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/* Copyright 2016 Joshua Gentry
 *
 * 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::sync::Arc;
use std::sync::atomic::{AtomicUsize, Ordering};


//*************************************************************************************************
/// Shareable usize data element.
///
/// # Examples
///
/// ```
/// use std::sync::mpsc;
/// use std::thread;
/// use shareable::SharedUsize;
///
/// // Multiple threads, atomic values are used.
/// let value1 = SharedUsize::new(63);
/// let value2 = value1.clone();
///
/// let (tx, rx) = mpsc::channel();
///
/// let thread = thread::spawn(move || {
///     rx.recv();
///     assert_eq!(value2.get(), 31);
/// });
///
/// value1.set(31);
///
/// tx.send(());
/// thread.join().unwrap();
/// ```
#[derive(Clone)]
pub struct SharedUsize
{
    //---------------------------------------------------------------------------------------------
    /// The internal data element.
    data : Arc<AtomicUsize>
}

impl SharedUsize
{
    //********************************************************************************************
    /// Construct a new instance of the object.
    pub fn new(
        value : usize
        ) -> SharedUsize
    {
        SharedUsize {
            data : Arc::new(AtomicUsize::new(value))
        }
    }

    //********************************************************************************************
    /// Set the value of the object.
    pub fn set(
        &self,
        value : usize
        )
    {
        self.data.store(value, Ordering::Relaxed);
    }

    //********************************************************************************************
    /// Returns the value of the object.
    pub fn get(&self) -> usize
    {
        self.data.load(Ordering::Relaxed)
    }
}

use std::fmt::{Debug, Display, Formatter, Error};

impl Debug for SharedUsize
{
    //*********************************************************************************************
    /// Implementation of Debug.
    fn fmt(
        &self,
        f : &mut Formatter
        ) -> Result<(), Error>
    {
        write!(f, "{:?}", self.get())
    }
}

impl Display for SharedUsize
{
    //*********************************************************************************************
    /// Implementation of Display.
    fn fmt(
        &self,
        f : &mut Formatter
        ) -> Result<(), Error>
    {
        write!(f, "{}", self.get())
    }
}

#[cfg(test)]
mod tests
{

    //*********************************************************************************************
    /// Test that get/set work with only 1 instance.
    #[test]
    fn test_single()
    {
        let test = super::SharedUsize::new(79);

        assert_eq!(test.get(), 79);
        test.set(41);
        assert_eq!(test.get(), 41);
    }

    //*********************************************************************************************
    /// Test that get/set work with multiple instances.
    #[test]
    fn test_multiple()
    {
        let test1 = super::SharedUsize::new(79);
        let test2 = test1.clone();
        let test3 = test2.clone();

        assert_eq!(test1.get(), 79);
        assert_eq!(test2.get(), 79);
        assert_eq!(test3.get(), 79);

        test1.set(51);

        assert_eq!(test1.get(), 51);
        assert_eq!(test2.get(), 51);
        assert_eq!(test3.get(), 51);

        test2.set(31);

        assert_eq!(test1.get(), 31);
        assert_eq!(test2.get(), 31);
        assert_eq!(test3.get(), 31);

        test3.set(11);

        assert_eq!(test1.get(), 11);
        assert_eq!(test2.get(), 11);
        assert_eq!(test3.get(), 11);
    }
}