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XPath: Number to string conversion uses ecvt_s under MSVC8+ (major speedup), minor conversion refactoring

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git-svn-id: http://pugixml.googlecode.com/svn/trunk@649 99668b35-9821-0410-8761-19e4c4f06640
This commit is contained in:
arseny.kapoulkine 2010-08-29 15:15:21 +00:00
parent 7aadde4229
commit 3284cc2f1b
1 changed files with 29 additions and 8 deletions
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37
src/pugixpath.cpp
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@ -337,11 +337,35 @@ namespace
return (value != 0 && !is_nan(value));
}
void truncate_zeros(char* begin, char* end)
{
while (begin != end && end[-1] == '0') end--;
*end = 0;
}
// gets mantissa digits in the form of 0.xxxxx with 0. implied and the exponent
void convert_number_to_mantissa_exponent(double value, char* buffer, char** out_mantissa, int* out_exponent)
#if defined(_MSC_VER) && _MSC_VER >= 1400
void convert_number_to_mantissa_exponent(double value, char* buffer, size_t buffer_size, char** out_mantissa, int* out_exponent)
{
// get base values
int sign, exponent;
_ecvt_s(buffer, buffer_size, value, DBL_DIG + 1, &exponent, &sign);
// truncate redundant zeros
truncate_zeros(buffer, buffer + strlen(buffer));
// fill results
*out_mantissa = buffer;
*out_exponent = exponent;
}
#else
void convert_number_to_mantissa_exponent(double value, char* buffer, size_t buffer_size, char** out_mantissa, int* out_exponent)
{
// get a scientific notation value with IEEE DBL_DIG decimals
sprintf(buffer, "%.15e", value);
sprintf(buffer, "%.*e", DBL_DIG, value);
assert(strlen(buffer) < buffer_size);
(void)!buffer_size;
// get the exponent (possibly negative)
char* exponent_string = strchr(buffer, 'e');
@ -359,16 +383,13 @@ namespace
exponent++;
// remove extra mantissa digits and zero-terminate mantissa
char* mantissa_end = exponent_string;
while (mantissa != mantissa_end && *(mantissa_end - 1) == '0') --mantissa_end;
*mantissa_end = 0;
truncate_zeros(mantissa, exponent_string);
// fill results
*out_mantissa = mantissa;
*out_exponent = exponent;
}
#endif
string_t convert_number_to_string(double value)
{
@ -381,7 +402,7 @@ namespace
char* mantissa;
int exponent;
convert_number_to_mantissa_exponent(value, mantissa_buffer, &mantissa, &exponent);
convert_number_to_mantissa_exponent(value, mantissa_buffer, sizeof(mantissa_buffer), &mantissa, &exponent);
// make the number!
char_t result[512];