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 (brace_token, brace_idx) = file
21        .syntax()
22        .token_at_offset(offset)
23        .filter_map(|node| {
24            let idx = BRACES.iter().position(|&brace| brace == node.kind())?;
25            Some((node, idx))
26        })
27        .last()?;
28    let parent = brace_token.parent()?;
29    if brace_token.kind() == T![|] && !ast::ParamList::can_cast(parent.kind()) {
30        cov_mark::hit!(pipes_not_braces);
31        return None;
32    }
33    let matching_kind = BRACES[brace_idx ^ 1];
34    let matching_node = parent
35        .children_with_tokens()
36        .filter_map(|it| it.into_token())
37        .find(|node| node.kind() == matching_kind && node != &brace_token)?;
38    Some(matching_node.text_range().start())
39}
40
41#[cfg(test)]
42mod tests {
43    use test_utils::{add_cursor, assert_eq_text, extract_offset};
44
45    use super::*;
46
47    #[test]
48    fn test_matching_brace() {
49        fn do_check(before: &str, after: &str) {
50            let (pos, before) = extract_offset(before);
51            let parse = SourceFile::parse(&before, span::Edition::CURRENT);
52            let new_pos = match matching_brace(&parse.tree(), pos) {
53                None => pos,
54                Some(pos) => pos,
55            };
56            let actual = add_cursor(&before, new_pos);
57            assert_eq_text!(after, &actual);
58        }
59
60        do_check("struct Foo { a: i32, }$0", "struct Foo $0{ a: i32, }");
61        do_check("fn main() { |x: i32|$0 x * 2;}", "fn main() { $0|x: i32| x * 2;}");
62        do_check("fn main() { $0|x: i32| x * 2;}", "fn main() { |x: i32$0| x * 2;}");
63        do_check(
64            "fn func(x) { return (2 * (x + 3)$0) + 5;}",
65            "fn func(x) { return $0(2 * (x + 3)) + 5;}",
66        );
67
68        {
69            cov_mark::check!(pipes_not_braces);
70            do_check(
71                "fn main() { match 92 { 1 | 2 |$0 3 => 92 } }",
72                "fn main() { match 92 { 1 | 2 |$0 3 => 92 } }",
73            );
74        }
75    }
76}
ide/matching_brace.rs

ide/
matching_brace.rs
