if (19 != size)
{
s[size] = 0;
throw Exception(std::string("Cannot parse datetime ") + s, ErrorCodes::CANNOT_PARSE_DATETIME);
}
UInt16 year = (s[0] - '0') * 1000 + (s[1] - '0') * 100 + (s[2] - '0') * 10 + (s[3] - '0');
UInt8 month = (s[5] - '0') * 10 + (s[6] - '0');
UInt8 day = (s[8] - '0') * 10 + (s[9] - '0');
UInt8 hour = (s[11] - '0') * 10 + (s[12] - '0');
UInt8 minute = (s[14] - '0') * 10 + (s[15] - '0');
UInt8 second = (s[17] - '0') * 10 + (s[18] - '0');
datetime = Yandex::DateLUTSingleton::instance().makeDateTime(year, month, day, hour, minute, second);
}
}
#endif