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// 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::fmt;
use std::default::Default;
use std::hash;
use std::{mem, raw, ptr, slice, vec};
use std::rt::heap::EMPTY;
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
data: *mut T,
len: uint,
}
impl<T:fmt::Show> fmt::Show for OwnedSlice<T> {
fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
try!("OwnedSlice {{".fmt(fmt));
for i in self.iter() {
try!(i.fmt(fmt));
}
try!("}}".fmt(fmt));
Ok(())
}
}
#[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::null_mut(), len: 0 }
}
#[inline(never)]
pub fn from_vec(mut v: Vec<T>) -> OwnedSlice<T> {
let len = v.len();
if len == 0 {
OwnedSlice::empty()
} else {
// drop excess capacity to avoid breaking sized deallocation
v.shrink_to_fit();
let p = v.as_mut_ptr();
// we own the allocation now
unsafe { mem::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
mem::forget(self);
ret
}
}
pub fn as_slice<'a>(&'a self) -> &'a [T] {
let ptr = if self.data.is_null() {
// length zero, i.e. this will never be read as a T.
EMPTY as *const T
} else {
self.data as *const T
};
let slice: &[T] = unsafe {mem::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 move_iter(self) -> vec::MoveItems<T> {
self.into_vec().into_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: hash::Writer, T: hash::Hash<S>> hash::Hash<S> for OwnedSlice<T> {
fn hash(&self, state: &mut S) {
self.as_slice().hash(state)
}
}
impl<T: PartialEq> PartialEq for OwnedSlice<T> {
fn eq(&self, other: &OwnedSlice<T>) -> bool {
self.as_slice() == other.as_slice()
}
}
impl<T: Eq> Eq for OwnedSlice<T> {}
impl<T> Collection for OwnedSlice<T> {
fn len(&self) -> uint { self.len }
}
impl<T> FromIterator<T> for OwnedSlice<T> {
fn from_iter<I: Iterator<T>>(mut iter: I) -> OwnedSlice<T> {
OwnedSlice::from_vec(iter.collect())
}
}
impl<S: Encoder<E>, T: Encodable<S, E>, E> Encodable<S, E> for OwnedSlice<T> {
fn encode(&self, s: &mut S) -> Result<(), E> {
self.as_slice().encode(s)
}
}
impl<D: Decoder<E>, T: Decodable<D, E>, E> Decodable<D, E> for OwnedSlice<T> {
fn decode(d: &mut D) -> Result<OwnedSlice<T>, E> {
Ok(OwnedSlice::from_vec(match Decodable::decode(d) {
Ok(t) => t,
Err(e) => return Err(e)
}))
}
}
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