timelang 0.1.3

//! # 🕗 Timelang
//!
//! [![Crates.io](https://img.shields.io/crates/v/timelang)](https://crates.io/crates/timelang)
//! [![docs.rs](https://img.shields.io/docsrs/timelang?label=docs)](https://docs.rs/timelang/latest/timelang/)
//! [![Build Status](https://img.shields.io/github/actions/workflow/status/sam0x17/timelang/ci.yaml)](https://github.com/sam0x17/timelang/actions/workflows/ci.yaml?query=branch%3Amain)
//! [![MIT License](https://img.shields.io/github/license/sam0x17/timelang)](https://github.com/sam0x17/timelang/blob/main/LICENSE)
//!
//! Timelang is a simple DSL (Domain Specific Language) for representing human-readable
//! time-related expressions including specific date/times, relative expressions like "3 hours
//! from now", time ranges, and durations.
//!
//!
//! ## Getting Started
//!
//! To use timelang, you should take a look at [TimeExpression], which is the top-level entry
//! point of the AST, or some of the more specific types like [Duration], [PointInTime],
//! and [TimeRange].
//!
//! All nodes in timelang impl [FromStr] as well as [syn::parse::Parse] which is used for the
//! internal parsing logic. The standard [Display] impl is used on all node types as the
//! preferred means of outputting them to a string.
//!
//! Note that for the moment, only years, months, weeks, days, hours, and minutes are supported
//! in timelang, but seconds and more might be added later. Generally better than minute
//! resolution is not needed in many of the common use-cases for timelang.
//!
//!
//! ## Examples
//!
//! The following are all examples of valid expressions in timelang:
//! - `now` ([RelativeTime])
//! - `tomorrow` ([RelativeTime])
//! - `next tuesday` ([RelativeTime])
//! - `day after tomorrow` ([RelativeTime])
//! - `the day before yesterday` ([RelativeTime])
//! - `20/4/2021` ([Date])
//! - `11:21 AM` ([Time])
//! - `15/6/2022 at 3:58 PM` ([DateTime] / [PointInTime::Absolute])
//! - `2 hours, 37 minutes` ([Duration])
//! - `5 years, 2 months, 3 weeks and 11 minutes` ([Duration])
//! - `7 days ago` ([RelativeTime])
//! - `2 years and 10 minutes from now` ([RelativeTime])
//! - `5 days, 3 weeks, 6 minutes after 15/4/2025 at 9:27 AM` ([RelativeTime])
//! - `from 1/1/2023 at 14:07 to 15/1/2023` ([TimeRange])
//! - `from 19/3/2024 at 10:07 AM to 3 months 2 days after 3/9/2027 at 5:27 PM` ([TimeRange])
//! - `2 days and 14 hours after the day after tomorrow` ([RelativeTime])
//!
//!
//! ## Context Free Grammar
//! Here is a rough CFG (Context Free Grammar) for timelang:
//!
//! ```cfg
//! S → TimeExpression
//! TimeExpression → PointInTime | TimeRange | Duration
//! PointInTime → AbsoluteTime | RelativeTime
//! TimeRange → 'from' PointInTime 'to' PointInTime
//! Duration → Number TimeUnit ((','? 'and')? Number TimeUnit)*
//! AbsoluteTime → Date | DateTime
//! RelativeTime → Duration TimeDirection | NamedRelativeTime | 'next' RelativeTimeUnit | 'last' RelativeTimeUnit
//! NamedRelativeTime → 'now' | 'today' | 'tomorrow' | 'yesterday' | 'day after tomorrow' | 'the day after tomorrow' | 'day before yesterday' | 'the day before yesterday'
//! Date → DayOfMonth '/' Month '/' Year
//! DateTime → Date ('at')? Time
//! Time → Hour ':' Minute AmPm?
//! Hour → Number
//! Minute → Number
//! Month → Number
//! DayOfMonth → Number
//! Year → Number
//! AmPm → 'AM' | 'PM'
//! TimeUnit → 'minutes' | 'hours' | 'days' | 'weeks' | 'months' | 'years'
//! TimeDirection → 'after' AbsoluteTime | 'before' AbsoluteTime | 'after' NamedRelativeTime | 'before' NamedRelativeTime | 'before' 'next' RelativeTimeUnit | 'before' 'last' RelativeTimeUnit | 'after' 'next' RelativeTimeUnit | 'after' 'last' RelativeTimeUnit | 'ago' | 'from now'
//! RelativeTimeUnit → 'week' | 'month' | 'year' | 'monday' | 'tuesday' | 'wednesday' | 'thursday' | 'friday' | 'saturday' | 'sunday'
//! Number → [Any positive integer value]
//! ```
//!
//! It is worth noting that this CFG is slightly more permissive than the actual timelang
//! grammar, particularly when it comes to validating the permitted number ranges for various
//! times.
//!
//! ## Notes
//!
//! * At the moment [syn](https://crates.io/crates/syn) is used for parsing. This will likely be
//!   swapped out for a TBD parsing crate, but it was easy to quickly get this off the ground using
//!   syn. Whatever new crate we use will hopefully allow us to make timelang compatible with no
//!   std.
//! * Timelang is unambiguous, meaning there is exactly one tree representation for all possible
//!   timelang sentences. If you can come up with an ambiguous sentence, please let us know by
//!   submitting a GitHub issue!

#![deny(missing_docs)]

use std::{
    fmt::Display,
    ops::{Add, Div, Mul, Sub},
    str::FromStr,
};
use syn::{
    parse::{Parse, ParseStream, Result},
    Error, Ident, LitInt, Token,
};

#[cfg(test)]
mod tests;

/// The top-level entry-point for the timelang AST.
///
/// Typically you will want to use a more specific type like [Duration], [PointInTime], or
/// [TimeRange], but this top-level node-type is provided so that we can consider timelang to
/// be a distinct language.
///
/// Note that [TimeExpression] is [Sized], and thus all expressions in timelang have a
/// predictable memory size and do not require any heap allocations. That said, _parsing_
/// expressions in timelang does require some temporary allocations that go away when parsing
/// is complete.
///
/// ## Examples
///
/// Specific Date:
/// ```
/// use timelang::*;
/// assert_eq!(
///     "20/4/2021".parse::<TimeExpression>().unwrap(),
///     TimeExpression::Specific(PointInTime::Absolute(AbsoluteTime::Date(Date(
///         Month::April,
///         DayOfMonth(20),
///         Year(2021)
///     ))))
/// );
/// ```
///
/// Specific DateTime:
/// ```
/// use timelang::*;
/// assert_eq!(
///     "15/6/2022 at 14:00".parse::<AbsoluteTime>().unwrap(),
///     AbsoluteTime::DateTime(DateTime(
///         Date(Month::June, DayOfMonth(15), Year(2022)),
///         Time(Hour::Hour24(14), Minute(0))
///     ))
/// );
/// ```
///
/// Time Range:
/// ```
/// use timelang::*;
/// assert_eq!(
///     "from 1/1/2023 to 15/1/2023"
///         .parse::<TimeExpression>()
///         .unwrap(),
///     TimeExpression::Range(TimeRange(
///         PointInTime::Absolute(AbsoluteTime::Date(Date(
///             Month::January,
///             DayOfMonth(1),
///             Year(2023)
///         ))),
///         PointInTime::Absolute(AbsoluteTime::Date(Date(
///             Month::January,
///             DayOfMonth(15),
///             Year(2023)
///         )))
///     ))
/// );
/// ```
///
/// Duration (multiple units with comma):
/// ```
/// use timelang::*;
/// assert_eq!(
///     "2 hours, 30 minutes".parse::<TimeExpression>().unwrap(),
///     TimeExpression::Duration(Duration {
///         hours: Number(2),
///         minutes: Number(30),
///         days: Number(0),
///         weeks: Number(0),
///         months: Number(0),
///         years: Number(0)
///     })
/// );
/// ```
///
/// Duration (multiple units with `and`):
/// ```
/// use timelang::*;
/// assert_eq!(
///     "1 year and 6 months".parse::<TimeExpression>().unwrap(),
///     TimeExpression::Duration(Duration {
///         years: Number(1),
///         months: Number(6),
///         days: Number(0),
///         weeks: Number(0),
///         hours: Number(0),
///         minutes: Number(0)
///     })
/// );
/// ```
///
/// Relative Time (using `ago`):
/// ```
/// use timelang::*;
/// assert_eq!(
///     "3 days ago".parse::<TimeExpression>().unwrap(),
///     TimeExpression::Specific(PointInTime::Relative(RelativeTime::Directional {
///         duration: Duration {
///             days: Number(3),
///             minutes: Number(0),
///             hours: Number(0),
///             weeks: Number(0),
///             months: Number(0),
///             years: Number(0)
///         },
///         dir: TimeDirection::Ago
///     }))
/// );
/// ```
///
/// Relative Time (using `from now`):
/// ```
/// use timelang::*;
/// assert_eq!(
///     "5 days, 10 hours, and 35 minutes from now"
///         .parse::<TimeExpression>()
///         .unwrap(),
///     TimeExpression::Specific(PointInTime::Relative(RelativeTime::Directional {
///         duration: Duration {
///             minutes: Number(35),
///             hours: Number(10),
///             days: Number(5),
///             weeks: Number(0),
///             months: Number(0),
///             years: Number(0)
///         },
///         dir: TimeDirection::FromNow
///     }))
/// );
/// ```
///
/// Relative Time (`after` a specific date):
/// ```
/// use timelang::*;
/// assert_eq!(
///     "2 hours, 3 minutes after 10/10/2022"
///         .parse::<TimeExpression>()
///         .unwrap(),
///     TimeExpression::Specific(PointInTime::Relative(RelativeTime::Directional {
///         duration: Duration {
///             hours: Number(2),
///             minutes: Number(3),
///             days: Number(0),
///             weeks: Number(0),
///             months: Number(0),
///             years: Number(0)
///         },
///         dir: TimeDirection::AfterAbsolute(AbsoluteTime::Date(Date(
///             Month::October,
///             DayOfMonth(10),
///             Year(2022)
///         )))
///     }))
/// );
/// ```
///
/// Relative Time (`before` a specific date/time):
/// ```
/// use timelang::*;
/// assert_eq!(
///     "1 day before 31/12/2023 at 11:13 PM"
///         .parse::<TimeExpression>()
///         .unwrap(),
///     TimeExpression::Specific(PointInTime::Relative(RelativeTime::Directional {
///         duration: Duration {
///             days: Number(1),
///             minutes: Number(0),
///             hours: Number(0),
///             weeks: Number(0),
///             months: Number(0),
///             years: Number(0)
///         },
///         dir: TimeDirection::BeforeAbsolute(AbsoluteTime::DateTime(DateTime(
///             Date(Month::December, DayOfMonth(31), Year(2023)),
///             Time(Hour::Hour12(11, AmPm::PM), Minute(13))
///         )))
///     }))
/// );
/// ```
///
/// Time Range (with specific date/times):
/// ```
/// use timelang::*;
/// assert_eq!(
///     "from 1/1/2024 at 10:00 to 2/1/2024 at 15:30"
///         .parse::<TimeExpression>()
///         .unwrap(),
///     TimeExpression::Range(TimeRange(
///         PointInTime::Absolute(AbsoluteTime::DateTime(DateTime(
///             Date(Month::January, DayOfMonth(1), Year(2024)),
///             Time(Hour::Hour24(10), Minute(0))
///         ))),
///         PointInTime::Absolute(AbsoluteTime::DateTime(DateTime(
///             Date(Month::January, DayOfMonth(2), Year(2024)),
///             Time(Hour::Hour24(15), Minute(30))
///         )))
///     ))
/// );
/// ```
///
/// Relative Time (Named):
/// ```
/// use timelang::*;
/// assert_eq!("now".parse::<RelativeTime>().unwrap(), RelativeTime::Named(NamedRelativeTime::Now));
/// assert_eq!(
///     "tomorrow".parse::<RelativeTime>().unwrap(),
///     RelativeTime::Named(NamedRelativeTime::Tomorrow)
/// );
/// assert_eq!(
///     "yesterday".parse::<RelativeTime>().unwrap(),
///     RelativeTime::Named(NamedRelativeTime::Yesterday)
/// );
/// assert_eq!(
///     "day before yesterday".parse::<RelativeTime>().unwrap(),
///     RelativeTime::Named(NamedRelativeTime::DayBeforeYesterday)
/// );
/// // note the optional `the`
/// assert_eq!(
///     "the day after tomorrow".parse::<RelativeTime>().unwrap(),
///     RelativeTime::Named(NamedRelativeTime::DayAfterTomorrow)
/// );
/// assert_eq!(
///     "next tuesday".parse::<RelativeTime>().unwrap(),
///     RelativeTime::Next(RelativeTimeUnit::Tuesday)
/// );
/// assert_eq!(
///     "last wednesday".parse::<RelativeTime>().unwrap(),
///     RelativeTime::Last(RelativeTimeUnit::Wednesday)
/// );
/// assert_eq!(
///     "3 days before yesterday".parse::<RelativeTime>().unwrap(),
///     RelativeTime::Directional {
///         duration: Duration {
///             minutes: Number(0),
///             hours: Number(0),
///             days: Number(3),
///             weeks: Number(0),
///             months: Number(0),
///             years: Number(0)
///         },
///         dir: TimeDirection::BeforeNamed(NamedRelativeTime::Yesterday)
///     }
/// );
/// assert_eq!(
///     "2 days and 14 hours after the day after tomorrow".parse::<RelativeTime>().unwrap(),
///     RelativeTime::Directional {
///         duration: Duration {
///             minutes: Number(0),
///             hours: Number(14),
///             days: Number(2),
///             weeks: Number(0),
///             months: Number(0),
///             years: Number(0)
///         },
///         dir: TimeDirection::AfterNamed(NamedRelativeTime::DayAfterTomorrow)
///     }
/// );
/// assert_eq!(
///     "2 weeks before last sunday".parse::<RelativeTime>().unwrap(),
///     RelativeTime::Directional {
///         duration: Duration {
///             minutes: Number(0),
///             hours: Number(0),
///             days: Number(0),
///             weeks: Number(2),
///             months: Number(0),
///             years: Number(0)
///         },
///         dir: TimeDirection::BeforeLast(RelativeTimeUnit::Sunday)
///     }
/// );
/// assert_eq!(
///     "3 years, 2 weeks after next thursday".parse::<RelativeTime>().unwrap(),
///     RelativeTime::Directional {
///         duration: Duration {
///             minutes: Number(0),
///             hours: Number(0),
///             days: Number(0),
///             weeks: Number(2),
///             months: Number(0),
///             years: Number(3)
///         },
///         dir: TimeDirection::AfterNext(RelativeTimeUnit::Thursday)
///     }
/// );
/// ```
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)]
pub enum TimeExpression {
    /// Represents a [PointInTime] expression.
    Specific(PointInTime), // (LitInt, Ident) or (LitInt, Token![/])
    /// Represents a [TimeRange] expression.
    Range(TimeRange), // Ident, LitInt
    /// Represents a [Duration] expression.
    Duration(Duration), // LitInt, Ident
}

impl Parse for TimeExpression {
    fn parse(input: ParseStream) -> Result<Self> {
        if !input.peek(Ident) && !input.peek(LitInt) {
            return Err(Error::new(input.span(), "expected [number] or [keyword]"));
        }
        if input.peek(Ident) {
            let ident = input.fork().parse::<Ident>()?;
            if ident.to_string().to_lowercase().as_str() == "from" {
                return Ok(TimeExpression::Range(input.parse()?));
            }
            return Ok(TimeExpression::Specific(input.parse()?));
        }
        if input.peek(LitInt) && input.peek2(Token![/]) {
            // case 2 for PointInTime
            return Ok(TimeExpression::Specific(input.parse()?));
        }
        // now we either have a Duration or PointInTime starting with a Duration
        let fork = input.fork();
        if fork.parse::<PointInTime>().is_ok() {
            return Ok(TimeExpression::Specific(input.parse()?));
        }
        Ok(TimeExpression::Duration(input.parse()?))
    }
}

impl Display for TimeExpression {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            TimeExpression::Specific(point) => write!(f, "{point}"),
            TimeExpression::Range(tr) => write!(f, "{tr}"),
            TimeExpression::Duration(dur) => write!(f, "{dur}"),
        }
    }
}

/// Represents a range of two valid [PointInTime]s that together define the start and end of
/// some defined period of time.
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)]
pub struct TimeRange(pub PointInTime, pub PointInTime);

impl Parse for TimeRange {
    fn parse(input: ParseStream) -> Result<Self> {
        let ident = input.parse::<Ident>()?;
        if ident.to_string().to_lowercase() != "from" {
            return Err(Error::new(ident.span(), "expected `from`"));
        }
        let t1 = input.parse::<PointInTime>()?;
        let ident = input.parse::<Ident>()?;
        if ident.to_string().to_lowercase() != "to" {
            return Err(Error::new(ident.span(), "expected `to`"));
        }
        let t2 = input.parse::<PointInTime>()?;
        Ok(TimeRange(t1, t2))
    }
}

impl Display for TimeRange {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(f, "from {} to {}", self.0, self.1)
    }
}

/// Represents a specific duration of time that is not anchored at any particular point in time.
///
/// Note that individual components, if not specified, will be recorded as `0`. Such components
/// will not appear when the [Duration] is rendered, printed, or displayed.
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)]
pub struct Duration {
    /// The number of minutes.
    pub minutes: Number,
    /// The number of hours.
    pub hours: Number,
    /// The number of days.
    pub days: Number,
    /// The number of weeks.
    pub weeks: Number,
    /// The number of months.
    pub months: Number,
    /// The number of years.
    pub years: Number,
}

impl Parse for Duration {
    fn parse(input: ParseStream) -> Result<Self> {
        let mut minutes: Option<Number> = None;
        let mut hours: Option<Number> = None;
        let mut days: Option<Number> = None;
        let mut weeks: Option<Number> = None;
        let mut months: Option<Number> = None;
        let mut years: Option<Number> = None;
        while input.peek(LitInt) {
            let num = input.parse::<Number>()?;
            let unit = input.parse::<TimeUnit>()?;
            match unit {
                TimeUnit::Minutes => minutes = Some(minutes.unwrap_or(Number(0)) + num),
                TimeUnit::Hours => hours = Some(hours.unwrap_or(Number(0)) + num),
                TimeUnit::Days => days = Some(days.unwrap_or(Number(0)) + num),
                TimeUnit::Weeks => weeks = Some(weeks.unwrap_or(Number(0)) + num),
                TimeUnit::Months => months = Some(months.unwrap_or(Number(0)) + num),
                TimeUnit::Years => years = Some(years.unwrap_or(Number(0)) + num),
            }
            if input.peek(Token![,]) {
                input.parse::<Token![,]>()?;
            }
            if input.peek(Ident) {
                let ident = input.fork().parse::<Ident>()?; // don't consume if it isn't `and`
                if ident.to_string().to_lowercase() == "and" {
                    input.parse::<Ident>()?; // consume the `and`
                }
            }
        }
        if minutes.is_none()
            && hours.is_none()
            && days.is_none()
            && weeks.is_none()
            && months.is_none()
            && years.is_none()
        {
            return Err(Error::new(
                input.span(),
                "expected [number] followed by one of `minutes`, `hours`, `days`, `years`",
            ));
        }
        Ok(Duration {
            minutes: minutes.unwrap_or(Number(0)),
            hours: hours.unwrap_or(Number(0)),
            days: days.unwrap_or(Number(0)),
            weeks: weeks.unwrap_or(Number(0)),
            months: months.unwrap_or(Number(0)),
            years: years.unwrap_or(Number(0)),
        })
    }
}

impl Display for Duration {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        let mut before = false;
        if self.years > 0 {
            before = true;
        }
        if self.years == 1 {
            write!(f, "1 year")?;
        } else if self.years > 1 {
            write!(f, "{} years", self.years)?;
        }
        if self.months > 0 {
            if before {
                write!(f, ", ")?;
            }
            before = true;
        }
        if self.months == 1 {
            write!(f, "1 month")?;
        } else if self.months > 1 {
            write!(f, "{} months", self.months)?;
        }
        if self.weeks > 0 {
            if before {
                write!(f, ", ")?;
            }
            before = true;
        }
        if self.weeks == 1 {
            write!(f, "1 week")?;
        } else if self.weeks > 1 {
            write!(f, "{} weeks", self.weeks)?;
        }
        if self.days > 0 {
            if before {
                write!(f, ", ")?;
            }
            before = true;
        }
        if self.days == 1 {
            write!(f, "1 day")?;
        } else if self.days > 1 {
            write!(f, "{} days", self.days)?;
        }
        if self.hours > 0 {
            if before {
                write!(f, ", ")?;
            }
            before = true;
        }
        if self.hours == 1 {
            write!(f, "1 hour")?;
        } else if self.hours > 1 {
            write!(f, "{} hours", self.hours)?;
        }
        if self.minutes > 0 {
            if before {
                write!(f, ", ")?;
            }
        }
        if self.minutes == 1 {
            write!(f, "1 minute")?;
        } else if self.minutes > 1 {
            write!(f, "{} minutes", self.minutes)?;
        }
        Ok(())
    }
}

/// Represents a specific point in time, which could either be an [AbsoluteTime] (corresponding
/// with a particular [Date] or [DateTime]), or a [RelativeTime] (corresponding with an offset
/// from some [AbsoluteTime] or "now").
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)]
pub enum PointInTime {
    /// Based on a specific [Date] or [DateTime] (fixed point) that involves no relative
    /// indirection, like "3 days after 18/3/2024".
    Absolute(AbsoluteTime),
    /// Based on an offset from some known fixed point in time, like "next tuesday".
    Relative(RelativeTime),
}

impl Parse for PointInTime {
    fn parse(input: ParseStream) -> Result<Self> {
        if input.peek(LitInt) && input.peek2(Token![/]) {
            Ok(PointInTime::Absolute(input.parse::<AbsoluteTime>()?))
        } else {
            Ok(PointInTime::Relative(input.parse::<RelativeTime>()?))
        }
    }
}

impl Display for PointInTime {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            PointInTime::Absolute(abs) => write!(f, "{abs}"),
            PointInTime::Relative(rel) => write!(f, "{rel}"),
        }
    }
}

/// Represents an absolute/fixed point in time, such as a [Date] or [DateTime].
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)]
pub enum AbsoluteTime {
    /// A [Date], such as "23/9/2028".
    Date(Date),
    /// A [DateTime], such as "28/1/2025 at 5:23 PM" or "1/1/2019 20:15".
    DateTime(DateTime),
}

impl Parse for AbsoluteTime {
    fn parse(input: ParseStream) -> Result<Self> {
        let fork = input.fork();
        fork.parse::<Date>()?;
        if (fork.peek(LitInt) && fork.peek2(Token![:]) && fork.peek3(LitInt))
            || (fork.peek(Ident) && fork.peek2(LitInt) && fork.peek3(Token![:]))
        {
            return Ok(AbsoluteTime::DateTime(input.parse()?));
        }
        Ok(AbsoluteTime::Date(input.parse()?))
    }
}

impl Display for AbsoluteTime {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            AbsoluteTime::Date(date) => write!(f, "{}", date),
            AbsoluteTime::DateTime(date_time) => write!(f, "{}", date_time),
        }
    }
}

/// Combined with "next" or "after" to denote specific [RelativeTime]s.
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)]
pub enum RelativeTimeUnit {
    /// Week
    Week,
    /// Month
    Month,
    /// Year
    Year,
    /// Monday
    Monday,
    /// Tuesday
    Tuesday,
    /// Wednesday
    Wednesday,
    /// Thursday
    Thursday,
    /// Friday
    Friday,
    /// Saturday
    Saturday,
    /// Sunday
    Sunday,
}

impl Parse for RelativeTimeUnit {
    fn parse(input: ParseStream) -> Result<Self> {
        let ident = input.parse::<Ident>()?;
        match ident.to_string().to_lowercase().as_str() {
            "week" => Ok(RelativeTimeUnit::Week),
            "month" => Ok(RelativeTimeUnit::Month),
            "year" => Ok(RelativeTimeUnit::Year),
            "monday" => Ok(RelativeTimeUnit::Monday),
            "tuesday" => Ok(RelativeTimeUnit::Tuesday),
            "wednesday" => Ok(RelativeTimeUnit::Wednesday),
            "thursday" => Ok(RelativeTimeUnit::Thursday),
            "friday" => Ok(RelativeTimeUnit::Friday),
            "saturday" => Ok(RelativeTimeUnit::Saturday),
            "sunday" => Ok(RelativeTimeUnit::Sunday),
            _ => Err(Error::new(
                ident.span(),
                "expected one of `week`, `month`, `year`, `monday`, `tuesday`, `wednesday`, \
                `thursday`, `friday`, `saturday` or `sunday`",
            )),
        }
    }
}

impl Display for RelativeTimeUnit {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            RelativeTimeUnit::Week => f.write_str("week"),
            RelativeTimeUnit::Month => f.write_str("month"),
            RelativeTimeUnit::Year => f.write_str("year"),
            RelativeTimeUnit::Monday => f.write_str("Monday"),
            RelativeTimeUnit::Tuesday => f.write_str("Tuesday"),
            RelativeTimeUnit::Wednesday => f.write_str("Wednesday"),
            RelativeTimeUnit::Thursday => f.write_str("Thursday"),
            RelativeTimeUnit::Friday => f.write_str("Friday"),
            RelativeTimeUnit::Saturday => f.write_str("Saturday"),
            RelativeTimeUnit::Sunday => f.write_str("Sunday"),
        }
    }
}

/// Corresponds with a named relative time, such as "now", "today", "tomorrow", etc.
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)]
pub enum NamedRelativeTime {
    /// Now
    Now,
    /// Today
    Today,
    /// Tomorrow
    Tomorrow,
    /// Yesterday
    Yesterday,
    /// The day after tomorrow
    DayAfterTomorrow,
    /// The day before yesterday
    DayBeforeYesterday,
}

impl Parse for NamedRelativeTime {
    fn parse(input: ParseStream) -> Result<Self> {
        let mut ident1 = input.parse::<Ident>()?;
        if let Some(variant) = match ident1.to_string().to_lowercase().as_str() {
            "now" => Some(NamedRelativeTime::Now),
            "today" => Some(NamedRelativeTime::Today),
            "tomorrow" => Some(NamedRelativeTime::Tomorrow),
            "yesterday" => Some(NamedRelativeTime::Yesterday),
            _ => None,
        } {
            // single-ident variants
            return Ok(variant);
        }
        if ident1 == "the" && input.peek(Ident) {
            // optional "the"
            ident1 = input.parse::<Ident>()?;
        }
        let ident2 = input.parse::<Ident>()?;
        let ident3 = input.parse::<Ident>()?;
        let ident1_str = ident1.to_string().to_lowercase();
        let ident2_str = ident2.to_string().to_lowercase();
        let ident3_str = ident3.to_string().to_lowercase();
        match (
            ident1_str.as_str(),
            ident2_str.as_str(),
            ident3_str.as_str(),
        ) {
            ("day", "after", "tomorrow") => Ok(NamedRelativeTime::DayAfterTomorrow),
            ("day", "before", "yesterday") => Ok(NamedRelativeTime::DayBeforeYesterday),
            _ => {
                if ident1_str != "day" {
                    return Err(Error::new(
                        ident1.span(),
                        "expected one of `day`, `now`, `today`, `tomorrow`, `yesterday`, `the`",
                    ));
                }
                if ident2_str != "before" && ident2_str != "after" {
                    return Err(Error::new(ident2.span(), "expected `before` or `after`"));
                }
                if ident3_str == "tomorrow" {
                    Err(Error::new(ident3.span(), "expected `yesterday`"))
                } else {
                    Err(Error::new(ident3.span(), "expected `tomorrow`"))
                }
            }
        }
    }
}

impl Display for NamedRelativeTime {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            NamedRelativeTime::Now => f.write_str("now"),
            NamedRelativeTime::Today => f.write_str("today"),
            NamedRelativeTime::Tomorrow => f.write_str("tomorrow"),
            NamedRelativeTime::Yesterday => f.write_str("yesterday"),
            NamedRelativeTime::DayAfterTomorrow => f.write_str("the day after tomorrow"),
            NamedRelativeTime::DayBeforeYesterday => f.write_str("the day before yesterday"),
        }
    }
}

/// Represents a specific point in time offset by some known duration or period, such as
/// "tomorrow", "now", "next tuesday", "3 days after 2/5/2028 at 7:11 PM" etc..
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)]
pub enum RelativeTime {
    /// e.g. "3 hours before 18/9/2024 at 4:32 PM", "7 days and 3 hours after tomorrow", "5
    /// days ago", "9 years from now".
    Directional {
        /// The [Duration] (how long).
        duration: Duration,
        /// e.g. "from now", "ago", "after tomorrow".
        dir: TimeDirection,
    },
    /// e.g. "the day before tomorrow", "now", "tomorrow", "yesterday".
    Named(NamedRelativeTime),
    /// e.g. "next wednesday", "next friday", "next year".
    Next(RelativeTimeUnit),
    /// e.g. "last month", "last tuesday", "last year".
    Last(RelativeTimeUnit),
}

impl Parse for RelativeTime {
    fn parse(input: ParseStream) -> Result<Self> {
        let fork = input.fork();
        if fork.peek(Ident) {
            let ident1 = fork.parse::<Ident>().unwrap().to_string().to_lowercase();
            match ident1.as_str() {
                "next" | "last" => {
                    // next / last [unit]
                    input.parse::<Ident>()?;
                    let unit = input.parse::<RelativeTimeUnit>()?;
                    if ident1 == "next" {
                        return Ok(RelativeTime::Next(unit));
                    } else {
                        return Ok(RelativeTime::Last(unit));
                    }
                }
                "day" | "now" | "today" | "tomorrow" | "yesterday" | "the" => {
                    return Ok(RelativeTime::Named(input.parse::<NamedRelativeTime>()?))
                }
                _ => (),
            }
        }
        let duration = input.parse::<Duration>()?;
        let dir = input.parse::<TimeDirection>()?;
        Ok(RelativeTime::Directional { duration, dir })
    }
}

impl Display for RelativeTime {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            RelativeTime::Directional { duration, dir } => write!(f, "{duration} {dir}"),
            RelativeTime::Next(unit) => write!(f, "next {unit}"),
            RelativeTime::Last(unit) => write!(f, "last {unit}"),
            RelativeTime::Named(named) => write!(f, "{named}"),
        }
    }
}

/// A `dd/mm/yyyy` style date.
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)]
pub struct Date(pub Month, pub DayOfMonth, pub Year);

impl Parse for Date {
    fn parse(input: ParseStream) -> Result<Self> {
        let day = input.parse::<DayOfMonth>()?;
        input.parse::<Token![/]>()?;
        let month = input.parse::<Month>()?;
        input.parse::<Token![/]>()?;
        let year = input.parse::<Year>()?;
        Ok(Date(month, day, year))
    }
}

impl Display for Date {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.write_fmt(format_args!("{}/{}/{}", self.1, self.0, self.2))
    }
}

/// e.g. `22/4/1991 5:25 PM`, `22/4/1991 at 5:25 PM`, `22/4/1991 15:28`.
///
/// Note that "at" is optional and time can either be 12-hour (must have am/pm specified) or
/// 24-hour.
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)]
pub struct DateTime(pub Date, pub Time); // 22/4/1991 5:25 PM

impl Parse for DateTime {
    fn parse(input: ParseStream) -> Result<Self> {
        let date = input.parse::<Date>()?;
        if input.peek(Ident) {
            let ident = input.parse::<Ident>()?;
            if ident.to_string().to_lowercase().as_str() != "at" {
                return Err(Error::new(ident.span(), "expected `at`"));
            }
        }
        let time = input.parse::<Time>()?;
        Ok(DateTime(date, time))
    }
}

impl Display for DateTime {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.write_fmt(format_args!("{} at {}", self.0, self.1))
    }
}

/// A simple representation of the time, e.g. `13:07` or `5:07 PM`.
///
/// Both 24-hour and 12-hour are supported (must specify `AM` or `PM` when using 12-hour).
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)]
pub struct Time(pub Hour, pub Minute);

impl Parse for Time {
    fn parse(input: ParseStream) -> Result<Self> {
        let hour_lit = input.parse::<LitInt>()?;
        let hour_val = hour_lit.base10_parse::<u8>()?;
        input.parse::<Token![:]>()?;
        let min = input.parse::<Minute>()?;
        if input.peek(Ident)
            && ["am", "pm"].contains(
                &input
                    .fork()
                    .parse::<Ident>()
                    .unwrap()
                    .to_string()
                    .to_lowercase()
                    .as_str(),
            )
        {
            let am_pm = input.parse::<AmPm>()?;
            if hour_val > 12 || hour_val == 0 {
                return Err(Error::new(
                    hour_lit.span(),
                    "hour must be between 1 and 12 (inclusive)",
                ));
            }
            return Ok(Time(Hour::Hour12(hour_val, am_pm), min));
        }
        if hour_val > 24 {
            return Err(Error::new(
                hour_lit.span(),
                "hour must be between 0 and 24 (inclusive)",
            ));
        }
        Ok(Time(Hour::Hour24(hour_val), min))
    }
}

impl Display for Time {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            Time(Hour::Hour12(hour, am_pm), minute) => {
                write!(f, "{}:{:02} {}", hour, minute, am_pm)
            }
            Time(Hour::Hour24(hour), minute) => write!(f, "{}:{:02}", hour, minute),
        }
    }
}

/// Represents a particular day of the month, which can range from 1 to 31.
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)]
pub struct DayOfMonth(pub u8);

impl Parse for DayOfMonth {
    fn parse(input: ParseStream) -> Result<Self> {
        let lit = input.parse::<LitInt>()?;
        let int_val = lit.base10_parse::<u8>()?;
        if int_val > 31 || int_val == 0 {
            return Err(Error::new(
                lit.span(),
                "day must be between 1 and 31 (inclusive)",
            ));
        }
        Ok(DayOfMonth(int_val))
    }
}

impl Display for DayOfMonth {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.write_fmt(format_args!("{}", self.0))
    }
}

/// Represents a year, which can be any valid [`u16`].
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)]
pub struct Year(pub u16);

impl Parse for Year {
    fn parse(input: ParseStream) -> Result<Self> {
        let lit = input.parse::<LitInt>()?;
        let int_val = lit.base10_parse::<u16>()?;
        Ok(Year(int_val))
    }
}

impl Display for Year {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.write_fmt(format_args!("{}", self.0))
    }
}

/// Represents an hour of the day in either 12-hour or 24-hour format.
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)]
pub enum Hour {
    /// 12-hour format, i.e. `5 PM`
    Hour12(u8, AmPm),
    /// 24-hour format, i.e. `18`
    Hour24(u8),
}

impl Parse for Hour {
    fn parse(input: ParseStream) -> Result<Self> {
        let lit = input.parse::<LitInt>()?;
        let int_val = lit.base10_parse::<u8>()?;
        if let Ok(am_pm) = input.parse::<AmPm>() {
            if int_val > 12 || int_val == 0 {
                return Err(Error::new(
                    lit.span(),
                    "hour must be between 1 and 12 (inclusive)",
                ));
            }
            return Ok(Hour::Hour12(int_val, am_pm));
        }
        if int_val > 24 {
            return Err(Error::new(
                lit.span(),
                "hour must be between 0 and 24 (inclusive)",
            ));
        }
        Ok(Hour::Hour24(int_val))
    }
}

impl Display for Hour {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            Hour::Hour12(hour, am_pm) => f.write_fmt(format_args!("{hour} {am_pm}",)),
            Hour::Hour24(hour) => f.write_fmt(format_args!("{hour}")),
        }
    }
}

/// Represents a minute of the hour, which can range from 0 to 60.
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)]
pub struct Minute(pub u8);

impl Parse for Minute {
    fn parse(input: ParseStream) -> Result<Self> {
        let lit = input.parse::<LitInt>()?;
        let int_val = lit.base10_parse::<u8>()?;
        if int_val > 60 {
            return Err(Error::new(
                lit.span(),
                "minute must be between 0 and 60 (inclusive)",
            ));
        }
        Ok(Minute(int_val))
    }
}

impl Display for Minute {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.write_fmt(format_args!("{:02}", self.0))
    }
}

/// Represents a particular month of the year, which can range from 1-12
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)]
#[repr(u8)]
pub enum Month {
    /// January (1)
    January = 1,
    /// February (2)
    February,
    /// March (3)
    March,
    /// April (4)
    April,
    /// May (5)
    May,
    /// June (6)
    June,
    /// July (7)
    July,
    /// August (8)
    August,
    /// September (9)
    September,
    /// October (10)
    October,
    /// November (11)
    November,
    /// December (12)
    December,
}

impl Parse for Month {
    fn parse(input: ParseStream) -> Result<Self> {
        let lit = input.parse::<LitInt>()?;
        let int_val = lit.base10_parse::<u8>()?;
        if int_val > 12 || int_val == 0 {
            return Err(Error::new(
                lit.span(),
                "month must be between 1 and 12 (inclusive)",
            ));
        }
        use Month::*;
        Ok(match int_val {
            1 => January,
            2 => February,
            3 => March,
            4 => April,
            5 => May,
            6 => June,
            7 => July,
            8 => August,
            9 => September,
            10 => October,
            11 => November,
            12 => December,
            _ => unreachable!(),
        })
    }
}

impl From<Month> for u8 {
    fn from(value: Month) -> Self {
        use Month::*;
        match value {
            January => 1,
            February => 2,
            March => 3,
            April => 4,
            May => 5,
            June => 6,
            July => 7,
            August => 8,
            September => 9,
            October => 10,
            November => 11,
            December => 12,
        }
    }
}

impl From<&Month> for u8 {
    fn from(value: &Month) -> Self {
        (*value).into()
    }
}

impl Display for Month {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        let as_u8: u8 = self.into();
        f.write_fmt(format_args!("{}", as_u8))
    }
}

/// Represents either AM or PM
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)]
pub enum AmPm {
    /// AM
    AM,
    /// PM
    PM,
}

impl Parse for AmPm {
    fn parse(input: ParseStream) -> Result<Self> {
        let ident = input.parse::<Ident>()?;
        match ident.to_string().to_lowercase().as_str() {
            "am" => Ok(AmPm::AM),
            "pm" => Ok(AmPm::PM),
            _ => Err(Error::new(ident.span(), "expected `AM` or `PM`")),
        }
    }
}

impl Display for AmPm {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            AmPm::AM => f.write_str("AM"),
            AmPm::PM => f.write_str("PM"),
        }
    }
}

impl AsRef<str> for AmPm {
    fn as_ref(&self) -> &str {
        match self {
            AmPm::AM => "AM",
            AmPm::PM => "PM",
        }
    }
}

/// Represents particular units of time, such as hours, minutes, etc.
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)]
pub enum TimeUnit {
    /// Minutes
    Minutes,
    /// Hours
    Hours,
    /// Days
    Days,
    /// Weeks
    Weeks,
    /// Months
    Months,
    /// Years
    Years,
}

impl Parse for TimeUnit {
    fn parse(input: ParseStream) -> Result<Self> {
        let ident = input.parse::<Ident>()?;
        use TimeUnit::*;
        Ok(match ident.to_string().to_lowercase().as_str() {
            "mins" | "minutes" | "minute" | "min" => Minutes,
            "hours" | "hrs" | "hour" | "hr" => Hours,
            "days" | "day" => Days,
            "weeks" | "week" => Weeks,
            "months" | "month" => Months,
            "years" | "yr" | "year" => Years,
            _ => {
                return Err(Error::new(
                    ident.span(),
                    "expected one of `minutes`, `hours`, `days`, `weeks`, `months`, and `years`",
                ))
            }
        })
    }
}

impl AsRef<str> for TimeUnit {
    fn as_ref(&self) -> &str {
        match self {
            TimeUnit::Minutes => "minutes",
            TimeUnit::Hours => "hours",
            TimeUnit::Days => "days",
            TimeUnit::Weeks => "minutes",
            TimeUnit::Months => "months",
            TimeUnit::Years => "years",
        }
    }
}

impl Display for TimeUnit {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.write_str(self.as_ref())
    }
}

/// Enumerates the various types of relative times that can be paired with a [Duration].
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)]
pub enum TimeDirection {
    /// e.g. `after 18/7/2025 at 3:22 PM`
    AfterAbsolute(AbsoluteTime),
    /// e.g. `before 18/7/2025 at 3:22 PM`
    BeforeAbsolute(AbsoluteTime),
    /// e.g. `after tomorrow`
    AfterNamed(NamedRelativeTime),
    /// e.g. `before yesterday`
    BeforeNamed(NamedRelativeTime),
    /// e.g. `before next tuesday`
    BeforeNext(RelativeTimeUnit),
    /// e.g. `before last week`
    BeforeLast(RelativeTimeUnit),
    /// e.g. `after next thursday`
    AfterNext(RelativeTimeUnit),
    /// e.g. `after last month`
    AfterLast(RelativeTimeUnit),
    /// Ago
    Ago,
    /// From now
    FromNow,
}

impl Parse for TimeDirection {
    fn parse(input: ParseStream) -> Result<Self> {
        let ident1 = input.parse::<Ident>()?;
        match ident1.to_string().to_lowercase().as_str() {
            "after" => {
                if input.peek(LitInt) {
                    Ok(TimeDirection::AfterAbsolute(input.parse()?))
                } else {
                    let ident2 = input.fork().parse::<Ident>()?.to_string().to_lowercase();
                    match ident2.as_str() {
                        "next" => {
                            input.parse::<Ident>()?;
                            Ok(TimeDirection::AfterNext(input.parse()?))
                        }
                        "last" => {
                            input.parse::<Ident>()?;
                            Ok(TimeDirection::AfterLast(input.parse()?))
                        }
                        _ => Ok(TimeDirection::AfterNamed(input.parse()?)),
                    }
                }
            }
            "before" => {
                if input.peek(LitInt) {
                    Ok(TimeDirection::BeforeAbsolute(input.parse()?))
                } else {
                    let ident2 = input.fork().parse::<Ident>()?.to_string().to_lowercase();
                    match ident2.as_str() {
                        "next" => {
                            input.parse::<Ident>()?;
                            Ok(TimeDirection::BeforeNext(input.parse()?))
                        }
                        "last" => {
                            input.parse::<Ident>()?;
                            Ok(TimeDirection::BeforeLast(input.parse()?))
                        }
                        _ => Ok(TimeDirection::BeforeNamed(input.parse()?)),
                    }
                }
            }
            "ago" => Ok(TimeDirection::Ago),
            "from" => {
                let ident2 = input.parse::<Ident>()?;
                if ident2.to_string().to_lowercase().as_str() != "now" {
                    return Err(Error::new(ident2.span(), "expected `now`"));
                }
                Ok(TimeDirection::FromNow)
            }
            _ => Err(Error::new(
                ident1.span(),
                "expected one of `after`, `before`, `ago`, `from`",
            )),
        }
    }
}

impl Display for TimeDirection {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            TimeDirection::AfterAbsolute(abs_time) => write!(f, "after {abs_time}"),
            TimeDirection::BeforeAbsolute(abs_time) => write!(f, "before {abs_time}"),
            TimeDirection::Ago => f.write_str("ago"),
            TimeDirection::FromNow => f.write_str("from now"),
            TimeDirection::AfterNamed(named) => write!(f, "after {named}"),
            TimeDirection::BeforeNamed(named) => write!(f, "before {named}"),
            TimeDirection::BeforeNext(unit) => write!(f, "before next {unit}"),
            TimeDirection::BeforeLast(unit) => write!(f, "before last {unit}"),
            TimeDirection::AfterNext(unit) => write!(f, "after next {unit}"),
            TimeDirection::AfterLast(unit) => write!(f, "after last {unit}"),
        }
    }
}

/// Represents a positive integer, stored as a [`u64`].
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)]
pub struct Number(pub u64);

impl From<u64> for Number {
    fn from(value: u64) -> Self {
        Number(value)
    }
}

impl From<Number> for u64 {
    fn from(value: Number) -> Self {
        value.0
    }
}

impl Add for Number {
    type Output = Number;

    fn add(self, rhs: Self) -> Self::Output {
        Number(self.0 + rhs.0)
    }
}

impl Sub for Number {
    type Output = Number;

    fn sub(self, rhs: Self) -> Self::Output {
        Number(self.0 - rhs.0)
    }
}

impl Mul for Number {
    type Output = Number;

    fn mul(self, rhs: Self) -> Self::Output {
        Number(self.0 * rhs.0)
    }
}

impl Div for Number {
    type Output = Number;

    fn div(self, rhs: Self) -> Self::Output {
        Number(self.0 / rhs.0)
    }
}

impl PartialEq<u64> for Number {
    fn eq(&self, other: &u64) -> bool {
        self.0 == *other
    }
}

impl PartialOrd<u64> for Number {
    fn partial_cmp(&self, other: &u64) -> Option<std::cmp::Ordering> {
        self.0.partial_cmp(other)
    }
}

impl Parse for Number {
    fn parse(input: ParseStream) -> Result<Self> {
        let lit = input.parse::<LitInt>()?;
        let int_val = lit.base10_parse::<u64>()?;
        Ok(Number(int_val))
    }
}

impl Display for Number {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.write_fmt(format_args!("{}", self.0))
    }
}

macro_rules! impl_parse_str {
    ($ident:ident) => {
        impl FromStr for $ident {
            type Err = syn::Error;

            fn from_str(s: &str) -> std::prelude::v1::Result<Self, Self::Err> {
                syn::parse_str(s)
            }
        }
    };
}

impl_parse_str!(TimeExpression);
impl_parse_str!(TimeDirection);
impl_parse_str!(TimeUnit);
impl_parse_str!(TimeRange);
impl_parse_str!(AmPm);
impl_parse_str!(DayOfMonth);
impl_parse_str!(Minute);
impl_parse_str!(Month);
impl_parse_str!(Hour);
impl_parse_str!(AbsoluteTime);
impl_parse_str!(Duration);
impl_parse_str!(RelativeTime);
impl_parse_str!(PointInTime);
impl_parse_str!(Time);
impl_parse_str!(DateTime);
impl_parse_str!(RelativeTimeUnit);
impl_parse_str!(NamedRelativeTime);

#[cfg(test)]
macro_rules! assert_impl_all {
    ($($typ:ty),* : $($tt:tt)*) => {{
        const fn _assert_impl<T>() where T: $($tt)*, {}
        $(_assert_impl::<$typ>();)*
    }};
}

#[test]
fn test_traits() {
    assert_impl_all!(
        TimeDirection,
        TimeUnit,
        AmPm,
        DayOfMonth,
        Minute,
        Month,
        Hour,
        AbsoluteTime,
        Duration,
        RelativeTime,
        PointInTime,
        Time,
        DateTime,
        RelativeTimeUnit,
        NamedRelativeTime,
        TimeRange,
        TimeExpression : Copy
        + Clone
        + PartialEq
        + Eq
        + PartialOrd
        + Ord
        + core::fmt::Debug
        + core::fmt::Display
        + Parse
        + core::hash::Hash
        + FromStr
    );
}