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Diffstat (limited to '')
| -rw-r--r-- | bin/ddc.y | 213 |
1 files changed, 213 insertions, 0 deletions
diff --git a/bin/ddc.y b/bin/ddc.y new file mode 100644 index 00000000..ffce22e0 --- /dev/null +++ b/bin/ddc.y @@ -0,0 +1,213 @@ +/* Copyright (C) 2019 C. McEnroe <june@causal.agency> + * + * 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 <http://www.gnu.org/licenses/>. + */ + +%{ + +#include <ctype.h> +#include <err.h> +#include <stdio.h> +#include <stdlib.h> +#include <strings.h> +#include <sysexits.h> +#include <time.h> + +static void yyerror(const char *str); +static int yylex(void); + +#define YYSTYPE struct tm + +static struct tm normalize(struct tm date) { + time_t time = mktime(&date); + struct tm *norm = localtime(&time); + if (!norm) err(EX_OSERR, "localtime"); + return *norm; +} + +static struct tm today(void) { + time_t now = time(NULL); + struct tm *date = localtime(&now); + if (!date) err(EX_OSERR, "localtime"); + date->tm_hour = date->tm_min = date->tm_sec = 0; + return *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 = { + .tm_mon = month, + .tm_mday = day, + .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 }; + if (a.tm_mday < b.tm_mday) { + diff.tm_mon = a.tm_mon - b.tm_mon - 1; + while (dateAdd(b, diff).tm_mday != a.tm_mday) diff.tm_mday++; + } else { + diff.tm_mon = a.tm_mon - b.tm_mon; + diff.tm_mday = a.tm_mday - b.tm_mday; + } + return diff; +} + +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 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\n", scalar.tm_mday); + } else { + printf("%dw\n", scalar.tm_mday / 7); + } +} + +%} + +%token Number Month Day +%left '+' '-' + +%% + +expr: + date { printDate($1); } + | scalar { printScalar($1); } + ; + +date: + dateSpec + | date '+' scalar { $$ = dateAdd($1, $3); } + | date '-' scalar { $$ = dateSub($1, $3); } + ; + +scalar: + scalarSpec + | scalar '+' scalar { $$ = scalarAdd($1, $3); } + | scalar '-' scalar { $$ = scalarSub($1, $3); } + | date '-' date { $$ = dateDiff($1, $3); } + ; + +dateSpec: + '.' { $$ = today(); } + | Month Number { $$ = monthDay($1.tm_mon, $2.tm_sec); } + | Month Number Number { $$ = monthDayYear($1.tm_mon, $2.tm_sec, $3.tm_sec); } + | Day { $$ = weekDay($1.tm_wday); } + ; + +scalarSpec: + Number 'd' { $$ = (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(void) { + char *buf = NULL; + size_t cap = 0; + while (0 < getline(&buf, &cap, stdin)) { + input = buf; + yyparse(); + printf("\n"); + } +} |