Immutable exact chunks

README.md

@@ -6,7 +6,7 @@ Yet another Rust ring buffer implementation.
 
 Features:
 * Checked/unchecked element/iterator safe push
-* Mutable exact chunk iterator (read contiguous slices)
+* Mutable/immutable exact chunk iterator (read contiguous slices)
 
 ## License
 

src/lib.rs

@@ -64,6 +64,16 @@ impl<T> RingBuf<T> {
 		len
 	}
 
+	pub fn chunks_exact(&mut self, chunk_size: usize) -> ChunksExact<T> {
+		assert_eq!(self.read_index % chunk_size, 0);
+		assert_eq!(self.data.len() % chunk_size, 0);
+
+		ChunksExact {
+			ringbuf: self,
+			chunk_size,
+		}
+	}
+
 	pub fn chunks_exact_mut(&mut self, chunk_size: usize) -> ChunksExactMut<T> {
 		assert_eq!(self.read_index % chunk_size, 0);
 		assert_eq!(self.data.len() % chunk_size, 0);
@@ -75,6 +85,28 @@ impl<T> RingBuf<T> {
 	}
 }
 
+pub struct ChunksExact<'a, T> {
+	ringbuf: &'a mut RingBuf<T>,
+	chunk_size: usize,
+}
+
+impl<'a, T> Iterator for ChunksExact<'a, T> {
+	type Item = &'a [T];
+	fn next(&mut self) -> Option<Self::Item> {
+		if self.ringbuf.available >= self.chunk_size {
+			let read_index = self.ringbuf.read_index;
+			self.ringbuf.read_index =
+				(self.ringbuf.read_index + self.chunk_size) % self.ringbuf.data.len();
+			self.ringbuf.available -= self.chunk_size;
+			let ret: &[T] = &self.ringbuf.data[read_index..read_index + self.chunk_size];
+			let ret: &'a [T] = unsafe { std::mem::transmute(ret) };
+			Some(ret)
+		} else {
+			None
+		}
+	}
+}
+
 pub struct ChunksExactMut<'a, T> {
 	ringbuf: &'a mut RingBuf<T>,
 	chunk_size: usize,