Parse simple dates and times

Cargo.lock

@@ -27,6 +27,29 @@ version = "0.2.106"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a60553f9a9e039a333b4e9b20573b9e9b9c0bb3a11e201ccc48ef4283456d673"
 
+[[package]]
+name = "memchr"
+version = "2.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "308cc39be01b73d0d18f82a0e7b2a3df85245f84af96fdddc5d202d27e47b86a"
+
+[[package]]
+name = "minimal-lexical"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "68354c5c6bd36d73ff3feceb05efa59b6acb7626617f4962be322a825e61f79a"
+
+[[package]]
+name = "nom"
+version = "7.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1b1d11e1ef389c76fe5b81bcaf2ea32cf88b62bc494e19f493d0b30e7a930109"
+dependencies = [
+ "memchr",
+ "minimal-lexical",
+ "version_check",
+]
+
 [[package]]
 name = "num-integer"
 version = "0.1.44"
@@ -62,8 +85,15 @@ name = "today"
 version = "0.1.0"
 dependencies = [
  "chrono",
+ "nom",
 ]
 
+[[package]]
+name = "version_check"
+version = "0.9.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5fecdca9a5291cc2b8dcf7dc02453fee791a280f3743cb0905f8822ae463b3fe"
+
 [[package]]
 name = "wasi"
 version = "0.10.0+wasi-snapshot-preview1"

Cargo.toml

@@ -5,3 +5,4 @@ edition = "2018"
 
 [dependencies]
 chrono = "0.4.19"
+nom = "7.1.0"

src/main.rs

@@ -1,4 +1,5 @@
 mod commands;
+mod parse;
 
 fn main() {
     println!("Hello, world!");

src/parse.rs

@@ -0,0 +1,151 @@
+use std::str::FromStr;
+
+use chrono::{NaiveDate, NaiveTime};
+use nom::branch::Alt;
+use nom::bytes::complete::{take_while1, take_while_m_n};
+use nom::character::complete::{char, digit1, newline};
+use nom::combinator::{eof, fail, map_opt, map_res};
+use nom::sequence::terminated;
+use nom::{IResult, Parser};
+
+fn line_ending(i: &str) -> IResult<&str, ()> {
+    (newline.map(|_| ()), eof.map(|_| ())).choice(i)
+}
+
+fn title(i: &str) -> IResult<&str, &str> {
+    terminated(take_while1(|c| c != '\n'), line_ending)(i)
+}
+
+fn number<N: FromStr>(i: &str) -> IResult<&str, N> {
+    map_res(digit1, str::parse)(i)
+}
+
+fn fixed_width_number<N: FromStr, const W: usize>(i: &str) -> IResult<&str, N> {
+    map_res(
+        take_while_m_n(W, W, |c: char| c.is_ascii_digit()),
+        str::parse,
+    )(i)
+}
+
+fn date(i: &str) -> IResult<&str, NaiveDate> {
+    let (i, year) = number::<i32>(i)?;
+    let (i, _) = char('-')(i)?;
+    let (i, month) = fixed_width_number::<u32, 2>(i)?;
+    let (i, _) = char('-')(i)?;
+    let (i, day) = fixed_width_number::<u32, 2>(i)?;
+    match NaiveDate::from_ymd_opt(year, month, day) {
+        Some(date) => Ok((i, date)),
+        None => fail(i),
+    }
+}
+
+fn time(i: &str) -> IResult<&str, NaiveTime> {
+    let (i, hour) = fixed_width_number::<u32, 2>(i)?;
+    let (i, _) = char(':')(i)?;
+    let (i, min) = fixed_width_number::<u32, 2>(i)?;
+    if hour < 24 && min < 60 {
+        Ok((i, NaiveTime::from_hms(hour, min, 0)))
+    } else {
+        fail(i)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_line_ending() {
+        assert_eq!(line_ending("\n"), Ok(("", ())));
+        assert_eq!(line_ending("\nbla"), Ok(("bla", ())));
+        assert_eq!(line_ending("\n\n"), Ok(("\n", ())));
+        assert_eq!(line_ending(""), Ok(("", ())));
+
+        assert!(line_ending("bla").is_err());
+        assert!(line_ending("\r").is_err());
+        assert!(line_ending("\r\n").is_err());
+    }
+
+    #[test]
+    fn test_title() {
+        assert_eq!(title("foo bar\nbaz"), Ok(("baz", "foo bar")));
+        assert_eq!(title("foo bar\n"), Ok(("", "foo bar")));
+        assert_eq!(title("foo bar"), Ok(("", "foo bar")));
+        assert_eq!(title(" \nbla"), Ok(("bla", " ")));
+        assert_eq!(
+            title("!\"§$%&/()'<>[]{}_:;.,-=\nbla"),
+            Ok(("bla", "!\"§$%&/()'<>[]{}_:;.,-="))
+        );
+
+        assert!(title("\nxyz").is_err());
+        assert!(title("").is_err());
+    }
+
+    #[test]
+    fn test_number() {
+        assert_eq!(number::<u32>("012345abc"), Ok(("abc", 12345)));
+        assert_eq!(number::<u8>("255"), Ok(("", 255)));
+        assert_eq!(number::<i64>("0x3f"), Ok(("x3f", 0)));
+
+        assert!(number::<u8>("256").is_err());
+        assert!(number::<i32>("xyz").is_err());
+        assert!(number::<i8>("").is_err());
+    }
+
+    #[test]
+    fn test_fixed_width_number() {
+        assert_eq!(
+            fixed_width_number::<u32, 2>("012345abc"),
+            Ok(("2345abc", 1))
+        );
+        assert_eq!(
+            fixed_width_number::<u32, 3>("012345abc"),
+            Ok(("345abc", 12))
+        );
+        assert_eq!(
+            fixed_width_number::<u32, 6>("012345abc"),
+            Ok(("abc", 12345))
+        );
+
+        assert!(fixed_width_number::<u8, 0>("012345abc").is_err());
+        assert!(fixed_width_number::<u8, 6>("012345abc").is_err());
+        assert!(fixed_width_number::<u8, 3>("14x").is_err());
+        assert!(fixed_width_number::<i8, 4>("").is_err());
+    }
+
+    #[test]
+    fn test_date() {
+        assert_eq!(
+            date("2021-11-06"),
+            Ok(("", NaiveDate::from_ymd(2021, 11, 6)))
+        );
+        assert_eq!(
+            date("2021-11-0678"),
+            Ok(("78", NaiveDate::from_ymd(2021, 11, 6)))
+        );
+        assert_eq!(date("0-01-01"), Ok(("", NaiveDate::from_ymd(0, 1, 1))));
+        assert_eq!(
+            date("2020-02-29"),
+            Ok(("", NaiveDate::from_ymd(2020, 2, 29)))
+        );
+
+        assert!(date("2021-11-6").is_err());
+        assert!(date("0000-00-00").is_err());
+        assert!(date("2021-02-29").is_err());
+    }
+
+    #[test]
+    fn test_time() {
+        assert_eq!(time("12:34"), Ok(("", NaiveTime::from_hms(12, 34, 0))));
+        assert_eq!(time("00:00"), Ok(("", NaiveTime::from_hms(0, 0, 0))));
+        assert_eq!(time("23:59"), Ok(("", NaiveTime::from_hms(23, 59, 0))));
+        assert_eq!(time("02:04:06"), Ok((":06", NaiveTime::from_hms(2, 4, 0))));
+
+        assert!(time("abc").is_err());
+        assert!(time("24:23").is_err());
+        assert!(time("12:60").is_err());
+        assert!(time("12-34").is_err());
+        assert!(time("2:34").is_err());
+        assert!(time("12:3").is_err());
+    }
+}