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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
//! Reference-counted pointers to flows.
//!
//! Eventually, with dynamically sized types in Rust, much of this code will be superfluous.
#![allow(unsafe_blocks)]
use flow::Flow;
use flow;
use std::mem;
use std::ops::{Deref, DerefMut};
use std::ptr;
use std::raw;
use std::sync::atomic::Ordering;
#[unsafe_no_drop_flag]
pub struct FlowRef {
object: raw::TraitObject,
}
unsafe impl Send for FlowRef {}
unsafe impl Sync for FlowRef {}
impl FlowRef {
pub fn new(mut flow: Box<Flow>) -> FlowRef {
unsafe {
let result = {
let flow_ref: &mut Flow = &mut *flow;
let object = mem::transmute::<&mut Flow, raw::TraitObject>(flow_ref);
FlowRef { object: object }
};
mem::forget(flow);
result
}
}
}
impl<'a> Deref for FlowRef {
type Target = Flow + 'a;
fn deref(&self) -> &(Flow + 'a) {
unsafe {
mem::transmute_copy::<raw::TraitObject, &(Flow + 'a)>(&self.object)
}
}
}
impl DerefMut for FlowRef {
fn deref_mut<'a>(&mut self) -> &mut (Flow + 'a) {
unsafe {
mem::transmute_copy::<raw::TraitObject, &mut (Flow + 'a)>(&self.object)
}
}
}
impl Drop for FlowRef {
fn drop(&mut self) {
unsafe {
if self.object.vtable.is_null() {
return
}
if flow::base(&**self).ref_count().fetch_sub(1, Ordering::SeqCst) > 1 {
return
}
let flow_ref: FlowRef = mem::replace(self, FlowRef {
object: raw::TraitObject {
vtable: ptr::null_mut(),
data: ptr::null_mut(),
}
});
drop(mem::transmute::<raw::TraitObject, Box<Flow>>(flow_ref.object));
mem::forget(flow_ref);
self.object.vtable = ptr::null_mut();
self.object.data = ptr::null_mut();
}
}
}
impl Clone for FlowRef {
fn clone(&self) -> FlowRef {
unsafe {
drop(flow::base(&**self).ref_count().fetch_add(1, Ordering::SeqCst));
FlowRef {
object: raw::TraitObject {
vtable: self.object.vtable,
data: self.object.data,
}
}
}
}
}
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