Convert NaiveDate/NaiveDateTime::checked_(add/sub)_days to return Result

Author: Zomtir

src/datetime/mod.rs

@@ -28,8 +28,7 @@ use crate::offset::Local;
 use crate::offset::{FixedOffset, Offset, TimeZone, Utc};
 #[cfg(any(feature = "clock", feature = "std"))]
 use crate::OutOfRange;
-use crate::{try_err, try_ok_or};
-use crate::{Datelike, Error, Months, TimeDelta, Timelike, Weekday};
+use crate::{try_err, try_ok_or, Datelike, Error, Months, TimeDelta, Timelike, Weekday};
 
 #[cfg(any(feature = "rkyv", feature = "rkyv-16", feature = "rkyv-32", feature = "rkyv-64"))]
 use rkyv::{Archive, Deserialize, Serialize};
@@ -396,9 +395,10 @@ impl<Tz: TimeZone> DateTime<Tz> {
         // `NaiveDate::add_days` has a fast path if the result remains within the same year, that
         // does not validate the resulting date. This allows us to return `Some` even for an out of
         // range local datetime when adding `Days(0)`.
-        self.overflowing_naive_local()
-            .checked_add_days(days)
-            .and_then(|dt| self.timezone().from_local_datetime(&dt).single())
+        let naive = self.overflowing_naive_local().checked_add_days(days).ok()?;
+        self.timezone()
+            .from_local_datetime(&naive)
+            .single()
             .filter(|dt| dt <= &DateTime::<Utc>::MAX_UTC)
     }
 
@@ -416,9 +416,10 @@ impl<Tz: TimeZone> DateTime<Tz> {
         // `NaiveDate::add_days` has a fast path if the result remains within the same year, that
         // does not validate the resulting date. This allows us to return `Some` even for an out of
         // range local datetime when adding `Days(0)`.
-        self.overflowing_naive_local()
-            .checked_sub_days(days)
-            .and_then(|dt| self.timezone().from_local_datetime(&dt).single())
+        let naive = self.overflowing_naive_local().checked_sub_days(days).ok()?;
+        self.timezone()
+            .from_local_datetime(&naive)
+            .single()
             .filter(|dt| dt >= &DateTime::<Utc>::MIN_UTC)
     }
 

src/naive/date/mod.rs

@@ -557,89 +557,83 @@ impl NaiveDate {
     ///
     /// # Errors
     ///
-    /// Returns `None` if the resulting date would be out of range.
+    /// Returns [`Error::OutOfRange`] if the resulting date would be out of range.
     ///
     /// # Example
     ///
     /// ```
-    /// # use chrono::{NaiveDate, Days};
-    /// assert_eq!(
-    ///     NaiveDate::from_ymd(2022, 2, 20).unwrap().checked_add_days(Days::new(9)),
-    ///     Some(NaiveDate::from_ymd(2022, 3, 1).unwrap())
-    /// );
+    /// # use chrono::{NaiveDate, Days, Error};
     /// assert_eq!(
-    ///     NaiveDate::from_ymd(2022, 7, 31).unwrap().checked_add_days(Days::new(2)),
-    ///     Some(NaiveDate::from_ymd(2022, 8, 2).unwrap())
+    ///     NaiveDate::from_ymd(2022, 2, 20)?.checked_add_days(Days::new(9)),
+    ///     NaiveDate::from_ymd(2022, 3, 1)
     /// );
     /// assert_eq!(
-    ///     NaiveDate::from_ymd(2022, 7, 31).unwrap().checked_add_days(Days::new(1000000000000)),
-    ///     None
+    ///     NaiveDate::from_ymd(2022, 7, 31)?.checked_add_days(Days::new(1000000000000)),
+    ///     Err(Error::OutOfRange)
     /// );
+    /// # Ok::<(), Error>(())
     /// ```
-    #[must_use]
-    pub const fn checked_add_days(self, days: Days) -> Option<Self> {
+    pub const fn checked_add_days(self, days: Days) -> Result<Self, Error> {
         match days.0 <= i32::MAX as u64 {
             true => self.add_days(days.0 as i32),
-            false => None,
+            false => Err(Error::OutOfRange),
         }
     }
 
     /// Subtract a duration in [`Days`] from the date
     ///
     /// # Errors
     ///
-    /// Returns `None` if the resulting date would be out of range.
+    /// Returns [`Error::OutOfRange`] if the resulting date would be out of range.
     ///
     /// # Example
     ///
     /// ```
-    /// # use chrono::{NaiveDate, Days};
+    /// # use chrono::{NaiveDate, Days, Error};
     /// assert_eq!(
-    ///     NaiveDate::from_ymd(2022, 2, 20).unwrap().checked_sub_days(Days::new(6)),
-    ///     Some(NaiveDate::from_ymd(2022, 2, 14).unwrap())
+    ///     NaiveDate::from_ymd(2022, 2, 20)?.checked_sub_days(Days::new(6)),
+    ///     NaiveDate::from_ymd(2022, 2, 14)
     /// );
     /// assert_eq!(
-    ///     NaiveDate::from_ymd(2022, 2, 20).unwrap().checked_sub_days(Days::new(1000000000000)),
-    ///     None
+    ///     NaiveDate::from_ymd(2022, 2, 20)?.checked_sub_days(Days::new(1000000000000)),
+    ///     Err(Error::OutOfRange)
     /// );
+    /// # Ok::<(), Error>(())
     /// ```
-    #[must_use]
-    pub const fn checked_sub_days(self, days: Days) -> Option<Self> {
+    pub const fn checked_sub_days(self, days: Days) -> Result<Self, Error> {
         match days.0 <= i32::MAX as u64 {
             true => self.add_days(-(days.0 as i32)),
-            false => None,
+            false => Err(Error::OutOfRange),
         }
     }
 
     /// Add a duration of `i32` days to the date.
-    pub(crate) const fn add_days(self, days: i32) -> Option<Self> {
+    pub(crate) const fn add_days(self, days: i32) -> Result<Self, Error> {
         // Fast path if the result is within the same year.
         // Also `DateTime::checked_(add|sub)_days` relies on this path, because if the value remains
         // within the year it doesn't do a check if the year is in range.
         // This way `DateTime:checked_(add|sub)_days(Days::new(0))` can be a no-op on dates were the
         // local datetime is beyond `NaiveDate::{MIN, MAX}.
         const ORDINAL_MASK: i32 = 0b1_1111_1111_0000;
-        if let Some(ordinal) = ((self.yof() & ORDINAL_MASK) >> 4).checked_add(days) {
+        let ordinal =
+            try_ok_or!(((self.yof() & ORDINAL_MASK) >> 4).checked_add(days), Error::OutOfRange);
+        {
             if ordinal > 0 && ordinal <= (365 + self.leap_year() as i32) {
                 let year_and_flags = self.yof() & !ORDINAL_MASK;
-                return Some(NaiveDate::from_yof(year_and_flags | (ordinal << 4)));
+                return Ok(NaiveDate::from_yof(year_and_flags | (ordinal << 4)));
             }
         }
         // do the full check
         let year = self.year();
         let (mut year_div_400, year_mod_400) = div_mod_floor(year, 400);
         let cycle = yo_to_cycle(year_mod_400 as u32, self.ordinal());
-        let cycle = try_opt!((cycle as i32).checked_add(days));
+        let cycle = try_ok_or!((cycle as i32).checked_add(days), Error::OutOfRange);
         let (cycle_div_400y, cycle) = div_mod_floor(cycle, 146_097);
         year_div_400 += cycle_div_400y;
 
         let (year_mod_400, ordinal) = cycle_to_yo(cycle as u32);
         let flags = YearFlags::from_year_mod_400(year_mod_400 as i32);
-        ok!(NaiveDate::from_ordinal_and_flags(
-            year_div_400 * 400 + year_mod_400 as i32,
-            ordinal,
-            flags
-        ))
+        NaiveDate::from_ordinal_and_flags(year_div_400 * 400 + year_mod_400 as i32, ordinal, flags)
     }
 
     /// Makes a new `NaiveDateTime` from the current date and given `NaiveTime`.
@@ -903,7 +897,7 @@ impl NaiveDate {
         if days < i32::MIN as i64 || days > i32::MAX as i64 {
             return None;
         }
-        self.add_days(days as i32)
+        ok!(self.add_days(days as i32))
     }
 
     /// Subtracts the number of whole days in the given `TimeDelta` from the current date.
@@ -936,7 +930,7 @@ impl NaiveDate {
         if days < i32::MIN as i64 || days > i32::MAX as i64 {
             return None;
         }
-        self.add_days(days as i32)
+        ok!(self.add_days(days as i32))
     }
 
     /// Subtracts another `NaiveDate` from the current date.
@@ -1995,7 +1989,7 @@ impl Iterator for NaiveDateWeeksIterator {
 
     fn next(&mut self) -> Option<Self::Item> {
         let current = self.value;
-        self.value = current.checked_add_days(Days::new(7))?;
+        self.value = current.checked_add_days(Days::new(7)).ok()?;
         Some(current)
     }
 
@@ -2010,7 +2004,7 @@ impl ExactSizeIterator for NaiveDateWeeksIterator {}
 impl DoubleEndedIterator for NaiveDateWeeksIterator {
     fn next_back(&mut self) -> Option<Self::Item> {
         let current = self.value;
-        self.value = current.checked_sub_days(Days::new(7))?;
+        self.value = current.checked_sub_days(Days::new(7)).ok()?;
         Some(current)
     }
 }

src/naive/date/tests.rs

@@ -499,10 +499,10 @@ fn test_date_signed_duration_since() {
 
 #[test]
 fn test_date_add_days() {
-    fn check(lhs: Option<NaiveDate>, days: Days, rhs: Option<NaiveDate>) {
+    fn check(lhs: Result<NaiveDate, Error>, days: Days, rhs: Result<NaiveDate, Error>) {
         assert_eq!(lhs.unwrap().checked_add_days(days), rhs);
     }
-    let ymd = |y, m, d| NaiveDate::from_ymd(y, m, d).ok();
+    let ymd = NaiveDate::from_ymd;
 
     check(ymd(2014, 1, 1), Days::new(0), ymd(2014, 1, 1));
     // always round towards zero
@@ -514,16 +514,16 @@ fn test_date_add_days() {
     check(ymd(-7, 1, 1), Days::new(365 * 12 + 3), ymd(5, 1, 1));
 
     // overflow check
-    check(ymd(0, 1, 1), Days::new(MAX_DAYS_FROM_YEAR_0.try_into().unwrap()), ymd(MAX_YEAR, 12, 31));
-    check(ymd(0, 1, 1), Days::new(u64::try_from(MAX_DAYS_FROM_YEAR_0).unwrap() + 1), None);
+    check(ymd(0, 1, 1), Days::new(MAX_DAYS_FROM_YEAR_0 as u64), ymd(MAX_YEAR, 12, 31));
+    check(ymd(0, 1, 1), Days::new(MAX_DAYS_FROM_YEAR_0 as u64 + 1), Err(Error::OutOfRange));
 }
 
 #[test]
 fn test_date_sub_days() {
-    fn check(lhs: Option<NaiveDate>, days: Days, rhs: Option<NaiveDate>) {
+    fn check(lhs: Result<NaiveDate, Error>, days: Days, rhs: Result<NaiveDate, Error>) {
         assert_eq!(lhs.unwrap().checked_sub_days(days), rhs);
     }
-    let ymd = |y, m, d| NaiveDate::from_ymd(y, m, d).ok();
+    let ymd = NaiveDate::from_ymd;
 
     check(ymd(2014, 1, 1), Days::new(0), ymd(2014, 1, 1));
     check(ymd(2014, 1, 2), Days::new(1), ymd(2014, 1, 1));
@@ -532,12 +532,8 @@ fn test_date_sub_days() {
     check(ymd(2018, 1, 1), Days::new(365 * 4 + 1), ymd(2014, 1, 1));
     check(ymd(2414, 1, 1), Days::new(365 * 400 + 97), ymd(2014, 1, 1));
 
-    check(ymd(MAX_YEAR, 12, 31), Days::new(MAX_DAYS_FROM_YEAR_0.try_into().unwrap()), ymd(0, 1, 1));
-    check(
-        ymd(0, 1, 1),
-        Days::new((-MIN_DAYS_FROM_YEAR_0).try_into().unwrap()),
-        ymd(MIN_YEAR, 1, 1),
-    );
+    check(ymd(MAX_YEAR, 12, 31), Days::new(MAX_DAYS_FROM_YEAR_0 as u64), ymd(0, 1, 1));
+    check(ymd(0, 1, 1), Days::new((-MIN_DAYS_FROM_YEAR_0) as u64), ymd(MIN_YEAR, 1, 1));
 }
 
 #[test]

src/naive/datetime/mod.rs

@@ -529,18 +529,16 @@ impl NaiveDateTime {
 
     /// Add a duration in [`Days`] to the date part of the `NaiveDateTime`
     ///
-    /// Returns `None` if the resulting date would be out of range.
-    #[must_use]
-    pub const fn checked_add_days(self, days: Days) -> Option<Self> {
-        Some(Self { date: try_opt!(self.date.checked_add_days(days)), ..self })
+    /// Returns [`Error::OutOfRange`] if the resulting date would be out of range.
+    pub const fn checked_add_days(self, days: Days) -> Result<Self, Error> {
+        Ok(Self { date: try_err!(self.date.checked_add_days(days)), ..self })
     }
 
     /// Subtract a duration in [`Days`] from the date part of the `NaiveDateTime`
     ///
-    /// Returns `None` if the resulting date would be out of range.
-    #[must_use]
-    pub const fn checked_sub_days(self, days: Days) -> Option<Self> {
-        Some(Self { date: try_opt!(self.date.checked_sub_days(days)), ..self })
+    /// Returns [`Error::OutOfRange`] if the resulting date would be out of range.
+    pub const fn checked_sub_days(self, days: Days) -> Result<Self, Error> {
+        Ok(Self { date: try_err!(self.date.checked_sub_days(days)), ..self })
     }
 
     /// Subtracts another `NaiveDateTime` from the current date and time.

src/naive/mod.rs

@@ -6,8 +6,8 @@
 
 use core::ops::RangeInclusive;
 
-use crate::expect;
 use crate::Weekday;
+use crate::{expect, ok};
 
 pub(crate) mod date;
 pub(crate) mod datetime;
@@ -63,7 +63,7 @@ impl NaiveWeek {
         // Do not construct an intermediate date beyond `self.date`, because that may be out of
         // range if `date` is close to `NaiveDate::MAX`.
         let days = start - ref_day - if start > ref_day { 7 } else { 0 };
-        expect!(self.date.add_days(days), "first weekday out of range for `NaiveDate`")
+        expect!(ok!(self.date.add_days(days)), "first weekday out of range for `NaiveDate`")
     }
 
     /// Returns a date representing the last day of the week.
@@ -91,7 +91,7 @@ impl NaiveWeek {
         // Do not construct an intermediate date before `self.date` (like with `first_day()`),
         // because that may be out of range if `date` is close to `NaiveDate::MIN`.
         let days = end - ref_day + if end < ref_day { 7 } else { 0 };
-        expect!(self.date.add_days(days), "last weekday out of range for `NaiveDate`")
+        expect!(ok!(self.date.add_days(days)), "last weekday out of range for `NaiveDate`")
     }
 
     /// Returns a [`RangeInclusive<T>`] representing the whole week bounded by