nushell/crates/nu-command/src/date/parser.rs
2021-10-31 07:54:51 +01:00

108 lines
3.2 KiB
Rust

// Modified from chrono::format::scan
use chrono::{DateTime, FixedOffset, Local, Offset, TimeZone};
use chrono_tz::Tz;
use titlecase::titlecase;
#[derive(Debug, Clone, PartialEq, Eq, Copy)]
pub enum ParseErrorKind {
/// Given field is out of permitted range.
OutOfRange,
/// The input string has some invalid character sequence for given formatting items.
Invalid,
/// The input string has been prematurely ended.
TooShort,
}
pub fn datetime_in_timezone(
dt: &DateTime<FixedOffset>,
s: &str,
) -> Result<DateTime<FixedOffset>, ParseErrorKind> {
match timezone_offset_internal(s, true, true) {
Ok(offset) => match FixedOffset::east_opt(offset) {
Some(offset) => Ok(dt.with_timezone(&offset)),
None => Err(ParseErrorKind::OutOfRange),
},
Err(ParseErrorKind::Invalid) => {
if s.to_lowercase() == "local" {
Ok(dt.with_timezone(Local::now().offset()))
} else {
let tz: Tz = parse_timezone_internal(s)?;
let offset = tz.offset_from_utc_datetime(&dt.naive_utc()).fix();
Ok(dt.with_timezone(&offset))
}
}
Err(e) => Err(e),
}
}
fn parse_timezone_internal(s: &str) -> Result<Tz, ParseErrorKind> {
if let Ok(tz) = s.parse() {
Ok(tz)
} else if let Ok(tz) = titlecase(s).parse() {
Ok(tz)
} else if let Ok(tz) = s.to_uppercase().parse() {
Ok(tz)
} else {
Err(ParseErrorKind::Invalid)
}
}
fn timezone_offset_internal(
mut s: &str,
consume_colon: bool,
allow_missing_minutes: bool,
) -> Result<i32, ParseErrorKind> {
fn digits(s: &str) -> Result<(u8, u8), ParseErrorKind> {
let b = s.as_bytes();
if b.len() < 2 {
Err(ParseErrorKind::TooShort)
} else {
Ok((b[0], b[1]))
}
}
let negative = match s.as_bytes().first() {
Some(&b'+') => false,
Some(&b'-') => true,
Some(_) => return Err(ParseErrorKind::Invalid),
None => return Err(ParseErrorKind::TooShort),
};
s = &s[1..];
// 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(ParseErrorKind::Invalid),
};
s = &s[2..];
// colons (and possibly other separators)
if consume_colon {
s = s.trim_start_matches(|c: char| c == ':' || c.is_whitespace());
}
// 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(ParseErrorKind::OutOfRange),
_ => return Err(ParseErrorKind::Invalid),
}
} else if allow_missing_minutes {
0
} else {
return Err(ParseErrorKind::TooShort);
};
match s.len() {
len if len >= 2 => &s[2..],
len if len == 0 => s,
_ => return Err(ParseErrorKind::TooShort),
};
let seconds = hours * 3600 + minutes * 60;
Ok(if negative { -seconds } else { seconds })
}