ide/
matching_brace.rs

1use syntax::{
2    SourceFile, SyntaxKind, T, TextSize,
3    ast::{self, AstNode},
4};
5
6// Feature: Matching Brace
7//
8// If the cursor is on any brace (`<>(){}[]||`) which is a part of a brace-pair,
9// moves cursor to the matching brace. It uses the actual parser to determine
10// braces, so it won't confuse generics with comparisons.
11//
12// | Editor  | Action Name |
13// |---------|-------------|
14// | VS Code | **rust-analyzer: Find matching brace** |
15//
16// ![Matching Brace](https://user-images.githubusercontent.com/48062697/113065573-04298180-91b1-11eb-8dec-d4e2a202f304.gif)
17pub(crate) fn matching_brace(file: &SourceFile, offset: TextSize) -> Option<TextSize> {
18    const BRACES: &[SyntaxKind] =
19        &[T!['{'], T!['}'], T!['['], T![']'], T!['('], T![')'], T![<], T![>], T![|], T![|]];
20    let current = file.syntax().token_at_offset(offset);
21    if let Some((brace_token, brace_idx)) = current
22        .clone()
23        .filter_map(|node| {
24            let idx = BRACES.iter().position(|&brace| brace == node.kind())?;
25            Some((node, idx))
26        })
27        .last()
28    {
29        let parent = brace_token.parent()?;
30        if brace_token.kind() == T![|] && !ast::ParamList::can_cast(parent.kind()) {
31            cov_mark::hit!(pipes_not_braces);
32            return None;
33        }
34        let matching_kind = BRACES[brace_idx ^ 1];
35        let matching_node = parent
36            .children_with_tokens()
37            .filter_map(|it| it.into_token())
38            .find(|node| node.kind() == matching_kind && node != &brace_token)?;
39        Some(matching_node.text_range().start())
40    } else {
41        // when the offset is not at a brace, find first parent
42        current.last()?.parent_ancestors().find_map(|x| {
43            x.children_with_tokens()
44                .filter_map(|it| it.into_token())
45                // with ending brace
46                .filter(|node| BRACES.contains(&node.kind()))
47                .last()
48                .map(|x| x.text_range().start())
49        })
50    }
51}
52
53#[cfg(test)]
54mod tests {
55    use test_utils::{add_cursor, assert_eq_text, extract_offset};
56
57    use super::*;
58
59    #[test]
60    fn test_matching_brace() {
61        fn do_check(before: &str, after: &str) {
62            let (pos, before) = extract_offset(before);
63            let parse = SourceFile::parse(&before, span::Edition::CURRENT);
64            let new_pos = match matching_brace(&parse.tree(), pos) {
65                None => pos,
66                Some(pos) => pos,
67            };
68            let actual = add_cursor(&before, new_pos);
69            assert_eq_text!(after, &actual);
70        }
71
72        do_check("struct Foo { a: i32, }$0", "struct Foo $0{ a: i32, }");
73        do_check("fn main() { |x: i32|$0 x * 2;}", "fn main() { $0|x: i32| x * 2;}");
74        do_check("fn main() { $0|x: i32| x * 2;}", "fn main() { |x: i32$0| x * 2;}");
75        do_check(
76            "fn func(x) { return (2 * (x + 3)$0) + 5;}",
77            "fn func(x) { return $0(2 * (x + 3)) + 5;}",
78        );
79        do_check(
80            "fn func(x) { return (2 * (x $0+ 3)) + 5;}",
81            "fn func(x) { return (2 * (x + 3$0)) + 5;}",
82        );
83        do_check(
84            "fn func(x) { re$0turn (2 * (x + 3)) + 5;}",
85            "fn func(x) { return (2 * (x + 3)) + 5;$0}",
86        );
87
88        {
89            cov_mark::check!(pipes_not_braces);
90            do_check(
91                "fn main() { match 92 { 1 | 2 |$0 3 => 92 } }",
92                "fn main() { match 92 { 1 | 2 |$0 3 => 92 } }",
93            );
94        }
95    }
96}
ide/matching_brace.rs

ide/
matching_brace.rs
