Merge pull request #77 from cakebaker/release_0_6_0

Bump version to 0.6.0

.github/workflows/ci.yml

@@ -14,14 +14,8 @@ jobs:
         os: [ubuntu-latest, macOS-latest, windows-latest]
     steps:
       - uses: actions/checkout@v4
-      - uses: actions-rs/toolchain@v1
-        with:
-          profile: minimal
-          toolchain: stable
-          override: true
-      - uses: actions-rs/cargo@v1
-        with:
-          command: check
+      - uses: dtolnay/rust-toolchain@stable
+      - run: cargo check
 
   test:
     name: cargo test
@@ -31,30 +25,17 @@ jobs:
         os: [ubuntu-latest, macOS-latest, windows-latest]
     steps:
       - uses: actions/checkout@v4
-      - uses: actions-rs/toolchain@v1
-        with:
-          profile: minimal
-          toolchain: stable
-          override: true
-      - uses: actions-rs/cargo@v1
-        with:
-          command: test
+      - uses: dtolnay/rust-toolchain@stable
+      - run: cargo test
 
   fmt:
     name: cargo fmt --all -- --check
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
-      - uses: actions-rs/toolchain@v1
-        with:
-          profile: minimal
-          toolchain: stable
-          override: true
+      - uses: dtolnay/rust-toolchain@stable
       - run: rustup component add rustfmt
-      - uses: actions-rs/cargo@v1
-        with:
-          command: fmt
-          args: --all -- --check
+      - run: cargo fmt --all -- --check
 
   clippy:
     name: cargo clippy -- -D warnings
@@ -64,16 +45,9 @@ jobs:
         os: [ubuntu-latest, macOS-latest, windows-latest]
     steps:
       - uses: actions/checkout@v4
-      - uses: actions-rs/toolchain@v1
-        with:
-          profile: minimal
-          toolchain: stable
-          override: true
+      - uses: dtolnay/rust-toolchain@stable
       - run: rustup component add clippy
-      - uses: actions-rs/cargo@v1
-        with:
-          command: clippy
-          args: -- -D warnings
+      - run: cargo clippy --all-targets -- -D warnings
 
   coverage:
     name: Code Coverage
@@ -108,16 +82,9 @@ jobs:
         outputs CODECOV_FLAGS
 
     - name: rust toolchain ~ install
-      uses: actions-rs/toolchain@v1
-      with:
-        toolchain: ${{ steps.vars.outputs.TOOLCHAIN }}
-        default: true
-        profile: minimal # minimal component installation (ie, no documentation)
+      uses: dtolnay/rust-toolchain@nightly
     - name: Test
-      uses: actions-rs/cargo@v1
-      with:
-        command: test
-        args: ${{ steps.vars.outputs.CARGO_FEATURES_OPTION }} --no-fail-fast
+      run: cargo test ${{ steps.vars.outputs.CARGO_FEATURES_OPTION }} --no-fail-fast
       env:
         CARGO_INCREMENTAL: "0"
         RUSTC_WRAPPER: ""
@@ -158,7 +125,7 @@ jobs:
       uses: codecov/codecov-action@v4
       # if: steps.vars.outputs.HAS_CODECOV_TOKEN
       with:
-        # token: ${{ secrets.CODECOV_TOKEN }}
+        token: ${{ secrets.CODECOV_TOKEN }}
         file: ${{ steps.coverage.outputs.report }}
         ## flags: IntegrationTests, UnitTests, ${{ steps.vars.outputs.CODECOV_FLAGS }}
         flags: ${{ steps.vars.outputs.CODECOV_FLAGS }}

Cargo.lock

@@ -114,9 +114,25 @@ checksum = "518ef76f2f87365916b142844c16d8fefd85039bc5699050210a7778ee1cd1de"
 
 [[package]]
 name = "memchr"
-version = "2.5.0"
+version = "2.6.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2dffe52ecf27772e601905b7522cb4ef790d2cc203488bbd0e2fe85fcb74566d"
+checksum = "f665ee40bc4a3c5590afb1e9677db74a508659dfd71e126420da8274909a0167"
+
+[[package]]
+name = "minimal-lexical"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "68354c5c6bd36d73ff3feceb05efa59b6acb7626617f4962be322a825e61f79a"
+
+[[package]]
+name = "nom"
+version = "7.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d273983c5a657a70a3e8f2a01329822f3b8c8172b73826411a55751e404a0a4a"
+dependencies = [
+ "memchr",
+ "minimal-lexical",
+]
 
 [[package]]
 name = "num-traits"
@@ -135,9 +151,10 @@ checksum = "dd8b5dd2ae5ed71462c540258bedcb51965123ad7e7ccf4b9a8cafaa4a63576d"
 
 [[package]]
 name = "parse_datetime"
-version = "0.5.0"
+version = "0.6.0"
 dependencies = [
  "chrono",
+ "nom",
  "regex",
 ]
 
@@ -161,9 +178,9 @@ dependencies = [
 
 [[package]]
 name = "regex"
-version = "1.9.1"
+version = "1.10.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b2eae68fc220f7cf2532e4494aded17545fce192d59cd996e0fe7887f4ceb575"
+checksum = "c117dbdfde9c8308975b6a18d71f3f385c89461f7b3fb054288ecf2a2058ba4c"
 dependencies = [
  "aho-corasick",
  "memchr",
@@ -173,9 +190,9 @@ dependencies = [
 
 [[package]]
 name = "regex-automata"
-version = "0.3.1"
+version = "0.4.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e9aaecc05d5c4b5f7da074b9a0d1a0867e71fd36e7fc0482d8bcfe8e8fc56290"
+checksum = "86b83b8b9847f9bf95ef68afb0b8e6cdb80f498442f5179a29fad448fcc1eaea"
 dependencies = [
  "aho-corasick",
  "memchr",
@@ -184,9 +201,9 @@ dependencies = [
 
 [[package]]
 name = "regex-syntax"
-version = "0.7.3"
+version = "0.8.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2ab07dc67230e4a4718e70fd5c20055a4334b121f1f9db8fe63ef39ce9b8c846"
+checksum = "adad44e29e4c806119491a7f06f03de4d1af22c3a680dd47f1e6e179439d1f56"
 
 [[package]]
 name = "syn"

Cargo.toml

@@ -1,12 +1,13 @@
 [package]
 name = "parse_datetime"
 description = "parsing human-readable time strings and converting them to a DateTime"
-version = "0.5.0"
+version = "0.6.0"
 edition = "2021"
 license = "MIT"
 repository = "https://github.com/uutils/parse_datetime"
 readme = "README.md"
 
 [dependencies]
-regex = "1.9"
+regex = "1.10.4"
 chrono = { version="0.4", default-features=false, features=["std", "alloc", "clock"] }
+nom = "7.1.3"

README.md

@@ -20,7 +20,7 @@ Add this to your `Cargo.toml`:
 
 ```toml
 [dependencies]
-parse_datetime = "0.4.0"
+parse_datetime = "0.5.0"
 ```
 
 Then, import the crate and use the `parse_datetime_at_date` function:
@@ -38,13 +38,13 @@ assert_eq!(
 );
 ```
 
-For DateTime parsing, import the `parse_datetime` module:
+For DateTime parsing, import the `parse_datetime` function:
 
 ```rs
-use parse_datetime::parse_datetime::from_str;
+use parse_datetime::parse_datetime;
 use chrono::{Local, TimeZone};
 
-let dt = from_str("2021-02-14 06:37:47");
+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());
 ```
 

fuzz/Cargo.lock

@@ -148,9 +148,9 @@ checksum = "6a987beff54b60ffa6d51982e1aa1146bc42f19bd26be28b0586f252fccf5317"
 
 [[package]]
 name = "libfuzzer-sys"
-version = "0.4.6"
+version = "0.4.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "beb09950ae85a0a94b27676cccf37da5ff13f27076aa1adbc6545dd0d0e1bd4e"
+checksum = "a96cfd5557eb82f2b83fed4955246c988d331975a002961b07c81584d107e7f7"
 dependencies = [
  "arbitrary",
  "cc",
@@ -169,6 +169,22 @@ version = "2.6.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "5486aed0026218e61b8a01d5fbd5a0a134649abb71a0e53b7bc088529dced86e"
 
+[[package]]
+name = "minimal-lexical"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "68354c5c6bd36d73ff3feceb05efa59b6acb7626617f4962be322a825e61f79a"
+
+[[package]]
+name = "nom"
+version = "7.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d273983c5a657a70a3e8f2a01329822f3b8c8172b73826411a55751e404a0a4a"
+dependencies = [
+ "memchr",
+ "minimal-lexical",
+]
+
 [[package]]
 name = "num-traits"
 version = "0.2.15"
@@ -189,6 +205,7 @@ name = "parse_datetime"
 version = "0.5.0"
 dependencies = [
  "chrono",
+ "nom",
  "regex",
 ]
 
@@ -248,9 +265,9 @@ dependencies = [
 
 [[package]]
 name = "regex"
-version = "1.9.5"
+version = "1.10.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "697061221ea1b4a94a624f67d0ae2bfe4e22b8a17b6a192afb11046542cc8c47"
+checksum = "c117dbdfde9c8308975b6a18d71f3f385c89461f7b3fb054288ecf2a2058ba4c"
 dependencies = [
  "aho-corasick",
  "memchr",
@@ -260,9 +277,9 @@ dependencies = [
 
 [[package]]
 name = "regex-automata"
-version = "0.3.8"
+version = "0.4.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c2f401f4955220693b56f8ec66ee9c78abffd8d1c4f23dc41a23839eb88f0795"
+checksum = "3b7fa1134405e2ec9353fd416b17f8dacd46c473d7d3fd1cf202706a14eb792a"
 dependencies = [
  "aho-corasick",
  "memchr",
@@ -271,9 +288,9 @@ dependencies = [
 
 [[package]]
 name = "regex-syntax"
-version = "0.7.5"
+version = "0.8.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "dbb5fb1acd8a1a18b3dd5be62d25485eb770e05afb408a9627d14d451bae12da"
+checksum = "c08c74e62047bb2de4ff487b251e4a92e24f48745648451635cec7d591162d9f"
 
 [[package]]
 name = "syn"

fuzz/Cargo.toml

@@ -8,8 +8,8 @@ cargo-fuzz = true
 
 [dependencies]
 rand = "0.8.5"
-libfuzzer-sys = "0.4"
-regex = "1.9.5"
+libfuzzer-sys = "0.4.7"
+regex = "1.10.4"
 chrono = { version="0.4", default-features=false, features=["std", "alloc", "clock"] }
 
 [dependencies.parse_datetime]

src/lib.rs

@@ -14,10 +14,18 @@ use std::fmt::{self, Display};
 
 // Expose parse_datetime
 mod parse_relative_time;
+mod parse_timestamp;
 
-use chrono::{DateTime, FixedOffset, Local, LocalResult, NaiveDateTime, TimeZone};
+mod parse_time_only_str;
+mod parse_weekday;
+
+use chrono::{
+    DateTime, Datelike, Duration, FixedOffset, Local, LocalResult, NaiveDateTime, TimeZone,
+    Timelike,
+};
 
 use parse_relative_time::parse_relative_time;
+use parse_timestamp::parse_timestamp;
 
 #[derive(Debug, PartialEq)]
 pub enum ParseDateTimeError {
@@ -168,19 +176,38 @@ pub fn parse_datetime_at_date<S: AsRef<str> + Clone>(
         }
     }
 
+    // parse weekday
+    if let Some(weekday) = parse_weekday::parse_weekday(s.as_ref()) {
+        let mut beginning_of_day = date
+            .with_hour(0)
+            .unwrap()
+            .with_minute(0)
+            .unwrap()
+            .with_second(0)
+            .unwrap()
+            .with_nanosecond(0)
+            .unwrap();
+
+        while beginning_of_day.weekday() != weekday {
+            beginning_of_day += Duration::days(1);
+        }
+
+        let dt = DateTime::<FixedOffset>::from(beginning_of_day);
+
+        return Ok(dt);
+    }
+
     // Parse epoch seconds
-    if s.as_ref().bytes().next() == Some(b'@') {
-        if let Ok(parsed) = NaiveDateTime::parse_from_str(&s.as_ref()[1..], "%s") {
-            if let Ok(dt) = naive_dt_to_fixed_offset(date, parsed) {
-                return Ok(dt);
-            }
+    if let Ok(timestamp) = parse_timestamp(s.as_ref()) {
+        if let Some(timestamp_date) = NaiveDateTime::from_timestamp_opt(timestamp, 0) {
+            return Ok(date.offset().from_utc_datetime(&timestamp_date));
         }
     }
 
-    let ts = s.as_ref().to_owned() + "0000";
+    let ts = s.as_ref().to_owned() + " 0000";
     // Parse date only formats - assume midnight local timezone
     for fmt in [format::ISO_8601, format::ISO_8601_NO_SEP] {
-        let f = fmt.to_owned() + "%H%M";
+        let f = fmt.to_owned() + " %H%M";
         if let Ok(parsed) = NaiveDateTime::parse_from_str(&ts, &f) {
             if let Ok(dt) = naive_dt_to_fixed_offset(date, parsed) {
                 return Ok(dt);
@@ -209,6 +236,11 @@ pub fn parse_datetime_at_date<S: AsRef<str> + Clone>(
         }
     }
 
+    // parse time only dates
+    if let Some(date_time) = parse_time_only_str::parse_time_only(date, s.as_ref()) {
+        return Ok(date_time);
+    }
+
     // Default parse and failure
     s.as_ref()
         .parse()
@@ -285,6 +317,31 @@ mod tests {
             let actual = parse_datetime(dt);
             assert_eq!(actual.unwrap().timestamp(), TEST_TIME);
         }
+
+        #[test]
+        fn test_epoch_seconds_non_utc() {
+            env::set_var("TZ", "EST");
+            let dt = "@1613371067";
+            let actual = parse_datetime(dt);
+            assert_eq!(actual.unwrap().timestamp(), TEST_TIME);
+        }
+    }
+
+    #[cfg(test)]
+    mod formats {
+        use crate::parse_datetime;
+        use chrono::{DateTime, Local, TimeZone};
+
+        #[test]
+        fn single_digit_month_day() {
+            let x = Local.with_ymd_and_hms(1987, 5, 7, 0, 0, 0).unwrap();
+            let expected = DateTime::fixed_offset(&x);
+
+            assert_eq!(Ok(expected), parse_datetime("1987-05-07"));
+            assert_eq!(Ok(expected), parse_datetime("1987-5-07"));
+            assert_eq!(Ok(expected), parse_datetime("1987-05-7"));
+            assert_eq!(Ok(expected), parse_datetime("1987-5-7"));
+        }
     }
 
     #[cfg(test)]
@@ -348,30 +405,101 @@ mod tests {
             ];
 
             for relative_time in relative_times {
-                assert_eq!(parse_datetime(relative_time).is_ok(), true);
+                assert!(parse_datetime(relative_time).is_ok());
             }
         }
     }
 
+    #[cfg(test)]
+    mod weekday {
+        use chrono::{DateTime, Local, TimeZone};
+
+        use crate::parse_datetime_at_date;
+
+        fn get_formatted_date(date: DateTime<Local>, weekday: &str) -> String {
+            let result = parse_datetime_at_date(date, weekday).unwrap();
+
+            return result.format("%F %T %f").to_string();
+        }
+        #[test]
+        fn test_weekday() {
+            // add some constant hours and minutes and seconds to check its reset
+            let date = Local.with_ymd_and_hms(2023, 2, 28, 10, 12, 3).unwrap();
+
+            // 2023-2-28 is tuesday
+            assert_eq!(
+                get_formatted_date(date, "tuesday"),
+                "2023-02-28 00:00:00 000000000"
+            );
+
+            // 2023-3-01 is wednesday
+            assert_eq!(
+                get_formatted_date(date, "wed"),
+                "2023-03-01 00:00:00 000000000"
+            );
+
+            assert_eq!(
+                get_formatted_date(date, "thu"),
+                "2023-03-02 00:00:00 000000000"
+            );
+
+            assert_eq!(
+                get_formatted_date(date, "fri"),
+                "2023-03-03 00:00:00 000000000"
+            );
+
+            assert_eq!(
+                get_formatted_date(date, "sat"),
+                "2023-03-04 00:00:00 000000000"
+            );
+
+            assert_eq!(
+                get_formatted_date(date, "sun"),
+                "2023-03-05 00:00:00 000000000"
+            );
+        }
+    }
+
     #[cfg(test)]
     mod timestamp {
         use crate::parse_datetime;
         use chrono::{TimeZone, Utc};
 
         #[test]
-        fn test_positive_offsets() {
+        fn test_positive_and_negative_offsets() {
             let offsets: Vec<i64> = vec![
                 0, 1, 2, 10, 100, 150, 2000, 1234400000, 1334400000, 1692582913, 2092582910,
             ];
 
             for offset in offsets {
+                // positive offset
                 let time = Utc.timestamp_opt(offset, 0).unwrap();
                 let dt = parse_datetime(format!("@{}", offset));
                 assert_eq!(dt.unwrap(), time);
+
+                // negative offset
+                let time = Utc.timestamp_opt(-offset, 0).unwrap();
+                let dt = parse_datetime(format!("@-{}", offset));
+                assert_eq!(dt.unwrap(), time);
             }
         }
     }
 
+    #[cfg(test)]
+    mod timeonly {
+        use crate::parse_datetime_at_date;
+        use chrono::{Local, TimeZone};
+        use std::env;
+        #[test]
+        fn test_time_only() {
+            env::set_var("TZ", "UTC");
+            let test_date = Local.with_ymd_and_hms(2024, 3, 3, 0, 0, 0).unwrap();
+            let parsed_time = parse_datetime_at_date(test_date, "9:04:30 PM +0530")
+                .unwrap()
+                .timestamp();
+            assert_eq!(parsed_time, 1709480070)
+        }
+    }
     /// Used to test example code presented in the README.
     mod readme_test {
         use crate::parse_datetime;

src/parse_relative_time.rs

@@ -1,3 +1,5 @@
+// For the full copyright and license information, please view the LICENSE
+// file that was distributed with this source code.
 use crate::ParseDateTimeError;
 use chrono::{Duration, Local, NaiveDate, Utc};
 use regex::Regex;

src/parse_time_only_str.rs

@@ -0,0 +1,120 @@
+use chrono::{DateTime, FixedOffset, Local, NaiveTime, TimeZone};
+use regex::Regex;
+
+mod time_only_formats {
+    pub const HH_MM: &str = "%R";
+    pub const HH_MM_SS: &str = "%T";
+    pub const TWELVEHOUR: &str = "%r";
+}
+
+pub(crate) fn parse_time_only(date: DateTime<Local>, s: &str) -> Option<DateTime<FixedOffset>> {
+    let re =
+        Regex::new(r"^(?<time>.*?)(?:(?<sign>\+|-)(?<h>[0-9]{1,2}):?(?<m>[0-9]{0,2}))?$").unwrap();
+    let captures = re.captures(s)?;
+
+    let parsed_offset = match captures.name("h") {
+        Some(hours) if !(hours.as_str().is_empty()) => {
+            let mut offset_in_sec = hours.as_str().parse::<i32>().unwrap() * 3600;
+            match captures.name("m") {
+                Some(minutes) if !(minutes.as_str().is_empty()) => {
+                    offset_in_sec += minutes.as_str().parse::<i32>().unwrap() * 60;
+                }
+                _ => (),
+            };
+            offset_in_sec *= if &captures["sign"] == "-" { -1 } else { 1 };
+            FixedOffset::east_opt(offset_in_sec)
+        }
+        _ => None,
+    };
+
+    for fmt in [
+        time_only_formats::HH_MM,
+        time_only_formats::HH_MM_SS,
+        time_only_formats::TWELVEHOUR,
+    ] {
+        if let Ok(parsed) = NaiveTime::parse_from_str(captures["time"].trim(), fmt) {
+            let parsed_dt = date.date_naive().and_time(parsed);
+            let offset = match parsed_offset {
+                Some(offset) => offset,
+                None => *date.offset(),
+            };
+            return offset.from_local_datetime(&parsed_dt).single();
+        }
+    }
+
+    None
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::parse_time_only_str::parse_time_only;
+    use chrono::{DateTime, Local, TimeZone};
+    use std::env;
+
+    fn get_test_date() -> DateTime<Local> {
+        Local.with_ymd_and_hms(2024, 3, 3, 0, 0, 0).unwrap()
+    }
+
+    #[test]
+    fn test_time_only() {
+        env::set_var("TZ", "UTC");
+        let parsed_time = parse_time_only(get_test_date(), "21:04")
+            .unwrap()
+            .timestamp();
+        assert_eq!(parsed_time, 1709499840)
+    }
+
+    #[test]
+    fn test_time_with_offset() {
+        env::set_var("TZ", "UTC");
+        let parsed_time = parse_time_only(get_test_date(), "21:04 +0530")
+            .unwrap()
+            .timestamp();
+        assert_eq!(parsed_time, 1709480040);
+    }
+
+    #[test]
+    fn test_time_with_hour_only_offset() {
+        env::set_var("TZ", "UTC");
+        let parsed_time = parse_time_only(get_test_date(), "22:04 +01")
+            .unwrap()
+            .timestamp();
+        assert_eq!(parsed_time, 1709499840);
+    }
+
+    #[test]
+    fn test_time_with_hour_only_neg_offset() {
+        env::set_var("TZ", "UTC");
+        let parsed_time = parse_time_only(get_test_date(), "17:04 -04")
+            .unwrap()
+            .timestamp();
+        assert_eq!(parsed_time, 1709499840);
+    }
+
+    #[test]
+    fn test_time_with_seconds() {
+        env::set_var("TZ", "UTC");
+        let parsed_time = parse_time_only(get_test_date(), "21:04:30")
+            .unwrap()
+            .timestamp();
+        assert_eq!(parsed_time, 1709499870)
+    }
+
+    #[test]
+    fn test_time_with_seconds_with_offset() {
+        env::set_var("TZ", "UTC");
+        let parsed_time = parse_time_only(get_test_date(), "21:04:30 +0530")
+            .unwrap()
+            .timestamp();
+        assert_eq!(parsed_time, 1709480070)
+    }
+
+    #[test]
+    fn test_twelve_hour_time() {
+        env::set_var("TZ", "UTC");
+        let parsed_time = parse_time_only(get_test_date(), "9:04:00 PM")
+            .unwrap()
+            .timestamp();
+        assert_eq!(parsed_time, 1709499840)
+    }
+}

src/parse_timestamp.rs

@@ -0,0 +1,111 @@
+// For the full copyright and license information, please view the LICENSE
+// file that was distributed with this source code.
+use core::fmt;
+use std::error::Error;
+use std::fmt::Display;
+use std::num::ParseIntError;
+
+use nom::branch::alt;
+use nom::character::complete::{char, digit1};
+use nom::combinator::all_consuming;
+use nom::multi::fold_many0;
+use nom::sequence::preceded;
+use nom::sequence::tuple;
+use nom::{self, IResult};
+
+#[derive(Debug, PartialEq)]
+pub enum ParseTimestampError {
+    InvalidNumber(ParseIntError),
+    InvalidInput,
+}
+
+impl Display for ParseTimestampError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::InvalidInput => {
+                write!(f, "Invalid input string: cannot be parsed as a timestamp")
+            }
+            Self::InvalidNumber(err) => {
+                write!(f, "Invalid timestamp number: {err}")
+            }
+        }
+    }
+}
+
+impl Error for ParseTimestampError {}
+
+// TODO is this necessary
+impl From<ParseIntError> for ParseTimestampError {
+    fn from(err: ParseIntError) -> Self {
+        Self::InvalidNumber(err)
+    }
+}
+
+type NomError<'a> = nom::Err<nom::error::Error<&'a str>>;
+
+impl<'a> From<NomError<'a>> for ParseTimestampError {
+    fn from(_err: NomError<'a>) -> Self {
+        Self::InvalidInput
+    }
+}
+
+pub(crate) fn parse_timestamp(s: &str) -> Result<i64, ParseTimestampError> {
+    let s = s.trim().to_lowercase();
+    let s = s.as_str();
+
+    let res: IResult<&str, (char, &str)> = all_consuming(preceded(
+        char('@'),
+        tuple((
+            // Note: to stay compatible with gnu date this code allows
+            // multiple + and - and only considers the last one
+            fold_many0(
+                // parse either + or -
+                alt((char('+'), char('-'))),
+                // start with a +
+                || '+',
+                // whatever we get (+ or -), update the accumulator to that value
+                |_, c| c,
+            ),
+            digit1,
+        )),
+    ))(s);
+
+    let (_, (sign, number_str)) = res?;
+
+    let mut number = number_str.parse::<i64>()?;
+
+    if sign == '-' {
+        number *= -1;
+    }
+
+    Ok(number)
+}
+
+#[cfg(test)]
+mod tests {
+
+    use crate::parse_timestamp::parse_timestamp;
+
+    #[test]
+    fn test_valid_timestamp() {
+        assert_eq!(parse_timestamp("@1234"), Ok(1234));
+        assert_eq!(parse_timestamp("@99999"), Ok(99999));
+        assert_eq!(parse_timestamp("@-4"), Ok(-4));
+        assert_eq!(parse_timestamp("@-99999"), Ok(-99999));
+        assert_eq!(parse_timestamp("@+4"), Ok(4));
+        assert_eq!(parse_timestamp("@0"), Ok(0));
+
+        // gnu date accepts numbers signs and uses the last sign
+        assert_eq!(parse_timestamp("@---+12"), Ok(12));
+        assert_eq!(parse_timestamp("@+++-12"), Ok(-12));
+        assert_eq!(parse_timestamp("@+----+12"), Ok(12));
+        assert_eq!(parse_timestamp("@++++-123"), Ok(-123));
+    }
+
+    #[test]
+    fn test_invalid_timestamp() {
+        assert!(parse_timestamp("@").is_err());
+        assert!(parse_timestamp("@+--+").is_err());
+        assert!(parse_timestamp("@+1ab2").is_err());
+    }
+}

src/parse_weekday.rs

@@ -0,0 +1,99 @@
+// For the full copyright and license information, please view the LICENSE
+// file that was distributed with this source code.
+use chrono::Weekday;
+use nom::branch::alt;
+use nom::bytes::complete::tag;
+use nom::combinator::value;
+use nom::{self, IResult};
+
+// Helper macro to simplify tag matching
+macro_rules! tag_match {
+    ($day:expr, $($pattern:expr),+) => {
+        value($day, alt(($(tag($pattern)),+)))
+    };
+}
+
+pub(crate) fn parse_weekday(s: &str) -> Option<Weekday> {
+    let s = s.trim().to_lowercase();
+    let s = s.as_str();
+
+    let parse_result: IResult<&str, Weekday> = nom::combinator::all_consuming(alt((
+        tag_match!(Weekday::Mon, "monday", "mon"),
+        tag_match!(Weekday::Tue, "tuesday", "tues", "tue"),
+        tag_match!(Weekday::Wed, "wednesday", "wednes", "wed"),
+        tag_match!(Weekday::Thu, "thursday", "thurs", "thur", "thu"),
+        tag_match!(Weekday::Fri, "friday", "fri"),
+        tag_match!(Weekday::Sat, "saturday", "sat"),
+        tag_match!(Weekday::Sun, "sunday", "sun"),
+    )))(s);
+
+    match parse_result {
+        Ok((_, weekday)) => Some(weekday),
+        Err(_) => None,
+    }
+}
+
+#[cfg(test)]
+mod tests {
+
+    use chrono::Weekday::*;
+
+    use crate::parse_weekday::parse_weekday;
+
+    #[test]
+    fn test_valid_weekdays() {
+        let days = [
+            ("mon", Mon),
+            ("monday", Mon),
+            ("tue", Tue),
+            ("tues", Tue),
+            ("tuesday", Tue),
+            ("wed", Wed),
+            ("wednes", Wed),
+            ("wednesday", Wed),
+            ("thu", Thu),
+            ("thursday", Thu),
+            ("fri", Fri),
+            ("friday", Fri),
+            ("sat", Sat),
+            ("saturday", Sat),
+            ("sun", Sun),
+            ("sunday", Sun),
+        ];
+
+        for (name, weekday) in days {
+            assert_eq!(parse_weekday(name), Some(weekday));
+            assert_eq!(parse_weekday(&format!(" {}", name)), Some(weekday));
+            assert_eq!(parse_weekday(&format!(" {} ", name)), Some(weekday));
+            assert_eq!(parse_weekday(&format!("{} ", name)), Some(weekday));
+
+            let (left, right) = name.split_at(1);
+            let (test_str1, test_str2) = (
+                format!("{}{}", left.to_uppercase(), right.to_lowercase()),
+                format!("{}{}", left.to_lowercase(), right.to_uppercase()),
+            );
+
+            assert_eq!(parse_weekday(&test_str1), Some(weekday));
+            assert_eq!(parse_weekday(&test_str2), Some(weekday));
+        }
+    }
+
+    #[test]
+    fn test_invalid_weekdays() {
+        let days = [
+            "mond",
+            "tuesda",
+            "we",
+            "th",
+            "fr",
+            "sa",
+            "su",
+            "garbageday",
+            "tomorrow",
+            "yesterday",
+        ];
+        for day in days {
+            assert!(parse_weekday(day).is_none());
+        }
+    }
+}