strftime.cpp

/*
    IL : Intlog Language
    Object Oriented Prolog Project
    Copyright (C) 1992-2021 - Ing. Capelli Carlo

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
*/

#include <ctime>
#include <sstream>
#include <iomanip>
using namespace std;

static char weekday[7][10] = {
    "Lunedi",
    "Martedi",
    "Mercoledi",
    "Giovedi",
    "Venerdi",
    "Sabato",
    "Domenica"
};
static char month[12][10] = {
    "Gennaio",
    "Febbraio",
    "Marzo",
    "Aprile",
    "Maggio",
    "Giugno",
    "Luglio",
    "Agosto",
    "Settembre",
    "Ottobre",
    "Novembre",
    "Dicembre"
};

size_t strftime(char *buf, size_t, const char *fmt, const struct tm *t) {
    ostringstream os(buf);
    os.fill('0');

    char c;
    while ((c = *fmt++) != 0)
        if (c == '%')
            switch (c = *fmt++) {
            case 'Z': // Time zone name or abbreviation; no characters if time zone is unknown
                os << "ITA";
                break;

            case 'p': // Current locale's AM/PM indicator for a 12-hour clock
                os << (t->tm_hour < 12? 'A' : 'P');
                break;

            case 'x': // Date representation for current locale
                os <<   setw(2) << t->tm_mday << '/' <<
                        setw(2) << t->tm_mon + 1 << '/' <<
                        setw(2) << t->tm_year;
                break;

            case 'X': // Time representation for current locale
                os <<   setw(2) << t->tm_hour << ':' <<
                        setw(2) << t->tm_min;
                break;

            case 'U': // Week of the year as a decimal number, with Sunday as the first day of the week (00-51)
            case 'W': // Week of the year as a decimal number, with Monday as the first day of the week (00-51)
                os << setw(2) << t->tm_yday % 7;
                break;

            case 'c': // Date and time representation appropriate for the locale
                os <<   setw(2) << t->tm_hour << ':' <<
                        setw(2) << t->tm_min << ' ' <<

                        setw(2) << t->tm_mday << '/' <<
                        setw(2) << t->tm_mon + 1 << '/' <<
                        setw(2) << t->tm_year;
                break;

            case 'a': // Abbreviated weekday name
                if (t->tm_wday >= 0 && t->tm_wday < 7)
                    os.write(weekday[t->tm_wday], 3);
                break;
            case 'A': // Full weekday name
                if (t->tm_wday >= 0 && t->tm_wday < 7)
                    os << weekday[t->tm_wday];
                break;
            case 'b': // Abbreviated month name
                if (t->tm_mon >= 0 && t->tm_mon < 12)
                    os.write(month[t->tm_mon], 3);
                break;
            case 'B': // Full month name
                if (t->tm_mon >= 0 && t->tm_mon < 12)
                    os << month[t->tm_mon];
                break;
            case 'd': // Day of the month as a decimal number (01-31)
                os << setw(2) << t->tm_mday;
                break;
            case 'H': // Hour in 24-hour format (00-23)
                os << setw(2) << t->tm_hour;
                break;
            case 'I': // Hour in 12-hour format (01-12)
                os << setw(2) << t->tm_hour / 2 + 1;
                break;
            case 'j': // Day of the year as a decimal number (001-366)
                os << setw(3) << t->tm_yday + 1;
                break;
            case 'm': // Month as a decimal number (01-12)
                os << setw(2) << t->tm_mon + 1;
                break;
            case 'M': // Minute as a decimal number (00-59)
                os << setw(2) << t->tm_min;
                break;
            case 'S': // Second as a decimal number (00-59)
                os << setw(2) << t->tm_sec;
                break;
            case 'w': // Weekday as a decimal number (0-6; Sunday is 0)
                os << t->tm_wday;
                break;
            case 'y': // Year without the century as a decimal number (00-99)
                os << setw(2) << t->tm_year % 100;
                break;
            case 'Y': // Year with the century as a decimal number
                os << 1900 + t->tm_year;
                break;

            case '%': // Percent sign
                os << c;
                break;

            default:
                break;
            }
        else
            os << c;

    os << ends;
    return size_t(os.tellp());
}