remove Buffers::collect; reinstate TryFrom impls for non-nested tuples

Remove Buffers::collect, Buffer(Mut)::collect, and FromBuffers trait in favor
of the standard TryFrom trait again. However, only impl TryFrom<Buffers> for
non-nested tuples; do not implement it for singular Buffer(Mut) types or for
arbitrarily nested tuples.

Author: micahrj

examples/gain/src/lib.rs

@@ -115,8 +115,8 @@ impl Processor for GainProcessor {
     fn reset(&mut self) {}
 
     fn process(&mut self, buffers: Buffers, events: Events) {
-        let mut buffer = buffers.collect::<BufferMut>().unwrap();
-        for (mut buffer, events) in buffer.split_at_events(events) {
+        let mut buffers: (BufferMut,) = buffers.try_into().unwrap();
+        for (mut buffer, events) in buffers.0.split_at_events(events) {
             for event in events {
                 if let Data::ParamChange { id, value } = event.data {
                     self.params.set_param(id, value);

src/buffers.rs

@@ -1,12 +1,11 @@
 use std::marker::PhantomData;
 use std::ops::{Index, IndexMut, Range};
-use std::{array, slice};
+use std::slice;
 
-pub mod collect;
+pub mod convert;
 pub mod iter;
 
 use crate::events::Events;
-use collect::FromBuffers;
 use iter::{BlockIterator, IntoBlocks, IntoSamples};
 
 #[derive(Copy, Clone, Eq, PartialEq)]
@@ -108,19 +107,6 @@ impl<'a, 'b> Buffers<'a, 'b> {
         }
     }
 
-    #[inline]
-    pub fn collect<B: FromBuffers<'a, 'b>>(self) -> Option<B> {
-        let mut iter = self.into_iter();
-
-        let result = B::from_buffers(&mut iter)?;
-
-        if iter.next().is_none() {
-            Some(result)
-        } else {
-            None
-        }
-    }
-
     #[inline]
     pub fn slice(&mut self, range: Range<usize>) -> Option<Buffers> {
         if range.start > range.end || range.end > self.len {
@@ -335,17 +321,6 @@ impl<'a, 'b> Buffer<'a, 'b> {
         self.ptrs.len()
     }
 
-    #[inline]
-    pub fn collect<const N: usize>(self) -> Option<[&'b [f32]; N]> {
-        if self.channel_count() != N {
-            return None;
-        }
-
-        Some(array::from_fn(|i| unsafe {
-            slice::from_raw_parts(self.ptrs[i].offset(self.offset), self.len)
-        }))
-    }
-
     #[inline]
     pub fn samples(&self) -> iter::SampleIter<'a, 'b> {
         self.into_samples()
@@ -515,17 +490,6 @@ impl<'a, 'b> BufferMut<'a, 'b> {
         }
     }
 
-    #[inline]
-    pub fn collect<const N: usize>(self) -> Option<[&'b mut [f32]; N]> {
-        if self.channel_count() != N {
-            return None;
-        }
-
-        Some(array::from_fn(|i| unsafe {
-            slice::from_raw_parts_mut(self.ptrs[i].offset(self.offset), self.len)
-        }))
-    }
-
     #[inline]
     pub fn samples<'c>(&'c mut self) -> iter::SampleIterMut<'a, 'c> {
         self.reborrow().into_samples()

src/buffers/collect.rs

@@ -0,0 +1,110 @@
+use std::error::Error;
+use std::{array, fmt, slice};
+
+use super::{AnyBuffer, Buffer, BufferMut, Buffers};
+
+impl<'a, 'b> TryFrom<AnyBuffer<'a, 'b>> for Buffer<'a, 'b> {
+    type Error = AnyBuffer<'a, 'b>;
+
+    #[inline]
+    fn try_from(value: AnyBuffer<'a, 'b>) -> Result<Buffer<'a, 'b>, Self::Error> {
+        match value {
+            AnyBuffer::Const(buffer) => Ok(buffer),
+            _ => Err(value),
+        }
+    }
+}
+
+impl<'a, 'b> TryFrom<AnyBuffer<'a, 'b>> for BufferMut<'a, 'b> {
+    type Error = AnyBuffer<'a, 'b>;
+
+    #[inline]
+    fn try_from(value: AnyBuffer<'a, 'b>) -> Result<BufferMut<'a, 'b>, Self::Error> {
+        match value {
+            AnyBuffer::Mut(buffer) => Ok(buffer),
+            _ => Err(value),
+        }
+    }
+}
+
+impl<'a, 'b, const N: usize> TryFrom<Buffer<'a, 'b>> for [&'b [f32]; N] {
+    type Error = Buffer<'a, 'b>;
+
+    #[inline]
+    fn try_from(value: Buffer<'a, 'b>) -> Result<[&'b [f32]; N], Self::Error> {
+        if value.channel_count() == N {
+            Ok(array::from_fn(|i| unsafe {
+                slice::from_raw_parts(value.ptrs[i].offset(value.offset), value.len)
+            }))
+        } else {
+            Err(value)
+        }
+    }
+}
+
+impl<'a, 'b, const N: usize> TryFrom<BufferMut<'a, 'b>> for [&'b mut [f32]; N] {
+    type Error = BufferMut<'a, 'b>;
+
+    #[inline]
+    fn try_from(value: BufferMut<'a, 'b>) -> Result<[&'b mut [f32]; N], Self::Error> {
+        if value.channel_count() == N {
+            Ok(array::from_fn(|i| unsafe {
+                slice::from_raw_parts_mut(value.ptrs[i].offset(value.offset), value.len)
+            }))
+        } else {
+            Err(value)
+        }
+    }
+}
+
+#[derive(Debug)]
+pub struct TryFromBuffersError;
+
+impl fmt::Display for TryFromBuffersError {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        "buffer layout does not match".fmt(fmt)
+    }
+}
+
+impl Error for TryFromBuffersError {}
+
+macro_rules! try_from_buffers {
+    ($($buffer:ident),*) => {
+        impl<'a, 'b, $($buffer),*> TryFrom<Buffers<'a, 'b>> for ($($buffer,)*)
+        where
+            $($buffer: TryFrom<AnyBuffer<'a, 'b>>),*
+        {
+            type Error = TryFromBuffersError;
+
+            #[inline]
+            fn try_from(value: Buffers<'a, 'b>) -> Result<Self, Self::Error> {
+                let mut iter = value.into_iter();
+
+                let result = (
+                    $({
+                        let next = iter.next().ok_or(TryFromBuffersError)?;
+                        $buffer::try_from(next).map_err(|_| TryFromBuffersError)?
+                    },)*
+                );
+
+                if iter.next().is_none() {
+                    Ok(result)
+                } else {
+                    Err(TryFromBuffersError)
+                }
+            }
+        }
+    }
+}
+
+try_from_buffers!();
+try_from_buffers!(B0);
+try_from_buffers!(B0, B1);
+try_from_buffers!(B0, B1, B2);
+try_from_buffers!(B0, B1, B2, B3);
+try_from_buffers!(B0, B1, B2, B3, B4);
+try_from_buffers!(B0, B1, B2, B3, B4, B5);
+try_from_buffers!(B0, B1, B2, B3, B4, B5, B6);
+try_from_buffers!(B0, B1, B2, B3, B4, B5, B6, B7);
+try_from_buffers!(B0, B1, B2, B3, B4, B5, B6, B7, B8);
+try_from_buffers!(B0, B1, B2, B3, B4, B5, B6, B7, B8, B9);