--- /dev/null
+// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use std::default::Default;
+use std::hash::Hash;
+use std::{cast, mem, raw, ptr, slice};
+use serialize::{Encodable, Decodable, Encoder, Decoder};
+
+/// A non-growable owned slice. This would preferably become `~[T]`
+/// under DST.
+#[unsafe_no_drop_flag] // data is set to null on destruction
+pub struct OwnedSlice<T> {
+ /// null iff len == 0
+ priv data: *mut T,
+ priv len: uint,
+}
+
+#[unsafe_destructor]
+impl<T> Drop for OwnedSlice<T> {
+ fn drop(&mut self) {
+ if self.data.is_null() { return }
+
+ // extract the vector
+ let v = mem::replace(self, OwnedSlice::empty());
+ // free via the Vec destructor
+ v.into_vec();
+ }
+}
+
+impl<T> OwnedSlice<T> {
+ pub fn empty() -> OwnedSlice<T> {
+ OwnedSlice { data: ptr::mut_null(), len: 0 }
+ }
+
+ #[inline(never)]
+ pub fn from_vec(mut v: Vec<T>) -> OwnedSlice<T> {
+ let len = v.len();
+
+ if len == 0 {
+ OwnedSlice::empty()
+ } else {
+ let p = v.as_mut_ptr();
+ // we own the allocation now
+ unsafe {cast::forget(v)}
+
+ OwnedSlice { data: p, len: len }
+ }
+ }
+
+ #[inline(never)]
+ pub fn into_vec(self) -> Vec<T> {
+ // null is ok, because len == 0 in that case, as required by Vec.
+ unsafe {
+ let ret = Vec::from_raw_parts(self.len, self.len, self.data);
+ // the vector owns the allocation now
+ cast::forget(self);
+ ret
+ }
+ }
+
+ pub fn as_slice<'a>(&'a self) -> &'a [T] {
+ static PTR_MARKER: u8 = 0;
+ let ptr = if self.data.is_null() {
+ // length zero, i.e. this will never be read as a T.
+ &PTR_MARKER as *u8 as *T
+ } else {
+ self.data as *T
+ };
+
+ let slice: &[T] = unsafe {cast::transmute(raw::Slice {
+ data: ptr,
+ len: self.len
+ })};
+
+ slice
+ }
+
+ pub fn get<'a>(&'a self, i: uint) -> &'a T {
+ self.as_slice().get(i).expect("OwnedSlice: index out of bounds")
+ }
+
+ pub fn iter<'r>(&'r self) -> slice::Items<'r, T> {
+ self.as_slice().iter()
+ }
+
+ pub fn map<U>(&self, f: |&T| -> U) -> OwnedSlice<U> {
+ self.iter().map(f).collect()
+ }
+}
+
+impl<T> Default for OwnedSlice<T> {
+ fn default() -> OwnedSlice<T> {
+ OwnedSlice::empty()
+ }
+}
+
+impl<T: Clone> Clone for OwnedSlice<T> {
+ fn clone(&self) -> OwnedSlice<T> {
+ OwnedSlice::from_vec(Vec::from_slice(self.as_slice()))
+ }
+}
+
+impl<S: Writer, T: Hash<S>> Hash<S> for OwnedSlice<T> {
+ fn hash(&self, state: &mut S) {
+ self.as_slice().hash(state)
+ }
+}
+
+impl<T: Eq> Eq for OwnedSlice<T> {
+ fn eq(&self, other: &OwnedSlice<T>) -> bool {
+ self.as_slice() == other.as_slice()
+ }
+}
+
+impl<T> Container for OwnedSlice<T> {
+ fn len(&self) -> uint { self.len }
+}
+
+impl<T> FromIterator<T> for OwnedSlice<T> {
+ fn from_iterator<I: Iterator<T>>(iter: &mut I) -> OwnedSlice<T> {
+ OwnedSlice::from_vec(iter.collect())
+ }
+}
+
+impl<S: Encoder, T: Encodable<S>> Encodable<S> for OwnedSlice<T> {
+ fn encode(&self, s: &mut S) {
+ self.as_slice().encode(s)
+ }
+}
+
+impl<D: Decoder, T: Decodable<D>> Decodable<D> for OwnedSlice<T> {
+ fn decode(d: &mut D) -> OwnedSlice<T> {
+ OwnedSlice::from_vec(Decodable::decode(d))
+ }
+}