<!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="Source of the Rust file `/Users/m018/.cargo/registry/src/github.com-1ecc6299db9ec823/chrono-tz-0.8.3/src/timezone_impl.rs`."><title>timezone_impl.rs - source</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../static.files/SourceSerif4-Regular-46f98efaafac5295.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../static.files/FiraSans-Regular-018c141bf0843ffd.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../static.files/FiraSans-Medium-8f9a781e4970d388.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../static.files/SourceCodePro-Regular-562dcc5011b6de7d.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../static.files/SourceSerif4-Bold-a2c9cd1067f8b328.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../static.files/SourceCodePro-Semibold-d899c5a5c4aeb14a.ttf.woff2"><link rel="stylesheet" href="../../static.files/normalize-76eba96aa4d2e634.css"><link rel="stylesheet" href="../../static.files/rustdoc-c4dbdcde0fbd8430.css" id="mainThemeStyle"><link rel="stylesheet" id="themeStyle" href="../../static.files/light-db279b6232be9c13.css"><link rel="stylesheet" disabled href="../../static.files/dark-cf923f49f397b216.css"><link rel="stylesheet" disabled href="../../static.files/ayu-be46fdc453a55015.css"><script src="../../static.files/storage-3891ce972e3a2bf8.js"></script><script defer src="../../static.files/source-script-1b95b7cca98b26e5.js"></script><script defer src="../../source-files.js"></script><script defer src="../../static.files/main-98a684e84ae5b08b.js"></script><noscript><link rel="stylesheet" href="../../static.files/noscript-13285aec31fa243e.css"></noscript><link rel="alternate icon" type="image/png" href="../../static.files/favicon-16x16-8b506e7a72182f1c.png"><link rel="alternate icon" type="image/png" href="../../static.files/favicon-32x32-422f7d1d52889060.png"><link rel="icon" type="image/svg+xml" href="../../static.files/favicon-2c020d218678b618.svg"></head><body class="rustdoc source"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"></nav><main><nav class="sub"><a class="sub-logo-container" href="../../chrono_tz/index.html"><img class="rust-logo" src="../../static.files/rust-logo-151179464ae7ed46.svg" alt="logo"></a><form class="search-form"><span></span><input class="search-input" name="search" aria-label="Run search in the documentation" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" title="help" tabindex="-1"><a href="../../help.html">?</a></div><div id="settings-menu" tabindex="-1"><a href="../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../static.files/wheel-7b819b6101059cd0.svg"></a></div></form></nav><section id="main-content" class="content"><div class="example-wrap"><pre class="src-line-numbers"><a href="#1" id="1">1</a>
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</pre><pre class="rust"><code><span class="kw">use </span>core::cmp::Ordering;
<span class="kw">use </span>core::fmt::{Debug, Display, Error, Formatter};
<span class="kw">use </span>chrono::{Duration, FixedOffset, LocalResult, NaiveDate, NaiveDateTime, Offset, TimeZone};
<span class="kw">use </span><span class="kw">crate</span>::binary_search::binary_search;
<span class="kw">use </span><span class="kw">crate</span>::timezones::Tz;
<span class="doccomment">/// An Offset that applies for a period of time
///
/// For example, [`::US::Eastern`] is composed of at least two
/// `FixedTimespan`s: `EST` and `EDT`, that are variously in effect.
</span><span class="attr">#[derive(Copy, Clone, PartialEq, Eq)]
</span><span class="kw">pub struct </span>FixedTimespan {
<span class="doccomment">/// The base offset from UTC; this usually doesn't change unless the government changes something
</span><span class="kw">pub </span>utc_offset: i32,
<span class="doccomment">/// The additional offset from UTC for this timespan; typically for daylight saving time
</span><span class="kw">pub </span>dst_offset: i32,
<span class="doccomment">/// The name of this timezone, for example the difference between `EDT`/`EST`
</span><span class="kw">pub </span>name: <span class="kw-2">&</span><span class="lifetime">'static </span>str,
}
<span class="kw">impl </span>Offset <span class="kw">for </span>FixedTimespan {
<span class="kw">fn </span>fix(<span class="kw-2">&</span><span class="self">self</span>) -> FixedOffset {
FixedOffset::east(<span class="self">self</span>.utc_offset + <span class="self">self</span>.dst_offset)
}
}
<span class="kw">impl </span>Display <span class="kw">for </span>FixedTimespan {
<span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, f: <span class="kw-2">&mut </span>Formatter<<span class="lifetime">'_</span>>) -> <span class="prelude-ty">Result</span><(), Error> {
<span class="macro">write!</span>(f, <span class="string">"{}"</span>, <span class="self">self</span>.name)
}
}
<span class="kw">impl </span>Debug <span class="kw">for </span>FixedTimespan {
<span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, f: <span class="kw-2">&mut </span>Formatter<<span class="lifetime">'_</span>>) -> <span class="prelude-ty">Result</span><(), Error> {
<span class="macro">write!</span>(f, <span class="string">"{}"</span>, <span class="self">self</span>.name)
}
}
<span class="attr">#[derive(Copy, Clone, PartialEq, Eq)]
</span><span class="kw">pub struct </span>TzOffset {
tz: Tz,
offset: FixedTimespan,
}
<span class="doccomment">/// Detailed timezone offset components that expose any special conditions currently in effect.
///
/// This trait breaks down an offset into the standard UTC offset and any special offset
/// in effect (such as DST) at a given time.
///
/// ```
/// # extern crate chrono;
/// # extern crate chrono_tz;
/// use chrono::{Duration, Offset, TimeZone};
/// use chrono_tz::Europe::London;
/// use chrono_tz::OffsetComponents;
///
/// # fn main() {
/// let london_time = London.ymd(2016, 5, 10).and_hms(12, 0, 0);
///
/// // London typically has zero offset from UTC, but has a 1h adjustment forward
/// // when summer time is in effect.
/// let lon_utc_offset = london_time.offset().base_utc_offset();
/// let lon_dst_offset = london_time.offset().dst_offset();
/// let total_offset = lon_utc_offset + lon_dst_offset;
/// assert_eq!(lon_utc_offset, Duration::hours(0));
/// assert_eq!(lon_dst_offset, Duration::hours(1));
///
/// // As a sanity check, make sure that the total offsets added together are equivalent to the
/// // total fixed offset.
/// assert_eq!(total_offset.num_seconds(), london_time.offset().fix().local_minus_utc() as i64);
/// # }
/// ```
</span><span class="kw">pub trait </span>OffsetComponents {
<span class="doccomment">/// The base offset from UTC; this usually doesn't change unless the government changes something
</span><span class="kw">fn </span>base_utc_offset(<span class="kw-2">&</span><span class="self">self</span>) -> Duration;
<span class="doccomment">/// The additional offset from UTC that is currently in effect; typically for daylight saving time
</span><span class="kw">fn </span>dst_offset(<span class="kw-2">&</span><span class="self">self</span>) -> Duration;
}
<span class="doccomment">/// Timezone offset name information.
///
/// This trait exposes display names that describe an offset in
/// various situations.
///
/// ```
/// # extern crate chrono;
/// # extern crate chrono_tz;
/// use chrono::{Duration, Offset, TimeZone};
/// use chrono_tz::Europe::London;
/// use chrono_tz::OffsetName;
///
/// # fn main() {
/// let london_time = London.ymd(2016, 2, 10).and_hms(12, 0, 0);
/// assert_eq!(london_time.offset().tz_id(), "Europe/London");
/// // London is normally on GMT
/// assert_eq!(london_time.offset().abbreviation(), "GMT");
///
/// let london_summer_time = London.ymd(2016, 5, 10).and_hms(12, 0, 0);
/// // The TZ ID remains constant year round
/// assert_eq!(london_summer_time.offset().tz_id(), "Europe/London");
/// // During the summer, this becomes British Summer Time
/// assert_eq!(london_summer_time.offset().abbreviation(), "BST");
/// # }
/// ```
</span><span class="kw">pub trait </span>OffsetName {
<span class="doccomment">/// The IANA TZDB identifier (ex: America/New_York)
</span><span class="kw">fn </span>tz_id(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="kw-2">&</span>str;
<span class="doccomment">/// The abbreviation to use in a longer timestamp (ex: EST)
///
/// This takes into account any special offsets that may be in effect.
/// For example, at a given instant, the time zone with ID *America/New_York*
/// may be either *EST* or *EDT*.
</span><span class="kw">fn </span>abbreviation(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="kw-2">&</span>str;
}
<span class="kw">impl </span>TzOffset {
<span class="kw">fn </span>new(tz: Tz, offset: FixedTimespan) -> <span class="self">Self </span>{
TzOffset { tz, offset }
}
<span class="kw">fn </span>map_localresult(tz: Tz, result: LocalResult<FixedTimespan>) -> LocalResult<<span class="self">Self</span>> {
<span class="kw">match </span>result {
LocalResult::None => LocalResult::None,
LocalResult::Single(s) => LocalResult::Single(TzOffset::new(tz, s)),
LocalResult::Ambiguous(a, b) => {
LocalResult::Ambiguous(TzOffset::new(tz, a), TzOffset::new(tz, b))
}
}
}
}
<span class="kw">impl </span>OffsetComponents <span class="kw">for </span>TzOffset {
<span class="kw">fn </span>base_utc_offset(<span class="kw-2">&</span><span class="self">self</span>) -> Duration {
Duration::seconds(<span class="self">self</span>.offset.utc_offset <span class="kw">as </span>i64)
}
<span class="kw">fn </span>dst_offset(<span class="kw-2">&</span><span class="self">self</span>) -> Duration {
Duration::seconds(<span class="self">self</span>.offset.dst_offset <span class="kw">as </span>i64)
}
}
<span class="kw">impl </span>OffsetName <span class="kw">for </span>TzOffset {
<span class="kw">fn </span>tz_id(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="kw-2">&</span>str {
<span class="self">self</span>.tz.name()
}
<span class="kw">fn </span>abbreviation(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="kw-2">&</span>str {
<span class="self">self</span>.offset.name
}
}
<span class="kw">impl </span>Offset <span class="kw">for </span>TzOffset {
<span class="kw">fn </span>fix(<span class="kw-2">&</span><span class="self">self</span>) -> FixedOffset {
<span class="self">self</span>.offset.fix()
}
}
<span class="kw">impl </span>Display <span class="kw">for </span>TzOffset {
<span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, f: <span class="kw-2">&mut </span>Formatter<<span class="lifetime">'_</span>>) -> <span class="prelude-ty">Result</span><(), Error> {
Display::fmt(<span class="kw-2">&</span><span class="self">self</span>.offset, f)
}
}
<span class="kw">impl </span>Debug <span class="kw">for </span>TzOffset {
<span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, f: <span class="kw-2">&mut </span>Formatter<<span class="lifetime">'_</span>>) -> <span class="prelude-ty">Result</span><(), Error> {
Debug::fmt(<span class="kw-2">&</span><span class="self">self</span>.offset, f)
}
}
<span class="doccomment">/// Represents the span of time that a given rule is valid for.
/// Note that I have made the assumption that all ranges are
/// left-inclusive and right-exclusive - that is to say,
/// if the clocks go forward by 1 hour at 1am, the time 1am
/// does not exist in local time (the clock goes from 00:59:59
/// to 02:00:00). Likewise, if the clocks go back by one hour
/// at 2am, the clock goes from 01:59:59 to 01:00:00. This is
/// an arbitrary choice, and I could not find a source to
/// confirm whether or not this is correct.
</span><span class="kw">struct </span>Span {
begin: <span class="prelude-ty">Option</span><i64>,
end: <span class="prelude-ty">Option</span><i64>,
}
<span class="kw">impl </span>Span {
<span class="kw">fn </span>contains(<span class="kw-2">&</span><span class="self">self</span>, x: i64) -> bool {
<span class="kw">match </span>(<span class="self">self</span>.begin, <span class="self">self</span>.end) {
(<span class="prelude-val">Some</span>(a), <span class="prelude-val">Some</span>(b)) <span class="kw">if </span>a <= x && x < b => <span class="bool-val">true</span>,
(<span class="prelude-val">Some</span>(a), <span class="prelude-val">None</span>) <span class="kw">if </span>a <= x => <span class="bool-val">true</span>,
(<span class="prelude-val">None</span>, <span class="prelude-val">Some</span>(b)) <span class="kw">if </span>b > x => <span class="bool-val">true</span>,
(<span class="prelude-val">None</span>, <span class="prelude-val">None</span>) => <span class="bool-val">true</span>,
<span class="kw">_ </span>=> <span class="bool-val">false</span>,
}
}
<span class="kw">fn </span>cmp(<span class="kw-2">&</span><span class="self">self</span>, x: i64) -> Ordering {
<span class="kw">match </span>(<span class="self">self</span>.begin, <span class="self">self</span>.end) {
(<span class="prelude-val">Some</span>(a), <span class="prelude-val">Some</span>(b)) <span class="kw">if </span>a <= x && x < b => Ordering::Equal,
(<span class="prelude-val">Some</span>(a), <span class="prelude-val">Some</span>(b)) <span class="kw">if </span>a <= x && b <= x => Ordering::Less,
(<span class="prelude-val">Some</span>(<span class="kw">_</span>), <span class="prelude-val">Some</span>(<span class="kw">_</span>)) => Ordering::Greater,
(<span class="prelude-val">Some</span>(a), <span class="prelude-val">None</span>) <span class="kw">if </span>a <= x => Ordering::Equal,
(<span class="prelude-val">Some</span>(<span class="kw">_</span>), <span class="prelude-val">None</span>) => Ordering::Greater,
(<span class="prelude-val">None</span>, <span class="prelude-val">Some</span>(b)) <span class="kw">if </span>b <= x => Ordering::Less,
(<span class="prelude-val">None</span>, <span class="prelude-val">Some</span>(<span class="kw">_</span>)) => Ordering::Equal,
(<span class="prelude-val">None</span>, <span class="prelude-val">None</span>) => Ordering::Equal,
}
}
}
<span class="attr">#[derive(Copy, Clone)]
</span><span class="kw">pub struct </span>FixedTimespanSet {
<span class="kw">pub </span>first: FixedTimespan,
<span class="kw">pub </span>rest: <span class="kw-2">&</span><span class="lifetime">'static </span>[(i64, FixedTimespan)],
}
<span class="kw">impl </span>FixedTimespanSet {
<span class="kw">fn </span>len(<span class="kw-2">&</span><span class="self">self</span>) -> usize {
<span class="number">1 </span>+ <span class="self">self</span>.rest.len()
}
<span class="kw">fn </span>utc_span(<span class="kw-2">&</span><span class="self">self</span>, index: usize) -> Span {
<span class="macro">debug_assert!</span>(index < <span class="self">self</span>.len());
Span {
begin: <span class="kw">if </span>index == <span class="number">0 </span>{ <span class="prelude-val">None </span>} <span class="kw">else </span>{ <span class="prelude-val">Some</span>(<span class="self">self</span>.rest[index - <span class="number">1</span>].<span class="number">0</span>) },
end: <span class="kw">if </span>index == <span class="self">self</span>.rest.len() { <span class="prelude-val">None </span>} <span class="kw">else </span>{ <span class="prelude-val">Some</span>(<span class="self">self</span>.rest[index].<span class="number">0</span>) },
}
}
<span class="kw">fn </span>local_span(<span class="kw-2">&</span><span class="self">self</span>, index: usize) -> Span {
<span class="macro">debug_assert!</span>(index < <span class="self">self</span>.len());
Span {
begin: <span class="kw">if </span>index == <span class="number">0 </span>{
<span class="prelude-val">None
</span>} <span class="kw">else </span>{
<span class="kw">let </span>span = <span class="self">self</span>.rest[index - <span class="number">1</span>];
<span class="prelude-val">Some</span>(span.<span class="number">0 </span>+ span.<span class="number">1</span>.utc_offset <span class="kw">as </span>i64 + span.<span class="number">1</span>.dst_offset <span class="kw">as </span>i64)
},
end: <span class="kw">if </span>index == <span class="self">self</span>.rest.len() {
<span class="prelude-val">None
</span>} <span class="kw">else if </span>index == <span class="number">0 </span>{
<span class="prelude-val">Some</span>(
<span class="self">self</span>.rest[index].<span class="number">0
</span>+ <span class="self">self</span>.first.utc_offset <span class="kw">as </span>i64
+ <span class="self">self</span>.first.dst_offset <span class="kw">as </span>i64,
)
} <span class="kw">else </span>{
<span class="prelude-val">Some</span>(
<span class="self">self</span>.rest[index].<span class="number">0
</span>+ <span class="self">self</span>.rest[index - <span class="number">1</span>].<span class="number">1</span>.utc_offset <span class="kw">as </span>i64
+ <span class="self">self</span>.rest[index - <span class="number">1</span>].<span class="number">1</span>.dst_offset <span class="kw">as </span>i64,
)
},
}
}
<span class="kw">fn </span>get(<span class="kw-2">&</span><span class="self">self</span>, index: usize) -> FixedTimespan {
<span class="macro">debug_assert!</span>(index < <span class="self">self</span>.len());
<span class="kw">if </span>index == <span class="number">0 </span>{
<span class="self">self</span>.first
} <span class="kw">else </span>{
<span class="self">self</span>.rest[index - <span class="number">1</span>].<span class="number">1
</span>}
}
}
<span class="kw">pub trait </span>TimeSpans {
<span class="kw">fn </span>timespans(<span class="kw-2">&</span><span class="self">self</span>) -> FixedTimespanSet;
}
<span class="kw">impl </span>TimeZone <span class="kw">for </span>Tz {
<span class="kw">type </span>Offset = TzOffset;
<span class="kw">fn </span>from_offset(offset: <span class="kw-2">&</span><span class="self">Self</span>::Offset) -> <span class="self">Self </span>{
offset.tz
}
<span class="kw">fn </span>offset_from_local_date(<span class="kw-2">&</span><span class="self">self</span>, local: <span class="kw-2">&</span>NaiveDate) -> LocalResult<<span class="self">Self</span>::Offset> {
<span class="kw">let </span>earliest = <span class="self">self</span>.offset_from_local_datetime(<span class="kw-2">&</span>local.and_hms(<span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>));
<span class="kw">let </span>latest = <span class="self">self</span>.offset_from_local_datetime(<span class="kw-2">&</span>local.and_hms(<span class="number">23</span>, <span class="number">59</span>, <span class="number">59</span>));
<span class="comment">// From the chrono docs:
//
// > This type should be considered ambiguous at best, due to the inherent lack of
// > precision required for the time zone resolution. There are some guarantees on the usage
// > of `Date<Tz>`:
// > - If properly constructed via `TimeZone::ymd` and others without an error,
// > the corresponding local date should exist for at least a moment.
// > (It may still have a gap from the offset changes.)
//
// > - The `TimeZone` is free to assign *any* `Offset` to the local date,
// > as long as that offset did occur in given day.
// > For example, if `2015-03-08T01:59-08:00` is followed by `2015-03-08T03:00-07:00`,
// > it may produce either `2015-03-08-08:00` or `2015-03-08-07:00`
// > but *not* `2015-03-08+00:00` and others.
//
// > - Once constructed as a full `DateTime`,
// > `DateTime::date` and other associated methods should return those for the original `Date`.
// > For example, if `dt = tz.ymd(y,m,d).hms(h,n,s)` were valid, `dt.date() == tz.ymd(y,m,d)`.
//
// > - The date is timezone-agnostic up to one day (i.e. practically always),
// > so the local date and UTC date should be equal for most cases
// > even though the raw calculation between `NaiveDate` and `Duration` may not.
//
// For these reasons we return always a single offset here if we can, rather than being
// technically correct and returning Ambiguous(_,_) on days when the clock changes. The
// alternative is painful errors when computing unambiguous times such as
// `TimeZone.ymd(ambiguous_date).hms(unambiguous_time)`.
</span><span class="kw">use </span>chrono::LocalResult::<span class="kw-2">*</span>;
<span class="kw">match </span>(earliest, latest) {
(result @ Single(<span class="kw">_</span>), <span class="kw">_</span>) => result,
(<span class="kw">_</span>, result @ Single(<span class="kw">_</span>)) => result,
(Ambiguous(offset, <span class="kw">_</span>), <span class="kw">_</span>) => Single(offset),
(<span class="kw">_</span>, Ambiguous(offset, <span class="kw">_</span>)) => Single(offset),
(<span class="prelude-val">None</span>, <span class="prelude-val">None</span>) => <span class="prelude-val">None</span>,
}
}
<span class="comment">// First search for a timespan that the local datetime falls into, then, if it exists,
// check the two surrounding timespans (if they exist) to see if there is any ambiguity.
</span><span class="kw">fn </span>offset_from_local_datetime(<span class="kw-2">&</span><span class="self">self</span>, local: <span class="kw-2">&</span>NaiveDateTime) -> LocalResult<<span class="self">Self</span>::Offset> {
<span class="kw">let </span>timestamp = local.timestamp();
<span class="kw">let </span>timespans = <span class="self">self</span>.timespans();
<span class="kw">let </span>index = binary_search(<span class="number">0</span>, timespans.len(), |i| timespans.local_span(i).cmp(timestamp));
TzOffset::map_localresult(
<span class="kw-2">*</span><span class="self">self</span>,
<span class="kw">match </span>index {
<span class="prelude-val">Ok</span>(<span class="number">0</span>) <span class="kw">if </span>timespans.len() == <span class="number">1 </span>=> LocalResult::Single(timespans.get(<span class="number">0</span>)),
<span class="prelude-val">Ok</span>(<span class="number">0</span>) <span class="kw">if </span>timespans.local_span(<span class="number">1</span>).contains(timestamp) => {
LocalResult::Ambiguous(timespans.get(<span class="number">0</span>), timespans.get(<span class="number">1</span>))
}
<span class="prelude-val">Ok</span>(<span class="number">0</span>) => LocalResult::Single(timespans.get(<span class="number">0</span>)),
<span class="prelude-val">Ok</span>(i) <span class="kw">if </span>timespans.local_span(i - <span class="number">1</span>).contains(timestamp) => {
LocalResult::Ambiguous(timespans.get(i - <span class="number">1</span>), timespans.get(i))
}
<span class="prelude-val">Ok</span>(i) <span class="kw">if </span>i == timespans.len() - <span class="number">1 </span>=> LocalResult::Single(timespans.get(i)),
<span class="prelude-val">Ok</span>(i) <span class="kw">if </span>timespans.local_span(i + <span class="number">1</span>).contains(timestamp) => {
LocalResult::Ambiguous(timespans.get(i), timespans.get(i + <span class="number">1</span>))
}
<span class="prelude-val">Ok</span>(i) => LocalResult::Single(timespans.get(i)),
<span class="prelude-val">Err</span>(<span class="kw">_</span>) => LocalResult::None,
},
)
}
<span class="kw">fn </span>offset_from_utc_date(<span class="kw-2">&</span><span class="self">self</span>, utc: <span class="kw-2">&</span>NaiveDate) -> <span class="self">Self</span>::Offset {
<span class="comment">// See comment above for why it is OK to just take any arbitrary time in the day
</span><span class="self">self</span>.offset_from_utc_datetime(<span class="kw-2">&</span>utc.and_hms(<span class="number">12</span>, <span class="number">0</span>, <span class="number">0</span>))
}
<span class="comment">// Binary search for the required timespan. Any i64 is guaranteed to fall within
// exactly one timespan, no matter what (so the `unwrap` is safe).
</span><span class="kw">fn </span>offset_from_utc_datetime(<span class="kw-2">&</span><span class="self">self</span>, utc: <span class="kw-2">&</span>NaiveDateTime) -> <span class="self">Self</span>::Offset {
<span class="kw">let </span>timestamp = utc.timestamp();
<span class="kw">let </span>timespans = <span class="self">self</span>.timespans();
<span class="kw">let </span>index =
binary_search(<span class="number">0</span>, timespans.len(), |i| timespans.utc_span(i).cmp(timestamp)).unwrap();
TzOffset::new(<span class="kw-2">*</span><span class="self">self</span>, timespans.get(index))
}
}
</code></pre></div>
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