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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 core::cmp::{Ord, PartialOrd};
use core::fmt;
use displaydoc::Display;
use zerovec::ule::{AsULE, UleError, ULE};
/// An error relating to the length of a field within a date pattern.
#[derive(Display, Debug, PartialEq, Copy, Clone)]
#[non_exhaustive]
pub enum LengthError {
/// The length of the field string within the pattern is invalid, according to
/// the field type and its supported field patterns in LDML. See [`FieldLength`].
#[displaydoc("Invalid length")]
InvalidLength,
}
#[cfg(feature = "std")]
impl std::error::Error for LengthError {}
/// An enum representing the length of a field within a date or time formatting pattern string.
///
/// Such strings represent fields as a letter occurring 1 or more times in a row, ex:
/// `MMM`, `dd`, `y`. See the
/// [LDML documentation in UTS 35](https://unicode.org/reports/tr35/tr35-dates.html#Date_Format_Patterns)
/// for more details.
#[derive(Debug, Eq, PartialEq, Clone, Copy, Ord, PartialOrd)]
#[cfg_attr(feature = "datagen", derive(serde::Serialize, databake::Bake))]
#[cfg_attr(feature = "datagen", databake(path = icu_datetime::fields))]
#[cfg_attr(feature = "serde", derive(serde::Deserialize))]
#[allow(clippy::exhaustive_enums)] // part of data struct
pub enum FieldLength {
/// Numeric: minimum digits
///
/// Text: same as [`Self::Three`]
One,
/// Numeric: pad to 2 digits
///
/// Text: same as [`Self::Three`]
Two,
/// Numeric: pad to 3 digits
///
/// Text: Abbreviated format.
Three,
/// Numeric: pad to 4 digits
///
/// Text: Wide format.
Four,
/// Numeric: pad to 5 digits
///
/// Text: Narrow format.
Five,
/// Numeric: pad to 6 digits
///
/// Text: Short format.
Six,
/// FieldLength::One (numeric), but overridden with a different numbering system
NumericOverride(FieldNumericOverrides),
}
/// First index used for numeric overrides in compact FieldLength representation
///
/// Currently 17 due to decision in <https://unicode-org.atlassian.net/browse/CLDR-17217>,
/// may become 16 if the `> 16` is updated to a ` >= 16`
const FIRST_NUMERIC_OVERRIDE: u8 = 17;
/// Last index used for numeric overrides
const LAST_NUMERIC_OVERRIDE: u8 = 31;
impl FieldLength {
#[inline]
pub(crate) fn idx(&self) -> u8 {
match self {
FieldLength::One => 1,
FieldLength::Two => 2,
FieldLength::Three => 3,
FieldLength::Four => 4,
FieldLength::Five => 5,
FieldLength::Six => 6,
FieldLength::NumericOverride(o) => FIRST_NUMERIC_OVERRIDE
.saturating_add(*o as u8)
.min(LAST_NUMERIC_OVERRIDE),
}
}
#[inline]
pub(crate) fn from_idx(idx: u8) -> Result<Self, LengthError> {
Ok(match idx {
1 => Self::One,
2 => Self::Two,
3 => Self::Three,
4 => Self::Four,
5 => Self::Five,
6 => Self::Six,
idx if (FIRST_NUMERIC_OVERRIDE..=LAST_NUMERIC_OVERRIDE).contains(&idx) => {
Self::NumericOverride((idx - FIRST_NUMERIC_OVERRIDE).try_into()?)
}
_ => return Err(LengthError::InvalidLength),
})
}
#[inline]
pub(crate) fn to_len(self) -> usize {
match self {
FieldLength::One => 1,
FieldLength::Two => 2,
FieldLength::Three => 3,
FieldLength::Four => 4,
FieldLength::Five => 5,
FieldLength::Six => 6,
FieldLength::NumericOverride(o) => FIRST_NUMERIC_OVERRIDE as usize + o as usize,
}
}
/// UTS 35 defines several 1 and 2 symbols to be the same as 3 symbols (abbreviated).
/// For example, 'a' represents an abbreviated day period, the same as 'aaa'.
///
/// This function maps field lengths 1 and 2 to field length 3.
pub(crate) fn numeric_to_abbr(self) -> Self {
match self {
FieldLength::One | FieldLength::Two => FieldLength::Three,
other => other,
}
}
}
#[repr(transparent)]
#[derive(Debug, Copy, Clone, PartialEq, Eq)]
pub struct FieldLengthULE(u8);
impl AsULE for FieldLength {
type ULE = FieldLengthULE;
fn to_unaligned(self) -> Self::ULE {
FieldLengthULE(self.idx())
}
fn from_unaligned(unaligned: Self::ULE) -> Self {
#[allow(clippy::unwrap_used)] // OK because the ULE is pre-validated
Self::from_idx(unaligned.0).unwrap()
}
}
impl FieldLengthULE {
#[inline]
pub(crate) fn validate_byte(byte: u8) -> Result<(), UleError> {
FieldLength::from_idx(byte)
.map(|_| ())
.map_err(|_| UleError::parse::<FieldLength>())
}
}
// Safety checklist for ULE:
//
// 1. Must not include any uninitialized or padding bytes (true since transparent over a ULE).
// 2. Must have an alignment of 1 byte (true since transparent over a ULE).
// 3. ULE::validate_byte_slice() checks that the given byte slice represents a valid slice.
// 4. ULE::validate_byte_slice() checks that the given byte slice has a valid length
// (true since transparent over a type of size 1).
// 5. All other methods must be left with their default impl.
// 6. Byte equality is semantic equality.
unsafe impl ULE for FieldLengthULE {
fn validate_byte_slice(bytes: &[u8]) -> Result<(), UleError> {
for byte in bytes {
Self::validate_byte(*byte)?;
}
Ok(())
}
}
/// Various numeric overrides for datetime patterns
/// as found in CLDR
#[derive(Debug, Eq, PartialEq, Clone, Copy, Ord, PartialOrd)]
#[cfg_attr(feature = "datagen", derive(serde::Serialize, databake::Bake))]
#[cfg_attr(feature = "datagen", databake(path = icu_datetime::fields))]
#[cfg_attr(feature = "serde", derive(serde::Deserialize))]
#[non_exhaustive]
pub enum FieldNumericOverrides {
/// `hanidec`
Hanidec = 0,
/// `hanidays`
Hanidays = 1,
/// `hebr`
Hebr = 2,
/// `romanlow`
Romanlow = 3,
/// `jpnyear`
Jpnyear = 4,
}
impl TryFrom<u8> for FieldNumericOverrides {
type Error = LengthError;
fn try_from(other: u8) -> Result<Self, LengthError> {
Ok(match other {
0 => Self::Hanidec,
1 => Self::Hanidays,
2 => Self::Hebr,
3 => Self::Romanlow,
4 => Self::Jpnyear,
_ => return Err(LengthError::InvalidLength),
})
}
}
impl FieldNumericOverrides {
/// Convert this to the corresponding string code
pub fn as_str(self) -> &'static str {
match self {
Self::Hanidec => "hanidec",
Self::Hanidays => "hanidays",
Self::Hebr => "hebr",
Self::Romanlow => "romanlow",
Self::Jpnyear => "jpnyear",
}
}
}
impl fmt::Display for FieldNumericOverrides {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
self.as_str().fmt(f)
}
}