deep_time/alloc_parse/
parse_duration.rs

1use crate::{Dt, DtErr, DtErrKind, Lang, Scale, an_err, natural_duration_to_iso};
2use alloc::string::String;
3
4impl Dt {
5    /// Parses duration strings, tries formats in the following order:
6    ///
7    /// 1. Strict ISO 8601 e.g. **`P1DT2H30M`**
8    /// 2. Common natural-language formats e.g. **`2 wks, 3 days, and 2 mins`**
9    /// 3. Media duration format e.g. **`1:07:54:30`**
10    /// 4. Numerical milliseconds, decimals counted as fractional milliseconds
11    ///
12    /// Returns a [`Dt`].
13    pub fn from_str_duration(s: &str, lang: Lang) -> Result<Dt, DtErr> {
14        if s.is_empty() {
15            return Err(an_err!(DtErrKind::Empty));
16        }
17
18        if Dt::looks_like_iso(s) {
19            return Dt::from_iso_duration(s).map_err(|e| {
20                an_err!(
21                    " {}",
22                    s => e
23                )
24            });
25        }
26
27        let lower = s.to_lowercase();
28        if let Ok(dur) = Dt::from_natural_duration(&lower, lang, true) {
29            return Ok(dur);
30        }
31
32        if let Ok(dur) = Dt::from_str_media_duration(s) {
33            return Ok(dur);
34        }
35
36        if let Ok(ms) = s.parse::<f64>() {
37            if !ms.is_finite() {
38                return Err(an_err!(DtErrKind::OutOfRange, "{}", s));
39            }
40            let nanos = (ms * 1_000_000.0).round() as i128;
41            let span = Dt::from_ns(nanos, Scale::TAI);
42            return Ok(span);
43        }
44
45        Err(an_err!(DtErrKind::InvalidInput, "{}", s))
46    }
47
48    /// Converts a natural language duration into an ISO duration.
49    pub fn natural_to_iso(s: &str, lang: Lang) -> Result<String, DtErr> {
50        let lower = s.to_lowercase();
51        match natural_duration_to_iso(&lower, lang, true) {
52            Ok(iso) => Ok(iso),
53            Err(e) => Err(an_err!(
54                " {}",
55                s => e
56            )),
57        }
58    }
59
60    /// Accepts: `P1Y`, `-P2W`, `PT1.5H`, `P1DT2H30M`, `+P3D`, `p1y`, `P1,5S`, `PT0S`, etc.
61    /// Rejects: anything with whitespace, lone "P"/"-P"/"PT", "P123", "Please wait 5m",
62    ///          "1.5h", "P1Yabc", "P1Y!", or **any string longer than 128 bytes**.
63    fn looks_like_iso(s: &str) -> bool {
64        let len = s.len();
65        if matches!(len, 0 | 1) {
66            return false;
67        }
68        let b = s.as_bytes();
69        let mut i = 0usize;
70        // Optional leading sign
71        if matches!(b[0], b'+' | b'-') {
72            i += 1;
73        }
74        // Must start with P/p after optional sign
75        if !matches!(b[i], b'P' | b'p') {
76            return false;
77        }
78        i += 1;
79        let mut has_digit = false;
80        let mut has_designator = false;
81        while i < len {
82            match b[i] {
83                b'0'..=b'9' => has_digit = true,
84                b'.' | b',' => {} // decimal separators allowed by ISO 8601
85                b'Y' | b'y' | b'M' | b'm' | b'W' | b'w' | b'D' | b'd' | b'T' | b't' | b'H'
86                | b'h' | b'S' | b's' => {
87                    has_designator = true;
88                }
89                _ => return false, // any other character = not ISO
90            }
91
92            i += 1;
93        }
94        // Must contain at least one digit *and* one designator after the initial P
95        has_digit && has_designator
96    }
97}
deep_time/alloc_parse/parse_duration.rs

deep_time/alloc_parse/
parse_duration.rs
