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use ra_syntax::{ast::AstNode, SourceFile, SyntaxKind, TextSize, T};
// Feature: Matching Brace
//
// If the cursor is on any brace (`<>(){}[]`) which is a part of a brace-pair,
// moves cursor to the matching brace. It uses the actual parser to determine
// braces, so it won't confuse generics with comparisons.
//
// |===
// | Editor | Action Name
//
// | VS Code | **Rust Analyzer: Find matching brace**
// |===
pub fn matching_brace(file: &SourceFile, offset: TextSize) -> Option<TextSize> {
const BRACES: &[SyntaxKind] =
&[T!['{'], T!['}'], T!['['], T![']'], T!['('], T![')'], T![<], T![>]];
let (brace_node, brace_idx) = file
.syntax()
.token_at_offset(offset)
.filter_map(|node| {
let idx = BRACES.iter().position(|&brace| brace == node.kind())?;
Some((node, idx))
})
.next()?;
let parent = brace_node.parent();
let matching_kind = BRACES[brace_idx ^ 1];
let matching_node = parent.children_with_tokens().find(|node| node.kind() == matching_kind)?;
Some(matching_node.text_range().start())
}
#[cfg(test)]
mod tests {
use test_utils::{add_cursor, assert_eq_text, extract_offset};
use super::*;
#[test]
fn test_matching_brace() {
fn do_check(before: &str, after: &str) {
let (pos, before) = extract_offset(before);
let parse = SourceFile::parse(&before);
let new_pos = match matching_brace(&parse.tree(), pos) {
None => pos,
Some(pos) => pos,
};
let actual = add_cursor(&before, new_pos);
assert_eq_text!(after, &actual);
}
do_check("struct Foo { a: i32, }<|>", "struct Foo <|>{ a: i32, }");
}
}
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