1 files changed, 227 insertions, 0 deletions
diff --git a/src/offset/local.rs b/src/offset/local.rs
new file mode 100644
index 0000000..1abb3a9
--- /dev/null
+++ b/src/offset/local.rs
@@ -0,0 +1,227 @@
+// This is a part of Chrono.
+// See README.md and LICENSE.txt for details.
+
+//! The local (system) time zone.
+
+#[cfg(not(all(target_arch = "wasm32", not(target_os = "wasi"), feature = "wasmbind")))]
+use sys::{self, Timespec};
+
+use super::fixed::FixedOffset;
+use super::{LocalResult, TimeZone};
+#[cfg(not(all(target_arch = "wasm32", not(target_os = "wasi"), feature = "wasmbind")))]
+use naive::NaiveTime;
+use naive::{NaiveDate, NaiveDateTime};
+use {Date, DateTime};
+#[cfg(not(all(target_arch = "wasm32", not(target_os = "wasi"), feature = "wasmbind")))]
+use {Datelike, Timelike};
+
+/// Converts a `time::Tm` struct into the timezone-aware `DateTime`.
+/// This assumes that `time` is working correctly, i.e. any error is fatal.
+#[cfg(not(all(target_arch = "wasm32", not(target_os = "wasi"), feature = "wasmbind")))]
+fn tm_to_datetime(mut tm: sys::Tm) -> DateTime<Local> {
+    if tm.tm_sec >= 60 {
+        tm.tm_nsec += (tm.tm_sec - 59) * 1_000_000_000;
+        tm.tm_sec = 59;
+    }
+
+    #[cfg(not(windows))]
+    fn tm_to_naive_date(tm: &sys::Tm) -> NaiveDate {
+        // from_yo is more efficient than from_ymd (since it's the internal representation).
+        NaiveDate::from_yo(tm.tm_year + 1900, tm.tm_yday as u32 + 1)
+    }
+
+    #[cfg(windows)]
+    fn tm_to_naive_date(tm: &sys::Tm) -> NaiveDate {
+        // ...but tm_yday is broken in Windows (issue #85)
+        NaiveDate::from_ymd(tm.tm_year + 1900, tm.tm_mon as u32 + 1, tm.tm_mday as u32)
+    }
+
+    let date = tm_to_naive_date(&tm);
+    let time = NaiveTime::from_hms_nano(
+        tm.tm_hour as u32,
+        tm.tm_min as u32,
+        tm.tm_sec as u32,
+        tm.tm_nsec as u32,
+    );
+    let offset = FixedOffset::east(tm.tm_utcoff);
+    DateTime::from_utc(date.and_time(time) - offset, offset)
+}
+
+/// Converts a local `NaiveDateTime` to the `time::Timespec`.
+#[cfg(not(all(target_arch = "wasm32", not(target_os = "wasi"), feature = "wasmbind")))]
+fn datetime_to_timespec(d: &NaiveDateTime, local: bool) -> sys::Timespec {
+    // well, this exploits an undocumented `Tm::to_timespec` behavior
+    // to get the exact function we want (either `timegm` or `mktime`).
+    // the number 1 is arbitrary but should be non-zero to trigger `mktime`.
+    let tm_utcoff = if local { 1 } else { 0 };
+
+    let tm = sys::Tm {
+        tm_sec: d.second() as i32,
+        tm_min: d.minute() as i32,
+        tm_hour: d.hour() as i32,
+        tm_mday: d.day() as i32,
+        tm_mon: d.month0() as i32, // yes, C is that strange...
+        tm_year: d.year() - 1900,  // this doesn't underflow, we know that d is `NaiveDateTime`.
+        tm_wday: 0,                // to_local ignores this
+        tm_yday: 0,                // and this
+        tm_isdst: -1,
+        tm_utcoff: tm_utcoff,
+        // do not set this, OS APIs are heavily inconsistent in terms of leap second handling
+        tm_nsec: 0,
+    };
+
+    tm.to_timespec()
+}
+
+/// The local timescale. This is implemented via the standard `time` crate.
+///
+/// Using the [`TimeZone`](./trait.TimeZone.html) methods
+/// on the Local struct is the preferred way to construct `DateTime<Local>`
+/// instances.
+///
+/// # Example
+///
+/// ~~~~
+/// use chrono::{Local, DateTime, TimeZone};
+///
+/// let dt: DateTime<Local> = Local::now();
+/// let dt: DateTime<Local> = Local.timestamp(0, 0);
+/// ~~~~
+#[derive(Copy, Clone, Debug)]
+pub struct Local;
+
+impl Local {
+    /// Returns a `Date` which corresponds to the current date.
+    pub fn today() -> Date<Local> {
+        Local::now().date()
+    }
+
+    /// Returns a `DateTime` which corresponds to the current date.
+    #[cfg(not(all(target_arch = "wasm32", not(target_os = "wasi"), feature = "wasmbind")))]
+    pub fn now() -> DateTime<Local> {
+        tm_to_datetime(Timespec::now().local())
+    }
+
+    /// Returns a `DateTime` which corresponds to the current date.
+    #[cfg(all(target_arch = "wasm32", not(target_os = "wasi"), feature = "wasmbind"))]
+    pub fn now() -> DateTime<Local> {
+        use super::Utc;
+        let now: DateTime<Utc> = super::Utc::now();
+
+        // Workaround missing timezone logic in `time` crate
+        let offset = FixedOffset::west((js_sys::Date::new_0().get_timezone_offset() as i32) * 60);
+        DateTime::from_utc(now.naive_utc(), offset)
+    }
+}
+
+impl TimeZone for Local {
+    type Offset = FixedOffset;
+
+    fn from_offset(_offset: &FixedOffset) -> Local {
+        Local
+    }
+
+    // they are easier to define in terms of the finished date and time unlike other offsets
+    fn offset_from_local_date(&self, local: &NaiveDate) -> LocalResult<FixedOffset> {
+        self.from_local_date(local).map(|date| *date.offset())
+    }
+
+    fn offset_from_local_datetime(&self, local: &NaiveDateTime) -> LocalResult<FixedOffset> {
+        self.from_local_datetime(local).map(|datetime| *datetime.offset())
+    }
+
+    fn offset_from_utc_date(&self, utc: &NaiveDate) -> FixedOffset {
+        *self.from_utc_date(utc).offset()
+    }
+
+    fn offset_from_utc_datetime(&self, utc: &NaiveDateTime) -> FixedOffset {
+        *self.from_utc_datetime(utc).offset()
+    }
+
+    // override them for avoiding redundant works
+    fn from_local_date(&self, local: &NaiveDate) -> LocalResult<Date<Local>> {
+        // this sounds very strange, but required for keeping `TimeZone::ymd` sane.
+        // in the other words, we use the offset at the local midnight
+        // but keep the actual date unaltered (much like `FixedOffset`).
+        let midnight = self.from_local_datetime(&local.and_hms(0, 0, 0));
+        midnight.map(|datetime| Date::from_utc(*local, *datetime.offset()))
+    }
+
+    #[cfg(all(target_arch = "wasm32", not(target_os = "wasi"), feature = "wasmbind"))]
+    fn from_local_datetime(&self, local: &NaiveDateTime) -> LocalResult<DateTime<Local>> {
+        let mut local = local.clone();
+        // Get the offset from the js runtime
+        let offset = FixedOffset::west((js_sys::Date::new_0().get_timezone_offset() as i32) * 60);
+        local -= ::Duration::seconds(offset.local_minus_utc() as i64);
+        LocalResult::Single(DateTime::from_utc(local, offset))
+    }
+
+    #[cfg(not(all(target_arch = "wasm32", not(target_os = "wasi"), feature = "wasmbind")))]
+    fn from_local_datetime(&self, local: &NaiveDateTime) -> LocalResult<DateTime<Local>> {
+        let timespec = datetime_to_timespec(local, true);
+
+        // datetime_to_timespec completely ignores leap seconds, so we need to adjust for them
+        let mut tm = timespec.local();
+        assert_eq!(tm.tm_nsec, 0);
+        tm.tm_nsec = local.nanosecond() as i32;
+
+        LocalResult::Single(tm_to_datetime(tm))
+    }
+
+    fn from_utc_date(&self, utc: &NaiveDate) -> Date<Local> {
+        let midnight = self.from_utc_datetime(&utc.and_hms(0, 0, 0));
+        Date::from_utc(*utc, *midnight.offset())
+    }
+
+    #[cfg(all(target_arch = "wasm32", not(target_os = "wasi"), feature = "wasmbind"))]
+    fn from_utc_datetime(&self, utc: &NaiveDateTime) -> DateTime<Local> {
+        // Get the offset from the js runtime
+        let offset = FixedOffset::west((js_sys::Date::new_0().get_timezone_offset() as i32) * 60);
+        DateTime::from_utc(*utc, offset)
+    }
+
+    #[cfg(not(all(target_arch = "wasm32", not(target_os = "wasi"), feature = "wasmbind")))]
+    fn from_utc_datetime(&self, utc: &NaiveDateTime) -> DateTime<Local> {
+        let timespec = datetime_to_timespec(utc, false);
+
+        // datetime_to_timespec completely ignores leap seconds, so we need to adjust for them
+        let mut tm = timespec.local();
+        assert_eq!(tm.tm_nsec, 0);
+        tm.tm_nsec = utc.nanosecond() as i32;
+
+        tm_to_datetime(tm)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Local;
+    use offset::TimeZone;
+    use Datelike;
+
+    #[test]
+    fn test_local_date_sanity_check() {
+        // issue #27
+        assert_eq!(Local.ymd(2999, 12, 28).day(), 28);
+    }
+
+    #[test]
+    fn test_leap_second() {
+        // issue #123
+        let today = Local::today();
+
+        let dt = today.and_hms_milli(1, 2, 59, 1000);
+        let timestr = dt.time().to_string();
+        // the OS API may or may not support the leap second,
+        // but there are only two sensible options.
+        assert!(timestr == "01:02:60" || timestr == "01:03:00", "unexpected timestr {:?}", timestr);
+
+        let dt = today.and_hms_milli(1, 2, 3, 1234);
+        let timestr = dt.time().to_string();
+        assert!(
+            timestr == "01:02:03.234" || timestr == "01:02:04.234",
+            "unexpected timestr {:?}",
+            timestr
+        );
+    }
+}