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// Copyright 2012 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.
//! A unique pointer type
use core::any::{Any, AnyRefExt};
use core::clone::Clone;
use core::cmp::{PartialEq, PartialOrd, Eq, Ord, Ordering};
use core::default::Default;
use core::fmt;
use core::intrinsics;
use core::mem;
use core::raw::TraitObject;
use core::result::{Ok, Err, Result};
/// A value that represents the global exchange heap. This is the default
/// place that the `box` keyword allocates into when no place is supplied.
///
/// The following two examples are equivalent:
///
/// use std::owned::HEAP;
///
/// # struct Bar;
/// # impl Bar { fn new(_a: int) { } }
/// let foo = box(HEAP) Bar::new(2);
/// let foo = box Bar::new(2);
#[lang="exchange_heap"]
pub static HEAP: () = ();
/// A type that represents a uniquely-owned value.
#[lang="owned_box"]
pub struct Box<T>(*T);
impl<T: Default> Default for Box<T> {
fn default() -> Box<T> { box Default::default() }
}
#[unstable]
impl<T: Clone> Clone for Box<T> {
/// Return a copy of the owned box.
#[inline]
fn clone(&self) -> Box<T> { box {(**self).clone()} }
/// Perform copy-assignment from `source` by reusing the existing allocation.
#[inline]
fn clone_from(&mut self, source: &Box<T>) {
(**self).clone_from(&(**source));
}
}
// box pointers
impl<T:PartialEq> PartialEq for Box<T> {
#[inline]
fn eq(&self, other: &Box<T>) -> bool { *(*self) == *(*other) }
#[inline]
fn ne(&self, other: &Box<T>) -> bool { *(*self) != *(*other) }
}
impl<T:PartialOrd> PartialOrd for Box<T> {
#[inline]
fn lt(&self, other: &Box<T>) -> bool { *(*self) < *(*other) }
#[inline]
fn le(&self, other: &Box<T>) -> bool { *(*self) <= *(*other) }
#[inline]
fn ge(&self, other: &Box<T>) -> bool { *(*self) >= *(*other) }
#[inline]
fn gt(&self, other: &Box<T>) -> bool { *(*self) > *(*other) }
}
impl<T: Ord> Ord for Box<T> {
#[inline]
fn cmp(&self, other: &Box<T>) -> Ordering { (**self).cmp(*other) }
}
impl<T: Eq> Eq for Box<T> {}
/// Extension methods for an owning `Any` trait object
pub trait AnyOwnExt {
/// Returns the boxed value if it is of type `T`, or
/// `Err(Self)` if it isn't.
fn move<T: 'static>(self) -> Result<Box<T>, Self>;
}
impl AnyOwnExt for Box<Any> {
#[inline]
fn move<T: 'static>(self) -> Result<Box<T>, Box<Any>> {
if self.is::<T>() {
unsafe {
// Get the raw representation of the trait object
let to: TraitObject =
*mem::transmute::<&Box<Any>, &TraitObject>(&self);
// Prevent destructor on self being run
intrinsics::forget(self);
// Extract the data pointer
Ok(mem::transmute(to.data))
}
} else {
Err(self)
}
}
}
impl<T: fmt::Show> fmt::Show for Box<T> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
(**self).fmt(f)
}
}
impl fmt::Show for Box<Any> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.pad("Box<Any>")
}
}
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