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/* 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");
}
}
|