beancount-parser 2.6.0

A beancount file parser library for rust
Documentation 
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use std::{cmp::Ordering, str::FromStr};

use nom::{
    bytes::complete::take,
    character::complete::{char, digit1},
    combinator::{all_consuming, cut, map_res, peek, verify},
    Finish, Parser,
};

use super::{IResult, Span};

/// A date
///
/// The parser has some sanity checks to make sure the date remotely makes sense
/// but it doesn't verify if it is an actual real valid date.
///
/// If that is important to you, you should use a date-time library to verify the validity.
///
/// # Example
///
/// ```
/// # use beancount_parser::BeancountFile;
/// let input = "2022-05-21 event \"location\" \"Middle earth\"";
/// let beancount: BeancountFile<f64> = input.parse().unwrap();
/// let date = beancount.directives[0].date;
/// assert_eq!(date.year, 2022);
/// assert_eq!(date.month, 5);
/// assert_eq!(date.day, 21);
/// ```
#[derive(Debug, Copy, Clone, Eq, PartialEq)]
pub struct Date {
    /// Year
    pub year: u16,
    /// Month (of year)
    pub month: u8,
    /// Day (of month)
    pub day: u8,
}

impl Date {
    /// Create a new date from year, month and day
    #[must_use]
    pub fn new(year: u16, month: u8, day: u8) -> Self {
        Self { year, month, day }
    }
}

impl PartialOrd for Date {
    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
        Some(self.cmp(other))
    }
}

impl Ord for Date {
    fn cmp(&self, other: &Self) -> Ordering {
        self.year
            .cmp(&other.year)
            .then_with(|| self.month.cmp(&other.month))
            .then_with(|| self.day.cmp(&other.day))
    }
}

impl FromStr for Date {
    type Err = crate::Error;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        let span = Span::new(s);
        match all_consuming(parse).parse(span).finish() {
            Ok((_, date)) => Ok(date),
            Err(_) => Err(crate::Error::new(s, span)),
        }
    }
}

pub(super) fn parse(input: Span<'_>) -> IResult<'_, Date> {
    let (input, _) = peek((digit1, char('-'), digit1, char('-'), digit1)).parse(input)?;
    cut(do_parse).parse(input)
}

fn do_parse(input: Span<'_>) -> IResult<'_, Date> {
    let (input, year) = year(input)?;
    let (input, _) = char('-')(input)?;
    let (input, month) = month(input)?;
    let (input, _) = char('-')(input)?;
    let (input, day) = day(input)?;
    Ok((input, Date { year, month, day }))
}

fn year(input: Span<'_>) -> IResult<'_, u16> {
    map_res(take(4usize), |s: Span<'_>| s.fragment().parse()).parse(input)
}

fn month(input: Span<'_>) -> IResult<'_, u8> {
    verify(
        map_res(take(2usize), |s: Span<'_>| s.fragment().parse()),
        |&n| n > 0 && n < 13,
    )
    .parse(input)
}

fn day(input: Span<'_>) -> IResult<'_, u8> {
    verify(
        map_res(take(2usize), |s: Span<'_>| s.fragment().parse()),
        |&n| n > 0 && n < 32,
    )
    .parse(input)
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn date_from_str_should_parse_valid_date() {
        let date: Date = "2023-03-12".parse().unwrap();
        assert_eq!(date.year, 2023);
        assert_eq!(date.month, 3);
        assert_eq!(date.day, 12);
    }

    #[test]
    fn date_from_str_should_not_parse_invalid_date() {
        let result: Result<Date, _> = "2023-03-12oops".parse();
        assert!(result.is_err(), "{result:?}");
    }
}