rxrust 0.1.0

A Rust implementation of Reactive Extensions.
Documentation 
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use crate::prelude::*;
use std::sync::Arc;

/// Creates a new stream which calls a closure on each element and uses
/// its return as the value.
///
pub trait Map<T> {
  fn map<B, F>(self, f: F) -> MapOp<Self, RxFnWrapper<F>>
  where
    Self: Sized,
    F: Fn(&T) -> B,
  {
    MapOp {
      source: self,
      func: RxFnWrapper::new(f),
    }
  }

  /// A version of map extension which return reference, and furthermoreļ¼Œreturn
  /// type and input item has same lifetime.
  fn map_return_ref<B, F>(self, f: F) -> MapReturnRefOp<Self, RxFnWrapper<F>>
  where
    Self: Sized,
    F: for<'r> Fn(&'r T) -> &'r B,
  {
    MapReturnRefOp {
      source: self,
      func: RxFnWrapper::new(f),
    }
  }
}

pub trait MapWithErr<T> {
  type Err;
  fn map_with_err<B, F>(self, f: F) -> MapWithErrOp<Self, RxFnWrapper<F>>
  where
    Self: Sized,
    F: Fn(&T) -> Result<B, Self::Err>,
  {
    MapWithErrOp {
      source: self,
      func: RxFnWrapper::new(f),
    }
  }

  /// A version of map_with_err extension which return reference, and
  /// furthermoreļ¼Œ return item and input item has same lifetime.
  fn map_return_ref_with_err<B, F>(
    self,
    f: F,
  ) -> MapReturnRefWithErrOp<Self, RxFnWrapper<F>>
  where
    Self: Sized,
    F: for<'r> Fn(&'r T) -> Result<&'r B, Self::Err>,
  {
    MapReturnRefWithErrOp {
      source: self,
      func: RxFnWrapper::new(f),
    }
  }
}

impl<'a, O> Map<O::Item> for O where O: RawSubscribable {}

impl<'a, O> MapWithErr<O::Item> for O
where
  O: RawSubscribable,
{
  type Err = O::Err;
}

pub struct MapOp<S, M> {
  source: S,
  func: M,
}

macro_rules! map_subscribe {
  ($subscribe: ident, $map: ident) => {
    RxFnWrapper::new(move |v: RxValue<&'_ _, &'_ _>| match v {
      RxValue::Next(nv) => $subscribe.call((RxValue::Next(&$map.call((nv,))),)),
      RxValue::Err(err) => $subscribe.call((RxValue::Err(err),)),
      RxValue::Complete => $subscribe.call((RxValue::Complete,)),
    })
  };
}

impl<S, B, M> RawSubscribable for MapOp<S, M>
where
  M: RxFn(&S::Item) -> B + Send + Sync + 'static,
  S: RawSubscribable,
{
  type Item = B;
  type Err = S::Err;

  fn raw_subscribe(
    self,
    subscribe: impl RxFn(
        RxValue<&'_ Self::Item, &'_ Self::Err>,
      ) -> RxReturn<Self::Err>
      + Send
      + Sync
      + 'static,
  ) -> Box<dyn Subscription + Send + Sync> {
    let map = self.func;
    self.source.raw_subscribe(map_subscribe!(subscribe, map))
  }
}

impl<S, B, M> Multicast for MapOp<S, M>
where
  S: Multicast,
  M: RxFn(&S::Item) -> B + Send + Sync + 'static,
{
  type Output = MapOp<S::Output, Arc<M>>;
  fn multicast(self) -> Self::Output {
    MapOp {
      source: self.source.multicast(),
      func: Arc::new(self.func),
    }
  }
}

impl<S, B, M> Fork for MapOp<S, Arc<M>>
where
  S: Fork,
  M: RxFn(&S::Item) -> B + Send + Sync + 'static,
{
  type Output = MapOp<S::Output, Arc<M>>;
  fn fork(&self) -> Self::Output {
    MapOp {
      source: self.source.fork(),
      func: self.func.clone(),
    }
  }
}

pub struct MapWithErrOp<S, M> {
  source: S,
  func: M,
}

macro_rules! map_subscribe_with_err {
  ($subscribe:ident, $map:ident) => {
    RxFnWrapper::new(move |v: RxValue<&'_ _, &'_ _>| match v {
      RxValue::Next(nv) => match $map.call((nv,)) {
        Ok(ref mv) => $subscribe.call((RxValue::Next(mv),)),
        Err(e) => RxReturn::Err(e),
      },
      RxValue::Err(err) => $subscribe.call((RxValue::Err(err),)),
      RxValue::Complete => $subscribe.call((RxValue::Complete,)),
    })
  };
}
impl<'a, S, B, M> RawSubscribable for MapWithErrOp<S, M>
where
  M: RxFn(&S::Item) -> Result<B, S::Err> + Send + Sync + 'static,
  S: RawSubscribable,
{
  type Item = B;
  type Err = S::Err;

  fn raw_subscribe(
    self,
    subscribe: impl RxFn(
        RxValue<&'_ Self::Item, &'_ Self::Err>,
      ) -> RxReturn<Self::Err>
      + Send
      + Sync
      + 'static,
  ) -> Box<dyn Subscription + Send + Sync> {
    let map = self.func;
    self
      .source
      .raw_subscribe(map_subscribe_with_err!(subscribe, map))
  }
}

impl<S, B, M> Multicast for MapWithErrOp<S, M>
where
  S: Multicast,
  M: RxFn(&S::Item) -> Result<B, S::Err> + Send + Sync + 'static,
{
  type Output = MapWithErrOp<S::Output, Arc<M>>;
  fn multicast(self) -> Self::Output {
    MapWithErrOp {
      source: self.source.multicast(),
      func: Arc::new(self.func),
    }
  }
}

impl<S, B, M> Fork for MapWithErrOp<S, Arc<M>>
where
  S: Fork,
  M: RxFn(&S::Item) -> Result<B, S::Err> + Send + Sync + 'static,
{
  type Output = MapWithErrOp<S::Output, Arc<M>>;
  fn fork(&self) -> Self::Output {
    MapWithErrOp {
      source: self.source.fork(),
      func: self.func.clone(),
    }
  }
}

pub struct MapReturnRefOp<S, M> {
  source: S,
  func: M,
}

impl<S, B, M> RawSubscribable for MapReturnRefOp<S, M>
where
  M: for<'r> RxFn(&'r S::Item) -> &'r B + Send + Sync + 'static,
  S: RawSubscribable,
{
  type Item = B;
  type Err = S::Err;

  fn raw_subscribe(
    self,
    subscribe: impl RxFn(
        RxValue<&'_ Self::Item, &'_ Self::Err>,
      ) -> RxReturn<Self::Err>
      + Send
      + Sync
      + 'static,
  ) -> Box<dyn Subscription + Send + Sync> {
    let map = self.func;
    self.source.raw_subscribe(map_subscribe!(subscribe, map))
  }
}

impl<S, B, M> Multicast for MapReturnRefOp<S, M>
where
  S: Multicast,
  M: for<'r> RxFn(&'r S::Item) -> &'r B + Send + Sync + 'static,
{
  type Output = MapReturnRefOp<S::Output, Arc<M>>;
  fn multicast(self) -> Self::Output {
    MapReturnRefOp {
      source: self.source.multicast(),
      func: Arc::new(self.func),
    }
  }
}

impl<S, B, M> Fork for MapReturnRefOp<S, Arc<M>>
where
  S: Fork,
  M: for<'r> RxFn(&'r S::Item) -> &'r B + Send + Sync + 'static,
{
  type Output = MapReturnRefOp<S::Output, Arc<M>>;
  fn fork(&self) -> Self::Output {
    MapReturnRefOp {
      source: self.source.fork(),
      func: self.func.clone(),
    }
  }
}

pub struct MapReturnRefWithErrOp<S, M> {
  source: S,
  func: M,
}

impl<S, B, M> RawSubscribable for MapReturnRefWithErrOp<S, M>
where
  M: for<'r> RxFn(&'r S::Item) -> Result<&'r B, S::Err> + Send + Sync + 'static,
  S: RawSubscribable,
{
  type Item = B;
  type Err = S::Err;

  fn raw_subscribe(
    self,
    subscribe: impl RxFn(
        RxValue<&'_ Self::Item, &'_ Self::Err>,
      ) -> RxReturn<Self::Err>
      + Send
      + Sync
      + 'static,
  ) -> Box<dyn Subscription + Send + Sync> {
    let map = self.func;
    self
      .source
      .raw_subscribe(map_subscribe_with_err!(subscribe, map))
  }
}

impl<S, B, M> Multicast for MapReturnRefWithErrOp<S, M>
where
  S: Multicast,
  M: for<'r> RxFn(&'r S::Item) -> Result<&'r B, S::Err> + Send + Sync + 'static,
{
  type Output = MapReturnRefWithErrOp<S::Output, Arc<M>>;
  fn multicast(self) -> Self::Output {
    MapReturnRefWithErrOp {
      source: self.source.multicast(),
      func: Arc::new(self.func),
    }
  }
}

impl<S, B, M> Fork for MapReturnRefWithErrOp<S, Arc<M>>
where
  S: Fork,
  M: for<'r> RxFn(&'r S::Item) -> Result<&'r B, S::Err> + Send + Sync + 'static,
{
  type Output = MapReturnRefWithErrOp<S::Output, Arc<M>>;
  fn fork(&self) -> Self::Output {
    MapReturnRefWithErrOp {
      source: self.source.fork(),
      func: self.func.clone(),
    }
  }
}

#[cfg(test)]
mod test {
  use crate::{
    ops::{Map, MapWithErr},
    prelude::*,
  };
  use std::sync::{Arc, Mutex};

  #[test]
  fn primitive_type() {
    let i = Arc::new(Mutex::new(0));
    let c_i = i.clone();
    observable::from_range(100..101)
      .map(|v| v * 2)
      .subscribe(move |v| *i.lock().unwrap() += *v);
    assert_eq!(*c_i.lock().unwrap(), 200);
  }

  #[test]
  fn reference_lifetime_should_work() {
    let i = Arc::new(Mutex::new(0));
    let c_i = i.clone();

    observable::of(100)
      .map_return_ref(|v: &i32| v)
      .subscribe(move |v| *i.lock().unwrap() += *v);
    assert_eq!(*c_i.lock().unwrap(), 100);
  }

  #[test]
  #[should_panic]
  fn with_err() {
    let subject = Subject::new();

    subject
      .clone()
      .map_with_err(|_| Err("should panic "))
      .subscribe_err(|_: &i32| {}, |err| panic!(*err));

    subject.next(&1);
  }

  #[test]
  #[should_panic]
  fn map_return_ref_with_err() {
    let subject = Subject::new();

    subject
      .clone()
      .map_return_ref_with_err(|_| Err("should panic "))
      .subscribe_err(|_: &i32| {}, |err| panic!(*err));

    subject.next(&1);
  }

  #[test]
  fn fork() {
    // type to type can fork
    let m = observable::from_range(0..100).map(|v| *v);
    m.multicast()
      .fork()
      .map(|v| *v)
      .multicast()
      .fork()
      .subscribe(|_| {});

    // ref to ref can fork
    let m = observable::from_range(0..100).map_return_ref(|v| v);
    m.multicast()
      .fork()
      .map_return_ref(|v| v)
      .multicast()
      .fork()
      .subscribe(|_| {});
    // type to type with error can fork
    let m = observable::from_range(0..100).map_with_err(|v| Ok(*v));
    m.multicast()
      .fork()
      .map_with_err(|v| Ok(*v))
      .multicast()
      .fork()
      .subscribe(|_| {});
    // ref to ref with error can fork
    let m = observable::from_range(0..100).map_return_ref_with_err(|v| Ok(v));
    m.multicast()
      .fork()
      .map_return_ref_with_err(|v| Ok(v))
      .multicast()
      .fork()
      .subscribe(|_| {});
  }
}