Merge pull request #248 from cakebaker/bump_version_to_0_13_3

chore: bump version to `0.13.3`

.github/workflows/ci.yml

@@ -4,6 +4,7 @@ name: Basic CI
 
 env:
   CARGO_TERM_COLOR: always
+  RUST_MIN_SRV: "1.71.1"
 
 jobs:
   check:
@@ -13,7 +14,7 @@ jobs:
       matrix:
         os: [ubuntu-latest, macOS-latest, windows-latest]
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: dtolnay/rust-toolchain@stable
       - run: cargo check
 
@@ -24,7 +25,7 @@ jobs:
       matrix:
         os: [ubuntu-latest, macOS-latest, windows-latest]
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: dtolnay/rust-toolchain@stable
       - run: cargo test
 
@@ -32,7 +33,7 @@ jobs:
     name: cargo fmt --all -- --check
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: dtolnay/rust-toolchain@stable
       - run: rustup component add rustfmt
       - run: cargo fmt --all -- --check
@@ -44,11 +45,24 @@ jobs:
       matrix:
         os: [ubuntu-latest, macOS-latest, windows-latest]
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: dtolnay/rust-toolchain@stable
       - run: rustup component add clippy
       - run: cargo clippy --all-targets -- -D warnings
 
+  min_version:
+    name: Minimum Supported Rust Version
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-latest, macOS-latest, windows-latest]
+    steps:
+      - uses: actions/checkout@v6
+      - uses: dtolnay/rust-toolchain@stable
+        with:
+          toolchain: ${{ env.RUST_MIN_SRV }}
+      - run: cargo test
+
   coverage:
     name: Code Coverage
     runs-on: ${{ matrix.job.os }}
@@ -60,7 +74,7 @@ jobs:
           - { os: macos-latest   , features: macos }
           - { os: windows-latest , features: windows }
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v6
     - name: Initialize workflow variables
       id: vars
       shell: bash
@@ -138,7 +152,7 @@ jobs:
     env:
       RUN_FOR: 60
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v6
     - uses: dtolnay/rust-toolchain@nightly
     - name: Install `cargo-fuzz`
       run: cargo install cargo-fuzz

Cargo.toml

@@ -1,13 +1,17 @@
 [package]
 name = "parse_datetime"
 description = "parsing human-readable time strings and converting them to a DateTime"
-version = "0.6.0"
+version = "0.13.3"
 edition = "2021"
 license = "MIT"
 repository = "https://github.com/uutils/parse_datetime"
 readme = "README.md"
+rust-version = "1.71.1"
 
 [dependencies]
-regex = "1.10.4"
-chrono = { version="0.4.38", default-features=false, features=["std", "alloc", "clock"] }
-nom = "7.1.3"
+winnow = "0.7.10"
+num-traits = "0.2.19"
+jiff = { version = "0.2.15", default-features = false, features = ["tz-system", "tzdb-bundle-platform", "tzdb-zoneinfo"] }
+
+[dev-dependencies]
+rstest = "0.26"

README.md

@@ -4,48 +4,47 @@
 [![License](http://img.shields.io/badge/license-MIT-blue.svg)](https://github.com/uutils/parse_datetime/blob/main/LICENSE)
 [![CodeCov](https://codecov.io/gh/uutils/parse_datetime/branch/main/graph/badge.svg)](https://codecov.io/gh/uutils/parse_datetime)
 
-A Rust crate for parsing human-readable relative time strings and human-readable datetime strings and converting them to a `DateTime`.
+A Rust crate for parsing human-readable relative time strings and human-readable datetime strings and converting them to a jiff's `Zoned` object.
 
 ## Features
 
 - Parses a variety of human-readable and standard time formats.
 - Supports positive and negative durations.
-- Allows for chaining time units (e.g., "1 hour 2 minutes" or "2 days and 2 hours").
+- Allows for chaining time units (e.g., "1 hour 2 minutes" or "2 days 2 hours ago").
 - Calculate durations relative to a specified date.
-- Relies on Chrono
+- Relies on Jiff
 
 ## Usage
 
-Add this to your `Cargo.toml`:
+Add `parse_datetime` to your `Cargo.toml` with:
 
-```toml
-[dependencies]
-parse_datetime = "0.6.0"
+```
+cargo add parse_datetime
 ```
 
 Then, import the crate and use the `parse_datetime_at_date` function:
 
 ```rs
-use chrono::{Duration, Local};
+use jiff::{ToSpan, Zoned};
 use parse_datetime::parse_datetime_at_date;
 
-let now = Local::now();
-let after = parse_datetime_at_date(now, "+3 days");
+let now = Zoned::now();
+let after = parse_datetime_at_date(now.clone(), "+3 days");
 
 assert_eq!(
-  (now + Duration::days(3)).naive_utc(),
-  after.unwrap().naive_utc()
+  now.checked_add(3.days()).unwrap(),
+  after.unwrap()
 );
 ```
 
 For DateTime parsing, import the `parse_datetime` function:
 
 ```rs
+use jiff::{civil::{date, time} ,Zoned};
 use parse_datetime::parse_datetime;
-use chrono::{Local, TimeZone};
 
 let dt = parse_datetime("2021-02-14 06:37:47");
-assert_eq!(dt.unwrap(), Local.with_ymd_and_hms(2021, 2, 14, 6, 37, 47).unwrap());
+assert_eq!(dt.unwrap(), Zoned::now().with().date(date(2021, 2, 14)).time(time(6, 37, 47, 0)).build().unwrap());
 ```
 
 ### Supported Formats
@@ -59,7 +58,6 @@ The `parse_datetime` and `parse_datetime_at_date` functions support absolute dat
 - "tomorrow"
 - use "ago" for the past
 - use "next" or "last" with `unit` (e.g., "next week", "last year")
-- combined units with "and" or "," (e.g., "2 years and 1 month", "1 day, 2 hours" or "2 weeks 1 second")
 - unix timestamps (for example "@0" "@1344000")
 
 `num` can be a positive or negative integer.
@@ -71,7 +69,7 @@ The `parse_datetime` and `parse_datetime_at_date` functions support absolute dat
 
 The `parse_datetime` and `parse_datetime_at_date` function return:
 
-- `Ok(DateTime<FixedOffset>)` - If the input string can be parsed as a datetime
+- `Ok(Zoned)` - If the input string can be parsed as a `Zoned` object
 - `Err(ParseDateTimeError::InvalidInput)` - If the input string cannot be parsed
 
 ## Fuzzer

fuzz/Cargo.toml

@@ -7,10 +7,7 @@ edition = "2021"
 cargo-fuzz = true
 
 [dependencies]
-rand = "0.8.5"
 libfuzzer-sys = "0.4.7"
-regex = "1.10.4"
-chrono = { version="0.4", default-features=false, features=["std", "alloc", "clock"] }
 
 [dependencies.parse_datetime]
 path = "../"

src/items/builder.rs

@@ -0,0 +1,321 @@
+// For the full copyright and license information, please view the LICENSE
+// file that was distributed with this source code.
+
+use jiff::{civil, Span, Zoned};
+
+use super::{date, epoch, error, offset, relative, time, weekday, year, Item};
+
+/// The builder is used to construct a DateTime object from various components.
+/// The parser creates a `DateTimeBuilder` object with the parsed components,
+/// but without the baseline date and time. So you normally need to set the base
+/// date and time using the `set_base()` method before calling `build()`, or
+/// leave it unset to use the current date and time as the base.
+#[derive(Debug, Default)]
+pub(crate) struct DateTimeBuilder {
+    base: Option<Zoned>,
+    timestamp: Option<epoch::Timestamp>,
+    date: Option<date::Date>,
+    time: Option<time::Time>,
+    weekday: Option<weekday::Weekday>,
+    offset: Option<offset::Offset>,
+    timezone: Option<jiff::tz::TimeZone>,
+    relative: Vec<relative::Relative>,
+}
+
+impl DateTimeBuilder {
+    pub(super) fn new() -> Self {
+        Self::default()
+    }
+
+    /// Sets the base date and time for the builder. If not set, the current
+    /// date and time will be used.
+    pub(super) fn set_base(mut self, base: Zoned) -> Self {
+        self.base = Some(base);
+        self
+    }
+
+    /// Sets the timezone rule for the builder.
+    ///
+    /// By default, the builder uses the time zone rules indicated by the `TZ`
+    /// environment variable, or the system default rules if `TZ` is not set.
+    /// This method allows overriding the time zone rules.
+    fn set_timezone(mut self, tz: jiff::tz::TimeZone) -> Result<Self, &'static str> {
+        if self.timezone.is_some() {
+            return Err("timezone rule cannot appear more than once");
+        }
+
+        self.timezone = Some(tz);
+        Ok(self)
+    }
+
+    /// Sets a timestamp value. Timestamp values are exclusive to other date/time
+    /// items (date, time, weekday, timezone, relative adjustments).
+    pub(super) fn set_timestamp(mut self, ts: epoch::Timestamp) -> Result<Self, &'static str> {
+        if self.timestamp.is_some() {
+            return Err("timestamp cannot appear more than once");
+        } else if self.date.is_some()
+            || self.time.is_some()
+            || self.weekday.is_some()
+            || self.offset.is_some()
+            || !self.relative.is_empty()
+        {
+            return Err("timestamp cannot be combined with other date/time items");
+        }
+
+        self.timestamp = Some(ts);
+        Ok(self)
+    }
+
+    fn set_date(mut self, date: date::Date) -> Result<Self, &'static str> {
+        if self.timestamp.is_some() {
+            return Err("timestamp cannot be combined with other date/time items");
+        } else if self.date.is_some() {
+            return Err("date cannot appear more than once");
+        }
+
+        self.date = Some(date);
+        Ok(self)
+    }
+
+    fn set_time(mut self, time: time::Time) -> Result<Self, &'static str> {
+        if self.timestamp.is_some() {
+            return Err("timestamp cannot be combined with other date/time items");
+        } else if self.time.is_some() {
+            return Err("time cannot appear more than once");
+        } else if self.offset.is_some() && time.offset.is_some() {
+            return Err("time offset and timezone are mutually exclusive");
+        }
+
+        self.time = Some(time);
+        Ok(self)
+    }
+
+    fn set_weekday(mut self, weekday: weekday::Weekday) -> Result<Self, &'static str> {
+        if self.timestamp.is_some() {
+            return Err("timestamp cannot be combined with other date/time items");
+        } else if self.weekday.is_some() {
+            return Err("weekday cannot appear more than once");
+        }
+
+        self.weekday = Some(weekday);
+        Ok(self)
+    }
+
+    fn set_offset(mut self, timezone: offset::Offset) -> Result<Self, &'static str> {
+        if self.timestamp.is_some() {
+            return Err("timestamp cannot be combined with other date/time items");
+        } else if self.offset.is_some()
+            || self.time.as_ref().and_then(|t| t.offset.as_ref()).is_some()
+        {
+            return Err("time offset cannot appear more than once");
+        }
+
+        self.offset = Some(timezone);
+        Ok(self)
+    }
+
+    fn push_relative(mut self, relative: relative::Relative) -> Result<Self, &'static str> {
+        if self.timestamp.is_some() {
+            return Err("timestamp cannot be combined with other date/time items");
+        }
+
+        self.relative.push(relative);
+        Ok(self)
+    }
+
+    /// Sets a pure number that can be interpreted as either a year or time
+    /// depending on the current state of the builder.
+    ///
+    /// If a date is already set but lacks a year, the number is interpreted as
+    /// a year. Otherwise, it's interpreted as a time in HHMM, HMM, HH, or H
+    /// format.
+    fn set_pure(mut self, pure: String) -> Result<Self, &'static str> {
+        if self.timestamp.is_some() {
+            return Err("timestamp cannot be combined with other date/time items");
+        }
+
+        if let Some(date) = self.date.as_mut() {
+            if date.year.is_none() {
+                date.year = Some(year::year_from_str(&pure)?);
+                return Ok(self);
+            }
+        }
+
+        let (mut hour_str, mut minute_str) = match pure.len() {
+            1..=2 => (pure.as_str(), "0"),
+            3..=4 => pure.split_at(pure.len() - 2),
+            _ => {
+                return Err("pure number must be 1-4 digits when interpreted as time");
+            }
+        };
+
+        let hour = time::hour24(&mut hour_str).map_err(|_| "invalid hour in pure number")?;
+        let minute = time::minute(&mut minute_str).map_err(|_| "invalid minute in pure number")?;
+
+        let time = time::Time {
+            hour,
+            minute,
+            ..Default::default()
+        };
+        self.set_time(time)
+    }
+
+    /// Build a `Zoned` object from the pieces accumulated in this builder.
+    ///
+    /// Resolution order (mirrors GNU `date` semantics):
+    ///
+    /// 1. Base instant.
+    ///   - a. If `self.base` is provided, start with it.
+    ///   - b. Else if a `timezone` rule is present, start with "now" in that
+    ///     timezone.
+    ///   - c. Else start with current system local time.
+    ///
+    /// 2. Absolute timestamp override.
+    ///   - a. If `self.timestamp` is set, it fully determines the result.
+    ///
+    /// 3. Time of day truncation.
+    ///   - a. If any of date, time, weekday, offset, timezone is set, zero the
+    ///     time of day to 00:00:00 before applying fields.
+    ///
+    /// 4. Fieldwise resolution (applied to the base instant).
+    ///   - a. Apply date. If year is absent in the parsed date, inherit the year
+    ///     from the base instant.
+    ///   - b. Apply time. If time carries an explicit numeric offset, apply the
+    ///     offset before setting time.
+    ///   - c. Apply weekday (e.g., "next Friday" or "last Monday").
+    ///   - d. Apply relative adjustments (e.g., "+3 days", "-2 months").
+    ///   - e. Apply final fixed offset if present.
+    pub(super) fn build(self) -> Result<Zoned, error::Error> {
+        // 1. Choose the base instant.
+        let base = match (self.base, &self.timezone) {
+            (Some(b), _) => b,
+            (None, Some(tz)) => jiff::Timestamp::now().to_zoned(tz.clone()),
+            (None, None) => Zoned::now(),
+        };
+
+        // 2. Absolute timestamp override everything else.
+        if let Some(ts) = self.timestamp {
+            let ts = jiff::Timestamp::try_from(ts)?;
+            return Ok(ts.to_zoned(base.offset().to_time_zone()));
+        }
+
+        // 3. Determine whether to truncate the time of day.
+        let need_midnight = self.date.is_some()
+            || self.time.is_some()
+            || self.weekday.is_some()
+            || self.offset.is_some()
+            || self.timezone.is_some();
+
+        let mut dt = if need_midnight {
+            base.with().time(civil::time(0, 0, 0, 0)).build()?
+        } else {
+            base
+        };
+
+        // 4a. Apply date.
+        if let Some(date) = self.date {
+            let d: civil::Date = if date.year.is_some() {
+                date.try_into()?
+            } else {
+                date.with_year(dt.date().year() as u16).try_into()?
+            };
+            dt = dt.with().date(d).build()?;
+        }
+
+        // 4b. Apply time.
+        if let Some(time) = self.time.clone() {
+            if let Some(offset) = &time.offset {
+                dt = dt.datetime().to_zoned(offset.try_into()?)?;
+            }
+
+            let t: civil::Time = time.try_into()?;
+            dt = dt.with().time(t).build()?;
+        }
+
+        // 4c. Apply weekday.
+        if let Some(weekday::Weekday { mut offset, day }) = self.weekday {
+            if self.time.is_none() {
+                dt = dt.with().time(civil::time(0, 0, 0, 0)).build()?;
+            }
+
+            let target = day.into();
+
+            // If the current day is not the target day, we need to adjust
+            // the x value to ensure we find the correct day.
+            //
+            // Consider this:
+            // Assuming today is Monday, next Friday is actually THIS Friday;
+            // but next Monday is indeed NEXT Monday.
+            if dt.date().weekday() != target && offset > 0 {
+                offset -= 1;
+            }
+
+            // Calculate the delta to the target day.
+            //
+            // Assuming today is Thursday, here are some examples:
+            //
+            // Example 1: last Thursday (x = -1, day = Thursday)
+            //            delta = (3 - 3) % 7 + (-1) * 7 = -7
+            //
+            // Example 2: last Monday (x = -1, day = Monday)
+            //            delta = (0 - 3) % 7 + (-1) * 7 = -3
+            //
+            // Example 3: next Monday (x = 1, day = Monday)
+            //            delta = (0 - 3) % 7 + (0) * 7 = 4
+            // (Note that we have adjusted the x value above)
+            //
+            // Example 4: next Thursday (x = 1, day = Thursday)
+            //            delta = (3 - 3) % 7 + (1) * 7 = 7
+            let delta = (target.since(civil::Weekday::Monday) as i32
+                - dt.date().weekday().since(civil::Weekday::Monday) as i32)
+                .rem_euclid(7)
+                + offset.checked_mul(7).ok_or("multiplication overflow")?;
+
+            dt = dt.checked_add(Span::new().try_days(delta)?)?;
+        }
+
+        // 4d. Apply relative adjustments.
+        for rel in self.relative {
+            dt = dt.checked_add::<Span>(if let relative::Relative::Months(x) = rel {
+                // *NOTE* This is done in this way to conform to GNU behavior.
+                let days = dt.date().last_of_month().day() as i32;
+                Span::new().try_days(days.checked_mul(x).ok_or("multiplication overflow")?)?
+            } else {
+                rel.try_into()?
+            })?;
+        }
+
+        // 4e. Apply final fixed offset.
+        if let Some(offset) = self.offset {
+            let (offset, hour_adjustment) = offset.normalize();
+            dt = dt.checked_add(Span::new().hours(hour_adjustment))?;
+            dt = dt.datetime().to_zoned((&offset).try_into()?)?;
+        }
+
+        Ok(dt)
+    }
+}
+
+impl TryFrom<Vec<Item>> for DateTimeBuilder {
+    type Error = &'static str;
+
+    fn try_from(items: Vec<Item>) -> Result<Self, Self::Error> {
+        let mut builder = DateTimeBuilder::new();
+
+        for item in items {
+            builder = match item {
+                Item::Timestamp(ts) => builder.set_timestamp(ts)?,
+                Item::DateTime(dt) => builder.set_date(dt.date)?.set_time(dt.time)?,
+                Item::Date(d) => builder.set_date(d)?,
+                Item::Time(t) => builder.set_time(t)?,
+                Item::Weekday(weekday) => builder.set_weekday(weekday)?,
+                Item::Offset(offset) => builder.set_offset(offset)?,
+                Item::Relative(rel) => builder.push_relative(rel)?,
+                Item::TimeZone(tz) => builder.set_timezone(tz)?,
+                Item::Pure(pure) => builder.set_pure(pure)?,
+            }
+        }
+
+        Ok(builder)
+    }
+}

src/items/combined.rs

@@ -0,0 +1,76 @@
+// For the full copyright and license information, please view the LICENSE
+// file that was distributed with this source code.
+
+//! Parse an ISO 8601 date and time item
+//!
+//! The GNU docs state:
+//!
+//! > The ISO 8601 date and time of day extended format consists of an ISO 8601
+//! > date, a ‘T’ character separator, and an ISO 8601 time of day. This format
+//! > is also recognized if the ‘T’ is replaced by a space.
+//! >
+//! > In this format, the time of day should use 24-hour notation. Fractional
+//! > seconds are allowed, with either comma or period preceding the fraction.
+//! > ISO 8601 fractional minutes and hours are not supported. Typically, hosts
+//! > support nanosecond timestamp resolution; excess precision is silently
+//! > discarded.
+use winnow::{
+    combinator::{alt, trace},
+    seq, ModalResult, Parser,
+};
+
+use crate::items::space;
+
+use super::{date, primitive::s, time};
+
+#[derive(PartialEq, Debug, Clone, Default)]
+pub(crate) struct DateTime {
+    pub(crate) date: date::Date,
+    pub(crate) time: time::Time,
+}
+
+pub(crate) fn parse(input: &mut &str) -> ModalResult<DateTime> {
+    seq!(DateTime {
+        date: trace("iso_date", alt((date::iso1, date::iso2))),
+        // Note: the `T` is lowercased by the main parse function
+        _: alt((s('t').void(), (' ', space).void())),
+        time: trace("iso_time", time::iso),
+    })
+    .parse_next(input)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::{parse, DateTime};
+    use crate::items::{date::Date, time::Time};
+
+    #[test]
+    fn some_date() {
+        let reference = Some(DateTime {
+            date: Date {
+                day: 10,
+                month: 10,
+                year: Some(2022),
+            },
+            time: Time {
+                hour: 10,
+                minute: 10,
+                second: 55,
+                nanosecond: 0,
+                offset: None,
+            },
+        });
+
+        for mut s in [
+            "2022-10-10t10:10:55",
+            "2022-10-10 10:10:55",
+            "2022-10-10    t   10:10:55",
+            "2022-10-10       10:10:55",
+            "2022-10-10  (A comment!) t   10:10:55",
+            "2022-10-10  (A comment!)   10:10:55",
+        ] {
+            let old_s = s.to_owned();
+            assert_eq!(parse(&mut s).ok(), reference, "Failed string: {old_s}")
+        }
+    }
+}

src/items/epoch.rs

@@ -0,0 +1,137 @@
+// For the full copyright and license information, please view the LICENSE
+// file that was distributed with this source code.
+
+//! Parse a timestamp item.
+//!
+//! From the GNU docs:
+//!
+//! > If you precede a number with ‘@’, it represents an internal timestamp as
+//! > a count of seconds.  The number can contain an internal decimal point
+//! > (either ‘.’ or ‘,’); any excess precision not supported by the internal
+//! > representation is truncated toward minus infinity.  Such a number cannot
+//! > be combined with any other date item, as it specifies a complete
+//! > timestamp.
+//! >
+//! >    On most hosts, these counts ignore the presence of leap seconds.  For
+//! > example, on most hosts ‘@1483228799’ represents 2016-12-31 23:59:59 UTC,
+//! > ‘@1483228800’ represents 2017-01-01 00:00:00 UTC, and there is no way to
+//! > represent the intervening leap second 2016-12-31 23:59:60 UTC.
+
+use winnow::{
+    ascii::digit1,
+    combinator::{opt, preceded},
+    token::one_of,
+    ModalResult, Parser,
+};
+
+use super::primitive::{dec_uint, plus_or_minus, s};
+
+/// Represents a timestamp with nanosecond accuracy.
+///
+/// # Invariants
+///
+/// - `nanosecond` is always in the range of `0..1_000_000_000`.
+/// - Negative timestamps are represented by a negative `second` value and a
+///   positive `nanosecond` value.
+#[derive(Debug, PartialEq)]
+pub(super) struct Timestamp {
+    second: i64,
+    nanosecond: u32,
+}
+
+impl TryFrom<Timestamp> for jiff::Timestamp {
+    type Error = &'static str;
+
+    fn try_from(ts: Timestamp) -> Result<Self, Self::Error> {
+        jiff::Timestamp::new(
+            ts.second,
+            i32::try_from(ts.nanosecond).map_err(|_| "nanosecond in timestamp exceeds i32::MAX")?,
+        )
+        .map_err(|_| "timestamp value is out of valid range")
+    }
+}
+
+/// Parse a timestamp in the form of `@1234567890` or `@-1234567890.12345` or
+/// `@1234567890,12345`.
+pub(super) fn parse(input: &mut &str) -> ModalResult<Timestamp> {
+    (s("@"), opt(plus_or_minus), s(sec_and_nsec))
+        .verify_map(|(_, sign, (sec, nsec))| {
+            let sec = i64::try_from(sec).ok()?;
+            let (second, nanosecond) = match (sign, nsec) {
+                (Some('-'), 0) => (-sec, 0),
+                // Truncate towards minus infinity.
+                (Some('-'), _) => ((-sec).checked_sub(1)?, 1_000_000_000 - nsec),
+                _ => (sec, nsec),
+            };
+            Some(Timestamp { second, nanosecond })
+        })
+        .parse_next(input)
+}
+
+/// Parse a second value in the form of `1234567890` or `1234567890.12345` or
+/// `1234567890,12345`.
+///
+/// The first part represents whole seconds. The optional second part represents
+/// fractional seconds, parsed as a nanosecond value from up to 9 digits
+/// (padded with zeros on the right if fewer digits are present). If the second
+/// part is omitted, it defaults to 0 nanoseconds.
+pub(super) fn sec_and_nsec(input: &mut &str) -> ModalResult<(u64, u32)> {
+    (dec_uint, opt(preceded(one_of(['.', ',']), digit1)))
+        .verify_map(|(sec, opt_nsec_str)| match opt_nsec_str {
+            Some(nsec_str) if nsec_str.len() >= 9 => Some((sec, nsec_str[..9].parse().ok()?)),
+            Some(nsec_str) => {
+                let multiplier = 10_u32.pow(9 - nsec_str.len() as u32);
+                Some((sec, nsec_str.parse::<u32>().ok()?.checked_mul(multiplier)?))
+            }
+            None => Some((sec, 0)),
+        })
+        .parse_next(input)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn ts(second: i64, nanosecond: u32) -> Timestamp {
+        Timestamp { second, nanosecond }
+    }
+
+    #[test]
+    fn parse_sec_and_nsec() {
+        for (input, expected) in [
+            ("1234567890", (1234567890, 0)),                       // only seconds
+            ("1234567890.12345", (1234567890, 123450000)), // seconds and nanoseconds, '.' as floating point
+            ("1234567890,12345", (1234567890, 123450000)), // seconds and nanoseconds, ',' as floating point
+            ("1234567890.1234567890123", (1234567890, 123456789)), // nanoseconds with more than 9 digits, truncated
+        ] {
+            let mut s = input;
+            assert_eq!(sec_and_nsec(&mut s).unwrap(), expected, "{input}");
+        }
+
+        for input in [
+            ".1234567890", // invalid: no leading seconds
+            "-1234567890", // invalid: negative input not allowed
+        ] {
+            let mut s = input;
+            assert!(sec_and_nsec(&mut s).is_err(), "{input}");
+        }
+    }
+
+    #[test]
+    fn timestamp() {
+        for (input, expected) in [
+            ("@1234567890", ts(1234567890, 0)), // positive seconds, no nanoseconds
+            ("@ 1234567890", ts(1234567890, 0)), // space after '@', positive seconds, no nanoseconds
+            ("@-1234567890", ts(-1234567890, 0)), // negative seconds, no nanoseconds
+            ("@ -1234567890", ts(-1234567890, 0)), // space after '@', negative seconds, no nanoseconds
+            ("@ - 1234567890", ts(-1234567890, 0)), // space after '@' and after '-', negative seconds, no nanoseconds
+            ("@1234567890.12345", ts(1234567890, 123450000)), // positive seconds with nanoseconds, '.' as floating point
+            ("@1234567890,12345", ts(1234567890, 123450000)), // positive seconds with nanoseconds, ',' as floating point
+            ("@-1234567890.12345", ts(-1234567891, 876550000)), // negative seconds with nanoseconds, '.' as floating point
+            ("@1234567890.1234567890123", ts(1234567890, 123456789)), // nanoseconds with more than 9 digits, truncated
+        ] {
+            let mut s = input;
+            assert_eq!(parse(&mut s).unwrap(), expected, "{input}");
+        }
+    }
+}

src/items/error.rs

@@ -0,0 +1,38 @@
+use std::fmt;
+
+use winnow::error::{ContextError, ErrMode};
+
+#[derive(Debug)]
+pub(crate) enum Error {
+    ParseError(String),
+}
+
+impl std::error::Error for Error {}
+
+impl fmt::Display for Error {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Error::ParseError(reason) => {
+                write!(f, "{reason}")
+            }
+        }
+    }
+}
+
+impl From<&'static str> for Error {
+    fn from(reason: &'static str) -> Self {
+        Error::ParseError(reason.to_owned())
+    }
+}
+
+impl From<ErrMode<ContextError>> for Error {
+    fn from(err: ErrMode<ContextError>) -> Self {
+        Error::ParseError(err.to_string())
+    }
+}
+
+impl From<jiff::Error> for Error {
+    fn from(err: jiff::Error) -> Self {
+        Error::ParseError(err.to_string())
+    }
+}

src/items/offset.rs

@@ -0,0 +1,468 @@
+// For the full copyright and license information, please view the LICENSE
+// file that was distributed with this source code.
+
+//! Parse an offset item.
+//!
+//! From the GNU docs:
+//!
+//! > A “time zone item” specifies an international time zone, indicated by a
+//! > small set of letters, e.g., ‘UTC’ or ‘Z’ for Coordinated Universal Time.
+//! > Any included periods are ignored.  By following a non-daylight-saving
+//! > time zone by the string ‘DST’ in a separate word (that is, separated by
+//! > some white space), the corresponding daylight saving time zone may be
+//! > specified.  Alternatively, a non-daylight-saving time zone can be
+//! > followed by a time zone correction, to add the two values.  This is
+//! > normally done only for ‘UTC’; for example, ‘UTC+05:30’ is equivalent to
+//! > ‘+05:30’.
+//! >
+//! >    Time zone items other than ‘UTC’ and ‘Z’ are obsolescent and are not
+//! > recommended, because they are ambiguous; for example, ‘EST’ has a
+//! > different meaning in Australia than in the United States, and ‘A’ has
+//! > different meaning as a military time zone than as an obsolete RFC 822
+//! > time zone.  Instead, it's better to use unambiguous numeric time zone
+//! > corrections like ‘-0500’, as described in the previous section.
+//! >
+//! >    If neither a time zone item nor a time zone correction is supplied,
+//! > timestamps are interpreted using the rules of the default time zone.
+
+use std::fmt::Display;
+
+use winnow::{
+    combinator::{alt, peek},
+    error::{ContextError, ErrMode},
+    stream::{AsChar, Stream},
+    token::take_while,
+    ModalResult, Parser,
+};
+
+use super::{
+    primitive::{colon, ctx_err, dec_uint, dec_uint_str, plus_or_minus, s},
+    relative,
+};
+
+/// Represents a time zone offset from UTC.
+///
+/// This struct is used to represent a time zone offset in hours and minutes,
+/// with a boolean indicating whether the offset is negative (i.e., west of
+/// UTC).
+#[derive(PartialEq, Debug, Clone, Default)]
+pub(super) struct Offset {
+    negative: bool,
+    hours: u8,
+    minutes: u8,
+}
+
+impl Offset {
+    /// Merge two timezone offsets.
+    ///
+    /// Note: when parsing an offset from a string (e.g., "+08:00"), the hours
+    /// and minutes are validated to ensure they fall within valid bounds. In
+    /// contrast, merging two offsets does not perform such validation. This
+    /// behavior is intentional to match GNU date.
+    fn merge(self, offset: Offset) -> Offset {
+        fn combine(a: u16, neg_a: bool, b: u16, neg_b: bool) -> (u16, bool) {
+            if neg_a == neg_b {
+                (a + b, neg_a)
+            } else if a > b {
+                (a - b, neg_a)
+            } else {
+                (b - a, neg_b)
+            }
+        }
+        let (total_minutes, negative) = combine(
+            (self.hours as u16) * 60 + (self.minutes as u16),
+            self.negative,
+            (offset.hours as u16) * 60 + (offset.minutes as u16),
+            offset.negative,
+        );
+        let hours = (total_minutes / 60) as u8;
+        let minutes = (total_minutes % 60) as u8;
+
+        Offset {
+            negative,
+            hours,
+            minutes,
+        }
+    }
+
+    /// Normalize the offset so that the hour field is within the accepted range.
+    ///
+    /// - If the hour field is less than 24, or exactly 24 with a zero minute,
+    ///   the offset is already normalized, and the function returns the offset
+    ///   itself along with a zero hour adjustment.
+    /// - Otherwise, the hour field is reduced to 23 while preserving the minute
+    ///   field, and the function returns the normalized offset along with the
+    ///   hour adjustment needed to reach the original offset.
+    pub(super) fn normalize(self) -> (Offset, i8) {
+        if self.hours < 24 || (self.hours == 24 && self.minutes == 0) {
+            return (self, 0);
+        }
+
+        let hour_adjustment = (self.hours as i8 - 23) * if self.negative { 1 } else { -1 };
+        (
+            Offset {
+                negative: self.negative,
+                hours: 23,
+                minutes: self.minutes,
+            },
+            hour_adjustment,
+        )
+    }
+}
+
+impl TryFrom<(bool, u8, u8)> for Offset {
+    type Error = &'static str;
+
+    fn try_from((negative, hours, minutes): (bool, u8, u8)) -> Result<Self, Self::Error> {
+        if hours > 24 {
+            return Err("timezone hour must be between 0 and 24");
+        }
+        if minutes > 60 || (hours == 24 && minutes != 0) {
+            return Err("timezone minute must be between 0 and 60");
+        }
+
+        Ok(Offset {
+            negative,
+            hours,
+            minutes,
+        })
+    }
+}
+
+impl TryFrom<&Offset> for jiff::tz::TimeZone {
+    type Error = &'static str;
+
+    fn try_from(
+        Offset {
+            negative,
+            hours,
+            minutes,
+        }: &Offset,
+    ) -> Result<Self, Self::Error> {
+        let secs = (*hours as i32) * 3600 + (*minutes as i32) * 60;
+        let secs = if *negative { -secs } else { secs };
+
+        let offset = jiff::tz::Offset::from_seconds(secs).map_err(|_| "offset is invalid")?;
+        Ok(jiff::tz::TimeZone::fixed(offset))
+    }
+}
+
+impl Display for Offset {
+    fn fmt(&self, fmt: &mut std::fmt::Formatter<'_>) -> Result<(), std::fmt::Error> {
+        write!(
+            fmt,
+            "{}{:02}:{:02}",
+            if self.negative { "-" } else { "+" },
+            self.hours,
+            self.minutes
+        )
+    }
+}
+
+pub(super) fn parse(input: &mut &str) -> ModalResult<Offset> {
+    timezone_name_offset.parse_next(input)
+}
+
+/// Parse a timezone starting with `+` or `-`.
+pub(super) fn timezone_offset(input: &mut &str) -> ModalResult<Offset> {
+    // Strings like "+8 years" are ambiguous, they can either be parsed as a
+    // timezone offset "+8" and a relative time "years", or just a relative time
+    // "+8 years". GNU date parses them the second way, so we do the same here.
+    //
+    // Return early if the input can be parsed as a relative time.
+    if peek(relative::parse).parse_next(input).is_ok() {
+        return Err(ErrMode::Backtrack(ContextError::new()));
+    }
+
+    alt((timezone_offset_colon, timezone_offset_colonless)).parse_next(input)
+}
+
+/// Parse a timezone by name, with an optional numeric offset appended.
+fn timezone_name_offset(input: &mut &str) -> ModalResult<Offset> {
+    /// I'm assuming there are no timezone abbreviations with more
+    /// than 6 charactres
+    const MAX_TZ_SIZE: usize = 6;
+    let nextword = s(take_while(1..=MAX_TZ_SIZE, AsChar::is_alpha)).parse_next(input)?;
+    let tz = timezone_name_to_offset(nextword)?;
+
+    // Strings like "UTC +8 years" are ambiguous, they can either be parsed as
+    // "UTC+8" and "years", or "UTC" and "+8 years". GNU date parses them the
+    // second way, so we do the same here.
+    //
+    // Only process if the input cannot be parsed as a relative time.
+    if peek(relative::parse).parse_next(input).is_err() {
+        let start = input.checkpoint();
+        if let Ok(other_tz) = timezone_offset.parse_next(input) {
+            let new_tz = tz.merge(other_tz);
+
+            return Ok(new_tz);
+        };
+        input.reset(&start);
+    }
+
+    Ok(tz)
+}
+
+/// Parse a timezone offset with a colon separating hours and minutes, e.g.,
+/// `+08:00`, `+8:00`, `+8:0`.
+fn timezone_offset_colon(input: &mut &str) -> ModalResult<Offset> {
+    (plus_or_minus, s(dec_uint), s(colon), s(dec_uint))
+        .parse_next(input)
+        .and_then(|(sign, hours, _, minutes)| {
+            (sign == '-', hours, minutes)
+                .try_into()
+                .map_err(|e| ErrMode::Cut(ctx_err(e)))
+        })
+}
+
+/// Parse a timezone offset without colon, e.g., `+0800`, `+800`, `+08`, `+8`.
+fn timezone_offset_colonless(input: &mut &str) -> ModalResult<Offset> {
+    (plus_or_minus, s(dec_uint_str))
+        .verify_map(|(sign, s)| {
+            // GNU date accepts numeric offset strings with leading zeroes. For
+            // example, `+000000110` is valid. In such cases, the string is
+            // truncated to the last four characters. Thus, `+000000110` becomes
+            // `+0110` (note that one leading zero is kept).
+            let s = if s.len() > 4 && s.trim_start_matches('0').len() <= 4 {
+                &s[s.len() - 4..]
+            } else {
+                s
+            };
+
+            // Hour and minute values are dependent on the length of the string.
+            // For example:
+            //
+            // - "5"   -> 05:00
+            // - "05"  -> 05:00
+            // - "530" -> 05:30 (the minute is the last two characters here)
+            // - "0530"-> 05:30
+            // - "0000530" -> 05:30
+            let (h_str, m_str) = match s.len() {
+                1 | 2 => (s, "0"),
+                3 => s.split_at(1),
+                4 => s.split_at(2),
+                _ => return None,
+            };
+
+            let hours = h_str.parse::<u8>().ok()?;
+            let minutes = m_str.parse::<u8>().ok()?;
+            Some((sign, hours, minutes))
+        })
+        .parse_next(input)
+        .and_then(|(sign, hours, minutes)| {
+            (sign == '-', hours, minutes)
+                .try_into()
+                .map_err(|e| ErrMode::Cut(ctx_err(e)))
+        })
+}
+
+/// Named timezone list.
+///
+/// The full list of timezones can be extracted from
+/// https://www.timeanddate.com/time/zones/. GNU date only supports a subset of
+/// these. We support the same subset as GNU date.
+fn timezone_name_to_offset(input: &str) -> ModalResult<Offset> {
+    let mut offset_str = match input {
+        "z" => Ok("+0"),
+        "y" => Ok("-12"),
+        "x" => Ok("-11"),
+        "wet" => Ok("+0"),
+        "west" => Ok("+1"),
+        "wat" => Ok("+1"),
+        "w" => Ok("-10"),
+        "v" => Ok("-9"),
+        "utc" => Ok("+0"),
+        "u" => Ok("-8"),
+        "t" => Ok("-7"),
+        "sst" => Ok("-11"),
+        "sgt" => Ok("+8"),
+        "sast" => Ok("+2"),
+        "s" => Ok("-6"),
+        "r" => Ok("-5"),
+        "q" => Ok("-4"),
+        "pst" => Ok("-8"),
+        "pdt" => Ok("-7"),
+        "p" => Ok("-3"),
+        "o" => Ok("-2"),
+        "nzst" => Ok("+12"),
+        "nzdt" => Ok("+13"),
+        "nst" => Ok("-3:30"),
+        "ndt" => Ok("-2:30"),
+        "n" => Ok("-1"),
+        "mst" => Ok("-7"),
+        "msk" => Ok("+3"),
+        "msd" => Ok("+4"),
+        "mdt" => Ok("-6"),
+        "m" => Ok("+12"),
+        "l" => Ok("+11"),
+        "k" => Ok("+10"),
+        "jst" => Ok("+9"),
+        "ist" => Ok("+5:30"),
+        "i" => Ok("+9"),
+        "hst" => Ok("-10"),
+        "h" => Ok("+8"),
+        "gst" => Ok("+4"),
+        "gmt" => Ok("+0"),
+        "g" => Ok("+7"),
+        "f" => Ok("+6"),
+        "est" => Ok("-5"),
+        "eet" => Ok("+2"),
+        "eest" => Ok("+3"),
+        "edt" => Ok("-4"),
+        "eat" => Ok("+3"),
+        "e" => Ok("+5"),
+        "d" => Ok("+4"),
+        "cst" => Ok("-6"),
+        "clt" => Ok("-4"),
+        "clst" => Ok("-3"),
+        "cet" => Ok("+1"),
+        "cest" => Ok("+2"),
+        "cdt" => Ok("-5"),
+        "cat" => Ok("+2"),
+        "c" => Ok("+3"),
+        "bst" => Ok("+6"),
+        "brt" => Ok("-3"),
+        "brst" => Ok("-2"),
+        "b" => Ok("+2"),
+        "ast" => Ok("-3"),
+        "art" => Ok("-3"),
+        "akst" => Ok("-9"),
+        "akdt" => Ok("-8"),
+        "adt" => Ok("+4"),
+        "a" => Ok("+1"),
+        _ => Err(ErrMode::Backtrack(ContextError::new())),
+    }?;
+
+    timezone_offset(&mut offset_str)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn off(negative: bool, hours: u8, minutes: u8) -> Offset {
+        Offset {
+            negative,
+            hours,
+            minutes,
+        }
+    }
+
+    #[test]
+    fn timezone_offset_with_colon() {
+        for (input, expected) in [
+            ("+00:00", off(false, 0, 0)),        // UTC
+            ("-00:00", off(true, 0, 0)),         // UTC
+            ("+01:00", off(false, 1, 0)),        // positive offset
+            ("-06:00", off(true, 6, 0)),         // negative offset
+            ("+05:30", off(false, 5, 30)),       // positive offset with non-zero minutes
+            ("-03:30", off(true, 3, 30)),        // negative offset with non-zero minutes
+            ("- 06:00", off(true, 6, 0)),        // space after sign
+            ("- 06 : 00", off(true, 6, 0)),      // space around colon
+            ("+5:3", off(false, 5, 3)),          // single-digit hours and single-digit minutes
+            ("+5:03", off(false, 5, 3)),         // single-digit hours
+            ("+05:3", off(false, 5, 3)),         // single-digit minutes
+            ("+00005:00030", off(false, 5, 30)), // leading zeroes in hours and minutes
+            ("+00:00abc", off(false, 0, 0)), // space separator can be ignored if immediately followed by alphas (GNU date behavior)
+        ] {
+            let mut s = input;
+            assert_eq!(timezone_offset(&mut s).unwrap(), expected, "{input}");
+        }
+
+        for input in [
+            "+25:00", // invalid: hours > 24
+            "-23:61", // invalid: minutes > 60
+            "+24:01", // invalid: minutes > 0 when hours == 24
+        ] {
+            let mut s = input;
+            assert!(timezone_offset(&mut s).is_err(), "{input}");
+        }
+    }
+
+    #[test]
+    fn timezone_offset_without_colon() {
+        for (input, expected) in [
+            ("+0000", off(false, 0, 0)),      // UTC
+            ("-0000", off(true, 0, 0)),       // UTC
+            ("+0100", off(false, 1, 0)),      // positive offset
+            ("-0600", off(true, 6, 0)),       // negative offset
+            ("+0530", off(false, 5, 30)),     // positive offset with non-zero minutes
+            ("-0330", off(true, 3, 30)),      // negative offset with non-zero minutes
+            ("- 0330", off(true, 3, 30)),     // space after sign
+            ("+530", off(false, 5, 30)),      // single-digit hours
+            ("+05", off(false, 5, 0)),        // double-digit hours and no minutes
+            ("+5", off(false, 5, 0)),         // single-digit hours and no minutes
+            ("+00000530", off(false, 5, 30)), // leading zeroes
+            ("+0000abc", off(false, 0, 0)), // space separator can be ignored if immediately followed by alphas (GNU date behavior)
+        ] {
+            let mut s = input;
+            assert_eq!(timezone_offset(&mut s).unwrap(), expected, "{input}");
+        }
+
+        for input in [
+            "+2500",    // invalid: hours > 24
+            "-2361",    // invalid: minutes > 60
+            "+2401",    // invalid: minutes > 0 when hours == 24
+            "+23 days", // invalid: ambiguous with relative time parsing
+        ] {
+            let mut s = input;
+            assert!(timezone_offset(&mut s).is_err(), "{input}");
+        }
+    }
+
+    #[test]
+    fn timezone_name_without_offset() {
+        for (input, expected) in [
+            ("utc", off(false, 0, 0)),  // UTC
+            ("gmt", off(false, 0, 0)),  // UTC
+            ("z", off(false, 0, 0)),    // UTC
+            ("west", off(false, 1, 0)), // positive offset
+            ("cst", off(true, 6, 0)),   // negative offset
+            ("ist", off(false, 5, 30)), // positive offset with non-zero minutes
+            ("nst", off(true, 3, 30)),  // negative offset with non-zero minutes
+            ("z123", off(false, 0, 0)), // space separator can be ignored if immediately followed by digits (GNU date behavior)
+        ] {
+            let mut s = input;
+            assert_eq!(timezone_name_offset(&mut s).unwrap(), expected, "{input}");
+        }
+
+        for input in [
+            "abc",    // invalid: non-existent timezone
+            "utcabc", // invalid: non-existent timezone
+        ] {
+            let mut s = input;
+            assert!(timezone_name_offset(&mut s).is_err(), "{input}");
+        }
+    }
+
+    #[test]
+    fn timezone_name_with_offset() {
+        for (input, expected) in [
+            ("utc+5:30", off(false, 5, 30)),     // UTC with possitive offset
+            ("utc-5:30", off(true, 5, 30)),      // UTC with negative offset
+            ("utc +5:30", off(false, 5, 30)),    // space after timezone name
+            ("utc + 5 : 30", off(false, 5, 30)), // spaces
+            ("a+5:30", off(false, 6, 30)),       // merge two positive offsets (a=+1)
+            ("a-5:30", off(true, 4, 30)),        // merge positive and negative offsets (a=+1)
+            ("n-5:30", off(true, 6, 30)),        // merge two negative offsets (n=-1)
+            ("n+5:30", off(false, 4, 30)),       // merge negative and positive offsets (n=-1)
+            ("m+24", off(false, 36, 0)),         // maximum possible positive offset (m=+12)
+            ("y-24", off(true, 36, 0)),          // maximum possible negative offset (y=-12)
+        ] {
+            let mut s = input;
+            assert_eq!(timezone_name_offset(&mut s).unwrap(), expected, "{input}");
+        }
+
+        for input in [
+            "abc+08:00",   // invalid: non-existent timezone
+            "utc+25",      // invalid: invalid offset
+            "utc+23 days", // invalid: ambiguous with relative time parsing
+        ] {
+            let mut s = input;
+            assert!(
+                timezone_name_offset(&mut s).is_err() || !s.is_empty(),
+                "{input}"
+            );
+        }
+    }
+}

src/items/ordinal.rs

@@ -0,0 +1,47 @@
+// For the full copyright and license information, please view the LICENSE
+// file that was distributed with this source code.
+
+use winnow::{
+    ascii::alpha1,
+    combinator::{alt, opt},
+    ModalResult, Parser,
+};
+
+use super::primitive::{dec_uint, s};
+
+pub(super) fn ordinal(input: &mut &str) -> ModalResult<i32> {
+    alt((text_ordinal, number_ordinal)).parse_next(input)
+}
+
+fn number_ordinal(input: &mut &str) -> ModalResult<i32> {
+    let sign = opt(alt(('+'.value(1), '-'.value(-1)))).map(|s| s.unwrap_or(1));
+    (s(sign), s(dec_uint))
+        .verify_map(|(s, u): (i32, u32)| {
+            let i: i32 = u.try_into().ok()?;
+            Some(s * i)
+        })
+        .parse_next(input)
+}
+
+fn text_ordinal(input: &mut &str) -> ModalResult<i32> {
+    s(alpha1)
+        .verify_map(|s: &str| {
+            Some(match s {
+                "last" => -1,
+                "this" => 0,
+                "next" | "first" => 1,
+                "third" => 3,
+                "fourth" => 4,
+                "fifth" => 5,
+                "sixth" => 6,
+                "seventh" => 7,
+                "eight" => 8,
+                "ninth" => 9,
+                "tenth" => 10,
+                "eleventh" => 11,
+                "twelfth" => 12,
+                _ => return None,
+            })
+        })
+        .parse_next(input)
+}

src/items/primitive.rs

@@ -0,0 +1,144 @@
+// For the full copyright and license information, please view the LICENSE
+// file that was distributed with this source code.
+
+//! Primitive combinators.
+
+use std::str::FromStr;
+
+use winnow::{
+    ascii::{digit1, multispace0, Uint},
+    combinator::{alt, delimited, not, opt, peek, preceded, repeat, separated},
+    error::{ContextError, ParserError, StrContext, StrContextValue},
+    stream::AsChar,
+    token::{none_of, one_of, take_while},
+    Parser,
+};
+
+/// Allow spaces and comments before a parser
+///
+/// Every token parser should be wrapped in this to allow spaces and comments.
+/// It is only preceding, because that allows us to check mandatory whitespace
+/// after running the parser.
+pub(super) fn s<'a, O, E>(p: impl Parser<&'a str, O, E>) -> impl Parser<&'a str, O, E>
+where
+    E: ParserError<&'a str>,
+{
+    preceded(space, p)
+}
+
+/// Parse the space in-between tokens
+///
+/// You probably want to use the [`s`] combinator instead.
+pub(super) fn space<'a, E>(input: &mut &'a str) -> winnow::Result<(), E>
+where
+    E: ParserError<&'a str>,
+{
+    separated(0.., multispace0, alt((comment, ignored_hyphen_or_plus))).parse_next(input)
+}
+
+/// A hyphen or plus is ignored when it is not followed by a digit
+///
+/// This includes being followed by a comment! Compare these inputs:
+/// ```txt
+/// - 12 weeks
+/// - (comment) 12 weeks
+/// ```
+/// The last comment should be ignored.
+///
+/// The plus is undocumented, but it seems to be ignored.
+fn ignored_hyphen_or_plus<'a, E>(input: &mut &'a str) -> winnow::Result<(), E>
+where
+    E: ParserError<&'a str>,
+{
+    (
+        alt(('-', '+')),
+        multispace0,
+        peek(not(take_while(1, AsChar::is_dec_digit))),
+    )
+        .void()
+        .parse_next(input)
+}
+
+/// Parse a comment
+///
+/// A comment is given between parentheses, which must be balanced. Any other
+/// tokens can be within the comment.
+fn comment<'a, E>(input: &mut &'a str) -> winnow::Result<(), E>
+where
+    E: ParserError<&'a str>,
+{
+    delimited(
+        '(',
+        repeat(0.., alt((none_of(['(', ')']).void(), comment))),
+        ')',
+    )
+    .parse_next(input)
+}
+
+/// Parse a signed decimal integer.
+///
+/// Rationale for not using `winnow::ascii::dec_int`: When upgrading winnow from
+/// 0.5 to 0.7, we discovered that `winnow::ascii::dec_int` now accepts only the
+/// following two forms:
+///
+/// - 0
+/// - [+-]?[1-9][0-9]*
+///
+/// Inputs like [+-]?0[0-9]* (e.g., `+012`) are therefore rejected. We provide a
+/// custom implementation to support such zero-prefixed integers.
+#[allow(unused)]
+pub(super) fn dec_int<'a, E>(input: &mut &'a str) -> winnow::Result<i32, E>
+where
+    E: ParserError<&'a str>,
+{
+    (opt(one_of(['+', '-'])), digit1)
+        .void()
+        .take()
+        .verify_map(|s: &str| s.parse().ok())
+        .parse_next(input)
+}
+
+/// Parse an unsigned decimal integer.
+///
+/// See the rationale for `dec_int` for why we don't use
+/// `winnow::ascii::dec_uint`.
+pub(super) fn dec_uint<'a, O, E>(input: &mut &'a str) -> winnow::Result<O, E>
+where
+    O: Uint + FromStr,
+    E: ParserError<&'a str>,
+{
+    dec_uint_str
+        .verify_map(|s: &str| s.parse().ok())
+        .parse_next(input)
+}
+
+/// Parse an unsigned decimal integer as a string slice.
+pub(super) fn dec_uint_str<'a, E>(input: &mut &'a str) -> winnow::Result<&'a str, E>
+where
+    E: ParserError<&'a str>,
+{
+    digit1.void().take().parse_next(input)
+}
+
+/// Parse a colon preceded by whitespace.
+pub(super) fn colon<'a, E>(input: &mut &'a str) -> winnow::Result<(), E>
+where
+    E: ParserError<&'a str>,
+{
+    s(':').void().parse_next(input)
+}
+
+/// Parse a plus or minus character optionally preceeded by whitespace.
+pub(super) fn plus_or_minus<'a, E>(input: &mut &'a str) -> winnow::Result<char, E>
+where
+    E: ParserError<&'a str>,
+{
+    s(alt(('+', '-'))).parse_next(input)
+}
+
+/// Create a context error with a reason.
+pub(super) fn ctx_err(reason: &'static str) -> ContextError {
+    let mut err = ContextError::new();
+    err.push(StrContext::Expected(StrContextValue::Description(reason)));
+    err
+}

src/items/pure.rs

@@ -0,0 +1,37 @@
+// For the full copyright and license information, please view the LICENSE
+// file that was distributed with this source code.
+
+//! Parse a pure number string.
+//!
+//! From the GNU docs:
+//!
+//! > The precise interpretation of a pure decimal number depends on the
+//! > context in the date string.
+//! >
+//! >    If the decimal number is of the form YYYYMMDD and no other calendar
+//! > date item (*note Calendar date items::) appears before it in the date
+//! > string, then YYYY is read as the year, MM as the month number and DD as
+//! > the day of the month, for the specified calendar date.
+//! >
+//! >    If the decimal number is of the form HHMM and no other time of day
+//! > item appears before it in the date string, then HH is read as the hour
+//! > of the day and MM as the minute of the hour, for the specified time of
+//! > day.  MM can also be omitted.
+//! >
+//! >    If both a calendar date and a time of day appear to the left of a
+//! > number in the date string, but no relative item, then the number
+//! > overrides the year.
+
+use winnow::{ModalResult, Parser};
+
+use super::primitive::{dec_uint_str, s};
+
+/// Parse a pure number string and return it as an owned `String`. We return a
+/// `String` here because the interpretation of the number depends on the
+/// parsing context in which it appears. The interpretation is deferred to the
+/// result building phase.
+pub(super) fn parse(input: &mut &str) -> ModalResult<String> {
+    s(dec_uint_str)
+        .map(|s: &str| s.to_owned())
+        .parse_next(input)
+}

src/items/relative.rs

@@ -0,0 +1,215 @@
+// For the full copyright and license information, please view the LICENSE
+// file that was distributed with this source code.
+
+//! Parse a relative datetime item
+//!
+//! The GNU docs state:
+//!
+//! > The unit of time displacement may be selected by the string ‘year’ or
+//! > ‘month’ for moving by whole years or months. These are fuzzy units, as
+//! > years and months are not all of equal duration. More precise units are
+//! > ‘fortnight’ which is worth 14 days, ‘week’ worth 7 days, ‘day’ worth 24
+//! > hours, ‘hour’ worth 60 minutes, ‘minute’ or ‘min’ worth 60 seconds, and
+//! > ‘second’ or ‘sec’ worth one second. An ‘s’ suffix on these units is
+//! > accepted and ignored.
+//! >
+//! > The unit of time may be preceded by a multiplier, given as an optionally
+//! > signed number. Unsigned numbers are taken as positively signed. No number
+//! > at all implies 1 for a multiplier. Following a relative item by the
+//! > string ‘ago’ is equivalent to preceding the unit by a multiplier with
+//! > value -1.
+//! >
+//! > The string ‘tomorrow’ is worth one day in the future (equivalent to
+//! > ‘day’), the string ‘yesterday’ is worth one day in the past (equivalent
+//! > to ‘day ago’).
+//! >
+//! > The strings ‘now’ or ‘today’ are relative items corresponding to
+//! > zero-valued time displacement, these strings come from the fact a
+//! > zero-valued time displacement represents the current time when not
+//! > otherwise changed by previous items. They may be used to stress other
+//! > items, like in ‘12:00 today’. The string ‘this’ also has the meaning of a
+//! > zero-valued time displacement, but is preferred in date strings like
+//! > ‘this thursday’.
+
+use winnow::{
+    ascii::alpha1,
+    combinator::{alt, opt},
+    ModalResult, Parser,
+};
+
+use super::{epoch::sec_and_nsec, ordinal::ordinal, primitive::s};
+
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub(crate) enum Relative {
+    Years(i32),
+    Months(i32),
+    Days(i32),
+    Hours(i32),
+    Minutes(i32),
+    Seconds(i64, u32),
+}
+
+impl TryFrom<Relative> for jiff::Span {
+    type Error = &'static str;
+
+    fn try_from(relative: Relative) -> Result<Self, Self::Error> {
+        match relative {
+            Relative::Years(years) => jiff::Span::new().try_years(years),
+            Relative::Months(months) => jiff::Span::new().try_months(months),
+            Relative::Days(days) => jiff::Span::new().try_days(days),
+            Relative::Hours(hours) => jiff::Span::new().try_hours(hours),
+            Relative::Minutes(minutes) => jiff::Span::new().try_minutes(minutes),
+            Relative::Seconds(seconds, nanoseconds) => jiff::Span::new()
+                .try_seconds(seconds)
+                .and_then(|span| span.try_nanoseconds(nanoseconds)),
+        }
+        .map_err(|_| "relative value is invalid")
+    }
+}
+
+pub(super) fn parse(input: &mut &str) -> ModalResult<Relative> {
+    alt((
+        s("tomorrow").value(Relative::Days(1)),
+        s("yesterday").value(Relative::Days(-1)),
+        // For "today" and "now", the unit is arbitrary
+        s("today").value(Relative::Days(0)),
+        s("now").value(Relative::Days(0)),
+        seconds,
+        displacement,
+    ))
+    .parse_next(input)
+}
+
+fn seconds(input: &mut &str) -> ModalResult<Relative> {
+    (
+        opt(alt((s('+').value(1), s('-').value(-1)))),
+        s(sec_and_nsec),
+        s(alpha1).verify(|s: &str| matches!(s, "seconds" | "second" | "sec" | "secs")),
+        ago,
+    )
+        .verify_map(|(sign, (sec, nsec), _, ago)| {
+            let sec = i64::try_from(sec).ok()?;
+            let sign = sign.unwrap_or(1) * if ago { -1 } else { 1 };
+            let (second, nanosecond) = match (sign, nsec) {
+                (-1, 0) => (-sec, 0),
+                // Truncate towards minus infinity.
+                (-1, _) => ((-sec).checked_sub(1)?, 1_000_000_000 - nsec),
+                _ => (sec, nsec),
+            };
+            Some(Relative::Seconds(second, nanosecond))
+        })
+        .parse_next(input)
+}
+
+fn displacement(input: &mut &str) -> ModalResult<Relative> {
+    (opt(ordinal), s(alpha1), ago)
+        .verify_map(|(n, unit, ago): (Option<i32>, &str, bool)| {
+            let multiplier = n.unwrap_or(1) * if ago { -1 } else { 1 };
+            Some(match unit.strip_suffix('s').unwrap_or(unit) {
+                "year" => Relative::Years(multiplier),
+                "month" => Relative::Months(multiplier),
+                "fortnight" => Relative::Days(multiplier.checked_mul(14)?),
+                "week" => Relative::Days(multiplier.checked_mul(7)?),
+                "day" => Relative::Days(multiplier),
+                "hour" => Relative::Hours(multiplier),
+                "minute" | "min" => Relative::Minutes(multiplier),
+                "second" | "sec" => Relative::Seconds(multiplier as i64, 0),
+                _ => return None,
+            })
+        })
+        .parse_next(input)
+}
+
+fn ago(input: &mut &str) -> ModalResult<bool> {
+    opt(s("ago")).map(|o| o.is_some()).parse_next(input)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::{parse, Relative};
+
+    #[test]
+    fn all() {
+        for (s, rel) in [
+            // Seconds
+            ("second", Relative::Seconds(1, 0)),
+            ("sec", Relative::Seconds(1, 0)),
+            ("seconds", Relative::Seconds(1, 0)),
+            ("secs", Relative::Seconds(1, 0)),
+            ("second ago", Relative::Seconds(-1, 0)),
+            ("3 seconds", Relative::Seconds(3, 0)),
+            ("+ 3 seconds", Relative::Seconds(3, 0)),
+            ("3.5 seconds", Relative::Seconds(3, 500_000_000)),
+            ("-3.5 seconds", Relative::Seconds(-4, 500_000_000)),
+            ("+3.5 seconds", Relative::Seconds(3, 500_000_000)),
+            ("+ 3.5 seconds", Relative::Seconds(3, 500_000_000)),
+            ("3.5 seconds ago", Relative::Seconds(-4, 500_000_000)),
+            ("-  3.5 seconds ago", Relative::Seconds(3, 500_000_000)),
+            // Minutes
+            ("minute", Relative::Minutes(1)),
+            ("minutes", Relative::Minutes(1)),
+            ("min", Relative::Minutes(1)),
+            ("mins", Relative::Minutes(1)),
+            ("10 minutes", Relative::Minutes(10)),
+            ("-10 minutes", Relative::Minutes(-10)),
+            ("- 10 minutes", Relative::Minutes(-10)),
+            ("10 minutes ago", Relative::Minutes(-10)),
+            ("-10 minutes ago", Relative::Minutes(10)),
+            ("- 10 minutes ago", Relative::Minutes(10)),
+            ("-10 minutes ago", Relative::Minutes(10)),
+            ("- 10 minutes ago", Relative::Minutes(10)),
+            // Hours
+            ("hour", Relative::Hours(1)),
+            ("hours", Relative::Hours(1)),
+            ("10 hours", Relative::Hours(10)),
+            ("+10 hours", Relative::Hours(10)),
+            ("+ 10 hours", Relative::Hours(10)),
+            ("-10 hours", Relative::Hours(-10)),
+            ("- 10 hours", Relative::Hours(-10)),
+            ("10 hours ago", Relative::Hours(-10)),
+            ("-10 hours ago", Relative::Hours(10)),
+            ("- 10 hours ago", Relative::Hours(10)),
+            // Days
+            ("day", Relative::Days(1)),
+            ("days", Relative::Days(1)),
+            ("10 days", Relative::Days(10)),
+            ("+10 days", Relative::Days(10)),
+            ("+ 10 days", Relative::Days(10)),
+            ("-10 days", Relative::Days(-10)),
+            ("- 10 days", Relative::Days(-10)),
+            ("10 days ago", Relative::Days(-10)),
+            ("-10 days ago", Relative::Days(10)),
+            ("- 10 days ago", Relative::Days(10)),
+            // Multiple days
+            ("fortnight", Relative::Days(14)),
+            ("fortnights", Relative::Days(14)),
+            ("2 fortnights ago", Relative::Days(-28)),
+            ("+2 fortnights ago", Relative::Days(-28)),
+            ("+ 2 fortnights ago", Relative::Days(-28)),
+            ("week", Relative::Days(7)),
+            ("weeks", Relative::Days(7)),
+            ("2 weeks ago", Relative::Days(-14)),
+            // Other
+            ("year", Relative::Years(1)),
+            ("years", Relative::Years(1)),
+            ("month", Relative::Months(1)),
+            ("months", Relative::Months(1)),
+            // Special
+            ("yesterday", Relative::Days(-1)),
+            ("tomorrow", Relative::Days(1)),
+            ("today", Relative::Days(0)),
+            ("now", Relative::Days(0)),
+            // This something
+            ("this day", Relative::Days(0)),
+            ("this second", Relative::Seconds(0, 0)),
+            ("this year", Relative::Years(0)),
+            // Weird stuff
+            ("next week ago", Relative::Days(-7)),
+            ("last week ago", Relative::Days(7)),
+            ("this week ago", Relative::Days(0)),
+        ] {
+            let mut t = s;
+            assert_eq!(parse(&mut t).ok(), Some(rel), "Failed string: {s}")
+        }
+    }
+}

src/items/time.rs

@@ -0,0 +1,444 @@
+// For the full copyright and license information, please view the LICENSE
+// file that was distributed with this source code.
+
+// spell-checker:ignore shhmm colonless
+
+//! Parse a time item (without a date).
+//!
+//! The GNU docs state:
+//!
+//! > More generally, the time of day may be given as ‘hour:minute:second’,
+//! > where hour is a number between 0 and 23, minute is a number between 0 and
+//! > 59, and second is a number between 0 and 59 possibly followed by ‘.’ or
+//! > ‘,’ and a fraction containing one or more digits. Alternatively,
+//! > ‘:second’ can be omitted, in which case it is taken to be zero. On the
+//! > rare hosts that support leap seconds, second may be 60.
+//! >
+//! > If the time is followed by ‘am’ or ‘pm’ (or ‘a.m.’ or ‘p.m.’), hour is
+//! > restricted to run from 1 to 12, and ‘:minute’ may be omitted (taken to be
+//! > zero). ‘am’ indicates the first half of the day, ‘pm’ indicates the
+//! > second half of the day. In this notation, 12 is the predecessor of 1:
+//! > midnight is ‘12am’ while noon is ‘12pm’. (This is the zero-oriented
+//! > interpretation of ‘12am’ and ‘12pm’, as opposed to the old tradition
+//! > derived from Latin which uses ‘12m’ for noon and ‘12pm’ for midnight.)
+//! >
+//! > The time may alternatively be followed by a time zone correction,
+//! > expressed as ‘shhmm’, where s is ‘+’ or ‘-’, hh is a number of zone hours
+//! > and mm is a number of zone minutes. The zone minutes term, mm, may be
+//! > omitted, in which case the one- or two-digit correction is interpreted as
+//! > a number of hours. You can also separate hh from mm with a colon. When a
+//! > time zone correction is given this way, it forces interpretation of the
+//! > time relative to Coordinated Universal Time (UTC), overriding any
+//! > previous specification for the time zone or the local time zone. For
+//! > example, ‘+0530’ and ‘+05:30’ both stand for the time zone 5.5 hours
+//! > ahead of UTC (e.g., India). This is the best way to specify a time zone
+//! > correction by fractional parts of an hour. The maximum zone correction is
+//! > 24 hours.
+//! >
+//! > Either ‘am’/‘pm’ or a time zone correction may be specified, but not both.
+
+use winnow::{
+    combinator::{alt, opt, preceded},
+    error::ErrMode,
+    ModalResult, Parser,
+};
+
+use super::{
+    epoch::sec_and_nsec,
+    offset::{timezone_offset, Offset},
+    primitive::{colon, ctx_err, dec_uint, s},
+};
+
+#[derive(PartialEq, Clone, Debug, Default)]
+pub(crate) struct Time {
+    pub(crate) hour: u8,
+    pub(crate) minute: u8,
+    pub(crate) second: u8,
+    pub(crate) nanosecond: u32,
+    pub(super) offset: Option<Offset>,
+}
+
+impl TryFrom<Time> for jiff::civil::Time {
+    type Error = &'static str;
+
+    fn try_from(time: Time) -> Result<Self, Self::Error> {
+        jiff::civil::Time::new(
+            time.hour as i8,
+            time.minute as i8,
+            time.second as i8,
+            time.nanosecond as i32,
+        )
+        .map_err(|_| "time is not valid")
+    }
+}
+
+#[derive(Clone)]
+enum Meridiem {
+    Am,
+    Pm,
+}
+
+pub(crate) fn parse(input: &mut &str) -> ModalResult<Time> {
+    alt((am_pm_time, iso)).parse_next(input)
+}
+
+/// Parse an ISO 8601 time string
+///
+/// Also used by the [`combined`](super::combined) module
+pub(super) fn iso(input: &mut &str) -> ModalResult<Time> {
+    alt((
+        (hour24, timezone_offset).map(|(hour, offset)| Time {
+            hour,
+            minute: 0,
+            second: 0,
+            nanosecond: 0,
+            offset: Some(offset),
+        }),
+        (
+            hour24,
+            colon,
+            minute,
+            opt(preceded(colon, second)),
+            opt(timezone_offset),
+        )
+            .map(|(hour, _, minute, sec_nsec, offset)| Time {
+                hour,
+                minute,
+                second: sec_nsec.map_or(0, |(s, _)| s),
+                nanosecond: sec_nsec.map_or(0, |(_, ns)| ns),
+                offset,
+            }),
+    ))
+    .parse_next(input)
+}
+
+/// Parse a time ending with AM or PM
+///
+/// The hours are restricted to 12 or lower in this format
+fn am_pm_time(input: &mut &str) -> ModalResult<Time> {
+    let (h, m, sec_nsec, meridiem) = (
+        hour12,
+        opt(preceded(colon, minute)),
+        opt(preceded(colon, second)),
+        alt((
+            s("am").value(Meridiem::Am),
+            s("a.m.").value(Meridiem::Am),
+            s("pm").value(Meridiem::Pm),
+            s("p.m.").value(Meridiem::Pm),
+        )),
+    )
+        .parse_next(input)?;
+
+    if h == 0 {
+        return Err(ErrMode::Cut(ctx_err(
+            "hour must be greater than 0 when meridiem is specified",
+        )));
+    }
+
+    let mut h = h % 12;
+    if let Meridiem::Pm = meridiem {
+        h += 12;
+    }
+    Ok(Time {
+        hour: h,
+        minute: m.unwrap_or(0),
+        second: sec_nsec.map_or(0, |(s, _)| s),
+        nanosecond: sec_nsec.map_or(0, |(_, ns)| ns),
+        offset: None,
+    })
+}
+
+/// Parse a number of hours in `0..24`.
+pub(super) fn hour24(input: &mut &str) -> ModalResult<u8> {
+    s(dec_uint).verify(|x| *x < 24).parse_next(input)
+}
+
+/// Parse a number of hours in `0..=12`.
+fn hour12(input: &mut &str) -> ModalResult<u8> {
+    s(dec_uint).verify(|x| *x <= 12).parse_next(input)
+}
+
+/// Parse a number of minutes in `0..60`.
+pub(super) fn minute(input: &mut &str) -> ModalResult<u8> {
+    s(dec_uint).verify(|x| *x < 60).parse_next(input)
+}
+
+/// Parse a number of seconds in `0..60` and an optional number of nanoseconds
+/// (default to 0 if not set).
+fn second(input: &mut &str) -> ModalResult<(u8, u32)> {
+    s(sec_and_nsec)
+        .verify_map(|(s, ns)| if s < 60 { Some((s as u8, ns)) } else { None })
+        .parse_next(input)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn simple() {
+        let reference = Time {
+            hour: 20,
+            minute: 2,
+            second: 0,
+            nanosecond: 0,
+            offset: None,
+        };
+
+        for mut s in [
+            "20:02:00.000000",
+            "20:02:00",
+            "20:02+:00",
+            "20:02-:00",
+            "20----:02--(these hyphens are ignored)--:00",
+            "20++++:02++(these plusses are ignored)++:00",
+            "20: (A comment!)   02 (Another comment!)  :00",
+            "20:02  (A nested (comment!))  :00",
+            "20:02  (So (many (nested) comments!!!!))  :00",
+            "20   :    02  :   00.000000",
+            "20:02",
+            "20  :   02",
+            "8:02pm",
+            "8:   02     pm",
+            "8:02p.m.",
+            "8:   02     p.m.",
+        ] {
+            let old_s = s.to_owned();
+            assert_eq!(
+                parse(&mut s).ok(),
+                Some(reference.clone()),
+                "Format string: {old_s}"
+            );
+        }
+    }
+
+    #[test]
+    fn invalid() {
+        assert!(parse(&mut "00:00am").is_err());
+        assert!(parse(&mut "00:00:00am").is_err());
+    }
+
+    #[test]
+    fn hours_only() {
+        let reference = Time {
+            hour: 11,
+            minute: 0,
+            second: 0,
+            nanosecond: 0,
+            offset: None,
+        };
+
+        for mut s in [
+            "11am",
+            "11 am",
+            "11 - am",
+            "11 + am",
+            "11 a.m.",
+            "11   :  00",
+            "11:00:00",
+        ] {
+            let old_s = s.to_owned();
+            assert_eq!(
+                parse(&mut s).ok(),
+                Some(reference.clone()),
+                "Format string: {old_s}"
+            );
+        }
+    }
+
+    #[test]
+    fn nanoseconds() {
+        let reference = Time {
+            hour: 11,
+            minute: 0,
+            second: 0,
+            nanosecond: 123450000,
+            offset: None,
+        };
+
+        for mut s in ["11:00:00.12345", "11:00:00.12345am"] {
+            let old_s = s.to_owned();
+            assert_eq!(
+                parse(&mut s).ok(),
+                Some(reference.clone()),
+                "Format string: {old_s}"
+            );
+        }
+
+        let reference = Time {
+            hour: 11,
+            minute: 0,
+            second: 0,
+            nanosecond: 123456789,
+            offset: None,
+        };
+
+        for mut s in ["11:00:00.123456789", "11:00:00.1234567890123"] {
+            let old_s = s.to_owned();
+            assert_eq!(
+                parse(&mut s).ok(),
+                Some(reference.clone()),
+                "Format string: {old_s}"
+            );
+        }
+    }
+
+    #[test]
+    fn noon() {
+        let reference = Time {
+            hour: 12,
+            minute: 0,
+            second: 0,
+            nanosecond: 0,
+            offset: None,
+        };
+
+        for mut s in [
+            "12:00",
+            "12pm",
+            "12 pm",
+            "12 (A comment!) pm",
+            "12 pm",
+            "12 p.m.",
+        ] {
+            let old_s = s.to_owned();
+            assert_eq!(
+                parse(&mut s).ok(),
+                Some(reference.clone()),
+                "Format string: {old_s}"
+            );
+        }
+    }
+
+    #[test]
+    fn midnight() {
+        let reference = Time {
+            hour: 0,
+            minute: 0,
+            second: 0,
+            nanosecond: 0,
+            offset: None,
+        };
+
+        for mut s in ["00:00", "12am"] {
+            let old_s = s.to_owned();
+            assert_eq!(
+                parse(&mut s).ok(),
+                Some(reference.clone()),
+                "Format string: {old_s}"
+            );
+        }
+    }
+
+    #[test]
+    fn offset_hours() {
+        let reference = Time {
+            hour: 1,
+            minute: 23,
+            second: 0,
+            nanosecond: 0,
+            offset: Some((false, 5, 0).try_into().unwrap()),
+        };
+
+        for mut s in [
+            "1:23+5",
+            "1:23 + 5",
+            "1:23+05",
+            "1:23 + 5 : 00",
+            "1:23+05:00",
+            "1:23+05:0",
+        ] {
+            let old_s = s.to_owned();
+            assert_eq!(
+                parse(&mut s).ok(),
+                Some(reference.clone()),
+                "Format string: {old_s}"
+            );
+        }
+    }
+
+    #[test]
+    fn offset_hours_and_minutes() {
+        let reference = Time {
+            hour: 3,
+            minute: 45,
+            second: 0,
+            nanosecond: 0,
+            offset: Some((false, 5, 35).try_into().unwrap()),
+        };
+
+        for mut s in [
+            "3:45+535",
+            "3:45-+535",
+            "03:45+535",
+            "3   :  45  +  535",
+            "3:45+0535",
+            "3:45+5:35",
+            "3:45+05:35",
+            "3:45  + 05 : 35",
+        ] {
+            let old_s = s.to_owned();
+            assert_eq!(
+                parse(&mut s).ok(),
+                Some(reference.clone()),
+                "Format string: {old_s}"
+            );
+        }
+    }
+
+    #[test]
+    fn offset_minutes() {
+        let reference = Time {
+            hour: 3,
+            minute: 45,
+            second: 0,
+            nanosecond: 0,
+            offset: Some((false, 0, 35).try_into().unwrap()),
+        };
+
+        for mut s in [
+            "3:45+035",
+            "03:45+035",
+            "3   :  45  +  035",
+            "3:45+0035",
+            "3:45+0:35",
+            "3:45+00:35",
+            "3:45  + 00 : 35",
+        ] {
+            let old_s = s.to_owned();
+            assert_eq!(
+                parse(&mut s).ok(),
+                Some(reference.clone()),
+                "Format string: {old_s}"
+            );
+        }
+    }
+
+    #[test]
+    fn offset_negative() {
+        let reference = Time {
+            hour: 3,
+            minute: 45,
+            second: 0,
+            nanosecond: 0,
+            offset: Some((true, 5, 35).try_into().unwrap()),
+        };
+
+        for mut s in [
+            "3:45-535",
+            "03:45-535",
+            "3   :  45  -  535",
+            "3:45-0535",
+            "3:45-5:35",
+            "3:45-05:35",
+            "3:45  - 05 : 35",
+        ] {
+            let old_s = s.to_owned();
+            assert_eq!(
+                parse(&mut s).ok(),
+                Some(reference.clone()),
+                "Format string: {old_s}"
+            );
+        }
+    }
+}

src/items/timezone.rs

@@ -0,0 +1,340 @@
+// For the full copyright and license information, please view the LICENSE
+// file that was distributed with this source code.
+
+//! Parse a timezone item. The timezone item must be at the beginning of the
+//! input string and in the `TZ="..."` format.
+//!
+//! From the GNU docs:
+//!
+//! > Normally, dates are interpreted using the rules of the current time zone,
+//! > which in turn are specified by the ‘TZ’ environment variable, or by a
+//! > system default if ‘TZ’ is not set. To specify a different set of default
+//! > time zone rules that apply just to one date, start the date with a string
+//! > of the form ‘TZ="RULE"’. The two quote characters (‘"’) must be present in
+//! > the date, and any quotes or backslashes within RULE must be escaped by a
+//! > backslash.
+
+use jiff::tz::{Offset, TimeZone};
+use winnow::{
+    combinator::{alt, delimited, opt, preceded, repeat},
+    stream::AsChar,
+    token::{one_of, take_while},
+    ModalResult, Parser,
+};
+
+use super::primitive::{dec_uint, plus_or_minus};
+
+pub(super) fn parse(input: &mut &str) -> ModalResult<TimeZone> {
+    delimited("TZ=\"", preceded(opt(':'), alt((posix, iana))), '"').parse_next(input)
+}
+
+/// Parse a posix (proleptic) timezone string (e.g., "UTC7", "JST-9").
+///
+/// TODO: This implementation is incomplete. It currently only parses the
+/// `STDOFFSET` part of the format.
+///
+/// From the GNU docs:
+///
+/// > The proleptic format is:
+/// >
+/// >   STDOFFSET[DST[OFFSET][,START[/TIME],END[/TIME]]]
+/// >
+/// > The STD string specifies the time zone abbreviation, which must be at
+/// > least three bytes long. ...
+/// >
+/// > The OFFSET specifies the time value you must add to the local time to
+/// > get a UTC value.  It has syntax like:
+/// >
+/// >   [+|-]HH[:MM[:SS]]
+/// >
+/// > This is positive if the local time zone is west of the Prime Meridian
+/// > and negative if it is east; this is opposite from the usual convention
+/// > that positive time zone offsets are east of the Prime Meridian.  The
+/// > hour HH must be between 0 and 24 and may be a single digit, and the
+/// > minutes MM and seconds SS, if present, must be between 0 and 59.
+fn posix(input: &mut &str) -> ModalResult<TimeZone> {
+    (take_while(3.., AsChar::is_alpha), posix_offset)
+        .verify_map(|(_, offset)| Offset::from_seconds(offset).ok().map(|o| o.to_time_zone()))
+        .parse_next(input)
+}
+
+/// Parse an IANA (geographical) timezone string (e.g., "Europe/Paris"). If the
+/// string is not a valid IANA timezone name, the UTC timezone is returned.
+///
+/// Compatibility notes:
+///
+/// - The implementation uses `jiff::tz::TimeZone::get()` to resolve time zones.
+///   Only canonical/aliased IANA names are accepted. Absolute file paths are
+///   not supported.
+/// - GNU `date` resolves time zones from the tzdata files under
+///   `/usr/share/zoneinfo` (respecting `TZDIR`) and also accepts an absolute
+///   path when the string starts with `/`.
+///
+/// From the GNU docs:
+///
+/// > If the format's CHARACTERS begin with ‘/’ it is an absolute file
+/// > name; otherwise the library looks for the file
+/// > ‘/usr/share/zoneinfo/CHARACTERS’.  The ‘zoneinfo’ directory contains
+/// > data files describing time zone rulesets in many different parts of the
+/// > world.  The names represent major cities, with subdirectories for
+/// > geographical areas; for example, ‘America/New_York’, ‘Europe/London’,
+/// > ‘Asia/Tokyo’.  These data files are installed by the system
+/// > administrator, who also sets ‘/etc/localtime’ to point to the data file
+/// > for the local time zone ruleset.
+fn iana(input: &mut &str) -> ModalResult<TimeZone> {
+    repeat(
+        0..,
+        alt((
+            preceded('\\', one_of(['\\', '"'])).map(|c: char| c.to_string()),
+            take_while(1, |c| c != '"' && c != '\\').map(str::to_string),
+        )),
+    )
+    .map(|parts: Vec<String>| parts.concat())
+    .map(|s| TimeZone::get(&s).unwrap_or(TimeZone::UTC))
+    .parse_next(input)
+}
+
+fn posix_offset(input: &mut &str) -> ModalResult<i32> {
+    let uint = dec_uint::<u32, _>;
+
+    (
+        opt(plus_or_minus),
+        alt((
+            (uint, preceded(':', uint), preceded(':', uint)).map(|(h, m, s)| (h, m, s)),
+            (uint, preceded(':', uint)).map(|(h, m)| (h, m, 0)),
+            uint.map(|h| (h, 0, 0)),
+        )),
+    )
+        .map(|(sign, (h, m, s))| {
+            // The sign is opposite from the usual convention:
+            // - Positive offsets are west of UTC.
+            // - Negative offsets are east of UTC.
+            let sign = if sign == Some('-') { 1 } else { -1 };
+
+            // - If hour is greater than 24, clamp it to 24.
+            // - If minute is greater than 59, clamp it to 59.
+            // - If second is greater than 59, clamp it to 59.
+            let h = h.min(24) as i32;
+            let m = m.min(59) as i32;
+            let s = s.min(59) as i32;
+
+            sign * (h * 3600 + m * 60 + s)
+        })
+        .parse_next(input)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn tz_rule() {
+        // empty string
+        for (input, expected) in [
+            (r#"TZ="""#, "UTC"),
+            (r#"TZ=":""#, "UTC"),
+            (r#"TZ="  ""#, "UTC"),
+            (r#"TZ=":  ""#, "UTC"),
+        ] {
+            let mut s = input;
+            assert_eq!(
+                parse(&mut s).unwrap().iana_name(),
+                Some(expected),
+                "{input}"
+            );
+        }
+
+        // iana
+        for (input, expected) in [
+            (r#"TZ="Etc/Zulu""#, "Etc/Zulu"),
+            (r#"TZ=":Etc/Zulu""#, "Etc/Zulu"),
+            (r#"TZ="America/New_York""#, "America/New_York"),
+            (r#"TZ=":America/New_York""#, "America/New_York"),
+            (r#"TZ="Asia/Tokyo""#, "Asia/Tokyo"),
+            (r#"TZ=":Asia/Tokyo""#, "Asia/Tokyo"),
+            (r#"TZ="Unknown/Timezone""#, "UTC"),
+            (r#"TZ=":Unknown/Timezone""#, "UTC"),
+        ] {
+            let mut s = input;
+            assert_eq!(
+                parse(&mut s).unwrap().iana_name(),
+                Some(expected),
+                "{input}"
+            );
+        }
+
+        // posix
+        for (input, expected) in [
+            (r#"TZ="UTC0""#, 0),
+            (r#"TZ=":UTC0""#, 0),
+            (r#"TZ="UTC+5""#, -5 * 3600),
+            (r#"TZ=":UTC+5""#, -5 * 3600),
+            (r#"TZ="UTC-5""#, 5 * 3600),
+            (r#"TZ=":UTC-5""#, 5 * 3600),
+            (r#"TZ="UTC+5:20""#, -(5 * 3600 + 20 * 60)),
+            (r#"TZ=":UTC+5:20""#, -(5 * 3600 + 20 * 60)),
+            (r#"TZ="UTC-5:20""#, 5 * 3600 + 20 * 60),
+            (r#"TZ=":UTC-5:20""#, 5 * 3600 + 20 * 60),
+            (r#"TZ="UTC+5:20:15""#, -(5 * 3600 + 20 * 60 + 15)),
+            (r#"TZ=":UTC+5:20:15""#, -(5 * 3600 + 20 * 60 + 15)),
+            (r#"TZ="UTC-5:20:15""#, 5 * 3600 + 20 * 60 + 15),
+            (r#"TZ=":UTC-5:20:15""#, 5 * 3600 + 20 * 60 + 15),
+        ] {
+            let mut s = input;
+            assert_eq!(
+                parse(&mut s).unwrap().to_fixed_offset().unwrap().seconds(),
+                expected,
+                "{input}"
+            );
+        }
+
+        // invalid
+        for input in [
+            r#"UTC"#,      // missing "TZ="
+            r#"tz="UTC""#, // lowercase "tz"
+            r#"TZ=UTC"#,   // missing quotes
+        ] {
+            let mut s = input;
+            assert!(parse(&mut s).is_err(), "{input}");
+        }
+    }
+
+    #[test]
+    fn parse_iana() {
+        for (input, expected) in [
+            ("UTC", "UTC"),                           // utc timezone
+            ("Etc/Zulu", "Etc/Zulu"),                 // etc timezone
+            ("America/New_York", "America/New_York"), // named timezone
+            ("Asia/Tokyo", "Asia/Tokyo"),             // named timezone
+            ("Unknown/Timezone", "UTC"),              // unknown timezone
+        ] {
+            let mut s = input;
+            assert_eq!(iana(&mut s).unwrap().iana_name(), Some(expected), "{input}");
+        }
+    }
+
+    #[test]
+    fn parse_posix() {
+        let to_seconds = |input: &str| {
+            let mut s = input;
+            posix(&mut s).unwrap().to_fixed_offset().unwrap().seconds()
+        };
+
+        // hour
+        for (input, expected) in [
+            ("UTC0", 0),
+            ("UTC+0", 0),
+            ("UTC-0", 0),
+            ("UTC000", 0),
+            ("UTC+5", -5 * 3600),
+            ("UTC-5", 5 * 3600),
+            ("ABC0", 0),
+            ("ABC+5", -5 * 3600),
+            ("ABC-5", 5 * 3600),
+        ] {
+            assert_eq!(to_seconds(input), expected, "{input}");
+        }
+
+        // hour:minute
+        for (input, expected) in [
+            ("UTC0:0", 0),
+            ("UTC+0:0", 0),
+            ("UTC-0:0", 0),
+            ("UTC00:00", 0),
+            ("UTC+5:20", -(5 * 3600 + 20 * 60)),
+            ("UTC-5:20", 5 * 3600 + 20 * 60),
+            ("ABC0:0", 0),
+            ("ABC+5:20", -(5 * 3600 + 20 * 60)),
+            ("ABC-5:20", 5 * 3600 + 20 * 60),
+        ] {
+            assert_eq!(to_seconds(input), expected, "{input}");
+        }
+
+        // hour:minute:second
+        for (input, expected) in [
+            ("UTC0:0:0", 0),
+            ("UTC+0:0:0", 0),
+            ("UTC-0:0:0", 0),
+            ("UTC00:00:00", 0),
+            ("UTC+5:20:15", -(5 * 3600 + 20 * 60 + 15)),
+            ("UTC-5:20:15", 5 * 3600 + 20 * 60 + 15),
+            ("ABC0:0:0", 0),
+            ("ABC+5:20:15", -(5 * 3600 + 20 * 60 + 15)),
+            ("ABC-5:20:15", 5 * 3600 + 20 * 60 + 15),
+        ] {
+            assert_eq!(to_seconds(input), expected, "{input}");
+        }
+
+        // invalid
+        for input in [
+            "AB",  // too short
+            "A1C", // not just letters
+        ] {
+            let mut s = input;
+            assert!(posix(&mut s).is_err(), "{input}");
+        }
+    }
+
+    #[test]
+    fn parse_posix_offset() {
+        // hour
+        for (input, expected) in [
+            ("0", 0),           // zero hour
+            ("00", 0),          // zero hour, two digits
+            ("000", 0),         // zero hour, three digits
+            ("+0", 0),          // zero hour, explicit plus
+            ("-0", 0),          // zero hour, explicit minus
+            ("5", -5 * 3600),   // positive hour
+            ("-5", 5 * 3600),   // negative hour
+            ("005", -5 * 3600), // positive hour with leading zeros
+            ("-05", 5 * 3600),  // negative hour with leading zeros
+            ("25", -24 * 3600), // hour > 24, clamps to 24
+            ("-25", 24 * 3600), // hour > 24, clamps to 24
+        ] {
+            let mut s = input;
+            assert_eq!(posix_offset(&mut s).unwrap(), expected, "{input}");
+        }
+
+        // hour:minute
+        for (input, expected) in [
+            ("0:0", 0),                         // zero hour and minute
+            ("00:00", 0),                       // zero hour and minute, two digits
+            ("000:000", 0),                     // zero hour and minute, three digits
+            ("+0:0", 0),                        // zero hour and minute, explicit plus
+            ("-0:0", 0),                        // zero hour and minute, explicit minus
+            ("5:20", -(5 * 3600 + 20 * 60)),    // positive hour and minute
+            ("-5:20", 5 * 3600 + 20 * 60),      // negative hour and minute
+            ("005:020", -(5 * 3600 + 20 * 60)), // positive hour and minute with leading zeros
+            ("-05:20", 5 * 3600 + 20 * 60),     // negative hour and minute with leading zeros
+            ("25:20", -(24 * 3600 + 20 * 60)),  // hour > 24, clamps to 24
+            ("-25:20", 24 * 3600 + 20 * 60),    // hour > 24, clamps to 24
+            ("5:60", -(5 * 3600 + 59 * 60)),    // minute > 59, clamps to 59
+            ("-5:60", 5 * 3600 + 59 * 60),      // minute > 59, clamps to 59
+        ] {
+            let mut s = input;
+            assert_eq!(posix_offset(&mut s).unwrap(), expected, "{input}");
+        }
+
+        // hour:minute:second
+        for (input, expected) in [
+            ("0:0:0", 0),                                // zero hour, minute, and second
+            ("00:00:00", 0),    // zero hour, minute, and second, two digits
+            ("000:000:000", 0), // zero hour, minute, and second, three digits
+            ("+0:0:0", 0),      // zero hour, minute, and second, explicit plus
+            ("-0:0:0", 0),      // zero hour, minute, and second, explicit minus
+            ("5:20:15", -(5 * 3600 + 20 * 60 + 15)), // positive hour, minute, and second
+            ("-5:20:15", 5 * 3600 + 20 * 60 + 15), // negative hour, minute, and second
+            ("005:020:015", -(5 * 3600 + 20 * 60 + 15)), // positive hour, minute, and second with leading zeros
+            ("-05:20:15", 5 * 3600 + 20 * 60 + 15), // negative hour, minute, and second with leading zeros
+            ("25:20:15", -(24 * 3600 + 20 * 60 + 15)), // hour > 24, clamps to 24
+            ("-25:20:15", 24 * 3600 + 20 * 60 + 15), // hour > 24, clamps to 24
+            ("5:60:15", -(5 * 3600 + 59 * 60 + 15)), // minute > 59, clamps to 59
+            ("-5:60:15", 5 * 3600 + 59 * 60 + 15),  // minute > 59, clamps to 59
+            ("5:20:60", -(5 * 3600 + 20 * 60 + 59)), // second > 59, clamps to 59
+            ("-5:20:60", 5 * 3600 + 20 * 60 + 59),  // second > 59, clamps to 59
+        ] {
+            let mut s = input;
+            assert_eq!(posix_offset(&mut s).unwrap(), expected, "{input}");
+        }
+    }
+}

src/items/weekday.rs

@@ -0,0 +1,156 @@
+// For the full copyright and license information, please view the LICENSE
+// file that was distributed with this source code.
+
+// spell-checker:ignore wednes
+
+//! The GNU docs state:
+//!
+//! > The explicit mention of a day of the week will forward the date (only if
+//! > necessary) to reach that day of the week in the future.
+//! >
+//! > Days of the week may be spelled out in full: ‘Sunday’, ‘Monday’,
+//! > ‘Tuesday’, ‘Wednesday’, ‘Thursday’, ‘Friday’ or ‘Saturday’. Days may be
+//! > abbreviated to their first three letters, optionally followed by a
+//! > period. The special abbreviations ‘Tues’ for ‘Tuesday’, ‘Wednes’ for
+//! > ‘Wednesday’ and ‘Thur’ or ‘Thurs’ for ‘Thursday’ are also allowed.
+//! >
+//! > A number may precede a day of the week item to move forward supplementary
+//! > weeks. It is best used in expression like ‘third monday’. In this
+//! > context, ‘last day’ or ‘next day’ is also acceptable; they move one week
+//! > before or after the day that day by itself would represent.
+//! >
+//! > A comma following a day of the week item is ignored.
+
+use winnow::{
+    ascii::alpha1,
+    combinator::{opt, terminated},
+    seq, ModalResult, Parser,
+};
+
+use super::{ordinal::ordinal, primitive::s};
+
+#[derive(PartialEq, Eq, Debug, Copy, Clone)]
+pub(crate) enum Day {
+    Monday,
+    Tuesday,
+    Wednesday,
+    Thursday,
+    Friday,
+    Saturday,
+    Sunday,
+}
+
+#[derive(PartialEq, Eq, Debug)]
+pub(crate) struct Weekday {
+    pub(crate) offset: i32,
+    pub(crate) day: Day,
+}
+
+impl From<Day> for jiff::civil::Weekday {
+    fn from(value: Day) -> Self {
+        match value {
+            Day::Monday => jiff::civil::Weekday::Monday,
+            Day::Tuesday => jiff::civil::Weekday::Tuesday,
+            Day::Wednesday => jiff::civil::Weekday::Wednesday,
+            Day::Thursday => jiff::civil::Weekday::Thursday,
+            Day::Friday => jiff::civil::Weekday::Friday,
+            Day::Saturday => jiff::civil::Weekday::Saturday,
+            Day::Sunday => jiff::civil::Weekday::Sunday,
+        }
+    }
+}
+
+/// Parse a weekday item.
+pub(super) fn parse(input: &mut &str) -> ModalResult<Weekday> {
+    seq!(Weekday {
+        offset: opt(ordinal).map(|o| o.unwrap_or_default()),
+        day: terminated(day, opt(s(","))),
+    })
+    .parse_next(input)
+}
+
+fn day(input: &mut &str) -> ModalResult<Day> {
+    s(alpha1)
+        .verify_map(|s: &str| {
+            Some(match s {
+                "monday" | "mon" | "mon." => Day::Monday,
+                "tuesday" | "tue" | "tue." | "tues" => Day::Tuesday,
+                "wednesday" | "wed" | "wed." | "wednes" => Day::Wednesday,
+                "thursday" | "thu" | "thu." | "thur" | "thurs" => Day::Thursday,
+                "friday" | "fri" | "fri." => Day::Friday,
+                "saturday" | "sat" | "sat." => Day::Saturday,
+                "sunday" | "sun" | "sun." => Day::Sunday,
+                _ => return None,
+            })
+        })
+        .parse_next(input)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::{parse, Day, Weekday};
+
+    #[test]
+    fn this_monday() {
+        for mut s in [
+            "monday",
+            "mon",
+            "mon.",
+            "this monday",
+            "this mon",
+            "this mon.",
+            "this    monday",
+            "this - monday",
+            "0 monday",
+        ] {
+            assert_eq!(
+                parse(&mut s).unwrap(),
+                Weekday {
+                    offset: 0,
+                    day: Day::Monday,
+                }
+            );
+        }
+    }
+
+    #[test]
+    fn next_tuesday() {
+        for s in ["tuesday", "tue", "tue.", "tues"] {
+            let s = format!("next {s}");
+            assert_eq!(
+                parse(&mut s.as_ref()).unwrap(),
+                Weekday {
+                    offset: 1,
+                    day: Day::Tuesday,
+                }
+            );
+        }
+    }
+
+    #[test]
+    fn last_wednesday() {
+        for s in ["wednesday", "wed", "wed.", "wednes"] {
+            let s = format!("last {s}");
+            assert_eq!(
+                parse(&mut s.as_ref()).unwrap(),
+                Weekday {
+                    offset: -1,
+                    day: Day::Wednesday,
+                }
+            );
+        }
+    }
+
+    #[test]
+    fn optional_comma() {
+        for mut s in ["monday,", "mon,", "mon.,", "mon. ,"] {
+            assert_eq!(
+                parse(&mut s).unwrap(),
+                Weekday {
+                    offset: 0,
+                    day: Day::Monday,
+                }
+            );
+        }
+    }
+}