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Diffstat (limited to 'vendor/time/src/parsing/combinator/mod.rs')
| -rw-r--r-- | vendor/time/src/parsing/combinator/mod.rs | 192 |
1 files changed, 192 insertions, 0 deletions
diff --git a/vendor/time/src/parsing/combinator/mod.rs b/vendor/time/src/parsing/combinator/mod.rs new file mode 100644 index 000000000..3b4bc7a81 --- /dev/null +++ b/vendor/time/src/parsing/combinator/mod.rs @@ -0,0 +1,192 @@ +//! Implementations of the low-level parser combinators. + +pub(crate) mod rfc; + +use crate::format_description::modifier::Padding; +use crate::parsing::shim::{Integer, IntegerParseBytes}; +use crate::parsing::ParsedItem; + +/// Parse a "+" or "-" sign. Returns the ASCII byte representing the sign, if present. +pub(crate) const fn sign(input: &[u8]) -> Option<ParsedItem<'_, u8>> { + match input { + [sign @ (b'-' | b'+'), remaining @ ..] => Some(ParsedItem(remaining, *sign)), + _ => None, + } +} + +/// Consume the first matching item, returning its associated value. +pub(crate) fn first_match<'a, T>( + options: impl IntoIterator<Item = (&'a [u8], T)>, + case_sensitive: bool, +) -> impl FnMut(&'a [u8]) -> Option<ParsedItem<'a, T>> { + let mut options = options.into_iter(); + move |input| { + options.find_map(|(expected, t)| { + if case_sensitive { + Some(ParsedItem(input.strip_prefix(expected)?, t)) + } else { + let n = expected.len(); + if n <= input.len() { + let (head, tail) = input.split_at(n); + if head.eq_ignore_ascii_case(expected) { + return Some(ParsedItem(tail, t)); + } + } + None + } + }) + } +} + +/// Consume zero or more instances of the provided parser. The parser must return the unit value. +pub(crate) fn zero_or_more<'a, P: Fn(&'a [u8]) -> Option<ParsedItem<'a, ()>>>( + parser: P, +) -> impl FnMut(&'a [u8]) -> ParsedItem<'a, ()> { + move |mut input| { + while let Some(remaining) = parser(input) { + input = remaining.into_inner(); + } + ParsedItem(input, ()) + } +} + +/// Consume one of or more instances of the provided parser. The parser must produce the unit value. +pub(crate) fn one_or_more<'a, P: Fn(&'a [u8]) -> Option<ParsedItem<'a, ()>>>( + parser: P, +) -> impl Fn(&'a [u8]) -> Option<ParsedItem<'a, ()>> { + move |mut input| { + input = parser(input)?.into_inner(); + while let Some(remaining) = parser(input) { + input = remaining.into_inner(); + } + Some(ParsedItem(input, ())) + } +} + +/// Consume between `n` and `m` instances of the provided parser. +pub(crate) fn n_to_m< + 'a, + const N: u8, + const M: u8, + T, + P: Fn(&'a [u8]) -> Option<ParsedItem<'a, T>>, +>( + parser: P, +) -> impl Fn(&'a [u8]) -> Option<ParsedItem<'a, &'a [u8]>> { + debug_assert!(M >= N); + move |mut input| { + // We need to keep this to determine the total length eventually consumed. + let orig_input = input; + + // Mandatory + for _ in 0..N { + input = parser(input)?.0; + } + + // Optional + for _ in N..M { + match parser(input) { + Some(parsed) => input = parsed.0, + None => break, + } + } + + Some(ParsedItem( + input, + &orig_input[..(orig_input.len() - input.len())], + )) + } +} + +/// Consume between `n` and `m` digits, returning the numerical value. +pub(crate) fn n_to_m_digits<const N: u8, const M: u8, T: Integer>( + input: &[u8], +) -> Option<ParsedItem<'_, T>> { + debug_assert!(M >= N); + n_to_m::<N, M, _, _>(any_digit)(input)?.flat_map(|value| value.parse_bytes()) +} + +/// Consume exactly `n` digits, returning the numerical value. +pub(crate) fn exactly_n_digits<const N: u8, T: Integer>(input: &[u8]) -> Option<ParsedItem<'_, T>> { + n_to_m_digits::<N, N, _>(input) +} + +/// Consume exactly `n` digits, returning the numerical value. +pub(crate) fn exactly_n_digits_padded<'a, const N: u8, T: Integer>( + padding: Padding, +) -> impl Fn(&'a [u8]) -> Option<ParsedItem<'a, T>> { + n_to_m_digits_padded::<N, N, _>(padding) +} + +/// Consume between `n` and `m` digits, returning the numerical value. +pub(crate) fn n_to_m_digits_padded<'a, const N: u8, const M: u8, T: Integer>( + padding: Padding, +) -> impl Fn(&'a [u8]) -> Option<ParsedItem<'a, T>> { + debug_assert!(M >= N); + move |mut input| match padding { + Padding::None => n_to_m_digits::<1, M, _>(input), + Padding::Space => { + debug_assert!(N > 0); + + let mut orig_input = input; + for _ in 0..(N - 1) { + match ascii_char::<b' '>(input) { + Some(parsed) => input = parsed.0, + None => break, + } + } + let pad_width = (orig_input.len() - input.len()) as u8; + + orig_input = input; + for _ in 0..(N - pad_width) { + input = any_digit(input)?.0; + } + for _ in N..M { + match any_digit(input) { + Some(parsed) => input = parsed.0, + None => break, + } + } + + ParsedItem(input, &orig_input[..(orig_input.len() - input.len())]) + .flat_map(|value| value.parse_bytes()) + } + Padding::Zero => n_to_m_digits::<N, M, _>(input), + } +} + +/// Consume exactly one digit. +pub(crate) const fn any_digit(input: &[u8]) -> Option<ParsedItem<'_, u8>> { + match input { + [c, remaining @ ..] if c.is_ascii_digit() => Some(ParsedItem(remaining, *c)), + _ => None, + } +} + +/// Consume exactly one of the provided ASCII characters. +pub(crate) fn ascii_char<const CHAR: u8>(input: &[u8]) -> Option<ParsedItem<'_, ()>> { + debug_assert!(CHAR.is_ascii_graphic() || CHAR.is_ascii_whitespace()); + match input { + [c, remaining @ ..] if *c == CHAR => Some(ParsedItem(remaining, ())), + _ => None, + } +} + +/// Consume exactly one of the provided ASCII characters, case-insensitive. +pub(crate) fn ascii_char_ignore_case<const CHAR: u8>(input: &[u8]) -> Option<ParsedItem<'_, ()>> { + debug_assert!(CHAR.is_ascii_graphic() || CHAR.is_ascii_whitespace()); + match input { + [c, remaining @ ..] if c.eq_ignore_ascii_case(&CHAR) => Some(ParsedItem(remaining, ())), + _ => None, + } +} + +/// Optionally consume an input with a given parser. +pub(crate) fn opt<'a, T>( + parser: impl Fn(&'a [u8]) -> Option<ParsedItem<'a, T>>, +) -> impl Fn(&'a [u8]) -> ParsedItem<'a, Option<T>> { + move |input| match parser(input) { + Some(value) => value.map(Some), + None => ParsedItem(input, None), + } +} |