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// This file is part of ICU4X. For terms of use, please see the file
// called LICENSE at the top level of the ICU4X source tree
// (online at: https://github.com/unicode-org/icu4x/blob/main/LICENSE ).
use super::{
super::{reference, PatternError},
super::{GenericPatternItem, PatternItem},
Pattern,
};
use alloc::vec::Vec;
use core::str::FromStr;
use icu_provider::prelude::*;
use zerovec::ZeroVec;
/// A raw, low-level pattern with literals and placeholders.
///
/// This is a datetime-specific type designed to be binary-compatible with
/// [`Pattern`]. ICU4X developers looking for this sort of type should use
/// the `icu_pattern` crate instead.
///
/// <div class="stab unstable">
/// 🚧 This code is considered unstable; it may change at any time, in breaking or non-breaking ways,
/// including in SemVer minor releases. While the serde representation of data structs is guaranteed
/// to be stable, their Rust representation might not be. Use with caution.
/// </div>
#[derive(Debug, PartialEq, Eq, Clone, yoke::Yokeable, zerofrom::ZeroFrom)]
#[allow(clippy::exhaustive_structs)] // this type is stable
#[cfg_attr(feature = "datagen", derive(databake::Bake))]
#[cfg_attr(feature = "datagen", databake(path = icu_datetime::provider::pattern::runtime))]
pub struct GenericPattern<'data> {
/// The list of [`GenericPatternItem`]s.
pub items: ZeroVec<'data, GenericPatternItem>,
}
/// A ZeroSlice containing a 0, 1, and 2 placeholder with no spaces
pub(crate) const ZERO_ONE_TWO_SLICE: &zerovec::ZeroSlice<GenericPatternItem> = zerovec::zeroslice!(
GenericPatternItem;
GenericPatternItem::to_unaligned_const;
[
GenericPatternItem::Placeholder(0),
GenericPatternItem::Placeholder(1),
GenericPatternItem::Placeholder(2),
]
);
impl<'data> GenericPattern<'data> {
/// The function allows for creation of new DTF pattern from a generic pattern
/// and replacement patterns.
///
/// # Examples
///
/// ```
/// use icu::datetime::provider::pattern::runtime::{GenericPattern, Pattern};
///
/// let date: Pattern = "y-M-d".parse().expect("Failed to parse pattern");
/// let time: Pattern = "HH:mm".parse().expect("Failed to parse pattern");
///
/// let glue: GenericPattern = "{1} 'at' {0}"
/// .parse()
/// .expect("Failed to parse generic pattern");
/// assert_eq!(
/// glue.combined(date, time)
/// .expect("Failed to combine patterns")
/// .to_string(),
/// "y-M-d 'at' HH:mm"
/// );
/// ```
pub fn combined(
self,
date: Pattern<'data>,
time: Pattern<'data>,
) -> Result<Pattern<'static>, PatternError> {
let size = date.items.len() + time.items.len();
let mut result = Vec::with_capacity(self.items.len() + size);
for item in self.items.iter() {
match item {
GenericPatternItem::Placeholder(0) => {
result.extend(time.items.iter());
}
GenericPatternItem::Placeholder(1) => {
result.extend(date.items.iter());
}
GenericPatternItem::Placeholder(idx) => {
#[allow(clippy::unwrap_used)] // idx is a valid base-10 digit
return Err(PatternError::UnknownSubstitution(
char::from_digit(idx as u32, 10).unwrap(),
));
}
GenericPatternItem::Literal(ch) => result.push(PatternItem::Literal(ch)),
}
}
Ok(Pattern::from(result))
}
}
impl Default for GenericPattern<'_> {
fn default() -> Self {
Self {
items: ZeroVec::new(),
}
}
}
impl From<&reference::GenericPattern> for GenericPattern<'_> {
fn from(input: &reference::GenericPattern) -> Self {
Self {
items: ZeroVec::alloc_from_slice(&input.items),
}
}
}
impl From<&GenericPattern<'_>> for reference::GenericPattern {
fn from(input: &GenericPattern<'_>) -> Self {
Self {
items: input.items.to_vec(),
}
}
}
impl FromStr for GenericPattern<'_> {
type Err = PatternError;
fn from_str(s: &str) -> Result<Self, Self::Err> {
let reference = reference::GenericPattern::from_str(s)?;
Ok(Self::from(&reference))
}
}
#[cfg(test)]
#[cfg(feature = "datagen")]
mod test {
use super::*;
#[test]
fn test_runtime_generic_pattern_combine() {
let pattern: GenericPattern = "{1} 'at' {0}"
.parse()
.expect("Failed to parse a generic pattern.");
let date = "y/M/d".parse().expect("Failed to parse a date pattern.");
let time = "HH:mm".parse().expect("Failed to parse a time pattern.");
let pattern = pattern
.combined(date, time)
.expect("Failed to combine date and time.");
assert_eq!(pattern.to_string(), "y/M/d 'at' HH:mm");
}
}