diff --git a/src/libcollections/ring_buf.rs b/src/libcollections/ring_buf.rs index cdb92d302e9d3..aa5679c43397d 100644 --- a/src/libcollections/ring_buf.rs +++ b/src/libcollections/ring_buf.rs @@ -78,7 +78,13 @@ impl Default for RingBuf { impl RingBuf { /// Turn ptr into a slice #[inline] - unsafe fn buffer_as_slice(&self) -> &[T] { + unsafe fn buffer_as_slice<'a>(&'a self) -> &'a [T] { + mem::transmute(RawSlice { data: self.ptr as *const T, len: self.cap }) + } + + /// Turn ptr into a mut slice + #[inline] + unsafe fn buffer_as_mut_slice<'a>(&'a mut self) -> &'a mut [T] { mem::transmute(RawSlice { data: self.ptr as *const T, len: self.cap }) } @@ -413,6 +419,48 @@ impl RingBuf { } } + /// Returns a pair of slices which contain, in order, the contents of the + /// `RingBuf`. + #[inline] + #[unstable = "matches collection reform specification, waiting for dust to settle"] + pub fn as_slices<'a>(&'a self) -> (&'a [T], &'a [T]) { + unsafe { + let contiguous = self.is_contiguous(); + let buf = self.buffer_as_slice(); + if contiguous { + let (empty, buf) = buf.split_at(0); + (buf[self.tail..self.head], empty) + } else { + let (mid, right) = buf.split_at(self.tail); + let (left, _) = mid.split_at(self.head); + (right, left) + } + } + } + + /// Returns a pair of slices which contain, in order, the contents of the + /// `RingBuf`. + #[inline] + #[unstable = "matches collection reform specification, waiting for dust to settle"] + pub fn as_mut_slices<'a>(&'a mut self) -> (&'a mut [T], &'a mut [T]) { + unsafe { + let contiguous = self.is_contiguous(); + let head = self.head; + let tail = self.tail; + let buf = self.buffer_as_mut_slice(); + + if contiguous { + let (empty, buf) = buf.split_at_mut(0); + (buf[mut tail..head], empty) + } else { + let (mid, right) = buf.split_at_mut(tail); + let (left, _) = mid.split_at_mut(head); + + (right, left) + } + } + } + /// Returns the number of elements in the `RingBuf`. /// /// # Examples @@ -663,6 +711,11 @@ impl RingBuf { } } + #[inline] + fn is_contiguous(&self) -> bool { + self.tail <= self.head + } + /// Inserts an element at position `i` within the ringbuf. Whichever /// end is closer to the insertion point will be moved to make room, /// and all the affected elements will be moved to new positions. @@ -715,7 +768,7 @@ impl RingBuf { let distance_to_tail = i; let distance_to_head = self.len() - i; - let contiguous = self.tail <= self.head; + let contiguous = self.is_contiguous(); match (contiguous, distance_to_tail <= distance_to_head, idx >= self.tail) { (true, true, _) if i == 0 => { @@ -2132,4 +2185,60 @@ mod tests { ring.pop_front(); assert_eq!(ring.front(), None); } + + #[test] + fn test_as_slices() { + let mut ring: RingBuf = RingBuf::with_capacity(127); + let cap = ring.capacity() as int; + let first = cap/2; + let last = cap - first; + for i in range(0, first) { + ring.push_back(i); + + let (left, right) = ring.as_slices(); + let expected: Vec<_> = range(0, i+1).collect(); + assert_eq!(left, expected); + assert_eq!(right, []); + } + + for j in range(-last, 0) { + ring.push_front(j); + let (left, right) = ring.as_slices(); + let expected_left: Vec<_> = range(-last, j+1).rev().collect(); + let expected_right: Vec<_> = range(0, first).collect(); + assert_eq!(left, expected_left); + assert_eq!(right, expected_right); + } + + assert_eq!(ring.len() as int, cap); + assert_eq!(ring.capacity() as int, cap); + } + + #[test] + fn test_as_mut_slices() { + let mut ring: RingBuf = RingBuf::with_capacity(127); + let cap = ring.capacity() as int; + let first = cap/2; + let last = cap - first; + for i in range(0, first) { + ring.push_back(i); + + let (left, right) = ring.as_mut_slices(); + let expected: Vec<_> = range(0, i+1).collect(); + assert_eq!(left, expected); + assert_eq!(right, []); + } + + for j in range(-last, 0) { + ring.push_front(j); + let (left, right) = ring.as_mut_slices(); + let expected_left: Vec<_> = range(-last, j+1).rev().collect(); + let expected_right: Vec<_> = range(0, first).collect(); + assert_eq!(left, expected_left); + assert_eq!(right, expected_right); + } + + assert_eq!(ring.len() as int, cap); + assert_eq!(ring.capacity() as int, cap); + } }