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1 // This is a part of Chrono.
2 // See README.md and LICENSE.txt for details.
3 
4 //! The time zone which has a fixed offset from UTC.
5 
6 use core::fmt;
7 use core::str::FromStr;
8 
9 #[cfg(any(feature = "rkyv", feature = "rkyv-16", feature = "rkyv-32", feature = "rkyv-64"))]
10 use rkyv::{Archive, Deserialize, Serialize};
11 
12 use super::{MappedLocalTime, Offset, TimeZone};
13 use crate::format::{scan, ParseError, OUT_OF_RANGE};
14 use crate::naive::{NaiveDate, NaiveDateTime};
15 
16 /// The time zone with fixed offset, from UTC-23:59:59 to UTC+23:59:59.
17 ///
18 /// Using the [`TimeZone`](./trait.TimeZone.html) methods
19 /// on a `FixedOffset` struct is the preferred way to construct
20 /// `DateTime<FixedOffset>` instances. See the [`east_opt`](#method.east_opt) and
21 /// [`west_opt`](#method.west_opt) methods for examples.
22 #[derive(PartialEq, Eq, Hash, Copy, Clone)]
23 #[cfg_attr(
24     any(feature = "rkyv", feature = "rkyv-16", feature = "rkyv-32", feature = "rkyv-64"),
25     derive(Archive, Deserialize, Serialize),
26     archive(compare(PartialEq)),
27     archive_attr(derive(Clone, Copy, PartialEq, Eq, Hash, Debug))
28 )]
29 #[cfg_attr(feature = "rkyv-validation", archive(check_bytes))]
30 pub struct FixedOffset {
31     local_minus_utc: i32,
32 }
33 
34 impl FixedOffset {
35     /// Makes a new `FixedOffset` for the Eastern Hemisphere with given timezone difference.
36     /// The negative `secs` means the Western Hemisphere.
37     ///
38     /// Panics on the out-of-bound `secs`.
39     #[deprecated(since = "0.4.23", note = "use `east_opt()` instead")]
40     #[must_use]
east(secs: i32) -> FixedOffset41     pub fn east(secs: i32) -> FixedOffset {
42         FixedOffset::east_opt(secs).expect("FixedOffset::east out of bounds")
43     }
44 
45     /// Makes a new `FixedOffset` for the Eastern Hemisphere with given timezone difference.
46     /// The negative `secs` means the Western Hemisphere.
47     ///
48     /// Returns `None` on the out-of-bound `secs`.
49     ///
50     /// # Example
51     ///
52     /// ```
53     /// # #[cfg(feature = "alloc")] {
54     /// use chrono::{FixedOffset, TimeZone};
55     /// let hour = 3600;
56     /// let datetime =
57     ///     FixedOffset::east_opt(5 * hour).unwrap().with_ymd_and_hms(2016, 11, 08, 0, 0, 0).unwrap();
58     /// assert_eq!(&datetime.to_rfc3339(), "2016-11-08T00:00:00+05:00")
59     /// # }
60     /// ```
61     #[must_use]
east_opt(secs: i32) -> Option<FixedOffset>62     pub const fn east_opt(secs: i32) -> Option<FixedOffset> {
63         if -86_400 < secs && secs < 86_400 {
64             Some(FixedOffset { local_minus_utc: secs })
65         } else {
66             None
67         }
68     }
69 
70     /// Makes a new `FixedOffset` for the Western Hemisphere with given timezone difference.
71     /// The negative `secs` means the Eastern Hemisphere.
72     ///
73     /// Panics on the out-of-bound `secs`.
74     #[deprecated(since = "0.4.23", note = "use `west_opt()` instead")]
75     #[must_use]
west(secs: i32) -> FixedOffset76     pub fn west(secs: i32) -> FixedOffset {
77         FixedOffset::west_opt(secs).expect("FixedOffset::west out of bounds")
78     }
79 
80     /// Makes a new `FixedOffset` for the Western Hemisphere with given timezone difference.
81     /// The negative `secs` means the Eastern Hemisphere.
82     ///
83     /// Returns `None` on the out-of-bound `secs`.
84     ///
85     /// # Example
86     ///
87     /// ```
88     /// # #[cfg(feature = "alloc")] {
89     /// use chrono::{FixedOffset, TimeZone};
90     /// let hour = 3600;
91     /// let datetime =
92     ///     FixedOffset::west_opt(5 * hour).unwrap().with_ymd_and_hms(2016, 11, 08, 0, 0, 0).unwrap();
93     /// assert_eq!(&datetime.to_rfc3339(), "2016-11-08T00:00:00-05:00")
94     /// # }
95     /// ```
96     #[must_use]
west_opt(secs: i32) -> Option<FixedOffset>97     pub const fn west_opt(secs: i32) -> Option<FixedOffset> {
98         if -86_400 < secs && secs < 86_400 {
99             Some(FixedOffset { local_minus_utc: -secs })
100         } else {
101             None
102         }
103     }
104 
105     /// Returns the number of seconds to add to convert from UTC to the local time.
106     #[inline]
local_minus_utc(&self) -> i32107     pub const fn local_minus_utc(&self) -> i32 {
108         self.local_minus_utc
109     }
110 
111     /// Returns the number of seconds to add to convert from the local time to UTC.
112     #[inline]
utc_minus_local(&self) -> i32113     pub const fn utc_minus_local(&self) -> i32 {
114         -self.local_minus_utc
115     }
116 }
117 
118 /// Parsing a `str` into a `FixedOffset` uses the format [`%z`](crate::format::strftime).
119 impl FromStr for FixedOffset {
120     type Err = ParseError;
from_str(s: &str) -> Result<Self, Self::Err>121     fn from_str(s: &str) -> Result<Self, Self::Err> {
122         let (_, offset) = scan::timezone_offset(s, scan::colon_or_space, false, false, true)?;
123         Self::east_opt(offset).ok_or(OUT_OF_RANGE)
124     }
125 }
126 
127 impl TimeZone for FixedOffset {
128     type Offset = FixedOffset;
129 
from_offset(offset: &FixedOffset) -> FixedOffset130     fn from_offset(offset: &FixedOffset) -> FixedOffset {
131         *offset
132     }
133 
offset_from_local_date(&self, _local: &NaiveDate) -> MappedLocalTime<FixedOffset>134     fn offset_from_local_date(&self, _local: &NaiveDate) -> MappedLocalTime<FixedOffset> {
135         MappedLocalTime::Single(*self)
136     }
offset_from_local_datetime(&self, _local: &NaiveDateTime) -> MappedLocalTime<FixedOffset>137     fn offset_from_local_datetime(&self, _local: &NaiveDateTime) -> MappedLocalTime<FixedOffset> {
138         MappedLocalTime::Single(*self)
139     }
140 
offset_from_utc_date(&self, _utc: &NaiveDate) -> FixedOffset141     fn offset_from_utc_date(&self, _utc: &NaiveDate) -> FixedOffset {
142         *self
143     }
offset_from_utc_datetime(&self, _utc: &NaiveDateTime) -> FixedOffset144     fn offset_from_utc_datetime(&self, _utc: &NaiveDateTime) -> FixedOffset {
145         *self
146     }
147 }
148 
149 impl Offset for FixedOffset {
fix(&self) -> FixedOffset150     fn fix(&self) -> FixedOffset {
151         *self
152     }
153 }
154 
155 impl fmt::Debug for FixedOffset {
fmt(&self, f: &mut fmt::Formatter) -> fmt::Result156     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
157         let offset = self.local_minus_utc;
158         let (sign, offset) = if offset < 0 { ('-', -offset) } else { ('+', offset) };
159         let sec = offset.rem_euclid(60);
160         let mins = offset.div_euclid(60);
161         let min = mins.rem_euclid(60);
162         let hour = mins.div_euclid(60);
163         if sec == 0 {
164             write!(f, "{}{:02}:{:02}", sign, hour, min)
165         } else {
166             write!(f, "{}{:02}:{:02}:{:02}", sign, hour, min, sec)
167         }
168     }
169 }
170 
171 impl fmt::Display for FixedOffset {
fmt(&self, f: &mut fmt::Formatter) -> fmt::Result172     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
173         fmt::Debug::fmt(self, f)
174     }
175 }
176 
177 #[cfg(all(feature = "arbitrary", feature = "std"))]
178 impl arbitrary::Arbitrary<'_> for FixedOffset {
arbitrary(u: &mut arbitrary::Unstructured) -> arbitrary::Result<FixedOffset>179     fn arbitrary(u: &mut arbitrary::Unstructured) -> arbitrary::Result<FixedOffset> {
180         let secs = u.int_in_range(-86_399..=86_399)?;
181         let fixed_offset = FixedOffset::east_opt(secs)
182             .expect("Could not generate a valid chrono::FixedOffset. It looks like implementation of Arbitrary for FixedOffset is erroneous.");
183         Ok(fixed_offset)
184     }
185 }
186 
187 #[cfg(test)]
188 mod tests {
189     use super::FixedOffset;
190     use crate::offset::TimeZone;
191     use std::str::FromStr;
192 
193     #[test]
test_date_extreme_offset()194     fn test_date_extreme_offset() {
195         // starting from 0.3 we don't have an offset exceeding one day.
196         // this makes everything easier!
197         let offset = FixedOffset::east_opt(86399).unwrap();
198         assert_eq!(
199             format!("{:?}", offset.with_ymd_and_hms(2012, 2, 29, 5, 6, 7).unwrap()),
200             "2012-02-29T05:06:07+23:59:59"
201         );
202         let offset = FixedOffset::east_opt(-86399).unwrap();
203         assert_eq!(
204             format!("{:?}", offset.with_ymd_and_hms(2012, 2, 29, 5, 6, 7).unwrap()),
205             "2012-02-29T05:06:07-23:59:59"
206         );
207         let offset = FixedOffset::west_opt(86399).unwrap();
208         assert_eq!(
209             format!("{:?}", offset.with_ymd_and_hms(2012, 3, 4, 5, 6, 7).unwrap()),
210             "2012-03-04T05:06:07-23:59:59"
211         );
212         let offset = FixedOffset::west_opt(-86399).unwrap();
213         assert_eq!(
214             format!("{:?}", offset.with_ymd_and_hms(2012, 3, 4, 5, 6, 7).unwrap()),
215             "2012-03-04T05:06:07+23:59:59"
216         );
217     }
218 
219     #[test]
test_parse_offset()220     fn test_parse_offset() {
221         let offset = FixedOffset::from_str("-0500").unwrap();
222         assert_eq!(offset.local_minus_utc, -5 * 3600);
223         let offset = FixedOffset::from_str("-08:00").unwrap();
224         assert_eq!(offset.local_minus_utc, -8 * 3600);
225         let offset = FixedOffset::from_str("+06:30").unwrap();
226         assert_eq!(offset.local_minus_utc, (6 * 3600) + 1800);
227     }
228 
229     #[test]
230     #[cfg(feature = "rkyv-validation")]
test_rkyv_validation()231     fn test_rkyv_validation() {
232         let offset = FixedOffset::from_str("-0500").unwrap();
233         let bytes = rkyv::to_bytes::<_, 4>(&offset).unwrap();
234         assert_eq!(rkyv::from_bytes::<FixedOffset>(&bytes).unwrap(), offset);
235     }
236 }
237