forked from chronotope/chrono
/
strftime.rs
486 lines (446 loc) · 25.2 KB
/
strftime.rs
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// This is a part of Chrono.
// See README.md and LICENSE.txt for details.
/*!
`strftime`/`strptime`-inspired date and time formatting syntax.
## Specifiers
The following specifiers are available both to formatting and parsing.
| Spec. | Example | Description |
|-------|----------|----------------------------------------------------------------------------|
| | | **DATE SPECIFIERS:** |
| `%Y` | `2001` | The full proleptic Gregorian year, zero-padded to 4 digits. [^1] |
| `%C` | `20` | The proleptic Gregorian year divided by 100, zero-padded to 2 digits. [^2] |
| `%y` | `01` | The proleptic Gregorian year modulo 100, zero-padded to 2 digits. [^2] |
| | | |
| `%m` | `07` | Month number (01--12), zero-padded to 2 digits. |
| `%b` | `Jul` | Abbreviated month name. Always 3 letters. |
| `%B` | `July` | Full month name. Also accepts corresponding abbreviation in parsing. |
| `%h` | `Jul` | Same to `%b`. |
| | | |
| `%d` | `08` | Day number (01--31), zero-padded to 2 digits. |
| `%e` | ` 8` | Same to `%d` but space-padded. Same to `%_d`. |
| | | |
| `%a` | `Sun` | Abbreviated weekday name. Always 3 letters. |
| `%A` | `Sunday` | Full weekday name. Also accepts corresponding abbreviation in parsing. |
| `%w` | `0` | Sunday = 0, Monday = 1, ..., Saturday = 6. |
| `%u` | `7` | Monday = 1, Tuesday = 2, ..., Sunday = 7. (ISO 8601) |
| | | |
| `%U` | `28` | Week number starting with Sunday (00--53), zero-padded to 2 digits. [^3] |
| `%W` | `27` | Same to `%U`, but week 1 starts with the first Monday in that year instead.|
| | | |
| `%G` | `2001` | Same to `%Y` but uses the year number in ISO 8601 week date. [^4] |
| `%g` | `01` | Same to `%y` but uses the year number in ISO 8601 week date. [^4] |
| `%V` | `27` | Same to `%U` but uses the week number in ISO 8601 week date (01--53). [^4] |
| | | |
| `%j` | `189` | Day of the year (001--366), zero-padded to 3 digits. |
| | | |
| `%D` | `07/08/01` | Month-day-year format. Same to `%m/%d/%y`. |
| `%x` | `07/08/01` | Same to `%D`. |
| `%F` | `2001-07-08` | Year-month-day format (ISO 8601). Same to `%Y-%m-%d`. |
| `%v` | ` 8-Jul-2001` | Day-month-year format. Same to `%e-%b-%Y`. |
| | | |
| | | **TIME SPECIFIERS:** |
| `%H` | `00` | Hour number (00--23), zero-padded to 2 digits. |
| `%k` | ` 0` | Same to `%H` but space-padded. Same to `%_H`. |
| `%I` | `12` | Hour number in 12-hour clocks (01--12), zero-padded to 2 digits. |
| `%l` | `12` | Same to `%I` but space-padded. Same to `%_I`. |
| | | |
| `%P` | `am` | `am` or `pm` in 12-hour clocks. |
| `%p` | `AM` | `AM` or `PM` in 12-hour clocks. |
| | | |
| `%M` | `34` | Minute number (00--59), zero-padded to 2 digits. |
| `%S` | `60` | Second number (00--60), zero-padded to 2 digits. [^5] |
| `%f` | `026490000` | The fractional seconds (in nanoseconds) since last whole second. [^8] |
| `%.f` | `.026490`| Similar to `.%f` but left-aligned. These all consume the leading dot. [^8] |
| `%.3f`| `.026` | Similar to `.%f` but left-aligned but fixed to a length of 3. [^8] |
| `%.6f`| `.026490` | Similar to `.%f` but left-aligned but fixed to a length of 6. [^8] |
| `%.9f`| `.026490000` | Similar to `.%f` but left-aligned but fixed to a length of 9. [^8] |
| `%3f` | `026` | Similar to `%.3f` but without the leading dot. [^8] |
| `%6f` | `026490` | Similar to `%.6f` but without the leading dot. [^8] |
| `%9f` | `026490000` | Similar to `%.9f` but without the leading dot. [^8] |
| | | |
| `%R` | `00:34` | Hour-minute format. Same to `%H:%M`. |
| `%T` | `00:34:60` | Hour-minute-second format. Same to `%H:%M:%S`. |
| `%X` | `00:34:60` | Same to `%T`. |
| `%r` | `12:34:60 AM` | Hour-minute-second format in 12-hour clocks. Same to `%I:%M:%S %p`. |
| | | |
| | | **TIME ZONE SPECIFIERS:** |
| `%Z` | `ACST` | *Formatting only:* Local time zone name. |
| `%z` | `+0930` | Offset from the local time to UTC (with UTC being `+0000`). |
| `%:z` | `+09:30` | Same to `%z` but with a colon. |
| `%#z` | `+09` | *Parsing only:* Same to `%z` but allows minutes to be missing or present. |
| | | |
| | | **DATE & TIME SPECIFIERS:** |
|`%c`|`Sun Jul 8 00:34:60 2001`|`ctime` date & time format. Same to `%a %b %e %T %Y` sans `\n`.|
| `%+` | `2001-07-08T00:34:60.026490+09:30` | ISO 8601 / RFC 3339 date & time format. [^6] |
| | | |
| `%s` | `994518299` | UNIX timestamp, the number of seconds since 1970-01-01 00:00 UTC. [^7]|
| | | |
| | | **SPECIAL SPECIFIERS:** |
| `%t` | | Literal tab (`\t`). |
| `%n` | | Literal newline (`\n`). |
| `%%` | | Literal percent sign. |
It is possible to override the default padding behavior of numeric specifiers `%?`.
This is not allowed for other specifiers and will result in the `BAD_FORMAT` error.
Modifier | Description
-------- | -----------
`%-?` | Suppresses any padding including spaces and zeroes. (e.g. `%j` = `012`, `%-j` = `12`)
`%_?` | Uses spaces as a padding. (e.g. `%j` = `012`, `%_j` = ` 12`)
`%0?` | Uses zeroes as a padding. (e.g. `%e` = ` 9`, `%0e` = `09`)
Notes:
[^1]: `%Y`:
Negative years are allowed in formatting but not in parsing.
[^2]: `%C`, `%y`:
This is floor division, so 100 BCE (year number -99) will print `-1` and `99` respectively.
[^3]: `%U`:
Week 1 starts with the first Sunday in that year.
It is possible to have week 0 for days before the first Sunday.
[^4]: `%G`, `%g`, `%V`:
Week 1 is the first week with at least 4 days in that year.
Week 0 does not exist, so this should be used with `%G` or `%g`.
[^5]: `%S`:
It accounts for leap seconds, so `60` is possible.
[^6]: `%+`: Same as `%Y-%m-%dT%H:%M:%S%.f%:z`, i.e. 0, 3, 6 or 9 fractional
digits for seconds and colons in the time zone offset.
<br>
<br>
The typical `strftime` implementations have different (and locale-dependent)
formats for this specifier. While Chrono's format for `%+` is far more
stable, it is best to avoid this specifier if you want to control the exact
output.
[^7]: `%s`:
This is not padded and can be negative.
For the purpose of Chrono, it only accounts for non-leap seconds
so it slightly differs from ISO C `strftime` behavior.
[^8]: `%f`, `%.f`, `%.3f`, `%.6f`, `%.9f`, `%3f`, `%6f`, `%9f`:
<br>
The default `%f` is right-aligned and always zero-padded to 9 digits
for the compatibility with glibc and others,
so it always counts the number of nanoseconds since the last whole second.
E.g. 7ms after the last second will print `007000000`,
and parsing `7000000` will yield the same.
<br>
<br>
The variant `%.f` is left-aligned and print 0, 3, 6 or 9 fractional digits
according to the precision.
E.g. 70ms after the last second under `%.f` will print `.070` (note: not `.07`),
and parsing `.07`, `.070000` etc. will yield the same.
Note that they can print or read nothing if the fractional part is zero or
the next character is not `.`.
<br>
<br>
The variant `%.3f`, `%.6f` and `%.9f` are left-aligned and print 3, 6 or 9 fractional digits
according to the number preceding `f`.
E.g. 70ms after the last second under `%.3f` will print `.070` (note: not `.07`),
and parsing `.07`, `.070000` etc. will yield the same.
Note that they can read nothing if the fractional part is zero or
the next character is not `.` however will print with the specified length.
<br>
<br>
The variant `%3f`, `%6f` and `%9f` are left-aligned and print 3, 6 or 9 fractional digits
according to the number preceding `f`, but without the leading dot.
E.g. 70ms after the last second under `%3f` will print `070` (note: not `07`),
and parsing `07`, `070000` etc. will yield the same.
Note that they can read nothing if the fractional part is zero.
*/
use super::{Item, Numeric, Fixed, InternalFixed, InternalInternal, Pad};
/// Parsing iterator for `strftime`-like format strings.
#[derive(Clone, Debug)]
pub struct StrftimeItems<'a> {
/// Remaining portion of the string.
remainder: &'a str,
/// If the current specifier is composed of multiple formatting items (e.g. `%+`),
/// parser refers to the statically reconstructed slice of them.
/// If `recons` is not empty they have to be returned earlier than the `remainder`.
recons: &'static [Item<'static>],
}
impl<'a> StrftimeItems<'a> {
/// Creates a new parsing iterator from the `strftime`-like format string.
pub fn new(s: &'a str) -> StrftimeItems<'a> {
static FMT_NONE: [Item<'static>; 0] = [];
StrftimeItems { remainder: s, recons: &FMT_NONE }
}
}
const HAVE_ALTERNATES: &'static str = "z";
impl<'a> Iterator for StrftimeItems<'a> {
type Item = Item<'a>;
fn next(&mut self) -> Option<Item<'a>> {
// we have some reconstructed items to return
if !self.recons.is_empty() {
let item = self.recons[0].clone();
self.recons = &self.recons[1..];
return Some(item);
}
match self.remainder.chars().next() {
// we are done
None => None,
// the next item is a specifier
Some('%') => {
self.remainder = &self.remainder[1..];
macro_rules! next {
() => (
match self.remainder.chars().next() {
Some(x) => {
self.remainder = &self.remainder[x.len_utf8()..];
x
},
None => return Some(Item::Error), // premature end of string
}
)
}
let spec = next!();
let pad_override = match spec {
'-' => Some(Pad::None),
'0' => Some(Pad::Zero),
'_' => Some(Pad::Space),
_ => None,
};
let is_alternate = spec == '#';
let spec = if pad_override.is_some() || is_alternate { next!() } else { spec };
if is_alternate && !HAVE_ALTERNATES.contains(spec) {
return Some(Item::Error);
}
macro_rules! recons {
[$head:expr, $($tail:expr),+] => ({
const RECONS: &'static [Item<'static>] = &[$($tail),+];
self.recons = RECONS;
$head
})
}
let item = match spec {
'A' => fix!(LongWeekdayName),
'B' => fix!(LongMonthName),
'C' => num0!(YearDiv100),
'D' => recons![num0!(Month), lit!("/"), num0!(Day), lit!("/"),
num0!(YearMod100)],
'F' => recons![num0!(Year), lit!("-"), num0!(Month), lit!("-"), num0!(Day)],
'G' => num0!(IsoYear),
'H' => num0!(Hour),
'I' => num0!(Hour12),
'M' => num0!(Minute),
'P' => fix!(LowerAmPm),
'R' => recons![num0!(Hour), lit!(":"), num0!(Minute)],
'S' => num0!(Second),
'T' => recons![num0!(Hour), lit!(":"), num0!(Minute), lit!(":"), num0!(Second)],
'U' => num0!(WeekFromSun),
'V' => num0!(IsoWeek),
'W' => num0!(WeekFromMon),
'X' => recons![num0!(Hour), lit!(":"), num0!(Minute), lit!(":"), num0!(Second)],
'Y' => num0!(Year),
'Z' => fix!(TimezoneName),
'a' => fix!(ShortWeekdayName),
'b' | 'h' => fix!(ShortMonthName),
'c' => recons![fix!(ShortWeekdayName), sp!(" "), fix!(ShortMonthName),
sp!(" "), nums!(Day), sp!(" "), num0!(Hour), lit!(":"),
num0!(Minute), lit!(":"), num0!(Second), sp!(" "), num0!(Year)],
'd' => num0!(Day),
'e' => nums!(Day),
'f' => num0!(Nanosecond),
'g' => num0!(IsoYearMod100),
'j' => num0!(Ordinal),
'k' => nums!(Hour),
'l' => nums!(Hour12),
'm' => num0!(Month),
'n' => sp!("\n"),
'p' => fix!(UpperAmPm),
'r' => recons![num0!(Hour12), lit!(":"), num0!(Minute), lit!(":"),
num0!(Second), sp!(" "), fix!(UpperAmPm)],
's' => num!(Timestamp),
't' => sp!("\t"),
'u' => num!(WeekdayFromMon),
'v' => recons![nums!(Day), lit!("-"), fix!(ShortMonthName), lit!("-"),
num0!(Year)],
'w' => num!(NumDaysFromSun),
'x' => recons![num0!(Month), lit!("/"), num0!(Day), lit!("/"),
num0!(YearMod100)],
'y' => num0!(YearMod100),
'z' => if is_alternate {
internal_fix!(TimezoneOffsetPermissive)
} else {
fix!(TimezoneOffset)
},
'+' => fix!(RFC3339),
':' => match next!() {
'z' => fix!(TimezoneOffsetColon),
_ => Item::Error,
},
'.' => match next!() {
'3' => match next!() {
'f' => fix!(Nanosecond3),
_ => Item::Error,
},
'6' => match next!() {
'f' => fix!(Nanosecond6),
_ => Item::Error,
},
'9' => match next!() {
'f' => fix!(Nanosecond9),
_ => Item::Error,
},
'f' => fix!(Nanosecond),
_ => Item::Error,
},
'3' => match next!() {
'f' => internal_fix!(Nanosecond3NoDot),
_ => Item::Error,
},
'6' => match next!() {
'f' => internal_fix!(Nanosecond6NoDot),
_ => Item::Error,
},
'9' => match next!() {
'f' => internal_fix!(Nanosecond9NoDot),
_ => Item::Error,
},
'%' => lit!("%"),
_ => Item::Error, // no such specifier
};
// adjust `item` if we have any padding modifier
if let Some(new_pad) = pad_override {
match item {
Item::Numeric(ref kind, _pad) if self.recons.is_empty() =>
Some(Item::Numeric(kind.clone(), new_pad)),
_ => Some(Item::Error), // no reconstructed or non-numeric item allowed
}
} else {
Some(item)
}
},
// the next item is space
Some(c) if c.is_whitespace() => {
// `%` is not a whitespace, so `c != '%'` is redundant
let nextspec = self.remainder.find(|c: char| !c.is_whitespace())
.unwrap_or_else(|| self.remainder.len());
assert!(nextspec > 0);
let item = sp!(&self.remainder[..nextspec]);
self.remainder = &self.remainder[nextspec..];
Some(item)
},
// the next item is literal
_ => {
let nextspec = self.remainder.find(|c: char| c.is_whitespace() || c == '%')
.unwrap_or_else(|| self.remainder.len());
assert!(nextspec > 0);
let item = lit!(&self.remainder[..nextspec]);
self.remainder = &self.remainder[nextspec..];
Some(item)
},
}
}
}
#[cfg(test)]
#[test]
fn test_strftime_items() {
fn parse_and_collect<'a>(s: &'a str) -> Vec<Item<'a>> {
// map any error into `[Item::Error]`. useful for easy testing.
let items = StrftimeItems::new(s);
let items = items.map(|spec| if spec == Item::Error {None} else {Some(spec)});
items.collect::<Option<Vec<_>>>().unwrap_or(vec![Item::Error])
}
assert_eq!(parse_and_collect(""), []);
assert_eq!(parse_and_collect(" \t\n\r "), [sp!(" \t\n\r ")]);
assert_eq!(parse_and_collect("hello?"), [lit!("hello?")]);
assert_eq!(parse_and_collect("a b\t\nc"), [lit!("a"), sp!(" "), lit!("b"), sp!("\t\n"),
lit!("c")]);
assert_eq!(parse_and_collect("100%%"), [lit!("100"), lit!("%")]);
assert_eq!(parse_and_collect("100%% ok"), [lit!("100"), lit!("%"), sp!(" "), lit!("ok")]);
assert_eq!(parse_and_collect("%%PDF-1.0"), [lit!("%"), lit!("PDF-1.0")]);
assert_eq!(parse_and_collect("%Y-%m-%d"), [num0!(Year), lit!("-"), num0!(Month), lit!("-"),
num0!(Day)]);
assert_eq!(parse_and_collect("[%F]"), parse_and_collect("[%Y-%m-%d]"));
assert_eq!(parse_and_collect("%m %d"), [num0!(Month), sp!(" "), num0!(Day)]);
assert_eq!(parse_and_collect("%"), [Item::Error]);
assert_eq!(parse_and_collect("%%"), [lit!("%")]);
assert_eq!(parse_and_collect("%%%"), [Item::Error]);
assert_eq!(parse_and_collect("%%%%"), [lit!("%"), lit!("%")]);
assert_eq!(parse_and_collect("foo%?"), [Item::Error]);
assert_eq!(parse_and_collect("bar%42"), [Item::Error]);
assert_eq!(parse_and_collect("quux% +"), [Item::Error]);
assert_eq!(parse_and_collect("%.Z"), [Item::Error]);
assert_eq!(parse_and_collect("%:Z"), [Item::Error]);
assert_eq!(parse_and_collect("%-Z"), [Item::Error]);
assert_eq!(parse_and_collect("%0Z"), [Item::Error]);
assert_eq!(parse_and_collect("%_Z"), [Item::Error]);
assert_eq!(parse_and_collect("%.j"), [Item::Error]);
assert_eq!(parse_and_collect("%:j"), [Item::Error]);
assert_eq!(parse_and_collect("%-j"), [num!(Ordinal)]);
assert_eq!(parse_and_collect("%0j"), [num0!(Ordinal)]);
assert_eq!(parse_and_collect("%_j"), [nums!(Ordinal)]);
assert_eq!(parse_and_collect("%.e"), [Item::Error]);
assert_eq!(parse_and_collect("%:e"), [Item::Error]);
assert_eq!(parse_and_collect("%-e"), [num!(Day)]);
assert_eq!(parse_and_collect("%0e"), [num0!(Day)]);
assert_eq!(parse_and_collect("%_e"), [nums!(Day)]);
assert_eq!(parse_and_collect("%z"), [fix!(TimezoneOffset)]);
assert_eq!(parse_and_collect("%#z"), [internal_fix!(TimezoneOffsetPermissive)]);
assert_eq!(parse_and_collect("%#m"), [Item::Error]);
}
#[cfg(test)]
#[test]
fn test_strftime_docs() {
use {FixedOffset, TimeZone, Timelike};
let dt = FixedOffset::east(34200).ymd(2001, 7, 8).and_hms_nano(0, 34, 59, 1_026_490_708);
// date specifiers
assert_eq!(dt.format("%Y").to_string(), "2001");
assert_eq!(dt.format("%C").to_string(), "20");
assert_eq!(dt.format("%y").to_string(), "01");
assert_eq!(dt.format("%m").to_string(), "07");
assert_eq!(dt.format("%b").to_string(), "Jul");
assert_eq!(dt.format("%B").to_string(), "July");
assert_eq!(dt.format("%h").to_string(), "Jul");
assert_eq!(dt.format("%d").to_string(), "08");
assert_eq!(dt.format("%e").to_string(), " 8");
assert_eq!(dt.format("%e").to_string(), dt.format("%_d").to_string());
assert_eq!(dt.format("%a").to_string(), "Sun");
assert_eq!(dt.format("%A").to_string(), "Sunday");
assert_eq!(dt.format("%w").to_string(), "0");
assert_eq!(dt.format("%u").to_string(), "7");
assert_eq!(dt.format("%U").to_string(), "28");
assert_eq!(dt.format("%W").to_string(), "27");
assert_eq!(dt.format("%G").to_string(), "2001");
assert_eq!(dt.format("%g").to_string(), "01");
assert_eq!(dt.format("%V").to_string(), "27");
assert_eq!(dt.format("%j").to_string(), "189");
assert_eq!(dt.format("%D").to_string(), "07/08/01");
assert_eq!(dt.format("%x").to_string(), "07/08/01");
assert_eq!(dt.format("%F").to_string(), "2001-07-08");
assert_eq!(dt.format("%v").to_string(), " 8-Jul-2001");
// time specifiers
assert_eq!(dt.format("%H").to_string(), "00");
assert_eq!(dt.format("%k").to_string(), " 0");
assert_eq!(dt.format("%k").to_string(), dt.format("%_H").to_string());
assert_eq!(dt.format("%I").to_string(), "12");
assert_eq!(dt.format("%l").to_string(), "12");
assert_eq!(dt.format("%l").to_string(), dt.format("%_I").to_string());
assert_eq!(dt.format("%P").to_string(), "am");
assert_eq!(dt.format("%p").to_string(), "AM");
assert_eq!(dt.format("%M").to_string(), "34");
assert_eq!(dt.format("%S").to_string(), "60");
assert_eq!(dt.format("%f").to_string(), "026490708");
assert_eq!(dt.format("%.f").to_string(), ".026490708");
assert_eq!(dt.with_nanosecond(1_026_490_000).unwrap().format("%.f").to_string(),
".026490");
assert_eq!(dt.format("%.3f").to_string(), ".026");
assert_eq!(dt.format("%.6f").to_string(), ".026490");
assert_eq!(dt.format("%.9f").to_string(), ".026490708");
assert_eq!(dt.format("%3f").to_string(), "026");
assert_eq!(dt.format("%6f").to_string(), "026490");
assert_eq!(dt.format("%9f").to_string(), "026490708");
assert_eq!(dt.format("%R").to_string(), "00:34");
assert_eq!(dt.format("%T").to_string(), "00:34:60");
assert_eq!(dt.format("%X").to_string(), "00:34:60");
assert_eq!(dt.format("%r").to_string(), "12:34:60 AM");
// time zone specifiers
//assert_eq!(dt.format("%Z").to_string(), "ACST");
assert_eq!(dt.format("%z").to_string(), "+0930");
assert_eq!(dt.format("%:z").to_string(), "+09:30");
// date & time specifiers
assert_eq!(dt.format("%c").to_string(), "Sun Jul 8 00:34:60 2001");
assert_eq!(dt.format("%+").to_string(), "2001-07-08T00:34:60.026490708+09:30");
assert_eq!(dt.with_nanosecond(1_026_490_000).unwrap().format("%+").to_string(),
"2001-07-08T00:34:60.026490+09:30");
assert_eq!(dt.format("%s").to_string(), "994518299");
// special specifiers
assert_eq!(dt.format("%t").to_string(), "\t");
assert_eq!(dt.format("%n").to_string(), "\n");
assert_eq!(dt.format("%%").to_string(), "%");
}