/* Copyright (C) 2019 C. McEnroe * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU Affero General Public License as published by * the Free Software Foundation, either version 3 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 Affero General Public License for more details. * * You should have received a copy of the GNU Affero General Public License * along with this program. If not, see . */ %{ #include #include #include #include #include #include #include static void yyerror(const char *str); static int yylex(void); #define YYSTYPE struct tm static const char *Days[7] = { "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat", }; static const char *Months[12] = { "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec", }; static const struct tm Week = { .tm_mday = 7 }; static struct tm normalize(struct tm date) { time_t time = timegm(&date); struct tm *norm = gmtime(&time); if (!norm) err(EX_OSERR, "gmtime"); return *norm; } static struct tm today(void) { time_t now = time(NULL); struct tm *local = localtime(&now); if (!local) err(EX_OSERR, "localtime"); struct tm date = { .tm_year = local->tm_year, .tm_mon = local->tm_mon, .tm_mday = local->tm_mday, }; return normalize(date); } static struct tm monthDay(int month, int day) { struct tm date = today(); date.tm_mon = month; date.tm_mday = day; return normalize(date); } static struct tm monthDayYear(int month, int day, int year) { struct tm date = today(); date.tm_mon = month; date.tm_mday = day; date.tm_year = year - 1900; return normalize(date); } static struct tm weekDay(int day) { struct tm date = today(); date.tm_mday += day - date.tm_wday; return normalize(date); } static struct tm scalarAdd(struct tm a, struct tm b) { a.tm_mday += b.tm_mday; a.tm_mon += b.tm_mon; a.tm_year += b.tm_year; return a; } static struct tm scalarSub(struct tm a, struct tm b) { a.tm_mday -= b.tm_mday; a.tm_mon -= b.tm_mon; a.tm_year -= b.tm_year; return a; } static struct tm dateAdd(struct tm date, struct tm scalar) { return normalize(scalarAdd(date, scalar)); } static struct tm dateSub(struct tm date, struct tm scalar) { return normalize(scalarSub(date, scalar)); } static struct tm dateDiff(struct tm a, struct tm b) { struct tm diff = { .tm_year = a.tm_year - b.tm_year, .tm_mon = a.tm_mon - b.tm_mon, .tm_mday = a.tm_mday - b.tm_mday, }; if (a.tm_mon < b.tm_mon) { diff.tm_year--; diff.tm_mon += 12; } if (a.tm_mday < b.tm_mday) { diff.tm_mon--; diff.tm_mday = 0; while (dateAdd(b, diff).tm_mday != a.tm_mday) diff.tm_mday++; } time_t atime = timegm(&a), btime = timegm(&b); diff.tm_yday = (atime - btime) / 24 / 60 / 60; return diff; } static void printDate(struct tm date) { printf( "%s %s %d %d\n", Days[date.tm_wday], Months[date.tm_mon], date.tm_mday, 1900 + date.tm_year ); } static void printScalar(struct tm scalar) { if (scalar.tm_year) printf("%dy ", scalar.tm_year); if (scalar.tm_mon) printf("%dm ", scalar.tm_mon); if (scalar.tm_mday % 7) { printf("%dd ", scalar.tm_mday); } else if (scalar.tm_mday) { printf("%dw ", scalar.tm_mday / 7); } if (scalar.tm_yday && scalar.tm_mon) { if (scalar.tm_yday % 7 == 0) { printf("(%dw) ", scalar.tm_yday / 7); } printf("(%dd) ", scalar.tm_yday); } printf("\n"); } %} %token Number Month Day %left '+' '-' %right '<' '>' %% expr: date { printDate($1); } | scalar { printScalar($1); } ; date: dateLit | '(' date ')' { $$ = $2; } | '<' date { $$ = dateSub($2, Week); } | '>' date { $$ = dateAdd($2, Week); } | date '+' scalar { $$ = dateAdd($1, $3); } | date '-' scalar { $$ = dateSub($1, $3); } ; scalar: scalarLit | '(' scalar ')' { $$ = $2; } | scalar '+' scalar { $$ = scalarAdd($1, $3); } | scalar '-' scalar { $$ = scalarSub($1, $3); } | date '-' date { $$ = dateDiff($1, $3); } ; dateLit: { $$ = today(); } | '.' { $$ = today(); } | Month Number { $$ = monthDay($1.tm_mon, $2.tm_sec); } | Month Number Number { $$ = monthDayYear($1.tm_mon, $2.tm_sec, $3.tm_sec); } | Day { $$ = weekDay($1.tm_wday); } ; scalarLit: Number 'd' { $$ = (struct tm) { .tm_mday = $1.tm_sec }; } | Number 'w' { $$ = (struct tm) { .tm_mday = 7 * $1.tm_sec }; } | Number 'm' { $$ = (struct tm) { .tm_mon = $1.tm_sec }; } | Number 'y' { $$ = (struct tm) { .tm_year = $1.tm_sec }; } ; %% static void yyerror(const char *str) { warnx("%s", str); } static const char *input; static int yylex(void) { while (isspace(*input)) input++; if (!*input) return EOF; if (isdigit(*input)) { char *rest; yylval.tm_sec = strtol(input, &rest, 10); input = rest; return Number; } for (int i = 0; i < 7; ++i) { if (strncasecmp(input, Days[i], 3)) continue; while (isalpha(*input)) input++; yylval.tm_wday = i; return Day; } for (int i = 0; i < 12; ++i) { if (strncasecmp(input, Months[i], 3)) continue; while (isalpha(*input)) input++; yylval.tm_mon = i; return Month; } return *input++; } int main(int argc, char *argv[]) { if (argc > 1) { input = argv[1]; return yyparse(); } struct tm date = today(); printDate(date); printf("\n"); char *line = NULL; size_t cap = 0; while (0 < getline(&line, &cap, stdin)) { if (line[0] == '\n') continue; if (today().tm_mday != date.tm_mday) { warnx("the date has changed"); date = today(); } input = line; yyparse(); printf("\n"); } }