fui_core 0.1.0

Core library of FUI MVVM UI Framework
Documentation 
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use std::cell::RefCell;
use std::collections::VecDeque;
use std::rc::{Rc, Weak};

thread_local! {
    static THREAD_CALLBACKS: RefCell<VecDeque<Box<dyn EmittedCallback>>> = RefCell::new(VecDeque::new());
}

///
/// Callback can hold one listener that can be queued to execute with emit() method.
/// The real execution will be done later on the same thread
/// (you must explicitly call CallbackExecutor::execute_all_in_queue() to do it).
/// Callbacks are queued because this prevents mutability problems when callbacks are called from callbacks.
///
/// Callback is the owner of the listener clousure.
///
#[derive(Clone)]
pub struct Callback<A> {
    callback: Option<Rc<dyn 'static + Fn(A)>>,
}

impl<A: 'static + Clone> Callback<A> {
    pub fn empty() -> Self {
        Callback { callback: None }
    }

    pub fn new<T: 'static, F: 'static + Fn(&mut T, A)>(vm: &Rc<RefCell<T>>, f: F) -> Self {
        let vm_clone = vm.clone();
        let f2 = move |args: A| {
            let mut vm = vm_clone.borrow_mut();
            f(&mut vm, args);
        };
        Callback {
            callback: Some(Rc::new(f2)),
        }
    }

    pub fn new_rc<T: 'static, F: 'static + Fn(Rc<RefCell<T>>, A)>(
        vm: &Rc<RefCell<T>>,
        f: F,
    ) -> Self {
        let vm_clone = vm.clone();
        let f2 = move |args: A| {
            let vm = vm_clone.clone();
            f(vm, args);
        };
        Callback {
            callback: Some(Rc::new(f2)),
        }
    }

    pub fn set<F: 'static + Fn(A)>(&mut self, f: F) {
        self.callback = Some(Rc::new(f));
    }

    pub fn set_vm<T: 'static, F: 'static + Fn(&mut T, A)>(&mut self, vm: &Rc<RefCell<T>>, f: F) {
        let vm_clone = vm.clone();
        let f2 = move |args: A| {
            let mut vm = vm_clone.borrow_mut();
            f(&mut vm, args);
        };
        self.callback = Some(Rc::new(f2));
    }

    pub fn clear(&mut self) {
        self.callback = None;
    }

    pub fn emit(&self, args: A) {
        if let Some(ref f) = self.callback {
            let e = EmittedCallbackStruct {
                callback: Rc::downgrade(f),
                args: args,
            };
            THREAD_CALLBACKS.with(|coll| {
                coll.borrow_mut().push_back(Box::new(e));
            });
        }
    }
}

///
/// Allows direct execution of callbacks stored in the thread local queue.
///
pub struct CallbackExecutor;

impl CallbackExecutor {
    pub fn execute_all_in_queue() {
        THREAD_CALLBACKS.with(|coll| {
            while coll.borrow().len() > 0 {
                let emitted = coll.borrow_mut().pop_front();
                if let Some(el) = emitted {
                    el.execute();
                }
            }
        });
    }
}

trait EmittedCallback {
    fn execute(&self);
}

struct EmittedCallbackStruct<A> {
    callback: Weak<dyn 'static + Fn(A)>,
    args: A,
}

impl<A: Clone> EmittedCallback for EmittedCallbackStruct<A> {
    fn execute(&self) {
        if let Some(callback) = self.callback.upgrade() {
            callback(self.args.clone());
        }
    }
}