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// Copyright 2019 DFINITY // // Licensed under the Apache License, Version 2.0 (the "License"); // you may not use this file except in compliance with the License. // You may obtain a copy of the License at // // http://www.apache.org/licenses/LICENSE-2.0 // // Unless required by applicable law or agreed to in writing, software // distributed under the License is distributed on an "AS IS" BASIS, // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. // See the License for the specific language governing permissions and // limitations under the License. use crate::amount::Amount; use crate::displayer::{DisplayProxy, DisplayerOf}; #[cfg(feature = "serde")] use serde::{Deserialize, Deserializer, Serialize, Serializer}; use std::cmp::Ordering; use std::fmt; use std::hash::{Hash, Hasher}; use std::marker::PhantomData; use std::ops::{Add, AddAssign, Div, Mul, MulAssign, Sub, SubAssign}; /// `Instant<Unit>` provides a type-safe way to keep absolute time of /// some events, expressed in `Unit`s (CPU ticks, seconds from epoch, /// years from birth, etc). /// /// You can compare instants: /// /// ``` /// use phantom_newtype::Instant; /// /// enum SecondsFromEpoch {} /// type UnixTime = Instant<SecondsFromEpoch, i64>; /// /// assert_eq!(true, UnixTime::from(3) < UnixTime::from(5)); /// assert_eq!(false, UnixTime::from(3) > UnixTime::from(5)); /// assert_eq!(true, UnixTime::from(3) != UnixTime::from(5)); /// assert_eq!(true, UnixTime::from(5) == UnixTime::from(5)); /// assert_eq!(false, UnixTime::from(5) != UnixTime::from(5)); /// /// assert_eq!(vec![UnixTime::from(3), UnixTime::from(5)].iter().max().unwrap(), /// &UnixTime::from(5)); /// ``` /// /// Instants support basic arithmetics, you can: /// * Subtract an instant from another instant to get amount of units between them. /// * Add/subtract amount of units to/from an instant to get another instant. /// /// ``` /// use phantom_newtype::{Amount, Instant}; /// /// enum SecondsFromEpoch {} /// /// type UnixTime = Instant<SecondsFromEpoch, i64>; /// type TimeDiff = Amount<SecondsFromEpoch, i64>; /// /// let epoch = UnixTime::from(0); /// let some_date = UnixTime::from(123456789); /// let diff = TimeDiff::from(123456789); /// /// assert_eq!(some_date - epoch, diff); /// assert_eq!(some_date - diff, epoch); /// assert_eq!(epoch + diff, some_date); /// ``` /// /// Direct multiplication of instants is not supported, however, you /// can scale them by a scalar or divide to get a scalar back: /// /// ``` /// use phantom_newtype::Instant; /// /// enum SecondsFromEpoch {} /// type UnixTime = Instant<SecondsFromEpoch, i64>; /// /// let x = UnixTime::from(123456); /// assert_eq!(x * 3, UnixTime::from(3 * 123456)); /// assert_eq!(1, x / x); /// assert_eq!(3, (x * 3) / x); /// ``` /// /// Note that the unit is only available at compile time, thus using /// `Instant` instead of `u64` doesn't incur any runtime penalty: /// /// ``` /// use phantom_newtype::Instant; /// /// enum SecondsFromEpoch {} /// /// let ms = Instant::<SecondsFromEpoch, u64>::from(10); /// assert_eq!(std::mem::size_of_val(&ms), std::mem::size_of::<u64>()); /// ``` /// /// Instants can be serialized and deserialized with `serde`. Serialized /// forms of `Instant<Unit, Repr>` and `Repr` are identical. /// /// ``` /// #[cfg(feature = "serde")] { /// use phantom_newtype::Instant; /// use serde::{Serialize, Deserialize}; /// use serde_json; /// /// enum SecondsFromEpoch {} /// type UnixTime = Instant<SecondsFromEpoch, i64>; /// /// let repr: u64 = 123456; /// let time = UnixTime::from(repr); /// assert_eq!(serde_json::to_string(&time).unwrap(), serde_json::to_string(&repr).unwrap()); /// /// let copy: UnitTime = serde_json::from_str(&serde_json::to_string(&time).unwrap()).unwrap(); /// assert_eq!(copy, time); /// } /// ``` /// /// You can also declare constants of `Instant<Unit, Repr>` using `new` /// function: /// ``` /// use phantom_newtype::Instant; /// /// enum SecondsFromEpoch {} /// type UnixTime = Instant<SecondsFromEpoch, u64>; /// /// const EPOCH: UnixTime = UnixTime::new(0); /// ``` /// /// Instants can be sent between threads if the `Repr` allows it, no /// matter which `Unit` is used. /// /// ``` /// use phantom_newtype::Instant; /// /// type Cell = std::cell::RefCell<i64>; /// type CellInstant = Instant<Cell, i64>; /// const I: CellInstant = CellInstant::new(1234); /// /// let instant_from_thread = std::thread::spawn(|| &I).join().unwrap(); /// assert_eq!(I, *instant_from_thread); /// ``` pub struct Instant<Unit, Repr>(Repr, PhantomData<std::sync::Mutex<Unit>>); impl<Unit, Repr: Copy> Instant<Unit, Repr> { /// Returns the wrapped value. /// /// ``` /// use phantom_newtype::Instant; /// /// enum Apples {} /// /// let three_apples = Instant::<Apples, u64>::from(3); /// assert_eq!(9, (three_apples * 3).get()); /// ``` pub fn get(&self) -> Repr { self.0 } } impl<Unit, Repr> Instant<Unit, Repr> { /// `new` is a synonym for `from` that can be evaluated in /// compile time. The main use-case of this functions is defining /// constants. pub const fn new(repr: Repr) -> Instant<Unit, Repr> { Instant(repr, PhantomData) } } impl<Unit: Default, Repr: Copy> Instant<Unit, Repr> { /// Provides a useful shortcut to access units of an instant if /// they implement the `Default` trait: /// /// ``` /// use phantom_newtype::Instant; /// /// #[derive(Debug, Default)] /// struct SecondsFromEpoch; /// let when = Instant::<SecondsFromEpoch, i64>::from(5); /// /// assert_eq!("5 SecondsFromEpoch", format!("{} {:?}", when, when.unit())); /// ``` pub fn unit(&self) -> Unit { Default::default() } } impl<Unit, Repr> Instant<Unit, Repr> where Unit: DisplayerOf<Instant<Unit, Repr>>, { /// `display` provides a machanism to implement a custom display /// for phantom types. /// /// ``` /// use phantom_newtype::{Instant, DisplayerOf}; /// use std::fmt; /// /// struct YearUnit; /// type YearAD = Instant<YearUnit, u64>; /// /// impl DisplayerOf<YearAD> for YearUnit { /// fn display(year: &YearAD, f: &mut fmt::Formatter<'_>) -> fmt::Result { /// write!(f, "{} AD", year.get()) /// } /// } /// /// assert_eq!(format!("{}", YearAD::from(1221).display()), "1221 AD"); /// ``` pub fn display(&self) -> DisplayProxy<'_, Self, Unit> { DisplayProxy::new(self) } } impl<Unit, Repr: Copy> From<Repr> for Instant<Unit, Repr> { fn from(repr: Repr) -> Self { Self::new(repr) } } impl<Unit, Repr: Copy> Clone for Instant<Unit, Repr> { fn clone(&self) -> Self { Instant(self.0, PhantomData) } } impl<Unit, Repr: Copy> Copy for Instant<Unit, Repr> {} impl<Unit, Repr: PartialEq> PartialEq for Instant<Unit, Repr> { fn eq(&self, rhs: &Self) -> bool { self.0.eq(&rhs.0) } } impl<Unit, Repr: Eq> Eq for Instant<Unit, Repr> {} impl<Unit, Repr: PartialOrd> PartialOrd for Instant<Unit, Repr> { fn partial_cmp(&self, rhs: &Self) -> Option<Ordering> { self.0.partial_cmp(&rhs.0) } } impl<Unit, Repr: Ord> Ord for Instant<Unit, Repr> { fn cmp(&self, rhs: &Self) -> Ordering { self.0.cmp(&rhs.0) } } impl<Unit, Repr: Hash> Hash for Instant<Unit, Repr> { fn hash<H: Hasher>(&self, state: &mut H) { self.0.hash(state) } } impl<Unit, Repr, Repr2> Add<Amount<Unit, Repr2>> for Instant<Unit, Repr> where Repr: AddAssign<Repr2> + Copy, Repr2: Copy, { type Output = Self; fn add(mut self, rhs: Amount<Unit, Repr2>) -> Self { self.add_assign(rhs); self } } impl<Unit, Repr, Repr2> AddAssign<Amount<Unit, Repr2>> for Instant<Unit, Repr> where Repr: AddAssign<Repr2> + Copy, Repr2: Copy, { fn add_assign(&mut self, rhs: Amount<Unit, Repr2>) { self.0 += rhs.get() } } impl<Unit, Repr, Repr2> SubAssign<Amount<Unit, Repr2>> for Instant<Unit, Repr> where Repr: SubAssign<Repr2> + Copy, Repr2: Copy, { fn sub_assign(&mut self, rhs: Amount<Unit, Repr2>) { self.0 -= rhs.get() } } impl<Unit, Repr> Sub for Instant<Unit, Repr> where Repr: Sub + Copy, { type Output = Amount<Unit, <Repr as Sub>::Output>; fn sub(self, rhs: Self) -> Self::Output { Amount::<Unit, <Repr as Sub>::Output>::new(self.0 - rhs.0) } } impl<Unit, Repr, Repr2> Sub<Amount<Unit, Repr2>> for Instant<Unit, Repr> where Repr: SubAssign<Repr2> + Copy, Repr2: Copy, { type Output = Self; fn sub(mut self, rhs: Amount<Unit, Repr2>) -> Self { self.sub_assign(rhs); self } } impl<Unit, Repr> MulAssign<Repr> for Instant<Unit, Repr> where Repr: MulAssign + Copy, { fn mul_assign(&mut self, rhs: Repr) { self.0 *= rhs; } } impl<Unit, Repr> Mul<Repr> for Instant<Unit, Repr> where Repr: MulAssign + Copy, { type Output = Self; fn mul(mut self, rhs: Repr) -> Self { self.mul_assign(rhs); self } } impl<Unit, Repr> Div<Self> for Instant<Unit, Repr> where Repr: Div<Repr> + Copy, { type Output = <Repr as Div>::Output; fn div(self, rhs: Self) -> Self::Output { self.0.div(rhs.0) } } impl<Unit, Repr> fmt::Debug for Instant<Unit, Repr> where Repr: fmt::Debug, { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { self.0.fmt(f) } } impl<Unit, Repr> fmt::Display for Instant<Unit, Repr> where Repr: fmt::Display, { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { self.0.fmt(f) } } #[cfg(feature = "serde")] impl<Unit, Repr: Serialize> Serialize for Instant<Unit, Repr> { fn serialize<S: Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error> { self.0.serialize(serializer) } } #[cfg(feature = "serde")] impl<'de, Unit, Repr> Deserialize<'de> for Instant<Unit, Repr> where Repr: Deserialize<'de>, { fn deserialize<D: Deserializer<'de>>(deserializer: D) -> Result<Self, D::Error> { Repr::deserialize(deserializer).map(Instant::<Unit, Repr>::new) } } #[cfg(test)] mod tests { use super::*; #[test] fn test_complex_instant_arithmetics() { enum Seconds {} enum UTC {} type Timestamp = Instant<Seconds, i64>; type TsDiff = Amount<Seconds, i64>; type Date = Instant<UTC, Timestamp>; let epoch = Date::new(Timestamp::new(0)); let date = Date::new(Timestamp::new(123456789)); let span = Amount::<UTC, TsDiff>::new(TsDiff::from(123456789)); assert_eq!(date - epoch, span); assert_eq!(date - span, epoch); assert_eq!(epoch + span, date); } }