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
use crate::{Dt, DtErr, Scale};
use alloc::string::String;
impl Dt {
/// Returns this instant as an **RFC 3339** / ISO 8601 timestamp in **UTC**
/// with the `Z` suffix.
///
/// - Always uses UTC (`Z` = Zulu = UTC).
/// - Default = 9 digits (nanoseconds) but **automatically trims trailing zeros**.
/// - If fractional part is zero → no decimal point at all (e.g. `...45Z`).
/// - Example: `"2024-03-14T15:30:45.123Z"`
#[inline]
pub fn to_str_rfc3339(&self, current: Scale) -> Result<String, DtErr> {
self.to_str_rfc3339_nf(current, 9)
}
/// Same as [`Dt::to_str_rfc3339`](../struct.Dt.html#method.to_str_rfc3339) but
/// with a configurable maximum number of fractional digits (0–18). Trailing zeros are
/// always trimmed.
pub fn to_str_rfc3339_nf(&self, current: Scale, max_precision: usize) -> Result<String, DtErr> {
let prec = max_precision.min(18);
// Uses the formatter with the `~` "trim trailing zeros" flag.
// The formatter already handles:
// - correct 4-digit years (with sign) for |yr| < 10000
// - full-width years otherwise
// - suppressing the decimal point entirely when the trimmed fraction is zero
let fmt = alloc::format!("%Y-%m-%dT%H:%M:%S%.{}~fZ", prec);
self.to_str_with_offset(current, &fmt, 0)
}
/// **ISO 8601 / RFC 3339** with **actual offset** (modern `+00:00` style).
///
/// - Uses colon-separated offset (`%:z`) instead of forcing `Z`.
/// - Still trims trailing zeros in the fractional part.
/// - Example: `"2025-04-16T14:30:45.123+00:00"`
#[inline]
pub fn to_str_iso8601(&self, current: Scale) -> Result<String, DtErr> {
self.to_str_with_offset(current, "%Y-%m-%dT%H:%M:%S%.~f%:z", 0)
}
/// **Compact ISO 8601 basic format** (no separators).
///
/// - Useful for filenames, URLs, database keys, etc.
/// - Example: `"20250416T143045.123456789Z"`
#[inline]
pub fn to_str_iso8601_basic(&self, current: Scale) -> Result<String, DtErr> {
self.to_str_with_offset(current, "%Y%m%dT%H%M%S%.~fZ", 0)
}
/// **HTTP-date** format (RFC 7231 / RFC 1123) — **always in GMT**.
///
/// This is the format used in `Date`, `Expires`, `Last-Modified` headers.
/// Example: `"Wed, 16 Apr 2025 14:30:45 GMT"`
#[inline]
pub fn to_str_http(&self, current: Scale) -> Result<String, DtErr> {
self.to_str_with_offset(current, "%a, %d %b %Y %H:%M:%S GMT", 0)
}
/// **RFC 2822** date format (used in email `Date` headers).
///
/// Example: `"Wed, 16 Apr 2025 14:30:45 +0000"`
#[inline]
pub fn to_str_rfc2822(&self, current: Scale) -> Result<String, DtErr> {
self.to_str_with_offset(current, "%a, %d %b %Y %H:%M:%S %z", 0)
}
/// **ISO 8601 week date**.
///
/// Example: `"2025-W16-3"` (year-week-day)
#[inline]
pub fn to_str_iso_week_date(&self, current: Scale) -> Result<String, DtErr> {
self.to_str_with_offset(current, "%G-W%V-%u", 0)
}
/// Just the **ISO date** part (no time).
///
/// Example: `"2025-04-16"`
#[inline]
pub fn to_str_iso_date(&self, current: Scale) -> Result<String, DtErr> {
self.to_str_with_offset(current, "%Y-%m-%d", 0)
}
/// Just the **time** part with fractional seconds (trimmed).
///
/// Example: `"14:30:45.123456789"`
#[inline]
pub fn to_str_iso_time(&self, current: Scale) -> Result<String, DtErr> {
self.to_str_with_offset(current, "%H:%M:%S%.~f", 0)
}
}