From 5eab21413e766e0eba500a8d7ff394f003d0b70a Mon Sep 17 00:00:00 2001
From: Vo Van Nghia <git@vnghia.com>
Date: Fri, 20 Sep 2024 10:48:20 +0200
Subject: [PATCH] add support for time

---
 Cargo.toml                 |  3 +-
 src/derive/datetime.rs     | 67 ++++++++++++++++++++++++++
 src/derive/duration.rs     | 19 +-------
 src/derive/mod.rs          |  1 +
 src/ext/mod.rs             |  2 +
 src/ext/time_crate/mod.rs  |  1 +
 src/ext/time_crate/time.rs | 97 ++++++++++++++++++++++++++++++++++++++
 7 files changed, 172 insertions(+), 18 deletions(-)
 create mode 100644 src/derive/datetime.rs
 create mode 100644 src/ext/time_crate/mod.rs
 create mode 100644 src/ext/time_crate/time.rs

diff --git a/Cargo.toml b/Cargo.toml
index 6cf91e2..8c4c9e5 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -19,6 +19,7 @@ bitcode_derive = { version = "0.6.3", path = "./bitcode_derive", optional = true
 bytemuck = { version = "1.14", features = [ "min_const_generics", "must_cast" ] }
 glam = { version = ">=0.21", default-features = false, optional = true }
 serde = { version = "1.0", default-features = false, features = [ "alloc" ], optional = true }
+time = { version = "0.3", default-features = false, features = [ "alloc" ], optional = true }
 
 [dev-dependencies]
 arrayvec = { version = "0.7", features = [ "serde" ] }
@@ -37,7 +38,7 @@ zstd = "0.13.0"
 
 [features]
 derive = [ "dep:bitcode_derive" ]
-std = [ "serde?/std", "glam?/std", "arrayvec?/std" ]
+std = [ "serde?/std", "glam?/std", "arrayvec?/std", "time?/std" ]
 default = [ "derive", "std" ]
 
 [package.metadata.docs.rs]
diff --git a/src/derive/datetime.rs b/src/derive/datetime.rs
new file mode 100644
index 0000000..63d8c8e
--- /dev/null
+++ b/src/derive/datetime.rs
@@ -0,0 +1,67 @@
+use bytemuck::CheckedBitPattern;
+
+use super::Decode;
+
+/// A u8 guaranteed to be < 24.
+#[derive(Copy, Clone)]
+#[repr(transparent)]
+pub struct Hour(pub u8);
+// Safety: u8 and Hour have the same layout since Hour is #[repr(transparent)].
+unsafe impl CheckedBitPattern for Hour {
+    type Bits = u8;
+    #[inline(always)]
+    fn is_valid_bit_pattern(bits: &Self::Bits) -> bool {
+        *bits < 24
+    }
+}
+impl<'a> Decode<'a> for Hour {
+    type Decoder = crate::int::CheckedIntDecoder<'a, Hour, u8>;
+}
+
+/// A u8 guaranteed to be < 60.
+#[derive(Copy, Clone)]
+#[repr(transparent)]
+pub struct Minute(pub u8);
+// Safety: u8 and Minute have the same layout since Minute is #[repr(transparent)].
+unsafe impl CheckedBitPattern for Minute {
+    type Bits = u8;
+    #[inline(always)]
+    fn is_valid_bit_pattern(bits: &Self::Bits) -> bool {
+        *bits < 60
+    }
+}
+impl<'a> Decode<'a> for Minute {
+    type Decoder = crate::int::CheckedIntDecoder<'a, Minute, u8>;
+}
+
+/// A u8 guaranteed to be < 60.
+#[derive(Copy, Clone)]
+#[repr(transparent)]
+pub struct Second(pub u8);
+// Safety: u8 and Second have the same layout since Second is #[repr(transparent)].
+unsafe impl CheckedBitPattern for Second {
+    type Bits = u8;
+    #[inline(always)]
+    fn is_valid_bit_pattern(bits: &Self::Bits) -> bool {
+        *bits < 60
+    }
+}
+impl<'a> Decode<'a> for Second {
+    type Decoder = crate::int::CheckedIntDecoder<'a, Second, u8>;
+}
+
+/// A u32 guaranteed to be < 1 billion.
+#[derive(Copy, Clone)]
+#[repr(transparent)]
+pub struct Nanoseconds(pub u32);
+// Safety: u32 and Nanoseconds have the same layout since Nanoseconds is #[repr(transparent)].
+unsafe impl CheckedBitPattern for Nanoseconds {
+    type Bits = u32;
+    #[inline(always)]
+    fn is_valid_bit_pattern(bits: &Self::Bits) -> bool {
+        *bits < 1_000_000_000
+    }
+}
+impl<'a> Decode<'a> for Nanoseconds {
+    type Decoder = crate::int::CheckedIntDecoder<'a, Nanoseconds, u32>;
+}
diff --git a/src/derive/duration.rs b/src/derive/duration.rs
index 52664d4..84878a6 100644
--- a/src/derive/duration.rs
+++ b/src/derive/duration.rs
@@ -1,4 +1,5 @@
 use crate::coder::{Buffer, Decoder, Encoder, Result, View};
+use crate::datetime::Nanoseconds;
 use crate::{Decode, Encode};
 use alloc::vec::Vec;
 use bytemuck::CheckedBitPattern;
@@ -32,22 +33,6 @@ impl Encode for Duration {
     type Encoder = DurationEncoder;
 }
 
-/// A u32 guaranteed to be < 1 billion. Prevents Duration::new from panicking.
-#[derive(Copy, Clone)]
-#[repr(transparent)]
-struct Nanoseconds(u32);
-// Safety: u32 and Nanoseconds have the same layout since Nanoseconds is #[repr(transparent)].
-unsafe impl CheckedBitPattern for Nanoseconds {
-    type Bits = u32;
-    #[inline(always)]
-    fn is_valid_bit_pattern(bits: &Self::Bits) -> bool {
-        *bits < 1_000_000_000
-    }
-}
-impl<'a> Decode<'a> for Nanoseconds {
-    type Decoder = crate::int::CheckedIntDecoder<'a, Nanoseconds, u32>;
-}
-
 #[derive(Default)]
 pub struct DurationDecoder<'a> {
     secs: <u64 as Decode<'a>>::Decoder,
@@ -95,5 +80,5 @@ mod tests {
             .map(|(s, n): (_, u32)| Duration::new(s, n % 1_000_000_000))
             .collect()
     }
-    crate::bench_encode_decode!(duration_vec: Vec<_>);
+    crate::bench_encode_decode!(duration_vec: Vec<Duration>);
 }
diff --git a/src/derive/mod.rs b/src/derive/mod.rs
index fc4c6fc..999edb5 100644
--- a/src/derive/mod.rs
+++ b/src/derive/mod.rs
@@ -6,6 +6,7 @@ use core::num::NonZeroUsize;
 
 mod array;
 mod convert;
+pub(crate) mod datetime;
 mod duration;
 mod empty;
 mod impls;
diff --git a/src/ext/mod.rs b/src/ext/mod.rs
index b7b26f1..684e3ae 100644
--- a/src/ext/mod.rs
+++ b/src/ext/mod.rs
@@ -3,6 +3,8 @@ mod arrayvec;
 #[cfg(feature = "glam")]
 #[rustfmt::skip] // Makes impl_struct! calls way longer.
 mod glam;
+#[cfg(feature = "time")]
+mod time_crate;
 
 #[allow(unused)]
 macro_rules! impl_struct {
diff --git a/src/ext/time_crate/mod.rs b/src/ext/time_crate/mod.rs
new file mode 100644
index 0000000..7d75173
--- /dev/null
+++ b/src/ext/time_crate/mod.rs
@@ -0,0 +1 @@
+mod time;
diff --git a/src/ext/time_crate/time.rs b/src/ext/time_crate/time.rs
new file mode 100644
index 0000000..7649c1d
--- /dev/null
+++ b/src/ext/time_crate/time.rs
@@ -0,0 +1,97 @@
+use crate::coder::{Buffer, Decoder, Encoder, Result, View};
+use crate::datetime::{Hour, Minute, Nanoseconds, Second};
+use crate::{Decode, Encode};
+use alloc::vec::Vec;
+use core::num::NonZeroUsize;
+use time::Time;
+
+#[derive(Default)]
+pub struct TimeEncoder {
+    hour: <u8 as Encode>::Encoder,
+    minute: <u8 as Encode>::Encoder,
+    second: <u8 as Encode>::Encoder,
+    nanosecond: <u32 as Encode>::Encoder,
+}
+impl Encoder<Time> for TimeEncoder {
+    #[inline(always)]
+    fn encode(&mut self, t: &Time) {
+        let (hour, minute, second, nanosecond) = t.as_hms_nano();
+        self.hour.encode(&hour);
+        self.minute.encode(&minute);
+        self.second.encode(&second);
+        self.nanosecond.encode(&nanosecond);
+    }
+}
+impl Buffer for TimeEncoder {
+    fn collect_into(&mut self, out: &mut Vec<u8>) {
+        self.hour.collect_into(out);
+        self.minute.collect_into(out);
+        self.second.collect_into(out);
+        self.nanosecond.collect_into(out);
+    }
+
+    fn reserve(&mut self, additional: NonZeroUsize) {
+        self.hour.reserve(additional);
+        self.minute.reserve(additional);
+        self.second.reserve(additional);
+        self.nanosecond.reserve(additional);
+    }
+}
+impl Encode for Time {
+    type Encoder = TimeEncoder;
+}
+
+#[derive(Default)]
+pub struct TimeDecoder<'a> {
+    hour: <Hour as Decode<'a>>::Decoder,
+    minute: <Minute as Decode<'a>>::Decoder,
+    second: <Second as Decode<'a>>::Decoder,
+    nanosecond: <Nanoseconds as Decode<'a>>::Decoder,
+}
+impl<'a> View<'a> for TimeDecoder<'a> {
+    fn populate(&mut self, input: &mut &'a [u8], length: usize) -> Result<()> {
+        self.hour.populate(input, length)?;
+        self.minute.populate(input, length)?;
+        self.second.populate(input, length)?;
+        self.nanosecond.populate(input, length)?;
+        Ok(())
+    }
+}
+impl<'a> Decoder<'a, Time> for TimeDecoder<'a> {
+    #[inline(always)]
+    fn decode(&mut self) -> Time {
+        let Hour(hour) = self.hour.decode();
+        let Minute(minute) = self.minute.decode();
+        let Second(second) = self.second.decode();
+        let Nanoseconds(nanosecond) = self.nanosecond.decode();
+        // Safety: should not fail because all input values are validated with CheckedBitPattern.
+        unsafe { Time::from_hms_nano(hour, minute, second, nanosecond).unwrap_unchecked() }
+    }
+}
+impl<'a> Decode<'a> for Time {
+    type Decoder = TimeDecoder<'a>;
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn test() {
+        assert!(crate::decode::<Time>(&crate::encode(&(23, 59, 59, 999_999_999))).is_ok());
+        assert!(crate::decode::<Time>(&crate::encode(&(24, 59, 59, 999_999_999))).is_err());
+        assert!(crate::decode::<Time>(&crate::encode(&(23, 60, 59, 999_999_999))).is_err());
+        assert!(crate::decode::<Time>(&crate::encode(&(23, 59, 60, 999_999_999))).is_err());
+        assert!(crate::decode::<Time>(&crate::encode(&(23, 59, 59, 1_000_000_000))).is_err());
+    }
+
+    use alloc::vec::Vec;
+    use time::Time;
+    fn bench_data() -> Vec<Time> {
+        crate::random_data(1000)
+            .into_iter()
+            .map(|(h, m, s, n): (u8, u8, u8, u32)| {
+                Time::from_hms_nano(h % 24, m % 60, s % 60, n % 1_000_000_000).unwrap()
+            })
+            .collect()
+    }
+    crate::bench_encode_decode!(duration_vec: Vec<_>);
+}