summaryrefslogtreecommitdiff
path: root/helix-core/src/auto_pairs.rs
blob: 3ba271058d617d178a1eeaf4c0ab97ae8639e505 (plain) (blame)
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
use crate::{Range, Rope, Selection, Tendril, Transaction};
use smallvec::SmallVec;

// Heavily based on https://github.com/codemirror/closebrackets/

const PAIRS: &[(char, char)] = &[
    ('(', ')'),
    ('{', '}'),
    ('[', ']'),
    ('\'', '\''),
    ('"', '"'),
    ('`', '`'),
];

const CLOSE_BEFORE: &str = ")]}'\":;> \n"; // includes space and newline

// insert hook:
// Fn(doc, selection, char) => Option<Transaction>
// problem is, we want to do this per range, so we can call default handler for some ranges
// so maybe ret Vec<Option<Change>>
// but we also need to be able to return transactions...
//
// to simplify, maybe return Option<Transaction> and just reimplement the default

// TODO: delete implementation where it erases the whole bracket (|) -> |

#[must_use]
pub fn hook(doc: &Rope, selection: &Selection, ch: char) -> Option<Transaction> {
    for &(open, close) in PAIRS {
        if open == ch {
            if open == close {
                return handle_same(doc, selection, open);
            } else {
                return Some(handle_open(doc, selection, open, close, CLOSE_BEFORE));
            }
        }

        if close == ch {
            // && char_at pos == close
            return Some(handle_close(doc, selection, open, close));
        }
    }

    None
}

// TODO: special handling for lifetimes in rust: if preceeded by & or < don't auto close '
// for example "&'a mut", or "fn<'a>"

fn next_char(doc: &Rope, pos: usize) -> Option<char> {
    if pos >= doc.len_chars() {
        return None;
    }
    Some(doc.char(pos))
}
// TODO: selections should be extended if range, moved if point.

// TODO: if not cursor but selection, wrap on both sides of selection (surround)
fn handle_open(
    doc: &Rope,
    selection: &Selection,
    open: char,
    close: char,
    close_before: &str,
) -> Transaction {
    let mut ranges = SmallVec::with_capacity(selection.len());

    let mut transaction = Transaction::change_by_selection(doc, selection, |range| {
        let pos = range.head;
        let next = next_char(doc, pos);

        ranges.push(Range::new(range.anchor, pos + open.len_utf8())); // pos + open

        match next {
            Some(ch) if !close_before.contains(ch) => {
                // TODO: else return (use default handler that inserts open)
                (pos, pos, Some(Tendril::from_char(open)))
            }
            // None | Some(ch) if close_before.contains(ch) => {}
            _ => {
                // insert open & close
                let mut pair = Tendril::with_capacity(2);
                pair.push_char(open);
                pair.push_char(close);

                (pos, pos, Some(pair))
            }
        }
    });

    transaction.with_selection(Selection::new(ranges, selection.primary_index()))
}

fn handle_close(doc: &Rope, selection: &Selection, _open: char, close: char) -> Transaction {
    let mut ranges = SmallVec::with_capacity(selection.len());

    let mut transaction = Transaction::change_by_selection(doc, selection, |range| {
        let pos = range.head;
        let next = next_char(doc, pos);

        ranges.push(Range::new(range.anchor, pos + close.len_utf8())); // pos + close

        if next == Some(close) {
            //  return transaction that moves past close
            (pos, pos, None) // no-op
        } else {
            // TODO: else return (use default handler that inserts close)
            (pos, pos, Some(Tendril::from_char(close)))
        }
    });

    transaction.with_selection(Selection::new(ranges, selection.primary_index()))
}

// handle cases where open and close is the same, or in triples ("""docstring""")
fn handle_same(doc: &Rope, selection: &Selection, token: char) -> Option<Transaction> {
    // if not cursor but selection, wrap
    // let next = next char

    // if next == bracket {
    //   // if start of syntax node, insert token twice (new pair because node is complete)
    //   // elseif colsedBracketAt
    //      // is_triple == allow triple && next 3 is equal
    //      // cursor jump over
    // }
    //} else if allow_triple && followed by triple {
    //}
    //} else if next != word char && prev != bracket && prev != word char {
    // // condition checks for cases like I' where you don't want I'' (or I'm)
    //  insert pair ("")
    //}
    None
}