icu_datetime/provider/pattern/runtime/
generic.rs

1// This file is part of ICU4X. For terms of use, please see the file
2// called LICENSE at the top level of the ICU4X source tree
3// (online at: https://github.com/unicode-org/icu4x/blob/main/LICENSE ).
4
5use super::{
6    super::{reference, PatternError},
7    super::{GenericPatternItem, PatternItem},
8    Pattern,
9};
10use alloc::vec::Vec;
11use core::str::FromStr;
12use icu_provider::prelude::*;
13use zerovec::ZeroVec;
14
15/// A raw, low-level pattern with literals and placeholders.
16///
17/// This is a datetime-specific type designed to be binary-compatible with
18/// [`Pattern`]. ICU4X developers looking for this sort of type should use
19/// the `icu_pattern` crate instead.
20///
21/// <div class="stab unstable">
22/// 🚧 This code is considered unstable; it may change at any time, in breaking or non-breaking ways,
23/// including in SemVer minor releases. While the serde representation of data structs is guaranteed
24/// to be stable, their Rust representation might not be. Use with caution.
25/// </div>
26#[derive(Debug, PartialEq, Eq, Clone, yoke::Yokeable, zerofrom::ZeroFrom)]
27#[allow(clippy::exhaustive_structs)] // this type is stable
28#[cfg_attr(feature = "datagen", derive(databake::Bake))]
29#[cfg_attr(feature = "datagen", databake(path = icu_datetime::provider::pattern::runtime))]
30pub struct GenericPattern<'data> {
31    /// The list of [`GenericPatternItem`]s.
32    pub items: ZeroVec<'data, GenericPatternItem>,
33}
34
35/// A ZeroSlice containing a 0, 1, and 2 placeholder with no spaces
36pub(crate) const ZERO_ONE_TWO_SLICE: &zerovec::ZeroSlice<GenericPatternItem> = zerovec::zeroslice!(
37    GenericPatternItem;
38    GenericPatternItem::to_unaligned_const;
39    [
40        GenericPatternItem::Placeholder(0),
41        GenericPatternItem::Placeholder(1),
42        GenericPatternItem::Placeholder(2),
43    ]
44);
45
46impl<'data> GenericPattern<'data> {
47    /// The function allows for creation of new DTF pattern from a generic pattern
48    /// and replacement patterns.
49    ///
50    /// # Examples
51    ///
52    /// ```
53    /// use icu::datetime::provider::pattern::runtime::{GenericPattern, Pattern};
54    ///
55    /// let date: Pattern = "y-M-d".parse().expect("Failed to parse pattern");
56    /// let time: Pattern = "HH:mm".parse().expect("Failed to parse pattern");
57    ///
58    /// let glue: GenericPattern = "{1} 'at' {0}"
59    ///     .parse()
60    ///     .expect("Failed to parse generic pattern");
61    /// assert_eq!(
62    ///     glue.combined(date, time)
63    ///         .expect("Failed to combine patterns")
64    ///         .to_string(),
65    ///     "y-M-d 'at' HH:mm"
66    /// );
67    /// ```
68    pub fn combined(
69        self,
70        date: Pattern<'data>,
71        time: Pattern<'data>,
72    ) -> Result<Pattern<'static>, PatternError> {
73        let size = date.items.len() + time.items.len();
74        let mut result = Vec::with_capacity(self.items.len() + size);
75
76        for item in self.items.iter() {
77            match item {
78                GenericPatternItem::Placeholder(0) => {
79                    result.extend(time.items.iter());
80                }
81                GenericPatternItem::Placeholder(1) => {
82                    result.extend(date.items.iter());
83                }
84                GenericPatternItem::Placeholder(idx) => {
85                    #[allow(clippy::unwrap_used)] // idx is a valid base-10 digit
86                    return Err(PatternError::UnknownSubstitution(
87                        char::from_digit(idx as u32, 10).unwrap(),
88                    ));
89                }
90                GenericPatternItem::Literal(ch) => result.push(PatternItem::Literal(ch)),
91            }
92        }
93
94        Ok(Pattern::from(result))
95    }
96}
97
98impl Default for GenericPattern<'_> {
99    fn default() -> Self {
100        Self {
101            items: ZeroVec::new(),
102        }
103    }
104}
105
106impl From<&reference::GenericPattern> for GenericPattern<'_> {
107    fn from(input: &reference::GenericPattern) -> Self {
108        Self {
109            items: ZeroVec::alloc_from_slice(&input.items),
110        }
111    }
112}
113
114impl From<&GenericPattern<'_>> for reference::GenericPattern {
115    fn from(input: &GenericPattern<'_>) -> Self {
116        Self {
117            items: input.items.to_vec(),
118        }
119    }
120}
121
122impl FromStr for GenericPattern<'_> {
123    type Err = PatternError;
124
125    fn from_str(s: &str) -> Result<Self, Self::Err> {
126        let reference = reference::GenericPattern::from_str(s)?;
127        Ok(Self::from(&reference))
128    }
129}
130
131#[cfg(test)]
132#[cfg(feature = "datagen")]
133mod test {
134    use super::*;
135
136    #[test]
137    fn test_runtime_generic_pattern_combine() {
138        let pattern: GenericPattern = "{1} 'at' {0}"
139            .parse()
140            .expect("Failed to parse a generic pattern.");
141
142        let date = "y/M/d".parse().expect("Failed to parse a date pattern.");
143
144        let time = "HH:mm".parse().expect("Failed to parse a time pattern.");
145
146        let pattern = pattern
147            .combined(date, time)
148            .expect("Failed to combine date and time.");
149
150        assert_eq!(pattern.to_string(), "y/M/d 'at' HH:mm");
151    }
152}
icu_datetime/provider/pattern/runtime/generic.rs

icu_datetime/provider/pattern/runtime/
generic.rs
