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//! A reference to a channel in a buffer. use crate::sample::Sample; use std::cmp; use std::fmt; use std::hash; use std::marker; /// A reference to a channel in a buffer. /// /// See [crate::Interleaved::get]. #[derive(Clone, Copy)] pub struct Channel<'a, T> where T: Sample, { pub(crate) inner: RawChannelRef<T>, pub(crate) _marker: marker::PhantomData<&'a T>, } unsafe impl<T> Send for Channel<'_, T> where T: Sample + Send {} unsafe impl<T> Sync for Channel<'_, T> where T: Sample + Sync {} impl<'a, T> Channel<'a, T> where T: Sample, { /// Get a reference to a frame. pub fn get(&self, frame: usize) -> Option<T> { Some(unsafe { *self.inner.frame_ref(frame)? }) } /// Construct an iterator over the current channel. pub fn iter(&self) -> ChannelIter<'_, T> { ChannelIter { inner: self.inner, frame: 0, _marker: marker::PhantomData, } } } impl<T> fmt::Debug for Channel<'_, T> where T: Sample + fmt::Debug, { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { f.debug_list().entries(self.iter()).finish() } } impl<T> cmp::PartialEq for Channel<'_, T> where T: Sample + cmp::PartialEq, { fn eq(&self, other: &Self) -> bool { self.iter().eq(other.iter()) } } impl<T> cmp::Eq for Channel<'_, T> where T: Sample + cmp::Eq {} impl<T> cmp::PartialOrd for Channel<'_, T> where T: Sample + cmp::PartialOrd, { fn partial_cmp(&self, other: &Self) -> Option<cmp::Ordering> { self.iter().partial_cmp(other.iter()) } } impl<T> cmp::Ord for Channel<'_, T> where T: Sample + cmp::Ord, { fn cmp(&self, other: &Self) -> cmp::Ordering { self.iter().cmp(other.iter()) } } impl<T> hash::Hash for Channel<'_, T> where T: Sample + hash::Hash, { fn hash<H: hash::Hasher>(&self, state: &mut H) { for frame in self.iter() { frame.hash(state); } } } /// An iterator over a channel. /// /// Created with [Channel::iter]. pub struct ChannelIter<'a, T> where T: Sample, { inner: RawChannelRef<T>, frame: usize, _marker: marker::PhantomData<&'a T>, } unsafe impl<T> Send for ChannelIter<'_, T> where T: Sample + Send {} unsafe impl<T> Sync for ChannelIter<'_, T> where T: Sample + Sync {} impl<'a, T> Iterator for ChannelIter<'a, T> where T: Sample, { type Item = &'a T; fn next(&mut self) -> Option<Self::Item> { let item = unsafe { &*self.inner.frame_ref(self.frame)? }; self.frame += 1; Some(item) } } #[derive(Clone, Copy)] pub(crate) struct RawChannelRef<T> { pub(crate) buffer: *const T, pub(crate) channel: usize, pub(crate) channels: usize, pub(crate) frames: usize, } impl<T> RawChannelRef<T> { /// Get a pointer to the given frame. /// /// This performs bounds checking to make sure that the frame is in bounds /// with the underlying collection. #[inline] fn frame_ref(self, frame: usize) -> Option<*const T> { if frame < self.frames { let offset = self.channels * frame + self.channel; // Safety: We hold all the parameters necessary to perform bounds // checking. let frame = unsafe { self.buffer.add(offset) }; Some(frame) } else { None } } } #[derive(Clone, Copy)] pub(crate) struct RawChannelMut<T> { pub(crate) buffer: *mut T, pub(crate) channel: usize, pub(crate) channels: usize, pub(crate) frames: usize, } impl<T> RawChannelMut<T> { #[inline] fn into_ref(self) -> RawChannelRef<T> { RawChannelRef { buffer: self.buffer as *const _, channel: self.channel, channels: self.channels, frames: self.frames, } } /// Get a mutable pointer to the given frame. /// /// This performs bounds checking to make sure that the frame is in bounds /// with the underlying collection. #[inline] fn frame_mut(self, frame: usize) -> Option<*mut T> { if frame < self.frames { let offset = self.channels * frame + self.channel; // Safety: We hold all the parameters necessary to perform bounds // checking. let frame = unsafe { self.buffer.add(offset) }; Some(frame) } else { None } } } /// A mutable reference to a channel in a buffer. /// /// See [crate::Interleaved::get_mut]. pub struct ChannelMut<'a, T> where T: Sample, { pub(crate) inner: RawChannelMut<T>, pub(crate) _marker: marker::PhantomData<&'a mut T>, } // Safety: the iterator is simply a container of mutable references to T's, any // Send/Sync properties are inherited. unsafe impl<T> Send for ChannelMut<'_, T> where T: Sample + Send {} unsafe impl<T> Sync for ChannelMut<'_, T> where T: Sample + Sync {} impl<'a, T> ChannelMut<'a, T> where T: Sample, { /// Get a reference to a frame. /// /// # Examples /// /// ```rust /// let mut buffer = rotary::Interleaved::<f32>::with_topology(2, 256); /// /// let left = buffer.get(0).unwrap(); /// /// assert_eq!(left.get(64), Some(0.0)); /// assert_eq!(left.get(255), Some(0.0)); /// assert_eq!(left.get(256), None); /// ``` pub fn get(&self, frame: usize) -> Option<T> { // Safety: The lifetime created is associated with the structure that // constructed this abstraction. unsafe { Some(*self.inner.into_ref().frame_ref(frame)?) } } /// Get a mutable reference to a frame. /// /// # Examples /// /// ```rust /// let mut buffer = rotary::Interleaved::<f32>::with_topology(2, 256); /// /// let mut left = buffer.get_mut(0).unwrap(); /// /// assert_eq!(left.get(64), Some(0.0)); /// *left.get_mut(64).unwrap() = 1.0; /// assert_eq!(left.get(64), Some(1.0)); /// ``` pub fn get_mut(&mut self, frame: usize) -> Option<&mut T> { // Safety: The lifetime created is associated with the structure that // constructed this abstraction. unsafe { Some(&mut *self.inner.frame_mut(frame)?) } } /// Convert the mutable channel into a single mutable frame. /// /// This is necessary in case you need to build a structure which wraps a /// mutable channel and you want it to return the same lifetime as the /// mutable channel is associated with. /// /// # Examples /// /// This does not build: /// /// ```rust,compile_fail /// struct Foo<'a> { /// left: rotary::channel::ChannelMut<'a, f32>, /// } /// /// impl<'a> Foo<'a> { /// fn get_mut(&mut self, frame: usize) -> Option<&'a mut f32> { /// self.left.get_mut(frame) /// } /// } /// /// let mut buffer = rotary::Interleaved::<f32>::with_topology(2, 256); /// /// let mut foo = Foo { /// left: buffer.get_mut(0).unwrap(), /// }; /// /// *foo.get_mut(64).unwrap() = 1.0; /// assert_eq!(buffer.frame(0, 64), Some(1.0)); /// ``` /// /// ```text /// error[E0495]: cannot infer an appropriate lifetime for autoref due to conflicting requirements /// --> examples\compile-fail.rs:7:19 /// | /// 7 | self.left.get_mut(frame) /// | ^^^^^^^ /// | /// ``` /// /// Because if it did, it would be permitted to extract multiple mutable /// references to potentially the same frame with the lifetime `'a`, because /// `Foo` holds onto the mutable channel. /// /// The way we can work around this is by allowing a function to consume the /// mutable channel. And we can do that with [ChannelMut::into_mut]. /// /// ```rust /// # struct Foo<'a> { /// # left: rotary::channel::ChannelMut<'a, f32>, /// # } /// /// impl<'a> Foo<'a> { /// fn into_mut(self, frame: usize) -> Option<&'a mut f32> { /// self.left.into_mut(frame) /// } /// } /// /// let mut buffer = rotary::Interleaved::<f32>::with_topology(2, 256); /// /// let mut foo = Foo { /// left: buffer.get_mut(0).unwrap(), /// }; /// /// *foo.into_mut(64).unwrap() = 1.0; /// assert_eq!(buffer.frame(0, 64), Some(1.0)); /// ``` pub fn into_mut(self, frame: usize) -> Option<&'a mut T> { // Safety: The lifetime created is associated with the structure that // constructed this abstraction. // // We also discard the current channel, which would otherwise allow us // to create more `&'a mut T` references, which would be illegal. unsafe { Some(&mut *self.inner.frame_mut(frame)?) } } /// Construct an iterator over the current channel. pub fn iter(&self) -> ChannelIter<'_, T> { ChannelIter { inner: self.inner.into_ref(), frame: 0, _marker: marker::PhantomData, } } /// Construct a mutable iterator over the current channel. pub fn iter_mut(&mut self) -> ChannelIterMut<'_, T> { ChannelIterMut { inner: self.inner, frame: 0, _marker: marker::PhantomData, } } } impl<T> fmt::Debug for ChannelMut<'_, T> where T: Sample + fmt::Debug, { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { f.debug_list().entries(self.iter()).finish() } } impl<T> cmp::PartialEq for ChannelMut<'_, T> where T: Sample + cmp::PartialEq, { fn eq(&self, other: &Self) -> bool { self.iter().eq(other.iter()) } } impl<T> cmp::Eq for ChannelMut<'_, T> where T: Sample + cmp::Eq {} impl<T> cmp::PartialOrd for ChannelMut<'_, T> where T: Sample + cmp::PartialOrd, { fn partial_cmp(&self, other: &Self) -> Option<cmp::Ordering> { self.iter().partial_cmp(other.iter()) } } impl<T> cmp::Ord for ChannelMut<'_, T> where T: Sample + cmp::Ord, { fn cmp(&self, other: &Self) -> cmp::Ordering { self.iter().cmp(other.iter()) } } impl<T> hash::Hash for ChannelMut<'_, T> where T: Sample + hash::Hash, { fn hash<H: hash::Hasher>(&self, state: &mut H) { for frame in self.iter() { frame.hash(state); } } } /// A mutable iterator over a channel. /// /// Created with [ChannelMut::iter_mut]. pub struct ChannelIterMut<'a, T> where T: Sample, { inner: RawChannelMut<T>, frame: usize, _marker: marker::PhantomData<&'a mut T>, } // Safety: the iterator is simply a container of references to T's, any // Send/Sync properties are inherited. unsafe impl<T> Send for ChannelIterMut<'_, T> where T: Sample + Send {} unsafe impl<T> Sync for ChannelIterMut<'_, T> where T: Sample + Sync {} impl<'a, T> Iterator for ChannelIterMut<'a, T> where T: Sample, { type Item = &'a mut T; fn next(&mut self) -> Option<Self::Item> { let item = unsafe { &mut *self.inner.frame_mut(self.frame)? }; self.frame += 1; Some(item) } }