Adds a public Month enum.

Implementation for a Month enum, allowing -ser|de-rialization.
The implementation mostly mirrors the Weekday enum.
It only adds the enum with minimal integration so as to
not cause any backwards compatibility issue.
A deeper integration should be up to discussion.
Suggested in Issue chronotope#202

CHANGELOG.md

@@ -12,13 +12,13 @@ Versions with only mechanical changes will be omitted from the following list.
 
 ### Features
 
-* Added day and week iterators for `NaiveDate` (@gnzlbg & @robyoung)
+* Add day and week iterators for `NaiveDate` (@gnzlbg & @robyoung)
+* Add a `Month` enum (@hhamana)
 
 ### Improvements
 
 * Added MIN and MAX values for `NaiveTime`, `NaiveDateTime` and `DateTime<Utc>`.
 
-
 ## 0.4.13
 
 ### Features

src/format/mod.rs

@@ -28,15 +28,14 @@ use core::str::FromStr;
 #[cfg(any(feature = "std", test))]
 use std::error::Error;
 
-#[cfg(any(feature = "alloc", feature = "std", test))]
 use div::{div_floor, mod_floor};
 #[cfg(any(feature = "alloc", feature = "std", test))]
 use naive::{NaiveDate, NaiveTime};
 #[cfg(any(feature = "alloc", feature = "std", test))]
 use offset::{FixedOffset, Offset};
 #[cfg(any(feature = "alloc", feature = "std", test))]
-use {Datelike, Timelike};
-use {ParseWeekdayError, Weekday};
+use {Datelike, Month, Timelike, Weekday};
+use {ParseMonthError, ParseWeekdayError};
 
 pub use self::parse::parse;
 pub use self::parsed::Parsed;
@@ -759,3 +758,54 @@ impl FromStr for Weekday {
         }
     }
 }
+
+/// Parsing a `str` into a `Month` uses the format [`%W`](./format/strftime/index.html).
+///
+/// # Example
+///
+/// ~~~~
+/// use chrono::Month;
+///
+/// assert_eq!("January".parse::<Month>(), Ok(Month::January));
+/// assert!("any day".parse::<Month>().is_err());
+/// ~~~~
+///
+/// The parsing is case-insensitive.
+///
+/// ~~~~
+/// # use chrono::Month;
+/// assert_eq!("fEbruARy".parse::<Month>(), Ok(Month::February));
+/// ~~~~
+///
+/// Only the shortest form (e.g. `jan`) and the longest form (e.g. `january`) is accepted.
+///
+/// ~~~~
+/// # use chrono::Month;
+/// assert!("septem".parse::<Month>().is_err());
+/// assert!("Augustin".parse::<Month>().is_err());
+/// ~~~~
+impl FromStr for Month {
+    type Err = ParseMonthError;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        if let Ok(("", w)) = scan::short_or_long_month0(s) {
+            match w {
+                0 => Ok(Month::January),
+                1 => Ok(Month::February),
+                2 => Ok(Month::March),
+                3 => Ok(Month::April),
+                4 => Ok(Month::May),
+                5 => Ok(Month::June),
+                6 => Ok(Month::July),
+                7 => Ok(Month::August),
+                8 => Ok(Month::September),
+                9 => Ok(Month::October),
+                10 => Ok(Month::November),
+                11 => Ok(Month::December),
+                _ => Err(ParseMonthError { _dummy: () }),
+            }
+        } else {
+            Err(ParseMonthError { _dummy: () })
+        }
+    }
+}