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XPath stack optimization: Reduce convert_number_to_string stack usage by reducing mantissa_buffer size and filling resulting string on heap without an extra copy from stack.

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git-svn-id: http://pugixml.googlecode.com/svn/trunk@933 99668b35-9821-0410-8761-19e4c4f06640
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arseny.kapoulkine@gmail.com 2012-11-18 23:11:59 +00:00
parent c95900e354
commit a3aa5d39b8
1 changed files with 8 additions and 4 deletions
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12
src/pugixml.cpp
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@ -6341,14 +6341,18 @@ PUGI__NS_BEGIN
if (special) return xpath_string_const(special);
// get mantissa + exponent form
char mantissa_buffer[64];
char mantissa_buffer[32];
char* mantissa;
int exponent;
convert_number_to_mantissa_exponent(value, mantissa_buffer, sizeof(mantissa_buffer), &mantissa, &exponent);
// allocate a buffer of suitable length for the number
size_t result_size = strlen(mantissa_buffer) + (exponent > 0 ? exponent : -exponent) + 4;
char_t* result = static_cast<char_t*>(alloc->allocate(sizeof(char_t) * result_size));
assert(result);
// make the number!
char_t result[512];
char_t* s = result;
// sign
@ -6391,10 +6395,10 @@ PUGI__NS_BEGIN
}
// zero-terminate
assert(s < result + sizeof(result) / sizeof(result[0]));
assert(s < result + result_size);
*s = 0;
return xpath_string(result, alloc);
return xpath_string(result, true);
}
PUGI__FN bool check_string_to_number_format(const char_t* string)