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use std::boxed::Box;
use std::ops::Deref;
use std::fmt;
use rustc_serialize::{Encodable, Encoder};
use rustc_serialize::{Decodable, Decoder};
pub struct RefBox<'a, T: 'a> {
inner: RefBoxInner<'a, T>
}
#[derive(Debug, Hash)]
enum RefBoxInner<'a, T: 'a> {
Ref(&'a T),
Box(Box<T>)
}
impl <'a, T> RefBox<'a, T> {
pub fn new(v: &'a T) -> RefBox<'a, T> {
RefBox {
inner: RefBoxInner::Ref(v)
}
}
}
impl <T> RefBox<'static, T> {
pub fn take(self) -> Box<T> {
match self.inner {
RefBoxInner::Box(b) => b,
_ => unreachable!()
}
}
pub fn try_take(self) -> Result<Box<T>, RefBox<'static, T>> {
match self.inner {
RefBoxInner::Box(b) => Ok(b),
o => Err(RefBox{ inner: o})
}
}
}
impl <'a, T: Encodable> Encodable for RefBox<'a, T> {
fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
self.inner.encode(s)
}
}
impl <T: Decodable> Decodable for RefBox<'static, T> {
fn decode<D: Decoder>(d: &mut D) -> Result<RefBox<'static, T>, D::Error> {
let inner = try!(Decodable::decode(d));
Ok(RefBox{inner: inner})
}
}
impl <'a, T: Encodable> Encodable for RefBoxInner<'a, T> {
fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
s.emit_enum("RefBox", |s| {
s.emit_enum_variant("Box", 1, 1, |s| {
s.emit_enum_variant_arg(0, |s| {
match self {
&RefBoxInner::Ref(ref r) => r.encode(s),
&RefBoxInner::Box(ref b) => b.encode(s)
}
})
})
})
}
}
impl <T: Decodable> Decodable for RefBoxInner<'static, T> {
fn decode<D: Decoder>(d: &mut D) -> Result<RefBoxInner<'static, T>, D::Error> {
d.read_enum("RefBox", |d| {
d.read_enum_variant(&["Ref", "Box"], |d, i| {
assert!(i == 1);
d.read_enum_variant_arg(0, |d| {
let decoded = try!(Decodable::decode(d));
Ok(RefBoxInner::Box(Box::new(decoded)))
})
})
})
}
}
impl <'a, T> Deref for RefBox<'a, T> {
type Target = T;
fn deref(&self) -> &T {
match &self.inner {
&RefBoxInner::Ref(ref t) => t,
&RefBoxInner::Box(ref b) => b.deref()
}
}
}
impl <'a, T: fmt::Debug> fmt::Debug for RefBox<'a, T> {
fn fmt(&self, fmt: &mut fmt::Formatter) -> Result<(), fmt::Error> {
write!(fmt, "RefBox({:?})", *self)
}
}