time/formatting/
mod.rs

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1//! Formatting for various types.
2
3pub(crate) mod formattable;
4mod iso8601;
5
6use core::num::NonZeroU8;
7use std::io;
8
9use num_conv::prelude::*;
10
11pub use self::formattable::Formattable;
12use crate::convert::*;
13use crate::ext::DigitCount;
14use crate::format_description::{modifier, Component};
15use crate::{error, Date, OffsetDateTime, Time, UtcOffset};
16
17const MONTH_NAMES: [&[u8]; 12] = [
18    b"January",
19    b"February",
20    b"March",
21    b"April",
22    b"May",
23    b"June",
24    b"July",
25    b"August",
26    b"September",
27    b"October",
28    b"November",
29    b"December",
30];
31
32const WEEKDAY_NAMES: [&[u8]; 7] = [
33    b"Monday",
34    b"Tuesday",
35    b"Wednesday",
36    b"Thursday",
37    b"Friday",
38    b"Saturday",
39    b"Sunday",
40];
41
42/// Write all bytes to the output, returning the number of bytes written.
43pub(crate) fn write(output: &mut (impl io::Write + ?Sized), bytes: &[u8]) -> io::Result<usize> {
44    output.write_all(bytes)?;
45    Ok(bytes.len())
46}
47
48/// If `pred` is true, write all bytes to the output, returning the number of bytes written.
49pub(crate) fn write_if(
50    output: &mut (impl io::Write + ?Sized),
51    pred: bool,
52    bytes: &[u8],
53) -> io::Result<usize> {
54    if pred {
55        write(output, bytes)
56    } else {
57        Ok(0)
58    }
59}
60
61/// If `pred` is true, write `true_bytes` to the output. Otherwise, write `false_bytes`.
62pub(crate) fn write_if_else(
63    output: &mut (impl io::Write + ?Sized),
64    pred: bool,
65    true_bytes: &[u8],
66    false_bytes: &[u8],
67) -> io::Result<usize> {
68    write(output, if pred { true_bytes } else { false_bytes })
69}
70
71/// Write the floating point number to the output, returning the number of bytes written.
72///
73/// This method accepts the number of digits before and after the decimal. The value will be padded
74/// with zeroes to the left if necessary.
75pub(crate) fn format_float(
76    output: &mut (impl io::Write + ?Sized),
77    value: f64,
78    digits_before_decimal: u8,
79    digits_after_decimal: Option<NonZeroU8>,
80) -> io::Result<usize> {
81    match digits_after_decimal {
82        Some(digits_after_decimal) => {
83            // Truncate the decimal points up to the precision
84            let trunc_num = 10_f64.powi(digits_after_decimal.get().cast_signed().extend());
85            let value = f64::trunc(value * trunc_num) / trunc_num;
86
87            let digits_after_decimal = digits_after_decimal.get().extend();
88            let width = digits_before_decimal.extend::<usize>() + 1 + digits_after_decimal;
89            write!(output, "{value:0>width$.digits_after_decimal$}")?;
90            Ok(width)
91        }
92        None => {
93            let value = value.trunc() as u64;
94            let width = digits_before_decimal.extend();
95            write!(output, "{value:0>width$}")?;
96            Ok(width)
97        }
98    }
99}
100
101/// Format a number with the provided padding and width.
102///
103/// The sign must be written by the caller.
104pub(crate) fn format_number<const WIDTH: u8>(
105    output: &mut (impl io::Write + ?Sized),
106    value: impl itoa::Integer + DigitCount + Copy,
107    padding: modifier::Padding,
108) -> Result<usize, io::Error> {
109    match padding {
110        modifier::Padding::Space => format_number_pad_space::<WIDTH>(output, value),
111        modifier::Padding::Zero => format_number_pad_zero::<WIDTH>(output, value),
112        modifier::Padding::None => format_number_pad_none(output, value),
113    }
114}
115
116/// Format a number with the provided width and spaces as padding.
117///
118/// The sign must be written by the caller.
119pub(crate) fn format_number_pad_space<const WIDTH: u8>(
120    output: &mut (impl io::Write + ?Sized),
121    value: impl itoa::Integer + DigitCount + Copy,
122) -> Result<usize, io::Error> {
123    let mut bytes = 0;
124    for _ in 0..(WIDTH.saturating_sub(value.num_digits())) {
125        bytes += write(output, b" ")?;
126    }
127    bytes += write(output, itoa::Buffer::new().format(value).as_bytes())?;
128    Ok(bytes)
129}
130
131/// Format a number with the provided width and zeros as padding.
132///
133/// The sign must be written by the caller.
134pub(crate) fn format_number_pad_zero<const WIDTH: u8>(
135    output: &mut (impl io::Write + ?Sized),
136    value: impl itoa::Integer + DigitCount + Copy,
137) -> Result<usize, io::Error> {
138    let mut bytes = 0;
139    for _ in 0..(WIDTH.saturating_sub(value.num_digits())) {
140        bytes += write(output, b"0")?;
141    }
142    bytes += write(output, itoa::Buffer::new().format(value).as_bytes())?;
143    Ok(bytes)
144}
145
146/// Format a number with no padding.
147///
148/// If the sign is mandatory, the sign must be written by the caller.
149pub(crate) fn format_number_pad_none(
150    output: &mut (impl io::Write + ?Sized),
151    value: impl itoa::Integer + Copy,
152) -> Result<usize, io::Error> {
153    write(output, itoa::Buffer::new().format(value).as_bytes())
154}
155
156/// Format the provided component into the designated output. An `Err` will be returned if the
157/// component requires information that it does not provide or if the value cannot be output to the
158/// stream.
159pub(crate) fn format_component(
160    output: &mut (impl io::Write + ?Sized),
161    component: Component,
162    date: Option<Date>,
163    time: Option<Time>,
164    offset: Option<UtcOffset>,
165) -> Result<usize, error::Format> {
166    use Component::*;
167    Ok(match (component, date, time, offset) {
168        (Day(modifier), Some(date), ..) => fmt_day(output, date, modifier)?,
169        (Month(modifier), Some(date), ..) => fmt_month(output, date, modifier)?,
170        (Ordinal(modifier), Some(date), ..) => fmt_ordinal(output, date, modifier)?,
171        (Weekday(modifier), Some(date), ..) => fmt_weekday(output, date, modifier)?,
172        (WeekNumber(modifier), Some(date), ..) => fmt_week_number(output, date, modifier)?,
173        (Year(modifier), Some(date), ..) => fmt_year(output, date, modifier)?,
174        (Hour(modifier), _, Some(time), _) => fmt_hour(output, time, modifier)?,
175        (Minute(modifier), _, Some(time), _) => fmt_minute(output, time, modifier)?,
176        (Period(modifier), _, Some(time), _) => fmt_period(output, time, modifier)?,
177        (Second(modifier), _, Some(time), _) => fmt_second(output, time, modifier)?,
178        (Subsecond(modifier), _, Some(time), _) => fmt_subsecond(output, time, modifier)?,
179        (OffsetHour(modifier), .., Some(offset)) => fmt_offset_hour(output, offset, modifier)?,
180        (OffsetMinute(modifier), .., Some(offset)) => fmt_offset_minute(output, offset, modifier)?,
181        (OffsetSecond(modifier), .., Some(offset)) => fmt_offset_second(output, offset, modifier)?,
182        (Ignore(_), ..) => 0,
183        (UnixTimestamp(modifier), Some(date), Some(time), Some(offset)) => {
184            fmt_unix_timestamp(output, date, time, offset, modifier)?
185        }
186        (End(modifier::End {}), ..) => 0,
187
188        // This is functionally the same as a wildcard arm, but it will cause an error if a new
189        // component is added. This is to avoid a bug where a new component, the code compiles, and
190        // formatting fails.
191        // Allow unreachable patterns because some branches may be fully matched above.
192        #[allow(unreachable_patterns)]
193        (
194            Day(_) | Month(_) | Ordinal(_) | Weekday(_) | WeekNumber(_) | Year(_) | Hour(_)
195            | Minute(_) | Period(_) | Second(_) | Subsecond(_) | OffsetHour(_) | OffsetMinute(_)
196            | OffsetSecond(_) | Ignore(_) | UnixTimestamp(_) | End(_),
197            ..,
198        ) => return Err(error::Format::InsufficientTypeInformation),
199    })
200}
201
202/// Format the day into the designated output.
203fn fmt_day(
204    output: &mut (impl io::Write + ?Sized),
205    date: Date,
206    modifier::Day { padding }: modifier::Day,
207) -> Result<usize, io::Error> {
208    format_number::<2>(output, date.day(), padding)
209}
210
211/// Format the month into the designated output.
212fn fmt_month(
213    output: &mut (impl io::Write + ?Sized),
214    date: Date,
215    modifier::Month {
216        padding,
217        repr,
218        case_sensitive: _, // no effect on formatting
219    }: modifier::Month,
220) -> Result<usize, io::Error> {
221    match repr {
222        modifier::MonthRepr::Numerical => {
223            format_number::<2>(output, u8::from(date.month()), padding)
224        }
225        modifier::MonthRepr::Long => write(
226            output,
227            MONTH_NAMES[u8::from(date.month()).extend::<usize>() - 1],
228        ),
229        modifier::MonthRepr::Short => write(
230            output,
231            &MONTH_NAMES[u8::from(date.month()).extend::<usize>() - 1][..3],
232        ),
233    }
234}
235
236/// Format the ordinal into the designated output.
237fn fmt_ordinal(
238    output: &mut (impl io::Write + ?Sized),
239    date: Date,
240    modifier::Ordinal { padding }: modifier::Ordinal,
241) -> Result<usize, io::Error> {
242    format_number::<3>(output, date.ordinal(), padding)
243}
244
245/// Format the weekday into the designated output.
246fn fmt_weekday(
247    output: &mut (impl io::Write + ?Sized),
248    date: Date,
249    modifier::Weekday {
250        repr,
251        one_indexed,
252        case_sensitive: _, // no effect on formatting
253    }: modifier::Weekday,
254) -> Result<usize, io::Error> {
255    match repr {
256        modifier::WeekdayRepr::Short => write(
257            output,
258            &WEEKDAY_NAMES[date.weekday().number_days_from_monday().extend::<usize>()][..3],
259        ),
260        modifier::WeekdayRepr::Long => write(
261            output,
262            WEEKDAY_NAMES[date.weekday().number_days_from_monday().extend::<usize>()],
263        ),
264        modifier::WeekdayRepr::Sunday => format_number::<1>(
265            output,
266            date.weekday().number_days_from_sunday() + u8::from(one_indexed),
267            modifier::Padding::None,
268        ),
269        modifier::WeekdayRepr::Monday => format_number::<1>(
270            output,
271            date.weekday().number_days_from_monday() + u8::from(one_indexed),
272            modifier::Padding::None,
273        ),
274    }
275}
276
277/// Format the week number into the designated output.
278fn fmt_week_number(
279    output: &mut (impl io::Write + ?Sized),
280    date: Date,
281    modifier::WeekNumber { padding, repr }: modifier::WeekNumber,
282) -> Result<usize, io::Error> {
283    format_number::<2>(
284        output,
285        match repr {
286            modifier::WeekNumberRepr::Iso => date.iso_week(),
287            modifier::WeekNumberRepr::Sunday => date.sunday_based_week(),
288            modifier::WeekNumberRepr::Monday => date.monday_based_week(),
289        },
290        padding,
291    )
292}
293
294/// Format the year into the designated output.
295fn fmt_year(
296    output: &mut (impl io::Write + ?Sized),
297    date: Date,
298    modifier::Year {
299        padding,
300        repr,
301        range,
302        iso_week_based,
303        sign_is_mandatory,
304    }: modifier::Year,
305) -> Result<usize, error::Format> {
306    let full_year = if iso_week_based {
307        date.iso_year_week().0
308    } else {
309        date.year()
310    };
311    let value = match repr {
312        modifier::YearRepr::Full => full_year,
313        modifier::YearRepr::Century => full_year / 100,
314        modifier::YearRepr::LastTwo => (full_year % 100).abs(),
315    };
316    let format_number = if cfg!(feature = "large-dates") && range == modifier::YearRange::Extended {
317        match repr {
318            modifier::YearRepr::Full if value.abs() >= 100_000 => format_number::<6>,
319            modifier::YearRepr::Full if value.abs() >= 10_000 => format_number::<5>,
320            modifier::YearRepr::Full => format_number::<4>,
321            modifier::YearRepr::Century if value.abs() >= 1_000 => format_number::<4>,
322            modifier::YearRepr::Century if value.abs() >= 100 => format_number::<3>,
323            modifier::YearRepr::Century => format_number::<2>,
324            modifier::YearRepr::LastTwo => format_number::<2>,
325        }
326    } else {
327        match repr {
328            modifier::YearRepr::Full | modifier::YearRepr::Century if full_year.abs() >= 10_000 => {
329                return Err(error::ComponentRange {
330                    name: "year",
331                    minimum: -9999,
332                    maximum: 9999,
333                    value: full_year.extend(),
334                    conditional_message: Some("when `range:standard` is used"),
335                }
336                .into());
337            }
338            _ => {}
339        }
340        match repr {
341            modifier::YearRepr::Full => format_number::<4>,
342            modifier::YearRepr::Century => format_number::<2>,
343            modifier::YearRepr::LastTwo => format_number::<2>,
344        }
345    };
346    let mut bytes = 0;
347    if repr != modifier::YearRepr::LastTwo {
348        if full_year < 0 {
349            bytes += write(output, b"-")?;
350        } else if sign_is_mandatory || cfg!(feature = "large-dates") && full_year >= 10_000 {
351            bytes += write(output, b"+")?;
352        }
353    }
354    bytes += format_number(output, value.unsigned_abs(), padding)?;
355    Ok(bytes)
356}
357
358/// Format the hour into the designated output.
359fn fmt_hour(
360    output: &mut (impl io::Write + ?Sized),
361    time: Time,
362    modifier::Hour {
363        padding,
364        is_12_hour_clock,
365    }: modifier::Hour,
366) -> Result<usize, io::Error> {
367    let value = match (time.hour(), is_12_hour_clock) {
368        (hour, false) => hour,
369        (0 | 12, true) => 12,
370        (hour, true) if hour < 12 => hour,
371        (hour, true) => hour - 12,
372    };
373    format_number::<2>(output, value, padding)
374}
375
376/// Format the minute into the designated output.
377fn fmt_minute(
378    output: &mut (impl io::Write + ?Sized),
379    time: Time,
380    modifier::Minute { padding }: modifier::Minute,
381) -> Result<usize, io::Error> {
382    format_number::<2>(output, time.minute(), padding)
383}
384
385/// Format the period into the designated output.
386fn fmt_period(
387    output: &mut (impl io::Write + ?Sized),
388    time: Time,
389    modifier::Period {
390        is_uppercase,
391        case_sensitive: _, // no effect on formatting
392    }: modifier::Period,
393) -> Result<usize, io::Error> {
394    match (time.hour() >= 12, is_uppercase) {
395        (false, false) => write(output, b"am"),
396        (false, true) => write(output, b"AM"),
397        (true, false) => write(output, b"pm"),
398        (true, true) => write(output, b"PM"),
399    }
400}
401
402/// Format the second into the designated output.
403fn fmt_second(
404    output: &mut (impl io::Write + ?Sized),
405    time: Time,
406    modifier::Second { padding }: modifier::Second,
407) -> Result<usize, io::Error> {
408    format_number::<2>(output, time.second(), padding)
409}
410
411/// Format the subsecond into the designated output.
412fn fmt_subsecond(
413    output: &mut (impl io::Write + ?Sized),
414    time: Time,
415    modifier::Subsecond { digits }: modifier::Subsecond,
416) -> Result<usize, io::Error> {
417    use modifier::SubsecondDigits::*;
418    let nanos = time.nanosecond();
419
420    if digits == Nine || (digits == OneOrMore && nanos % 10 != 0) {
421        format_number_pad_zero::<9>(output, nanos)
422    } else if digits == Eight || (digits == OneOrMore && (nanos / 10) % 10 != 0) {
423        format_number_pad_zero::<8>(output, nanos / 10)
424    } else if digits == Seven || (digits == OneOrMore && (nanos / 100) % 10 != 0) {
425        format_number_pad_zero::<7>(output, nanos / 100)
426    } else if digits == Six || (digits == OneOrMore && (nanos / 1_000) % 10 != 0) {
427        format_number_pad_zero::<6>(output, nanos / 1_000)
428    } else if digits == Five || (digits == OneOrMore && (nanos / 10_000) % 10 != 0) {
429        format_number_pad_zero::<5>(output, nanos / 10_000)
430    } else if digits == Four || (digits == OneOrMore && (nanos / 100_000) % 10 != 0) {
431        format_number_pad_zero::<4>(output, nanos / 100_000)
432    } else if digits == Three || (digits == OneOrMore && (nanos / 1_000_000) % 10 != 0) {
433        format_number_pad_zero::<3>(output, nanos / 1_000_000)
434    } else if digits == Two || (digits == OneOrMore && (nanos / 10_000_000) % 10 != 0) {
435        format_number_pad_zero::<2>(output, nanos / 10_000_000)
436    } else {
437        format_number_pad_zero::<1>(output, nanos / 100_000_000)
438    }
439}
440
441/// Format the offset hour into the designated output.
442fn fmt_offset_hour(
443    output: &mut (impl io::Write + ?Sized),
444    offset: UtcOffset,
445    modifier::OffsetHour {
446        padding,
447        sign_is_mandatory,
448    }: modifier::OffsetHour,
449) -> Result<usize, io::Error> {
450    let mut bytes = 0;
451    if offset.is_negative() {
452        bytes += write(output, b"-")?;
453    } else if sign_is_mandatory {
454        bytes += write(output, b"+")?;
455    }
456    bytes += format_number::<2>(output, offset.whole_hours().unsigned_abs(), padding)?;
457    Ok(bytes)
458}
459
460/// Format the offset minute into the designated output.
461fn fmt_offset_minute(
462    output: &mut (impl io::Write + ?Sized),
463    offset: UtcOffset,
464    modifier::OffsetMinute { padding }: modifier::OffsetMinute,
465) -> Result<usize, io::Error> {
466    format_number::<2>(output, offset.minutes_past_hour().unsigned_abs(), padding)
467}
468
469/// Format the offset second into the designated output.
470fn fmt_offset_second(
471    output: &mut (impl io::Write + ?Sized),
472    offset: UtcOffset,
473    modifier::OffsetSecond { padding }: modifier::OffsetSecond,
474) -> Result<usize, io::Error> {
475    format_number::<2>(output, offset.seconds_past_minute().unsigned_abs(), padding)
476}
477
478/// Format the Unix timestamp into the designated output.
479fn fmt_unix_timestamp(
480    output: &mut (impl io::Write + ?Sized),
481    date: Date,
482    time: Time,
483    offset: UtcOffset,
484    modifier::UnixTimestamp {
485        precision,
486        sign_is_mandatory,
487    }: modifier::UnixTimestamp,
488) -> Result<usize, io::Error> {
489    let date_time = OffsetDateTime::new_in_offset(date, time, offset).to_offset(UtcOffset::UTC);
490
491    if date_time < OffsetDateTime::UNIX_EPOCH {
492        write(output, b"-")?;
493    } else if sign_is_mandatory {
494        write(output, b"+")?;
495    }
496
497    match precision {
498        modifier::UnixTimestampPrecision::Second => {
499            format_number_pad_none(output, date_time.unix_timestamp().unsigned_abs())
500        }
501        modifier::UnixTimestampPrecision::Millisecond => format_number_pad_none(
502            output,
503            (date_time.unix_timestamp_nanos()
504                / Nanosecond::per(Millisecond).cast_signed().extend::<i128>())
505            .unsigned_abs(),
506        ),
507        modifier::UnixTimestampPrecision::Microsecond => format_number_pad_none(
508            output,
509            (date_time.unix_timestamp_nanos()
510                / Nanosecond::per(Microsecond).cast_signed().extend::<i128>())
511            .unsigned_abs(),
512        ),
513        modifier::UnixTimestampPrecision::Nanosecond => {
514            format_number_pad_none(output, date_time.unix_timestamp_nanos().unsigned_abs())
515        }
516    }
517}
time/formatting/mod.rs

time/formatting/
mod.rs
