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
|
use crate::{ChangeSet, Rope, State, Transaction};
use smallvec::{smallvec, SmallVec};
/// Undo-tree style history store.
pub struct History {
revisions: Vec<Revision>,
cursor: usize,
}
#[derive(Debug)]
struct Revision {
parent: usize,
children: SmallVec<[(usize, Transaction); 1]>,
/// The transaction to revert to previous state.
revert: Transaction,
// selection before, selection after?
}
impl Default for History {
fn default() -> Self {
// Add a dummy root revision with empty transaction
Self {
revisions: vec![Revision {
parent: 0,
children: SmallVec::new(),
revert: Transaction::from(ChangeSet::new(&Rope::new())),
}],
cursor: 0,
}
}
}
impl History {
pub fn commit_revision(&mut self, transaction: &Transaction, original: &State) {
// TODO: could store a single transaction, if deletes also stored the text they delete
let revert = transaction
.invert(&original.doc)
// Store the current cursor position
.with_selection(original.selection.clone());
let new_cursor = self.revisions.len();
self.revisions.push(Revision {
parent: self.cursor,
children: SmallVec::new(),
revert,
});
// add a reference to the parent
self.revisions
.get_mut(self.cursor)
.unwrap() // TODO: get_unchecked_mut
.children
.push((new_cursor, transaction.clone()));
self.cursor = new_cursor;
}
#[inline]
pub const fn at_root(&self) -> bool {
self.cursor == 0
}
// TODO: I'd like to pass Transaction by reference but it fights with the borrowck
pub fn undo(&mut self) -> Option<Transaction> {
if self.at_root() {
// We're at the root of undo, nothing to do.
return None;
}
let current_revision = &self.revisions[self.cursor];
self.cursor = current_revision.parent;
Some(current_revision.revert.clone())
}
pub fn redo(&mut self) -> Option<Transaction> {
let current_revision = &self.revisions[self.cursor];
// for now, simply pick the latest child (linear undo / redo)
if let Some((index, transaction)) = current_revision.children.last() {
self.cursor = *index;
return Some(transaction.clone());
}
None
}
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn test_undo_redo() {
let mut history = History::default();
let doc = Rope::from("hello");
let mut state = State::new(doc);
let transaction1 =
Transaction::change(&state.doc, vec![(5, 5, Some(" world!".into()))].into_iter());
// Need to commit before applying!
history.commit_revision(&transaction1, &state);
transaction1.apply(&mut state.doc);
assert_eq!("hello world!", state.doc);
// ---
let transaction2 =
Transaction::change(&state.doc, vec![(6, 11, Some("世界".into()))].into_iter());
// Need to commit before applying!
history.commit_revision(&transaction2, &state);
transaction2.apply(&mut state.doc);
assert_eq!("hello 世界!", state.doc);
// ---
fn undo(history: &mut History, state: &mut State) {
if let Some(transaction) = history.undo() {
transaction.apply(&mut state.doc);
}
}
fn redo(history: &mut History, state: &mut State) {
if let Some(transaction) = history.redo() {
transaction.apply(&mut state.doc);
}
}
undo(&mut history, &mut state);
assert_eq!("hello world!", state.doc);
redo(&mut history, &mut state);
assert_eq!("hello 世界!", state.doc);
undo(&mut history, &mut state);
undo(&mut history, &mut state);
assert_eq!("hello", state.doc);
// undo at root is a no-op
undo(&mut history, &mut state);
assert_eq!("hello", state.doc);
}
}
|
