tenant.openagents/omega

1use crate::UndoOperation;
2use clock::Lamport;
3use std::cmp;
4use sum_tree::{Bias, SumTree};
5
6#[derive(Copy, Clone, Debug)]
7struct UndoMapEntry {
8    key: UndoMapKey,
9    undo_count: u32,
10}
11
12impl sum_tree::Item for UndoMapEntry {
13    type Summary = UndoMapKey;
14
15    fn summary(&self, _cx: ()) -> Self::Summary {
16        self.key
17    }
18}
19
20impl sum_tree::KeyedItem for UndoMapEntry {
21    type Key = UndoMapKey;
22
23    fn key(&self) -> Self::Key {
24        self.key
25    }
26}
27
28#[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord)]
29struct UndoMapKey {
30    edit_id: clock::Lamport,
31    undo_id: clock::Lamport,
32}
33
34impl sum_tree::ContextLessSummary for UndoMapKey {
35    fn zero() -> Self {
36        UndoMapKey {
37            edit_id: Lamport::MIN,
38            undo_id: Lamport::MIN,
39        }
40    }
41
42    fn add_summary(&mut self, summary: &Self) {
43        *self = cmp::max(*self, *summary);
44    }
45}
46
47#[derive(Clone, Default)]
48pub struct UndoMap(SumTree<UndoMapEntry>);
49
50impl UndoMap {
51    pub fn insert(&mut self, undo: &UndoOperation) {
52        let edits = undo
53            .counts
54            .iter()
55            .map(|(edit_id, count)| {
56                sum_tree::Edit::Insert(UndoMapEntry {
57                    key: UndoMapKey {
58                        edit_id: *edit_id,
59                        undo_id: undo.timestamp,
60                    },
61                    undo_count: *count,
62                })
63            })
64            .collect::<Vec<_>>();
65        self.0.edit(edits, ());
66    }
67
68    pub fn is_undone(&self, edit_id: clock::Lamport) -> bool {
69        self.undo_count(edit_id) % 2 == 1
70    }
71    pub fn was_undone(&self, edit_id: clock::Lamport, version: &clock::Global) -> bool {
72        let mut cursor = self.0.cursor::<UndoMapKey>(());
73        cursor.seek(
74            &UndoMapKey {
75                edit_id,
76                undo_id: Lamport::MIN,
77            },
78            Bias::Left,
79        );
80
81        let mut undo_count = 0;
82        for entry in cursor {
83            if entry.key.edit_id != edit_id {
84                break;
85            }
86
87            if version.observed(entry.key.undo_id) {
88                undo_count = cmp::max(undo_count, entry.undo_count);
89            }
90        }
91
92        undo_count % 2 == 1
93    }
94
95    pub fn undo_count(&self, edit_id: clock::Lamport) -> u32 {
96        let mut cursor = self.0.cursor::<UndoMapKey>(());
97        cursor.seek(
98            &UndoMapKey {
99                edit_id,
100                undo_id: Lamport::MIN,
101            },
102            Bias::Left,
103        );
104
105        let mut undo_count = 0;
106        for entry in cursor {
107            if entry.key.edit_id != edit_id {
108                break;
109            }
110
111            undo_count = cmp::max(undo_count, entry.undo_count);
112        }
113        undo_count
114    }
115}
116