date.h

 
//
//  FILE:       date.h
//              Date format and inline date functions.
//
//  Part of:    Scid (Shane's Chess Information Database)
//  Version:    1.9
//
//  Notice:     Copyright (c) 1999  Shane Hudson.  All rights reserved.
//
//  Author:     Shane Hudson (sgh@users.sourceforge.net)
//
 
 
#ifndef SCID_DATE_H
#define SCID_DATE_H
 
#include <algorithm>
#include <cassert>
#include <cstddef>
#include <cstdlib>
#include <stdint.h>
 
// DATE STORAGE FORMAT:
// In memory, dates are stored in a 32-bit (4-byte) uint, of which only
// the lowest 3 bytes need be used, with the lowest 5 bits for the
// day, the next highest 4 bits for the month and the highest bits for
// the year. This makes date comparisons easy: a bigger date value is
// a more recent date.  If a field is unknown, its value is set to zero.
// On disk, the date is stored in 3 bytes.
 
 
//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
//  CONSTANTS and MACROS:
 
namespace scid::core {
 
typedef uint32_t    dateT;
 
const dateT ZERO_DATE = 0;
 
const uint32_t  YEAR_SHIFT  = 9;
const uint32_t  MONTH_SHIFT = 5;
const uint32_t  DAY_SHIFT   = 0;
 
// DAY (31 days) 5 bits (32) , MONTH (12 months) 4 bits (16)
 
const uint32_t YEAR_MAX = 2047;  // 2^11 - 1
 
#define DATE_MAKE(y,m,d) (((y) << scid::core::YEAR_SHIFT) | ((m) << scid::core::MONTH_SHIFT) | (d))
 
 
//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// date_GetYear():
//      Get the year from a date.
inline uint32_t
date_GetYear (dateT date)
{
    return (uint32_t) (date >> YEAR_SHIFT);
}
 
//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// date_GetMonth():
//      Get the month from a date.
inline uint32_t
date_GetMonth (dateT date)
{
    return (uint32_t) ((date >> MONTH_SHIFT) & 15);
}
 
//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
//### date_GetDay():
//      Get the day of the month from a date.
inline uint32_t
date_GetDay (dateT date)
{
    return (uint32_t) (date & 31);
}
 
// Return true if the date does not include the year, the month or the day.
inline bool date_isPartial(dateT date) {
    return date_GetYear(date) == 0 || date_GetMonth(date) == 0 ||
           date_GetDay(date) == 0;
}
 
//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// date_DecodeToString(): convert date to PGN tag string.
inline void
date_DecodeToString (dateT date, char * str)
{
    assert(str != NULL);
    uint32_t year, month, day;
 
    year = date_GetYear (date);
    month = date_GetMonth (date);
    day = date_GetDay (date);
 
    if (year == 0) {
        *str++ = '?'; *str++ = '?'; *str++ = '?'; *str++ = '?';
    } else {
        *str++ = '0' + (year / 1000);
        *str++ = '0' + (year % 1000) / 100;
        *str++ = '0' + (year % 100) / 10;
        *str++ = '0' + (year % 10);
    }
    *str++ = '.';
 
    if (month == 0) {
        *str++ = '?'; *str++ = '?';
    } else {
        *str++ = '0' + (month / 10);
        *str++ = '0' + (month % 10);
    }
    *str++ = '.';
 
    if (day == 0) {
        *str++ = '?'; *str++ = '?';
    } else {
        *str++ = '0' + (day / 10);
        *str++ = '0' + (day % 10);
    }
    *str = 0;
}
 
//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// date_EncodeFromString(): convert PGN tag string to date.
//      The date string format is: "yyyy.mm.dd".
inline dateT
date_EncodeFromString (const char * str)
{
    // Do checks on str's validity as a date string:
    assert(str != NULL);
 
    dateT date;
    uint32_t year, month, day;
 
    // convert year:
    year = std::strtoul(str, NULL, 10);
    if (year > YEAR_MAX) { year = 0; }
    date = year << YEAR_SHIFT;
    while (*str != 0  &&  *str != '.') { str++; }
    if (*str == '.') { str++; }
 
    // convert month:
    month = std::strtoul(str, NULL, 10);
    if (month > 12) { return date; }
    date |= (month << MONTH_SHIFT);
    while (*str != 0  &&  *str != '.') { str++; }
    if (*str == '.') { str++; }
 
    // convert day:
    day = std::strtoul(str, NULL, 10);
    if (day > 31) { return date; }
    date |= (day << DAY_SHIFT);
 
    return date;
}
 
inline dateT date_parsePGNTag(const char* str, size_t len) {
    auto is_digit = [](auto v) { return v >= 0 && v <= 9; };
 
    if (len < 4 || len > 10)
        return {};
 
    int tmp[10];
    std::transform(str, str + len, tmp, [](unsigned char ch) {
        return ch - static_cast<unsigned char>('0');
    });
    std::fill(tmp + len, tmp + 10, -1);
 
    uint32_t year = tmp[0] * 1000 + tmp[1] * 100 + tmp[2] * 10 + tmp[3];
    if (!std::all_of(tmp, tmp + 4, is_digit) || year > YEAR_MAX)
        return {};
 
    uint32_t month = 0;
    if (!is_digit(tmp[4]) && is_digit(tmp[5])) {
        if (!is_digit(tmp[6])) {
            // Accept the format YYYY.M.DD or YYYY.M.D
            std::rotate(tmp + 5, tmp + 9, tmp + 10);
            tmp[5] = 0;
        }
        month = tmp[5] * 10 + tmp[6];
        if (month > 12)
            month = 0;
    }
 
    uint32_t day = 0;
    if (!is_digit(tmp[7]) && is_digit(tmp[8])) {
        day = is_digit(tmp[9]) ? tmp[8] * 10 + tmp[9] : tmp[8];
        if (day > 31)
            day = 0;
    }
 
    return (year << YEAR_SHIFT) | (month << MONTH_SHIFT) | (day << DAY_SHIFT);
}
 
inline dateT date_parsePGNTag(std::pair<const char*, const char*> str) {
    return date_parsePGNTag(str.first, std::distance(str.first, str.second));
}
 
 
} // namespace scid::core
#endif   // #ifndef SCID_DATE_H
 
//  EOF: date.h