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
|
use itertools::Itertools as _;
use super::{
Channel, Id,
event::{Created, Deleted, Event},
};
use crate::event::{Instant, Sequence};
#[derive(Clone, Debug, Eq, PartialEq)]
pub struct History {
pub channel: Channel,
pub deleted: Option<Instant>,
}
// State interface
impl History {
pub fn id(&self) -> &Id {
&self.channel.id
}
// Snapshot of this channel as it was when created. (Note to the future: it's
// okay if this returns a redacted or modified version of the channel. If we
// implement renames by redacting the original name, then this should return the
// renamed channel, not the original, even if that's not how it was "as
// created.")
pub fn as_created(&self) -> Channel {
self.channel.clone()
}
pub fn as_of<S>(&self, sequence: S) -> Option<Channel>
where
S: Into<Sequence>,
{
self.events()
.filter(Sequence::up_to(sequence.into()))
.collect()
}
// Snapshot of this channel as of all events recorded in this history.
pub fn as_snapshot(&self) -> Option<Channel> {
self.events().collect()
}
}
// Event factories
impl History {
pub fn events(&self) -> impl Iterator<Item = Event> + use<> {
[self.created()]
.into_iter()
.merge_by(self.deleted(), Sequence::merge)
}
fn created(&self) -> Event {
Created {
channel: self.channel.clone(),
}
.into()
}
fn deleted(&self) -> Option<Event> {
self.deleted.map(|instant| {
Deleted {
instant,
id: self.channel.id.clone(),
}
.into()
})
}
}
|
