mapnik/plugins/input/postgis/numeric2string.hpp
2024-07-22 10:20:47 +01:00

149 lines
4.2 KiB
C++

/*****************************************************************************
*
* This file is part of Mapnik (c++ mapping toolkit)
*
* Copyright (C) 2024 Artem Pavlenko
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
*****************************************************************************/
#ifndef MAPNIK_NUMERIC_2_STRING_HPP
#define MAPNIK_NUMERIC_2_STRING_HPP
#include <mapnik/global.hpp>
#include <string>
#include <sstream>
#include <memory>
#include <algorithm>
static inline std::string numeric2string(const char* buf)
{
std::int16_t ndigits = int2net(buf);
std::int16_t weight = int2net(buf + 2);
std::int16_t sign = int2net(buf + 4);
std::int16_t dscale = int2net(buf + 6);
std::unique_ptr<std::int16_t[]> digits(new std::int16_t[ndigits]);
for (int n = 0; n < ndigits; ++n)
{
digits[n] = int2net(buf + 8 + n * 2);
}
std::ostringstream ss;
if (sign == 0x4000)
ss << "-";
int i = std::max(weight, std::int16_t(0));
int d = 0;
// Each numeric "digit" is actually a value between 0000 and 9999 stored in a 16 bit field.
// For example, the number 1234567809990001 is stored as four digits: [1234] [5678] [999] [1].
// Note that the last two digits show that the leading 0's are lost when the number is split.
// We must be careful to re-insert these 0's when building the string.
while (i >= 0)
{
if (i <= weight && d < ndigits)
{
// All digits after the first must be padded to make the field 4 characters long
if (d != 0)
{
#ifdef _WIN32
int dig = digits[d];
if (dig < 10)
{
ss << "000"; // 0000 - 0009
}
else if (dig < 100)
{
ss << "00"; // 0010 - 0099
}
else
{
ss << "0"; // 0100 - 0999;
}
#else
switch (digits[d])
{
case 0 ... 9:
ss << "000"; // 0000 - 0009
break;
case 10 ... 99:
ss << "00"; // 0010 - 0099
break;
case 100 ... 999:
ss << "0"; // 0100 - 0999
break;
}
#endif
}
ss << digits[d++];
}
else
{
if (d == 0)
ss << "0";
else
ss << "0000";
}
i--;
}
if (dscale > 0)
{
ss << '.';
// dscale counts the number of decimal digits following the point, not the numeric digits
while (dscale > 0)
{
int value;
if (i <= weight && d < ndigits)
value = digits[d++];
else
value = 0;
// Output up to 4 decimal digits for this value
if (dscale > 0)
{
ss << (value / 1000);
value %= 1000;
dscale--;
}
if (dscale > 0)
{
ss << (value / 100);
value %= 100;
dscale--;
}
if (dscale > 0)
{
ss << (value / 10);
value %= 10;
dscale--;
}
if (dscale > 0)
{
ss << value;
dscale--;
}
i--;
}
}
return ss.str();
}
#endif