Date.cc

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#include "Date.hh"
#include <sstream>
#include <iomanip>
#include <cstdio>
#include <cstring>

namespace openmsx {

namespace Date {

const char* const days[7] = {
        "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" ,"Sun"
};

const char* const months[12] = {
        "Jan", "Feb", "Mar", "Apr", "May", "Jun",
        "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
};

template<bool FIRST, unsigned MUL, typename T>
static inline bool parseDigit(unsigned c, T& t)
{
        c -= '0';
        if (c > 9) return false;
        if (FIRST) {
                t = c * MUL;
        } else {
                t += c * MUL;
        }
        return true;
}

time_t fromString(const char* p)
{
        struct tm tm;

        // skip day
        p += 3;

        // space
        if (*p++ != ' ') return time_t(-1);

        // Parse month
        switch (*p++) {
        case 'J': // Jan Jun Jul
                switch (*p++) {
                case 'a': // Jan
                        if (*p++ != 'n') return time_t(-1);
                        tm.tm_mon = 0; break;
                case 'u': // Jun Jul
                        switch (*p++) {
                        case 'n': tm.tm_mon = 5; break;
                        case 'l': tm.tm_mon = 6; break;
                        default: return time_t(-1);
                        }
                        break;
                default: return time_t(-1);
                }
                break;
        case 'F': // Feb
                if (*p++ != 'e') return time_t(-1);
                if (*p++ != 'b') return time_t(-1);
                tm.tm_mon = 1;
                break;
        case 'M': // Mar May
                if (*p++ != 'a') return time_t(-1);
                switch (*p++) {
                case 'r': tm.tm_mon = 2; break;
                case 'y': tm.tm_mon = 4; break;
                default: return time_t(-1);
                }
                break;
        case 'A': // Apr Aug
                switch (*p++) {
                case 'p': // Apr
                        if (*p++ != 'r') return time_t(-1);
                        tm.tm_mon = 3; break;
                case 'u': // Aug
                        if (*p++ != 'g') return time_t(-1);
                        tm.tm_mon = 7; break;
                default: return time_t(-1);
                }
                break;
        case 'S': // Sep
                if (*p++ != 'e') return time_t(-1);
                if (*p++ != 'p') return time_t(-1);
                tm.tm_mon = 8;
                break;
        case 'O': // Oct
                if (*p++ != 'c') return time_t(-1);
                if (*p++ != 't') return time_t(-1);
                tm.tm_mon = 9;
                break;
        case 'N': // Nov
                if (*p++ != 'o') return time_t(-1);
                if (*p++ != 'v') return time_t(-1);
                tm.tm_mon = 10;
                break;
        case 'D': // Dec
                if (*p++ != 'e') return time_t(-1);
                if (*p++ != 'c') return time_t(-1);
                tm.tm_mon = 11;
                break;
        default: return time_t(-1);
        }

        // space
        if (*p++ != ' ') return time_t(-1);

        // parse mday
        if (!parseDigit<true, 10>(*p++, tm.tm_mday)) return time_t(-1);
        if (!parseDigit<false, 1>(*p++, tm.tm_mday)) return time_t(-1);
        if ((tm.tm_mday < 1) || (31 < tm.tm_mday) ) return time_t(-1);

        // space
        if (*p++ != ' ') return time_t(-1);

        // parse hour
        if (!parseDigit<true, 10>(*p++, tm.tm_hour)) return time_t(-1);
        if (!parseDigit<false, 1>(*p++, tm.tm_hour)) return time_t(-1);
        if ((tm.tm_hour < 0) || (23 < tm.tm_hour)) return time_t(-1);

        // colon
        if (*p++ != ':') return time_t(-1);

        // parse minute
        if (!parseDigit<true, 10>(*p++, tm.tm_min)) return time_t(-1);
        if (!parseDigit<false, 1>(*p++, tm.tm_min)) return time_t(-1);
        if ((tm.tm_min < 0) || (59 < tm.tm_min)) return time_t(-1);

        // colon
        if (*p++ != ':') return time_t(-1);

        // parse second
        if (!parseDigit<true, 10>(*p++, tm.tm_sec)) return time_t(-1);
        if (!parseDigit<false, 1>(*p++, tm.tm_sec)) return time_t(-1);
        if ((tm.tm_sec < 0) || (59 < tm.tm_sec)) return time_t(-1);

        // space
        if (*p++ != ' ') return time_t(-1);

        // parse year
        if (!parseDigit<true, 1000>(*p++, tm.tm_year)) return time_t(-1);
        if (!parseDigit<false, 100>(*p++, tm.tm_year)) return time_t(-1);
        if (!parseDigit<false,  10>(*p++, tm.tm_year)) return time_t(-1);
        if (!parseDigit<false,   1>(*p++, tm.tm_year)) return time_t(-1);
        tm.tm_year -= 1900;
        if (tm.tm_year < 0) return time_t(-1);

        tm.tm_isdst = -1;
        return mktime(&tm);
}

std::string toString(time_t time)
{
        if (time < 0) time = 0;
        struct tm* tm;
        tm = localtime(&time);
        std::ostringstream sstr;
        sstr << std::setfill('0')
             << days  [tm->tm_wday] << ' '
             << months[tm->tm_mon]  << ' '
             << std::setw(2) << tm->tm_mday << ' '
             << std::setw(2) << tm->tm_hour << ':'
             << std::setw(2) << tm->tm_min  << ':'
             << std::setw(2) << tm->tm_sec  << ' '
             << std::setw(4) << (tm->tm_year + 1900);
        return sstr.str();
}

} // namespace Date

} // namespace openmsx