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/*******************************************************************************
* librepfunc: A tiny lib of common functions and tasks in my c++ projects.
* See the README file for copyright information and how to reach the author.
******************************************************************************/
#include <string> // std::stod
#include <iostream> // std::cerr
#include <limits> // std::numeric_limits
#include <repfunc.h>
/* A valid floating point number using the "C" locale is formed by
* an optional sign character (+ or -),
* followed by one of:
* - A sequence of digits, optionally containing a decimal-point character (.),
* optionally followed by an exponent part (an e or E character followed by
* an optional sign and a sequence of digits).
* - A 0x or 0X prefix, then a sequence of hexadecimal digits (as in isxdigit)
* optionally containing a period which separates the whole and fractional
* number parts. Optionally followed by a power of 2 exponent
* (a p or P character followed by an optional sign and a sequence of hexa-
* decimal digits).
* - INF or INFINITY (ignoring case).
* - NAN or NANsequence (ignoring case), where sequence is a sequence of char,
* where each character is either an alphanumeric character (as in isalnum)
* or the underscore character (_).
*/
/* IMPORTANT!
* 1. Different to std::stod() and strtod(), StrToFloat silently accepts
* period (.) and comma (,) as decimal-separator.
*
* 2. StrToFloat is locale-independent.
*
* 3. Any lower control char is considered a whitespace and left trimmed,
* whereas std::stod() and strtod() trims only those as isspace knows.
*
* 4. StrToFloat shouldn' throw exceptions. At least, thats one goal.
*/
double StrToFloat(const std::string& s, size_t* pos) {
size_t p, len = s.size();
const char* P = s.c_str();
// trim left any lower control chars.
for(p=0;p<len;p++) if (P[p] > 0x20) break;
char first = P[p];
if (first == 0) {
std::cerr << __FUNCTION__ << ": cannot parse '" << s << "'" << std::endl;
if (pos) *pos = p;
return std::numeric_limits<double>::quiet_NaN();
}
// optional sign character (+ or -)
bool plus = first == '+';
bool minus = first == '-';
if (plus or minus) {
p++;
first = P[p];
}
char second = len > (p+1) ? P[p+1] : 0;
char third = len > (p+2) ? P[p+2] : 0;
// NAN or NANsequence
bool nan = ((first == 'N') or (first == 'n')) and
((second == 'A') or (second == 'a')) and
((third == 'N') or (third == 'n'));
if (nan) {
p += 3;
for(;p<len;) {
char sequence = P[p];
if ((sequence == '_') or
((sequence >= 'A') and (sequence <= 'Z')) or
((sequence >= 'a') and (sequence <= 'z')))
p++;
else
break;
}
if (pos) *pos = p;
return std::numeric_limits<double>::quiet_NaN();
}
// INF or INFINITY (ignoring case)
bool inf = ((first == 'I') or (first == 'i')) and
((second == 'N') or (second == 'n')) and
((third == 'F') or (third == 'f'));
if (inf) {
p += 3;
char c4 = len > (p+1) ? P[p+1] : 0;
char c5 = len > (p+2) ? P[p+2] : 0;
char c6 = len > (p+3) ? P[p+3] : 0;
char c7 = len > (p+4) ? P[p+4] : 0;
char c8 = len > (p+5) ? P[p+5] : 0;
if (((c4 == 'I') or (c4 == 'i')) and
((c5 == 'N') or (c5 == 'n')) and
((c6 == 'I') or (c6 == 'i')) and
((c7 == 'T') or (c7 == 't')) and
((c8 == 'Y') or (c8 == 'y')))
p += 5;
if (pos) *pos = p;
if (minus)
return -std::numeric_limits<double>::infinity();
else
return std::numeric_limits<double>::infinity();
}
bool hex = (first == '0') and
((second == 'X') or (second == 'x'));
if (hex) {
/* - A 0x or 0X prefix, then a sequence of hexadecimal digits (as in isxdigit)
* optionally containing a period which separates the whole and fractional
* number parts. Optionally followed by a power of 2 exponent
* (a p or P character followed by an optional sign and a sequence of hexa-
* decimal digits).
*/
p += 2; // skip prefix "0x"
size_t whole_part = 0;
size_t fract_part = 0;
size_t fract_div = 1;
size_t exp_part = 0;
bool exp_sign = true;
char next = 0;
for(; p<len; p++) {
next = P[p];
if ((next >= '0') and (next <= '9')) {
whole_part *= 16;
whole_part += (next - '0');
}
else if ((next >= 'A') and (next <= 'F')) {
whole_part *= 16;
whole_part += 10 + (next - 'A');
}
else if ((next >= 'a') and (next <= 'f')) {
whole_part *= 16;
whole_part += 10 + (next - 'a');
}
else
break;
}
if ((next == '.') or (next == ',')) {
for(p++; p<len; p++) {
next = P[p];
if ((next >= '0') and (next <= '9')) {
fract_div *= 16;
fract_part *= 16;
fract_part += (next - '0');
}
else if ((next >= 'A') and (next <= 'F')) {
fract_div *= 16;
fract_part *= 16;
fract_part += 10 + (next - 'A');
}
else if ((next >= 'a') and (next <= 'f')) {
fract_div *= 16;
fract_part *= 16;
fract_part += 10 + (next - 'a');
}
else
break;
}
}
if ((next == 'P') or (next == 'p')) {
p++;
next = P[p];
if ((next == '+') or (next == '-')) {
exp_sign = (next == '+');
p++;
next = P[p];
}
for(; p<len; p++) {
next = P[p];
if ((next >= '0') and (next <= '9')) {
exp_part *= 16;
exp_part += (next - '0');
}
else if ((next >= 'A') and (next <= 'F')) {
exp_part *= 16;
exp_part += 10 + (next - 'A');
}
else if ((next >= 'a') and (next <= 'f')) {
exp_part *= 16;
exp_part += 10 + (next - 'a');
}
else
break;
}
}
double fract = (double)fract_part / (double)fract_div;
double result = (double)whole_part + fract;
if (minus)
result *= -1.0;
if (exp_part) {
double pow = (double) (1 << exp_part);
if (exp_sign)
result *= pow;
else
result *= 1.0/pow;
}
if (pos) *pos = p;
return result;
}
else {
/* - A sequence of digits, optionally containing a decimal-point character (.),
* optionally followed by an exponent part (an e or E character followed by
* an optional sign and a sequence of digits).
*/
size_t whole_part = 0;
size_t fract_part = 0;
size_t fract_div = 1;
size_t exp_part = 0;
bool exp_sign = true;
char next = 0;
for(; p<len; p++) {
next = P[p];
if ((next < '0') or (next > '9'))
break;
whole_part *= 10;
whole_part += (next - '0');
}
if ((next == '.') or (next == ',')) {
for(p++; p<len; p++) {
next = P[p];
if ((next < '0') or (next > '9'))
break;
fract_div *= 10;
fract_part *= 10;
fract_part += (next - '0');
}
}
if ((next == 'E') or (next == 'e')) {
p++;
next = P[p];
if ((next == '+') or (next == '-')) {
exp_sign = (next == '+');
p++;
next = P[p];
}
for(; p<len; p++) {
next = P[p];
if ((next < '0') or (next > '9'))
break;
exp_part *= 10;
exp_part += (next - '0');
}
}
double fract = (double)fract_part / (double)fract_div;
double result = (double)whole_part + fract;
if (minus)
result *= -1.0;
if (exp_part) {
size_t pow = 1;
for(;exp_part;exp_part--) pow *= 10;
if (exp_sign)
result *= (double)pow;
else
result *= 1.0/((double)pow);
}
if (pos) *pos = p;
return result;
}
// never reached.
std::cerr << __FUNCTION__ << ":" << __LINE__ << ": something is wrong here.";
return std::numeric_limits<double>::quiet_NaN();
}
double WStrToFloat(const std::wstring& ws, size_t* pos) {
std::string s = WStrToStr(ws);
return StrToFloat(s, pos);
}
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