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120 lines
2.2 KiB
C++
120 lines
2.2 KiB
C++
// SPDX-License-Identifier: GPL-2.0
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/*
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* Sane helper for 'strtod()'.
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*
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* Sad that we even need this, but the C library version has
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* insane locale behavior, and while the Qt "toDouble()" routines
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* are better in that regard, they don't have an end pointer
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* (having replaced it with the completely idiotic "ok" boolean
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* pointer instead).
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*
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* So if you want the C locale kind of parsing, use the
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* ascii_strtod() function. But if you want a more relaxed
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* "Hey, Europeans are people too, even if they have locales
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* with commas", use general_strtod() instead.
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*/
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#include <ctype.h>
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#include "subsurface-string.h"
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static double strtod_flags(const char *str, const char **ptr, bool no_comma)
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{
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char c;
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const char *p = str, *ep;
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double val = 0.0;
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double decimal = 1.0;
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bool sign = false, esign = false;
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bool numbers = false, dot = false;
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/* skip spaces */
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while (isspace(c = *p++))
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/* */;
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/* optional sign */
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switch (c) {
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case '-':
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sign = true;
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/* fallthrough */
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case '+':
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c = *p++;
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}
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/* Mantissa */
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for (;; c = *p++) {
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if (c == '.' || (c == ',' && !no_comma)) {
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if (dot)
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goto done;
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dot = true;
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continue;
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}
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if (c >= '0' && c <= '9') {
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numbers = true;
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val = (val * 10) + (c - '0');
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if (dot)
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decimal *= 10;
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continue;
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}
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if (c != 'e' && c != 'E')
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goto done;
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break;
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}
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if (!numbers)
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goto done;
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/* Exponent */
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ep = p;
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c = *ep++;
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switch (c) {
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case '-':
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esign = true;
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/* fallthrough */
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case '+':
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c = *ep++;
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}
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if (c >= '0' && c <= '9') {
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p = ep;
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int exponent = c - '0';
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for (;;) {
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c = *p++;
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if (c < '0' || c > '9')
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break;
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exponent *= 10;
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exponent += c - '0';
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}
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/* We're not going to bother playing games */
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if (exponent > 308)
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exponent = 308;
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while (exponent-- > 0) {
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if (esign)
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decimal *= 10;
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else
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decimal /= 10;
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}
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}
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done:
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if (!numbers)
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goto no_conversion;
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if (ptr)
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*ptr = p - 1;
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return (sign ? -val : val) / decimal;
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no_conversion:
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if (ptr)
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*ptr = str;
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return 0.0;
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}
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extern "C" double permissive_strtod(const char *str, const char **ptr)
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{
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return strtod_flags(str, ptr, false);
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}
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extern "C" double ascii_strtod(const char *str, const char **ptr)
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{
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return strtod_flags(str, ptr, true);
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}
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