// This file is part of Intrusive.

// Intrusive is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// Intrusive is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Lesser General Public License for more details.

// You should have received a copy of the GNU Lesser General Public License
// along with Intrusive.  If not, see <http://www.gnu.org/licenses/>.

// Copyright 2012-2015 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.
#[cfg(all(feature="nostd",not(test)))]
use core::prelude::*;
use std::mem;
use std::ptr;

#[allow(raw_pointer_derive)]
#[derive(Debug)]
pub struct Rawlink<T> {
    p: *mut T
}

impl<T> Copy for Rawlink<T> {}
unsafe impl<T:'static+Send> Send for Rawlink<T> {}
unsafe impl<T:Send+Sync> Sync for Rawlink<T> {}

/// Rawlink is a type like Option<T> but for holding a raw pointer
impl<T> Rawlink<T> {
    /// Like Option::None for Rawlink
    pub fn none() -> Rawlink<T> {
        Rawlink{p: ptr::null_mut()}
    }

    /// Like Option::Some for Rawlink
    pub fn some(n: &mut T) -> Rawlink<T> {
        Rawlink{p: n}
    }

    /// Convert the `Rawlink` into an Option value
    pub fn resolve<'a>(&self) -> Option<&'a T> {
        unsafe {
            mem::transmute(self.p.as_ref())
        }
    }

    /// Convert the `Rawlink` into an Option value
    pub fn resolve_mut<'a>(&mut self) -> Option<&'a mut T> {
        if self.p.is_null() {
            None
        } else {
            Some(unsafe { mem::transmute(self.p) })
        }
    }

    /// Return the `Rawlink` and replace with `Rawlink::none()`
    pub fn take(&mut self) -> Rawlink<T> {
        mem::replace(self, Rawlink::none())
    }
}

impl<T> PartialEq for Rawlink<T> {
    #[inline]
    fn eq(&self, other: &Rawlink<T>) -> bool {
        self.p == other.p
    }
}

impl<T> Clone for Rawlink<T> {
    #[inline]
    fn clone(&self) -> Rawlink<T> {
        Rawlink{p: self.p}
    }
}

impl<T> Default for Rawlink<T> {
    fn default() -> Rawlink<T> { Rawlink::none() }
}