| // This is a part of Chrono. |
| // See README.md and LICENSE.txt for details. |
| |
| /*! |
| * Various scanning routines for the parser. |
| */ |
| |
| use super::{ParseResult, INVALID, OUT_OF_RANGE, TOO_SHORT}; |
| use crate::Weekday; |
| |
| /// Tries to parse the non-negative number from `min` to `max` digits. |
| /// |
| /// The absence of digits at all is an unconditional error. |
| /// More than `max` digits are consumed up to the first `max` digits. |
| /// Any number that does not fit in `i64` is an error. |
| #[inline] |
| pub(super) fn number(s: &str, min: usize, max: usize) -> ParseResult<(&str, i64)> { |
| assert!(min <= max); |
| |
| // We are only interested in ascii numbers, so we can work with the `str` as bytes. We stop on |
| // the first non-numeric byte, which may be another ascii character or beginning of multi-byte |
| // UTF-8 character. |
| let bytes = s.as_bytes(); |
| if bytes.len() < min { |
| return Err(TOO_SHORT); |
| } |
| |
| let mut n = 0i64; |
| for (i, c) in bytes.iter().take(max).cloned().enumerate() { |
| // cloned() = copied() |
| if !c.is_ascii_digit() { |
| if i < min { |
| return Err(INVALID); |
| } else { |
| return Ok((&s[i..], n)); |
| } |
| } |
| |
| n = match n.checked_mul(10).and_then(|n| n.checked_add((c - b'0') as i64)) { |
| Some(n) => n, |
| None => return Err(OUT_OF_RANGE), |
| }; |
| } |
| |
| Ok((&s[core::cmp::min(max, bytes.len())..], n)) |
| } |
| |
| /// Tries to consume at least one digits as a fractional second. |
| /// Returns the number of whole nanoseconds (0--999,999,999). |
| pub(super) fn nanosecond(s: &str) -> ParseResult<(&str, i64)> { |
| // record the number of digits consumed for later scaling. |
| let origlen = s.len(); |
| let (s, v) = number(s, 1, 9)?; |
| let consumed = origlen - s.len(); |
| |
| // scale the number accordingly. |
| static SCALE: [i64; 10] = |
| [0, 100_000_000, 10_000_000, 1_000_000, 100_000, 10_000, 1_000, 100, 10, 1]; |
| let v = v.checked_mul(SCALE[consumed]).ok_or(OUT_OF_RANGE)?; |
| |
| // if there are more than 9 digits, skip next digits. |
| let s = s.trim_start_matches(|c: char| c.is_ascii_digit()); |
| |
| Ok((s, v)) |
| } |
| |
| /// Tries to consume a fixed number of digits as a fractional second. |
| /// Returns the number of whole nanoseconds (0--999,999,999). |
| pub(super) fn nanosecond_fixed(s: &str, digits: usize) -> ParseResult<(&str, i64)> { |
| // record the number of digits consumed for later scaling. |
| let (s, v) = number(s, digits, digits)?; |
| |
| // scale the number accordingly. |
| static SCALE: [i64; 10] = |
| [0, 100_000_000, 10_000_000, 1_000_000, 100_000, 10_000, 1_000, 100, 10, 1]; |
| let v = v.checked_mul(SCALE[digits]).ok_or(OUT_OF_RANGE)?; |
| |
| Ok((s, v)) |
| } |
| |
| /// Tries to parse the month index (0 through 11) with the first three ASCII letters. |
| pub(super) fn short_month0(s: &str) -> ParseResult<(&str, u8)> { |
| if s.len() < 3 { |
| return Err(TOO_SHORT); |
| } |
| let buf = s.as_bytes(); |
| let month0 = match (buf[0] | 32, buf[1] | 32, buf[2] | 32) { |
| (b'j', b'a', b'n') => 0, |
| (b'f', b'e', b'b') => 1, |
| (b'm', b'a', b'r') => 2, |
| (b'a', b'p', b'r') => 3, |
| (b'm', b'a', b'y') => 4, |
| (b'j', b'u', b'n') => 5, |
| (b'j', b'u', b'l') => 6, |
| (b'a', b'u', b'g') => 7, |
| (b's', b'e', b'p') => 8, |
| (b'o', b'c', b't') => 9, |
| (b'n', b'o', b'v') => 10, |
| (b'd', b'e', b'c') => 11, |
| _ => return Err(INVALID), |
| }; |
| Ok((&s[3..], month0)) |
| } |
| |
| /// Tries to parse the weekday with the first three ASCII letters. |
| pub(super) fn short_weekday(s: &str) -> ParseResult<(&str, Weekday)> { |
| if s.len() < 3 { |
| return Err(TOO_SHORT); |
| } |
| let buf = s.as_bytes(); |
| let weekday = match (buf[0] | 32, buf[1] | 32, buf[2] | 32) { |
| (b'm', b'o', b'n') => Weekday::Mon, |
| (b't', b'u', b'e') => Weekday::Tue, |
| (b'w', b'e', b'd') => Weekday::Wed, |
| (b't', b'h', b'u') => Weekday::Thu, |
| (b'f', b'r', b'i') => Weekday::Fri, |
| (b's', b'a', b't') => Weekday::Sat, |
| (b's', b'u', b'n') => Weekday::Sun, |
| _ => return Err(INVALID), |
| }; |
| Ok((&s[3..], weekday)) |
| } |
| |
| /// Tries to parse the month index (0 through 11) with short or long month names. |
| /// It prefers long month names to short month names when both are possible. |
| pub(super) fn short_or_long_month0(s: &str) -> ParseResult<(&str, u8)> { |
| // lowercased month names, minus first three chars |
| static LONG_MONTH_SUFFIXES: [&[u8]; 12] = [ |
| b"uary", b"ruary", b"ch", b"il", b"", b"e", b"y", b"ust", b"tember", b"ober", b"ember", |
| b"ember", |
| ]; |
| |
| let (mut s, month0) = short_month0(s)?; |
| |
| // tries to consume the suffix if possible |
| let suffix = LONG_MONTH_SUFFIXES[month0 as usize]; |
| if s.len() >= suffix.len() && s.as_bytes()[..suffix.len()].eq_ignore_ascii_case(suffix) { |
| s = &s[suffix.len()..]; |
| } |
| |
| Ok((s, month0)) |
| } |
| |
| /// Tries to parse the weekday with short or long weekday names. |
| /// It prefers long weekday names to short weekday names when both are possible. |
| pub(super) fn short_or_long_weekday(s: &str) -> ParseResult<(&str, Weekday)> { |
| // lowercased weekday names, minus first three chars |
| static LONG_WEEKDAY_SUFFIXES: [&[u8]; 7] = |
| [b"day", b"sday", b"nesday", b"rsday", b"day", b"urday", b"day"]; |
| |
| let (mut s, weekday) = short_weekday(s)?; |
| |
| // tries to consume the suffix if possible |
| let suffix = LONG_WEEKDAY_SUFFIXES[weekday.num_days_from_monday() as usize]; |
| if s.len() >= suffix.len() && s.as_bytes()[..suffix.len()].eq_ignore_ascii_case(suffix) { |
| s = &s[suffix.len()..]; |
| } |
| |
| Ok((s, weekday)) |
| } |
| |
| /// Tries to consume exactly one given character. |
| pub(super) fn char(s: &str, c1: u8) -> ParseResult<&str> { |
| match s.as_bytes().first() { |
| Some(&c) if c == c1 => Ok(&s[1..]), |
| Some(_) => Err(INVALID), |
| None => Err(TOO_SHORT), |
| } |
| } |
| |
| /// Tries to consume one or more whitespace. |
| pub(super) fn space(s: &str) -> ParseResult<&str> { |
| let s_ = s.trim_start(); |
| if s_.len() < s.len() { |
| Ok(s_) |
| } else if s.is_empty() { |
| Err(TOO_SHORT) |
| } else { |
| Err(INVALID) |
| } |
| } |
| |
| /// Consumes any number (including zero) of colon or spaces. |
| pub(crate) fn colon_or_space(s: &str) -> ParseResult<&str> { |
| Ok(s.trim_start_matches(|c: char| c == ':' || c.is_whitespace())) |
| } |
| |
| /// Parse a timezone from `s` and return the offset in seconds. |
| /// |
| /// The `consume_colon` function is used to parse a mandatory or optional `:` |
| /// separator between hours offset and minutes offset. |
| /// |
| /// The `allow_missing_minutes` flag allows the timezone minutes offset to be |
| /// missing from `s`. |
| /// |
| /// The `allow_tz_minus_sign` flag allows the timezone offset negative character |
| /// to also be `−` MINUS SIGN (U+2212) in addition to the typical |
| /// ASCII-compatible `-` HYPHEN-MINUS (U+2D). |
| /// This is part of [RFC 3339 & ISO 8601]. |
| /// |
| /// [RFC 3339 & ISO 8601]: https://en.wikipedia.org/w/index.php?title=ISO_8601&oldid=1114309368#Time_offsets_from_UTC |
| pub(crate) fn timezone_offset<F>( |
| mut s: &str, |
| mut consume_colon: F, |
| allow_zulu: bool, |
| allow_missing_minutes: bool, |
| allow_tz_minus_sign: bool, |
| ) -> ParseResult<(&str, i32)> |
| where |
| F: FnMut(&str) -> ParseResult<&str>, |
| { |
| if allow_zulu { |
| if let Some(&b'Z' | &b'z') = s.as_bytes().first() { |
| return Ok((&s[1..], 0)); |
| } |
| } |
| |
| const fn digits(s: &str) -> ParseResult<(u8, u8)> { |
| let b = s.as_bytes(); |
| if b.len() < 2 { |
| Err(TOO_SHORT) |
| } else { |
| Ok((b[0], b[1])) |
| } |
| } |
| let negative = match s.chars().next() { |
| Some('+') => { |
| // PLUS SIGN (U+2B) |
| s = &s['+'.len_utf8()..]; |
| |
| false |
| } |
| Some('-') => { |
| // HYPHEN-MINUS (U+2D) |
| s = &s['-'.len_utf8()..]; |
| |
| true |
| } |
| Some('−') => { |
| // MINUS SIGN (U+2212) |
| if !allow_tz_minus_sign { |
| return Err(INVALID); |
| } |
| s = &s['−'.len_utf8()..]; |
| |
| true |
| } |
| Some(_) => return Err(INVALID), |
| None => return Err(TOO_SHORT), |
| }; |
| |
| // hours (00--99) |
| let hours = match digits(s)? { |
| (h1 @ b'0'..=b'9', h2 @ b'0'..=b'9') => i32::from((h1 - b'0') * 10 + (h2 - b'0')), |
| _ => return Err(INVALID), |
| }; |
| s = &s[2..]; |
| |
| // colons (and possibly other separators) |
| s = consume_colon(s)?; |
| |
| // minutes (00--59) |
| // if the next two items are digits then we have to add minutes |
| let minutes = if let Ok(ds) = digits(s) { |
| match ds { |
| (m1 @ b'0'..=b'5', m2 @ b'0'..=b'9') => i32::from((m1 - b'0') * 10 + (m2 - b'0')), |
| (b'6'..=b'9', b'0'..=b'9') => return Err(OUT_OF_RANGE), |
| _ => return Err(INVALID), |
| } |
| } else if allow_missing_minutes { |
| 0 |
| } else { |
| return Err(TOO_SHORT); |
| }; |
| s = match s.len() { |
| len if len >= 2 => &s[2..], |
| 0 => s, |
| _ => return Err(TOO_SHORT), |
| }; |
| |
| let seconds = hours * 3600 + minutes * 60; |
| Ok((s, if negative { -seconds } else { seconds })) |
| } |
| |
| /// Same as `timezone_offset` but also allows for RFC 2822 legacy timezones. |
| /// May return `None` which indicates an insufficient offset data (i.e. `-0000`). |
| /// See [RFC 2822 Section 4.3]. |
| /// |
| /// [RFC 2822 Section 4.3]: https://tools.ietf.org/html/rfc2822#section-4.3 |
| pub(super) fn timezone_offset_2822(s: &str) -> ParseResult<(&str, i32)> { |
| // tries to parse legacy time zone names |
| let upto = s.as_bytes().iter().position(|&c| !c.is_ascii_alphabetic()).unwrap_or(s.len()); |
| if upto > 0 { |
| let name = &s.as_bytes()[..upto]; |
| let s = &s[upto..]; |
| let offset_hours = |o| Ok((s, o * 3600)); |
| // RFC 2822 requires support for some named North America timezones, a small subset of all |
| // named timezones. |
| if name.eq_ignore_ascii_case(b"gmt") |
| || name.eq_ignore_ascii_case(b"ut") |
| || name.eq_ignore_ascii_case(b"z") |
| { |
| return offset_hours(0); |
| } else if name.eq_ignore_ascii_case(b"edt") { |
| return offset_hours(-4); |
| } else if name.eq_ignore_ascii_case(b"est") || name.eq_ignore_ascii_case(b"cdt") { |
| return offset_hours(-5); |
| } else if name.eq_ignore_ascii_case(b"cst") || name.eq_ignore_ascii_case(b"mdt") { |
| return offset_hours(-6); |
| } else if name.eq_ignore_ascii_case(b"mst") || name.eq_ignore_ascii_case(b"pdt") { |
| return offset_hours(-7); |
| } else if name.eq_ignore_ascii_case(b"pst") { |
| return offset_hours(-8); |
| } else if name.len() == 1 { |
| if let b'a'..=b'i' | b'k'..=b'y' | b'A'..=b'I' | b'K'..=b'Y' = name[0] { |
| // recommended by RFC 2822: consume but treat it as -0000 |
| return Ok((s, 0)); |
| } |
| } |
| Err(INVALID) |
| } else { |
| timezone_offset(s, |s| Ok(s), false, false, false) |
| } |
| } |
| |
| /// Tries to consume an RFC2822 comment including preceding ` `. |
| /// |
| /// Returns the remaining string after the closing parenthesis. |
| pub(super) fn comment_2822(s: &str) -> ParseResult<(&str, ())> { |
| use CommentState::*; |
| |
| let s = s.trim_start(); |
| |
| let mut state = Start; |
| for (i, c) in s.bytes().enumerate() { |
| state = match (state, c) { |
| (Start, b'(') => Next(1), |
| (Next(1), b')') => return Ok((&s[i + 1..], ())), |
| (Next(depth), b'\\') => Escape(depth), |
| (Next(depth), b'(') => Next(depth + 1), |
| (Next(depth), b')') => Next(depth - 1), |
| (Next(depth), _) | (Escape(depth), _) => Next(depth), |
| _ => return Err(INVALID), |
| }; |
| } |
| |
| Err(TOO_SHORT) |
| } |
| |
| enum CommentState { |
| Start, |
| Next(usize), |
| Escape(usize), |
| } |
| |
| #[cfg(test)] |
| mod tests { |
| use super::{ |
| comment_2822, nanosecond, nanosecond_fixed, short_or_long_month0, short_or_long_weekday, |
| timezone_offset_2822, |
| }; |
| use crate::format::{INVALID, TOO_SHORT}; |
| use crate::Weekday; |
| |
| #[test] |
| fn test_rfc2822_comments() { |
| let testdata = [ |
| ("", Err(TOO_SHORT)), |
| (" ", Err(TOO_SHORT)), |
| ("x", Err(INVALID)), |
| ("(", Err(TOO_SHORT)), |
| ("()", Ok("")), |
| (" \r\n\t()", Ok("")), |
| ("() ", Ok(" ")), |
| ("()z", Ok("z")), |
| ("(x)", Ok("")), |
| ("(())", Ok("")), |
| ("((()))", Ok("")), |
| ("(x(x(x)x)x)", Ok("")), |
| ("( x ( x ( x ) x ) x )", Ok("")), |
| (r"(\)", Err(TOO_SHORT)), |
| (r"(\()", Ok("")), |
| (r"(\))", Ok("")), |
| (r"(\\)", Ok("")), |
| ("(()())", Ok("")), |
| ("( x ( x ) x ( x ) x )", Ok("")), |
| ]; |
| |
| for (test_in, expected) in testdata.iter() { |
| let actual = comment_2822(test_in).map(|(s, _)| s); |
| assert_eq!( |
| *expected, actual, |
| "{:?} expected to produce {:?}, but produced {:?}.", |
| test_in, expected, actual |
| ); |
| } |
| } |
| |
| #[test] |
| fn test_timezone_offset_2822() { |
| assert_eq!(timezone_offset_2822("cSt").unwrap(), ("", -21600)); |
| assert_eq!(timezone_offset_2822("pSt").unwrap(), ("", -28800)); |
| assert_eq!(timezone_offset_2822("mSt").unwrap(), ("", -25200)); |
| assert_eq!(timezone_offset_2822("-1551").unwrap(), ("", -57060)); |
| assert_eq!(timezone_offset_2822("Gp"), Err(INVALID)); |
| } |
| |
| #[test] |
| fn test_short_or_long_month0() { |
| assert_eq!(short_or_long_month0("JUn").unwrap(), ("", 5)); |
| assert_eq!(short_or_long_month0("mAy").unwrap(), ("", 4)); |
| assert_eq!(short_or_long_month0("AuG").unwrap(), ("", 7)); |
| assert_eq!(short_or_long_month0("Aprâ").unwrap(), ("â", 3)); |
| assert_eq!(short_or_long_month0("JUl").unwrap(), ("", 6)); |
| assert_eq!(short_or_long_month0("mAr").unwrap(), ("", 2)); |
| assert_eq!(short_or_long_month0("Jan").unwrap(), ("", 0)); |
| } |
| |
| #[test] |
| fn test_short_or_long_weekday() { |
| assert_eq!(short_or_long_weekday("sAtu").unwrap(), ("u", Weekday::Sat)); |
| assert_eq!(short_or_long_weekday("thu").unwrap(), ("", Weekday::Thu)); |
| } |
| |
| #[test] |
| fn test_nanosecond_fixed() { |
| assert_eq!(nanosecond_fixed("", 0usize).unwrap(), ("", 0)); |
| assert!(nanosecond_fixed("", 1usize).is_err()); |
| } |
| |
| #[test] |
| fn test_nanosecond() { |
| assert_eq!(nanosecond("2Ù").unwrap(), ("Ù", 200000000)); |
| assert_eq!(nanosecond("8").unwrap(), ("", 800000000)); |
| } |
| } |
