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Parsing preparations #1479

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Parsing preparations #1479

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3af5d5b
Use `format::parse` in `DateTime<FixedOffset>::from_str`
pitdicker Mar 2, 2024
94fcec0
Move `FromStr` impl to `datetime` module
pitdicker Mar 2, 2024
1dc14e0
Use `format::parse` in `FixedOffset::from_str`
pitdicker Mar 2, 2024
c2d3345
Simplify digit parsing in `timezone_offset`
pitdicker Mar 2, 2024
a799ecf
Support parsing negative timestamps
pitdicker Mar 2, 2024
3b7fa22
Remove duplicate checks
pitdicker Mar 5, 2024
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22 changes: 22 additions & 0 deletions src/datetime/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1788,6 +1788,28 @@ where
}
}

/// Accepts a relaxed form of RFC3339.
/// A space or a 'T' are acepted as the separator between the date and time
/// parts. Additional spaces are allowed between each component.
///
/// All of these examples are equivalent:
/// ```
/// # use chrono::{DateTime, offset::FixedOffset};
/// "2012-12-12T12:12:12Z".parse::<DateTime<FixedOffset>>()?;
/// "2012-12-12 12:12:12Z".parse::<DateTime<FixedOffset>>()?;
/// "2012- 12-12T12: 12:12Z".parse::<DateTime<FixedOffset>>()?;
/// # Ok::<(), chrono::ParseError>(())
/// ```
impl str::FromStr for DateTime<FixedOffset> {
type Err = ParseError;

fn from_str(s: &str) -> ParseResult<DateTime<FixedOffset>> {
let mut parsed = Parsed::new();
parse(&mut parsed, s, [Item::Fixed(Fixed::RFC3339), Item::Space("")].iter())?;
parsed.to_datetime()
}
}

/// Accepts a relaxed form of RFC3339.
/// A space or a 'T' are accepted as the separator between the date and time
/// parts.
Expand Down
48 changes: 7 additions & 41 deletions src/format/parse.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -12,7 +12,7 @@ use super::scan;
use super::{Fixed, InternalFixed, InternalInternal, Item, Numeric, Pad, Parsed};
use super::{ParseError, ParseResult};
use super::{BAD_FORMAT, INVALID, OUT_OF_RANGE, TOO_LONG, TOO_SHORT};
use crate::{DateTime, FixedOffset, Weekday};
use crate::Weekday;

fn set_weekday_with_num_days_from_sunday(p: &mut Parsed, v: i64) -> ParseResult<()> {
p.set_weekday(match v {
Expand Down Expand Up @@ -357,7 +357,7 @@ where
Minute => (2, false, Parsed::set_minute),
Second => (2, false, Parsed::set_second),
Nanosecond => (9, false, Parsed::set_nanosecond),
Timestamp => (usize::MAX, false, Parsed::set_timestamp),
Timestamp => (usize::MAX, true, Parsed::set_timestamp),

// for the future expansion
Internal(ref int) => match int._dummy {},
Expand All @@ -366,8 +366,7 @@ where
s = s.trim_start();
let v = if signed {
if s.starts_with('-') {
let v = try_consume!(scan::number(&s[1..], 1, usize::MAX));
0i64.checked_sub(v).ok_or(OUT_OF_RANGE)?
try_consume!(scan::negative_number(&s[1..], 1, usize::MAX))
} else if s.starts_with('+') {
try_consume!(scan::number(&s[1..], 1, usize::MAX))
} else {
Expand Down Expand Up @@ -425,25 +424,16 @@ where
}

&Internal(InternalFixed { val: InternalInternal::Nanosecond3NoDot }) => {
if s.len() < 3 {
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Can you explain in the commit message why they're duplicate (that is, how these invariants are upheld)? It's not clear in the diff.

return Err(TOO_SHORT);
}
let nano = try_consume!(scan::nanosecond_fixed(s, 3));
parsed.set_nanosecond(nano)?;
}

&Internal(InternalFixed { val: InternalInternal::Nanosecond6NoDot }) => {
if s.len() < 6 {
return Err(TOO_SHORT);
}
let nano = try_consume!(scan::nanosecond_fixed(s, 6));
parsed.set_nanosecond(nano)?;
}

&Internal(InternalFixed { val: InternalInternal::Nanosecond9NoDot }) => {
if s.len() < 9 {
return Err(TOO_SHORT);
}
let nano = try_consume!(scan::nanosecond_fixed(s, 9));
parsed.set_nanosecond(nano)?;
}
Expand Down Expand Up @@ -508,31 +498,6 @@ where
Ok(s)
}

/// Accepts a relaxed form of RFC3339.
/// A space or a 'T' are acepted as the separator between the date and time
/// parts. Additional spaces are allowed between each component.
///
/// All of these examples are equivalent:
/// ```
/// # use chrono::{DateTime, offset::FixedOffset};
/// "2012-12-12T12:12:12Z".parse::<DateTime<FixedOffset>>()?;
/// "2012-12-12 12:12:12Z".parse::<DateTime<FixedOffset>>()?;
/// "2012- 12-12T12: 12:12Z".parse::<DateTime<FixedOffset>>()?;
/// # Ok::<(), chrono::ParseError>(())
/// ```
impl str::FromStr for DateTime<FixedOffset> {
type Err = ParseError;

fn from_str(s: &str) -> ParseResult<DateTime<FixedOffset>> {
let mut parsed = Parsed::new();
let (s, _) = parse_rfc3339_relaxed(&mut parsed, s)?;
if !s.trim_start().is_empty() {
return Err(TOO_LONG);
}
parsed.to_datetime()
}
}

/// Accepts a relaxed form of RFC3339.
///
/// Differences with RFC3339:
Expand Down Expand Up @@ -790,6 +755,7 @@ mod tests {
check(" + 42", &[Space(" "), num(Year)], Err(INVALID));
check("-", &[num(Year)], Err(TOO_SHORT));
check("+", &[num(Year)], Err(TOO_SHORT));
check("-9223372036854775808", &[num(Timestamp)], parsed!(timestamp: i64::MIN));

// unsigned numeric
check("345", &[num(Ordinal)], parsed!(ordinal: 345));
Expand Down Expand Up @@ -1317,7 +1283,7 @@ mod tests {
check("12345678", &[internal_fixed(TimezoneOffsetPermissive)], Err(INVALID));
check("+1", &[internal_fixed(TimezoneOffsetPermissive)], Err(TOO_SHORT));
check("+12", &[internal_fixed(TimezoneOffsetPermissive)], parsed!(offset: 43_200));
check("+123", &[internal_fixed(TimezoneOffsetPermissive)], Err(TOO_SHORT));
check("+123", &[internal_fixed(TimezoneOffsetPermissive)], Err(TOO_LONG));
check("+1234", &[internal_fixed(TimezoneOffsetPermissive)], parsed!(offset: 45_240));
check("-1234", &[internal_fixed(TimezoneOffsetPermissive)], parsed!(offset: -45_240));
check("−1234", &[internal_fixed(TimezoneOffsetPermissive)], parsed!(offset: -45_240)); // MINUS SIGN (U+2212)
Expand All @@ -1334,7 +1300,7 @@ mod tests {
check("12:34:56", &[internal_fixed(TimezoneOffsetPermissive)], Err(INVALID));
check("+1:", &[internal_fixed(TimezoneOffsetPermissive)], Err(INVALID));
check("+12:", &[internal_fixed(TimezoneOffsetPermissive)], parsed!(offset: 43_200));
check("+12:3", &[internal_fixed(TimezoneOffsetPermissive)], Err(TOO_SHORT));
check("+12:3", &[internal_fixed(TimezoneOffsetPermissive)], Err(TOO_LONG));
check("+12:34", &[internal_fixed(TimezoneOffsetPermissive)], parsed!(offset: 45_240));
check("-12:34", &[internal_fixed(TimezoneOffsetPermissive)], parsed!(offset: -45_240));
check("−12:34", &[internal_fixed(TimezoneOffsetPermissive)], parsed!(offset: -45_240)); // MINUS SIGN (U+2212)
Expand Down Expand Up @@ -1384,7 +1350,7 @@ mod tests {
);
check("🤠+12:34", &[internal_fixed(TimezoneOffsetPermissive)], Err(INVALID));
check("+12:34🤠", &[internal_fixed(TimezoneOffsetPermissive)], Err(TOO_LONG));
check("+12:🤠34", &[internal_fixed(TimezoneOffsetPermissive)], Err(INVALID));
check("+12:🤠34", &[internal_fixed(TimezoneOffsetPermissive)], Err(TOO_LONG));
check(
"+12:34🤠",
&[internal_fixed(TimezoneOffsetPermissive), Literal("🤠")],
Expand Down
76 changes: 41 additions & 35 deletions src/format/scan.rs
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Expand Up @@ -15,6 +15,28 @@
/// 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)> {
let (s, n) = unsigned_number(s, min, max)?;
Ok((s, n.try_into().map_err(|_| OUT_OF_RANGE)?))
}

/// Tries to parse the 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 negative_number(s: &str, min: usize, max: usize) -> ParseResult<(&str, i64)> {
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I'd prefer to inline this in the caller (more like before), since there aren't any other users, anyway.

Is there a way to more directly express the precondition for negating the number? This feels kind of roundabout -- even the previous 0i64.checked_sub(v).ok_or() feels clearer.

let (s, n) = unsigned_number(s, min, max)?;
let signed_neg = (n as i64).wrapping_neg();
if !signed_neg.is_negative() {
return Err(OUT_OF_RANGE);

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}
Ok((s, signed_neg))
}

/// Tries to parse a number from `min` to `max` digits as an unsigned integer.
#[inline]
pub(super) fn unsigned_number(s: &str, min: usize, max: usize) -> ParseResult<(&str, u64)> {
assert!(min <= max);

// We are only interested in ascii numbers, so we can work with the `str` as bytes. We stop on
Expand All @@ -25,7 +47,7 @@
return Err(TOO_SHORT);
}

let mut n = 0i64;
let mut n = 0u64;
for (i, c) in bytes.iter().take(max).cloned().enumerate() {
// cloned() = copied()
if !c.is_ascii_digit() {
Expand All @@ -36,7 +58,7 @@
}
}

n = match n.checked_mul(10).and_then(|n| n.checked_add((c - b'0') as i64)) {
n = match n.checked_mul(10).and_then(|n| n.checked_add((c - b'0') as u64)) {
Some(n) => n,
None => return Err(OUT_OF_RANGE),
};
Expand Down Expand Up @@ -181,7 +203,7 @@
}

/// Consumes any number (including zero) of colon or spaces.
pub(crate) fn colon_or_space(s: &str) -> ParseResult<&str> {
pub(super) fn colon_or_space(s: &str) -> ParseResult<&str> {
Ok(s.trim_start_matches(|c: char| c == ':' || c.is_whitespace()))
}

Expand All @@ -199,7 +221,7 @@
/// 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>(
pub(super) fn timezone_offset<F>(
mut s: &str,
mut consume_colon: F,
allow_zulu: bool,
Expand All @@ -215,67 +237,51 @@
}
}

const fn digits(s: &str) -> ParseResult<(u8, u8)> {
fn digits(s: &str) -> ParseResult<u8> {
let b = s.as_bytes();
if b.len() < 2 {
Err(TOO_SHORT)
} else {
Ok((b[0], b[1]))
return Err(TOO_SHORT);
}
match (b[0], b[1]) {
(h1 @ b'0'..=b'9', h2 @ b'0'..=b'9') => Ok((h1 - b'0') * 10 + (h2 - b'0')),
_ => Err(INVALID),
}
}
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('−') => {
Some('−') if allow_tz_minus_sign => {
// 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),
};
let hours = digits(s)? as i32;
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),
let minutes = match digits(s) {
Ok(m) if m >= 60 => return Err(OUT_OF_RANGE),
Ok(m) => {
s = &s[2..];
m as i32
}
} 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),
Err(_) if allow_missing_minutes => 0,
Err(e) => return Err(e),
};

let seconds = hours * 3600 + minutes * 60;
Expand Down
8 changes: 5 additions & 3 deletions src/offset/fixed.rs
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Expand Up @@ -10,7 +10,7 @@ use core::str::FromStr;
use rkyv::{Archive, Deserialize, Serialize};

use super::{MappedLocalTime, Offset, TimeZone};
use crate::format::{scan, ParseError, OUT_OF_RANGE};
use crate::format::{parse, Fixed, Item, ParseError, Parsed};
use crate::naive::{NaiveDate, NaiveDateTime};

/// The time zone with fixed offset, from UTC-23:59:59 to UTC+23:59:59.
Expand Down Expand Up @@ -118,9 +118,11 @@ impl FixedOffset {
/// Parsing a `str` into a `FixedOffset` uses the format [`%z`](crate::format::strftime).
impl FromStr for FixedOffset {
type Err = ParseError;

fn from_str(s: &str) -> Result<Self, Self::Err> {
let (_, offset) = scan::timezone_offset(s, scan::colon_or_space, false, false, true)?;
Self::east_opt(offset).ok_or(OUT_OF_RANGE)
let mut parsed = Parsed::new();
parse(&mut parsed, s, [Item::Fixed(Fixed::TimezoneOffset)].iter())?;
parsed.to_fixed_offset()
}
}

Expand Down
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