1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159

use std::cell::{Cell, Ref, RefCell};
use std::fmt;
use std::ops::Deref;
use std::rc::Rc;

use educe::Educe;
use indexmap::{IndexMap, IndexSet};

use super::{Revisable, RevisableId, TRACKING_STACK};
use crate::ViewId;

#[derive(Educe)]
#[educe(Debug)]
pub struct Bond<T>
where
    T: fmt::Debug + 'static,
{
    id: RevisableId,
    version: Rc<Cell<usize>>,
    gathers: Rc<RefCell<IndexMap<RevisableId, Box<dyn Revisable>>>>,
    view_ids: Rc<RefCell<IndexMap<ViewId, usize>>>,
    #[educe(Debug(ignore))]
    mapper: Rc<Box<dyn Fn() -> T + 'static>>,
    #[educe(Debug(ignore))]
    value: Rc<RefCell<T>>,
}

impl<T> Bond<T>
where
    T: fmt::Debug + 'static,
{
    pub fn new(mapper: impl Fn() -> T + 'static) -> Self {
        let (gathers, value) = crate::reflow::gather(&mapper);
        let version = gathers.values().map(|g| g.version()).sum();
        Self {
            id: RevisableId::next(),
            version: Rc::new(Cell::new(version)),
            gathers: Rc::new(RefCell::new(gathers)),
            view_ids: Default::default(),
            mapper: Rc::new(Box::new(mapper)),
            value: Rc::new(RefCell::new(value)),
        }
    }
    pub fn get(&self) -> Ref<'_, T> {
        let new_version = self.gathers.borrow().values().map(|g| g.version()).sum();
        if self.version() != new_version {
            *self.gathers.borrow_mut() = crate::reflow::gather(|| self.value.replace((self.mapper)())).0;
            self.version.set(new_version);
            for view_id in self.view_ids.borrow().keys() {
                for (_, gather) in self.gathers.borrow().deref() {
                    gather.bind_view(view_id);
                }
            }
        } else {
            let gathers = &self.gathers;
            TRACKING_STACK.with(|tracking_items| {
                let mut tracking_items = tracking_items.borrow_mut();
                if !tracking_items.is_idle() {
                    for revisable in gathers.borrow().values() {
                        tracking_items.track(revisable.clone_boxed());
                    }
                }
            });
        }

        self.value.borrow()
    }
    pub fn get_untracked(&self) -> Ref<'_, T> {
        let new_version = self.gathers.borrow().values().map(|g| g.version()).sum();
        if self.version() != new_version {
            self.value.replace((self.mapper)());
            self.version.set(new_version);
        }
        self.value.borrow()
    }

    pub fn map<M, G>(&self, mapper: M) -> Bond<G>
    where
        M: Fn(Ref<'_, T>) -> G + Clone + 'static,
        G: fmt::Debug + 'static,
    {
        let this = self.clone();
        Bond::new(move || mapper(this.get()))
    }
}

impl<T> Clone for Bond<T>
where
    T: fmt::Debug + 'static,
{
    fn clone(&self) -> Self {
        Self {
            id: self.id,
            version: self.version.clone(),
            gathers: self.gathers.clone(),
            view_ids: self.view_ids.clone(),
            value: self.value.clone(),
            mapper: self.mapper.clone(),
        }
    }
}

impl<T> Revisable for Bond<T>
where
    T: fmt::Debug + 'static,
{
    fn id(&self) -> RevisableId {
        self.id
    }
    #[cfg(not(feature = "__single_holder"))]
    fn holder_id(&self) -> Option<crate::HolderId> {
        self.view_ids.borrow().first().map(|(view_id, _)| view_id.holder_id())
    }

    fn version(&self) -> usize {
        self.version.get()
    }
    fn view_ids(&self) -> Rc<RefCell<IndexSet<ViewId>>> {
        Rc::new(RefCell::new(IndexSet::from_iter(self.view_ids.borrow().keys().cloned())))
    }
    fn is_revising(&self) -> bool {
        for (_, gather) in self.gathers.borrow().deref() {
            if gather.is_revising() {
                return true;
            }
        }
        false
    }
    fn bind_view(&self, view_id: &ViewId) {
        let mut view_ids = self.view_ids.borrow_mut();
        let count = view_ids.get(view_id).cloned().unwrap_or(0);
        view_ids.insert(view_id.clone(), count + 1);
        for (_, gather) in self.gathers.borrow().deref() {
            gather.bind_view(view_id);
        }
    }
    fn unbind_view(&self, view_id: &ViewId) {
        let count = self.view_ids.borrow_mut().remove(view_id).unwrap_or(0);
        for (_, gather) in self.gathers.borrow().deref() {
            gather.unlace_view(view_id, count);
        }
    }
    fn unlace_view(&self, view_id: &ViewId, loose: usize) {
        let count = self.view_ids.borrow_mut().get(view_id).cloned().unwrap_or(0);
        let loose = if loose >= count {
            self.view_ids.borrow_mut().remove(view_id);
            count
        } else {
            self.view_ids.borrow_mut().insert(view_id.clone(), count - loose);
            loose
        };
        for (_, gather) in self.gathers.borrow().deref() {
            gather.unlace_view(view_id, loose);
        }
    }
    fn clone_boxed(&self) -> Box<dyn Revisable> {
        Box::new(self.clone())
    }
}