add time unit abbr parser combinator

Cargo.toml

@@ -21,6 +21,7 @@ time = { version = "0.3.17", optional = true }
 
 serde = { version = "1.0.147", features = ["derive"], optional = true }
 rust_decimal = { version = "1.29.1", default-features = false }
+winnow = {version = "*",features = ["debug"]}
 
 [dev-dependencies]
 serde_json = { version = "1.0.87" }

src/lib.rs

@@ -165,6 +165,8 @@
 //! }
 //! ```
 
+mod parser;
+
 #[cfg(all(feature = "chrono", feature = "serde"))]
 use chrono::Duration as CDuration;
 
@@ -174,6 +176,7 @@ use nom::sequence::tuple;
 use rust_decimal::prelude::ToPrimitive;
 use rust_decimal::Decimal;
 use std::convert::TryFrom;
+use std::str::FromStr;
 use std::time::Duration;
 use thiserror::Error;
 #[cfg(all(feature = "time", feature = "serde"))]
@@ -212,6 +215,31 @@ enum TimeUnit {
     NanoSecond,
 }
 
+impl FromStr for TimeUnit {
+    type Err = DError;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        match &*s.to_lowercase() {
+            "y" | "year" => Ok(TimeUnit::Year),
+            "mon" | "month" => Ok(TimeUnit::Month),
+            "w" | "week" => Ok(TimeUnit::Week),
+            "d" | "day" => Ok(TimeUnit::Day),
+            "h" | "hour" | "hr" => Ok(TimeUnit::Hour),
+            "m" | "min" | "minute" => Ok(TimeUnit::Minute),
+            "s" | "sec" | "second" => Ok(TimeUnit::Second),
+            "ms" | "msec" | "millisecond" => Ok(TimeUnit::MilliSecond),
+            "µs" | "µsec" | "µsecond" | "us" | "usec" | "usecond" | "microsecond" => {
+                Ok(TimeUnit::MicroSecond)
+            }
+            "ns" | "nsec" | "nanosecond" => Ok(TimeUnit::NanoSecond),
+            _ => Err(DError::ParseError(format!(
+                "expect one of [y,mon,w,d,h,m,s,ms,µs,us,ns] or their longer forms.but find:{}",
+                s,
+            ))),
+        }
+    }
+}
+
 const ONE_MICROSECOND_NANOSECOND: u64 = 1000;
 const ONE_MILLISECOND_NANOSECOND: u64 = 1000 * ONE_MICROSECOND_NANOSECOND;
 const ONE_SECOND_NANOSECOND: u64 = 1000 * ONE_MILLISECOND_NANOSECOND;

src/parser.rs

@@ -0,0 +1,61 @@
+use crate::TimeUnit;
+use winnow::stream::AsChar;
+use winnow::token::take_while;
+use winnow::PResult;
+use winnow::Parser;
+
+fn time_unit_abbr(input: &mut &str) -> PResult<TimeUnit> {
+    take_while(1.., |c: char| c.is_alpha() || c == 'µ')
+        .try_map(str::parse)
+        .parse_next(input)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use winnow::Partial;
+
+    #[test]
+    fn test_time_unit_abbr() {
+        assert_eq!(
+            time_unit_abbr.parse_peek(&Partial::new("y")),
+            Ok(("", TimeUnit::Year))
+        );
+        assert_eq!(
+            time_unit_abbr.parse_peek(&Partial::new("mon")),
+            Ok(("", TimeUnit::Month))
+        );
+        assert_eq!(
+            time_unit_abbr.parse_peek(&Partial::new("w")),
+            Ok(("", TimeUnit::Week))
+        );
+        assert_eq!(
+            time_unit_abbr.parse_peek(&Partial::new("d")),
+            Ok(("", TimeUnit::Day))
+        );
+        assert_eq!(
+            time_unit_abbr.parse_peek(&Partial::new("h")),
+            Ok(("", TimeUnit::Hour))
+        );
+        assert_eq!(
+            time_unit_abbr.parse_peek(&Partial::new("m")),
+            Ok(("", TimeUnit::Minute))
+        );
+        assert_eq!(
+            time_unit_abbr.parse_peek(&Partial::new("s")),
+            Ok(("", TimeUnit::Second))
+        );
+        assert_eq!(
+            time_unit_abbr.parse_peek(&Partial::new("ms")),
+            Ok(("", TimeUnit::MilliSecond))
+        );
+        assert_eq!(
+            time_unit_abbr.parse_peek(&Partial::new("µs")),
+            Ok(("", TimeUnit::MicroSecond))
+        );
+        assert_eq!(
+            time_unit_abbr.parse_peek(&Partial::new("ns")),
+            Ok(("", TimeUnit::NanoSecond))
+        );
+    }
+}