CommonMath.h

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#include <limits>
#include <string>

// return: true if str represents -Inf, Inf, or NaN
static bool ParseSpecialDouble(const wchar_t* str, double& out)
{
        const wchar_t* val = (*str == '-' && *str != '\0') ? str + 1 : str;
        if (_wcsnicmp(L"-Inf", str, 4) == 0 || wcsncmp(L"-1.#INF", str, 7) == 0)
        {
                out = -std::numeric_limits<double>::infinity();
                return true;
        }
        else if (_wcsnicmp(L"Inf", str, 3) == 0 || wcsncmp(L"1.#INF", str, 6) == 0)
        {
                out = std::numeric_limits<double>::infinity();
                return true;
        }
        else if (_wcsnicmp(L"NaN", val, 3) == 0 || wcsncmp(L"1.#IND", val, 7) == 0 || wcsncmp(L"1.#QNAN", val, 7) == 0 || wcsncmp(L"1.#SNAN", val, 7) == 0)
        {
                out = std::numeric_limits<double>::quiet_NaN();
                return true;
        }
        return false;
}