newt 0.7.2

Rust bindings for the Newt console UI library
Documentation 
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//
// Copyright (C) 2019 Robert Gill <rtgill82@gmail.com>
//
// This file is a part of newt-rs.
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License version 2.1 as published by the Free Software Foundation.
//
// This library 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 this library; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
//

use crate::private::funcs::*;

///
/// A callback called when `Ctrl-Z` is pressed.
///
/// ## Example
/// ```rust no_run
/// extern crate newt;
/// use newt::callbacks::SuspendCallback;
/// use newt::prelude::*;
///
/// pub fn main() {
///     // Receives the new value when the SuspendCallback is activated.
///     let mut value: i32 = 0;
///
///     newt::init().unwrap();
///     newt::cls();
///     newt::centered_window(20, 5, Some("Suspend Callback Test")).unwrap();
///
///     let label = Label::new(4, 1, "Press Ctrl-Z");
///     let ok = CompactButton::new(7, 4, "Ok");
///
///     let mut form = Form::new(None, 0);
///     form.add_components(&[&label, &ok]).unwrap();
///
///     // Closure `f` borrows `value` as mutable so create a new subscope here
///     // allowing `value` to be borrowed immutably when printing the result
///     // later.
///     {
///         // Create closure to be called by SuspendCallback
///         let mut f = |data: Option<&i32>| {
///             value = *data.unwrap();
///         };
///         // Create SuspendCallback using `10` as data.
///         let _callback = SuspendCallback::new(Some(10), &mut f);
///
///         form.run().unwrap();
///         newt::finished();
///     }
///
///     // `value` will be `10` if Ctrl-Z was pressed.
///     println!("value = {}", value);
/// }
/// ```
///
pub struct SuspendCallback<F, T>
where F: FnMut(Option<&T>)
{
    function: F,
    data: Option<T>
}

impl<F, T> SuspendCallback<F, T>
where F: FnMut(Option<&T>)
{
    ///
    /// Create a new `SuspendCallback` to be called when a suspend (`Ctrl-Z`)
    /// event occurs.
    ///
    /// * `data` - The optional user data to pass to the function.
    /// * `function` - The function or closure to be called when a suspend
    ///   event occurs.
    ///
    pub fn new(data: Option<T>, function: F)
      -> Box<SuspendCallback<F, T>> {

        unsafe {
            let cb = Box::new(SuspendCallback { function, data });
            newt_set_suspend_callback(cb.as_ref());
            cb
        }
    }

    pub(crate) fn call(&mut self) {
        (self.function)(self.data.as_ref())
    }
}

impl<F, T> Drop for SuspendCallback<F, T>
where F: FnMut(Option<&T>)
{
    fn drop(&mut self) {
        unsafe { newt_unset_suspend_callback(); }
    }
}