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

use super::{ExcerptId, MultiBufferSnapshot, ToOffset, ToOffsetUtf16, ToPoint};
use language::{OffsetUtf16, Point, TextDimension};
use std::{
    cmp::Ordering,
    ops::{Range, Sub},
};
use sum_tree::Bias;

#[derive(Clone, Copy, Eq, PartialEq, Debug, Hash)]
pub struct Anchor {
    pub buffer_id: Option<u64>,
    pub excerpt_id: ExcerptId,
    pub text_anchor: text::Anchor,
}

impl Anchor {
    pub fn min() -> Self {
        Self {
            buffer_id: None,
            excerpt_id: ExcerptId::min(),
            text_anchor: text::Anchor::MIN,
        }
    }

    pub fn max() -> Self {
        Self {
            buffer_id: None,
            excerpt_id: ExcerptId::max(),
            text_anchor: text::Anchor::MAX,
        }
    }

    pub fn cmp(&self, other: &Anchor, snapshot: &MultiBufferSnapshot) -> Ordering {
        let excerpt_id_cmp = self.excerpt_id.cmp(&other.excerpt_id, snapshot);
        if excerpt_id_cmp.is_eq() {
            if self.excerpt_id == ExcerptId::min() || self.excerpt_id == ExcerptId::max() {
                Ordering::Equal
            } else if let Some(excerpt) = snapshot.excerpt(self.excerpt_id) {
                self.text_anchor.cmp(&other.text_anchor, &excerpt.buffer)
            } else {
                Ordering::Equal
            }
        } else {
            excerpt_id_cmp
        }
    }

    pub fn bias(&self) -> Bias {
        self.text_anchor.bias
    }

    pub fn bias_left(&self, snapshot: &MultiBufferSnapshot) -> Anchor {
        if self.text_anchor.bias != Bias::Left {
            if let Some(excerpt) = snapshot.excerpt(self.excerpt_id) {
                return Self {
                    buffer_id: self.buffer_id,
                    excerpt_id: self.excerpt_id.clone(),
                    text_anchor: self.text_anchor.bias_left(&excerpt.buffer),
                };
            }
        }
        self.clone()
    }

    pub fn bias_right(&self, snapshot: &MultiBufferSnapshot) -> Anchor {
        if self.text_anchor.bias != Bias::Right {
            if let Some(excerpt) = snapshot.excerpt(self.excerpt_id) {
                return Self {
                    buffer_id: self.buffer_id,
                    excerpt_id: self.excerpt_id.clone(),
                    text_anchor: self.text_anchor.bias_right(&excerpt.buffer),
                };
            }
        }
        self.clone()
    }

    pub fn summary<D>(&self, snapshot: &MultiBufferSnapshot) -> D
    where
        D: TextDimension + Ord + Sub<D, Output = D>,
    {
        snapshot.summary_for_anchor(self)
    }

    pub fn is_valid(&self, snapshot: &MultiBufferSnapshot) -> bool {
        if *self == Anchor::min() || *self == Anchor::max() {
            true
        } else if let Some(excerpt) = snapshot.excerpt(self.excerpt_id) {
            excerpt.contains(self)
                && (self.text_anchor == excerpt.range.context.start
                    || self.text_anchor == excerpt.range.context.end
                    || self.text_anchor.is_valid(&excerpt.buffer))
        } else {
            false
        }
    }
}

impl ToOffset for Anchor {
    fn to_offset(&self, snapshot: &MultiBufferSnapshot) -> usize {
        self.summary(snapshot)
    }
}

impl ToOffsetUtf16 for Anchor {
    fn to_offset_utf16(&self, snapshot: &MultiBufferSnapshot) -> OffsetUtf16 {
        self.summary(snapshot)
    }
}

impl ToPoint for Anchor {
    fn to_point<'a>(&self, snapshot: &MultiBufferSnapshot) -> Point {
        self.summary(snapshot)
    }
}

pub trait AnchorRangeExt {
    fn cmp(&self, b: &Range<Anchor>, buffer: &MultiBufferSnapshot) -> Ordering;
    fn to_offset(&self, content: &MultiBufferSnapshot) -> Range<usize>;
    fn to_point(&self, content: &MultiBufferSnapshot) -> Range<Point>;
}

impl AnchorRangeExt for Range<Anchor> {
    fn cmp(&self, other: &Range<Anchor>, buffer: &MultiBufferSnapshot) -> Ordering {
        match self.start.cmp(&other.start, buffer) {
            Ordering::Equal => other.end.cmp(&self.end, buffer),
            ord => ord,
        }
    }

    fn to_offset(&self, content: &MultiBufferSnapshot) -> Range<usize> {
        self.start.to_offset(content)..self.end.to_offset(content)
    }

    fn to_point(&self, content: &MultiBufferSnapshot) -> Range<Point> {
        self.start.to_point(content)..self.end.to_point(content)
    }
}