//! FIXME: write short doc here use ra_syntax::{ast::AstNode, SourceFile, SyntaxKind, TextUnit, T}; pub fn matching_brace(file: &SourceFile, offset: TextUnit) -> Option<TextUnit> { 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, }"); } }