hron 1.0.0

Human-readable cron — scheduling expressions that are a superset of what cron can express
Documentation
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
use std::fmt;

use crate::ast::*;

impl fmt::Display for Schedule {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        // Write the expression
        write!(f, "{}", self.expr)?;

        // Write trailing clauses in order: except, until, starting, during, timezone
        if !self.except.is_empty() {
            write!(f, " except ")?;
            for (i, exc) in self.except.iter().enumerate() {
                if i > 0 {
                    write!(f, ", ")?;
                }
                match exc {
                    Exception::Named { month, day } => write!(f, "{} {}", month.as_str(), day)?,
                    Exception::Iso(d) => write!(f, "{d}")?,
                }
            }
        }

        if let Some(until) = &self.until {
            match until {
                UntilSpec::Iso(d) => write!(f, " until {d}")?,
                UntilSpec::Named { month, day } => write!(f, " until {} {}", month.as_str(), day)?,
            }
        }

        if let Some(anchor) = &self.anchor {
            write!(f, " starting {anchor}")?;
        }

        if !self.during.is_empty() {
            write!(f, " during ")?;
            for (i, month) in self.during.iter().enumerate() {
                if i > 0 {
                    write!(f, ", ")?;
                }
                write!(f, "{}", month.as_str())?;
            }
        }

        if let Some(tz) = &self.timezone {
            write!(f, " in {tz}")?;
        }

        Ok(())
    }
}

impl fmt::Display for ScheduleExpr {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            ScheduleExpr::IntervalRepeat {
                interval,
                unit,
                from,
                to,
                day_filter,
            } => {
                write!(f, "every {interval} {}", unit_display(*interval, *unit))?;
                write!(f, " from {from} to {to}")?;
                if let Some(df) = day_filter {
                    write!(f, " on {df}")?;
                }
            }
            ScheduleExpr::DayRepeat {
                interval,
                days,
                times,
            } => {
                if *interval > 1 {
                    write!(f, "every {interval} days at ")?;
                } else {
                    write!(f, "every {days} at ")?;
                }
                write_time_list(f, times)?;
            }
            ScheduleExpr::WeekRepeat {
                interval,
                days,
                times,
            } => {
                if *interval > 1 {
                    write!(f, "every {interval} weeks on ")?;
                } else {
                    write!(f, "every week on ")?;
                }
                write_day_list(f, days)?;
                write!(f, " at ")?;
                write_time_list(f, times)?;
            }
            ScheduleExpr::MonthRepeat {
                interval,
                target,
                times,
            } => {
                if *interval > 1 {
                    write!(f, "every {interval} months on the ")?;
                } else {
                    write!(f, "every month on the ")?;
                }
                match target {
                    MonthTarget::Days(specs) => write_ordinal_day_specs(f, specs)?,
                    MonthTarget::LastDay => write!(f, "last day")?,
                    MonthTarget::LastWeekday => write!(f, "last weekday")?,
                    MonthTarget::NearestWeekday { day, direction } => {
                        if let Some(dir) = direction {
                            match dir {
                                NearestDirection::Next => write!(f, "next ")?,
                                NearestDirection::Previous => write!(f, "previous ")?,
                            }
                        }
                        write!(f, "nearest weekday to {}{}", day, ordinal_suffix(*day))?;
                    }
                    MonthTarget::OrdinalWeekday { ordinal, weekday } => {
                        write!(f, "{} {}", ordinal.as_str(), weekday.as_str())?;
                    }
                }
                write!(f, " at ")?;
                write_time_list(f, times)?;
            }
            ScheduleExpr::SingleDate { date, times } => {
                write!(f, "on ")?;
                match date {
                    DateSpec::Named { month, day } => {
                        write!(f, "{} {day}", month.as_str())?;
                    }
                    DateSpec::Iso(d) => {
                        write!(f, "{d}")?;
                    }
                }
                write!(f, " at ")?;
                write_time_list(f, times)?;
            }
            ScheduleExpr::YearRepeat {
                interval,
                target,
                times,
            } => {
                if *interval > 1 {
                    write!(f, "every {interval} years on ")?;
                } else {
                    write!(f, "every year on ")?;
                }
                match target {
                    YearTarget::Date { month, day } => {
                        write!(f, "{} {day}", month.as_str())?;
                    }
                    YearTarget::OrdinalWeekday {
                        ordinal,
                        weekday,
                        month,
                    } => {
                        write!(
                            f,
                            "the {} {} of {}",
                            ordinal.as_str(),
                            weekday.as_str(),
                            month.as_str()
                        )?;
                    }
                    YearTarget::DayOfMonth { day, month } => {
                        write!(
                            f,
                            "the {}{} of {}",
                            day,
                            ordinal_suffix(*day),
                            month.as_str()
                        )?;
                    }
                    YearTarget::LastWeekday { month } => {
                        write!(f, "the last weekday of {}", month.as_str())?;
                    }
                }
                write!(f, " at ")?;
                write_time_list(f, times)?;
            }
        }
        Ok(())
    }
}

impl fmt::Display for TimeOfDay {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "{:02}:{:02}", self.hour, self.minute)
    }
}

impl fmt::Display for DayFilter {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            DayFilter::Every => write!(f, "day"),
            DayFilter::Weekday => write!(f, "weekday"),
            DayFilter::Weekend => write!(f, "weekend"),
            DayFilter::Days(days) => write_day_list(f, days),
        }
    }
}

fn write_time_list(f: &mut fmt::Formatter<'_>, times: &[TimeOfDay]) -> fmt::Result {
    for (i, t) in times.iter().enumerate() {
        if i > 0 {
            write!(f, ", ")?;
        }
        write!(f, "{t}")?;
    }
    Ok(())
}

fn write_day_list(f: &mut fmt::Formatter<'_>, days: &[Weekday]) -> fmt::Result {
    for (i, day) in days.iter().enumerate() {
        if i > 0 {
            write!(f, ", ")?;
        }
        write!(f, "{}", day.as_str())?;
    }
    Ok(())
}

fn write_ordinal_day_specs(f: &mut fmt::Formatter<'_>, specs: &[DayOfMonthSpec]) -> fmt::Result {
    for (i, spec) in specs.iter().enumerate() {
        if i > 0 {
            write!(f, ", ")?;
        }
        match spec {
            DayOfMonthSpec::Single(d) => write!(f, "{}{}", d, ordinal_suffix(*d))?,
            DayOfMonthSpec::Range(start, end) => {
                write!(
                    f,
                    "{}{} to {}{}",
                    start,
                    ordinal_suffix(*start),
                    end,
                    ordinal_suffix(*end)
                )?;
            }
        }
    }
    Ok(())
}

fn ordinal_suffix(n: u8) -> &'static str {
    match n % 100 {
        11..=13 => "th",
        _ => match n % 10 {
            1 => "st",
            2 => "nd",
            3 => "rd",
            _ => "th",
        },
    }
}

fn unit_display(interval: u32, unit: IntervalUnit) -> &'static str {
    match unit {
        IntervalUnit::Minutes => {
            if interval == 1 {
                "minute"
            } else {
                "min"
            }
        }
        IntervalUnit::Hours => {
            if interval == 1 {
                "hour"
            } else {
                "hours"
            }
        }
    }
}

#[cfg(test)]
mod tests {
    use crate::parser::parse;

    #[test]
    fn test_roundtrip_every_day() {
        let s = parse("every day at 09:00").unwrap();
        assert_eq!(s.to_string(), "every day at 09:00");
    }

    #[test]
    fn test_roundtrip_weekday() {
        let s = parse("every weekday at 9:00").unwrap();
        assert_eq!(s.to_string(), "every weekday at 09:00");
    }

    #[test]
    fn test_roundtrip_interval() {
        let s = parse("every 30 min from 09:00 to 17:00").unwrap();
        assert_eq!(s.to_string(), "every 30 min from 09:00 to 17:00");
    }

    #[test]
    fn test_roundtrip_month() {
        let s = parse("every month on the 1st, 15th at 09:00").unwrap();
        assert_eq!(s.to_string(), "every month on the 1st, 15th at 09:00");
    }

    #[test]
    fn test_roundtrip_ordinal_weekday() {
        let s = parse("every month on the first monday at 10:00").unwrap();
        assert_eq!(s.to_string(), "every month on the first monday at 10:00");
    }

    #[test]
    fn test_roundtrip_on_named() {
        let s = parse("on feb 14 at 9:00").unwrap();
        assert_eq!(s.to_string(), "on feb 14 at 09:00");
    }

    #[test]
    fn test_roundtrip_on_iso() {
        let s = parse("on 2026-03-15 at 14:30").unwrap();
        assert_eq!(s.to_string(), "on 2026-03-15 at 14:30");
    }

    #[test]
    fn test_roundtrip_timezone() {
        let s = parse("every weekday at 9:00 in America/Vancouver").unwrap();
        assert_eq!(s.to_string(), "every weekday at 09:00 in America/Vancouver");
    }

    #[test]
    fn test_roundtrip_except() {
        let s = parse("every weekday at 9:00 except dec 25, jan 1").unwrap();
        assert_eq!(s.to_string(), "every weekday at 09:00 except dec 25, jan 1");
    }

    #[test]
    fn test_roundtrip_until_iso() {
        let s = parse("every day at 09:00 until 2026-12-31").unwrap();
        assert_eq!(s.to_string(), "every day at 09:00 until 2026-12-31");
    }

    #[test]
    fn test_roundtrip_starting() {
        let s = parse("every 2 weeks on monday at 9:00 starting 2026-01-05").unwrap();
        assert_eq!(
            s.to_string(),
            "every 2 weeks on monday at 09:00 starting 2026-01-05"
        );
    }

    #[test]
    fn test_roundtrip_year_date() {
        let s = parse("every year on dec 25 at 00:00").unwrap();
        assert_eq!(s.to_string(), "every year on dec 25 at 00:00");
    }

    #[test]
    fn test_roundtrip_year_ordinal_weekday() {
        let s = parse("every year on the first monday of march at 10:00").unwrap();
        assert_eq!(
            s.to_string(),
            "every year on the first monday of mar at 10:00"
        );
    }

    #[test]
    fn test_roundtrip_year_day_of_month() {
        let s = parse("every year on the 15th of march at 09:00").unwrap();
        assert_eq!(s.to_string(), "every year on the 15th of mar at 09:00");
    }

    #[test]
    fn test_roundtrip_year_last_weekday() {
        let s = parse("every year on the last weekday of december at 17:00").unwrap();
        assert_eq!(
            s.to_string(),
            "every year on the last weekday of dec at 17:00"
        );
    }

    #[test]
    fn test_roundtrip_all_clauses() {
        let s = parse(
            "every weekday at 9:00 except dec 25 until 2027-12-31 starting 2026-01-01 in UTC",
        )
        .unwrap();
        assert_eq!(
            s.to_string(),
            "every weekday at 09:00 except dec 25 until 2027-12-31 starting 2026-01-01 in UTC"
        );
    }

    #[test]
    fn test_roundtrip_multi_time() {
        let s = parse("every day at 9:00, 12:00, 17:00").unwrap();
        assert_eq!(s.to_string(), "every day at 09:00, 12:00, 17:00");
    }

    #[test]
    fn test_roundtrip_during() {
        let s = parse("every weekday at 9:00 during jan, jun").unwrap();
        assert_eq!(s.to_string(), "every weekday at 09:00 during jan, jun");
    }

    #[test]
    fn test_roundtrip_day_range() {
        let s = parse("every month on the 1st to 15th at 9:00").unwrap();
        assert_eq!(s.to_string(), "every month on the 1st to 15th at 09:00");
    }

    #[test]
    fn test_roundtrip_day_range_mixed() {
        let s = parse("every month on the 1st to 10th, 20th at 9:00").unwrap();
        assert_eq!(
            s.to_string(),
            "every month on the 1st to 10th, 20th at 09:00"
        );
    }

    #[test]
    fn test_roundtrip_all_new_clauses() {
        let s = parse(
            "every weekday at 9:00, 17:00 except dec 25 until 2027-12-31 during jan, mar in UTC",
        )
        .unwrap();
        assert_eq!(
            s.to_string(),
            "every weekday at 09:00, 17:00 except dec 25 until 2027-12-31 during jan, mar in UTC"
        );
    }
}