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use crate::{Rope, Syntax};
const PAIRS: &[(char, char)] = &[('(', ')'), ('{', '}'), ('[', ']'), ('<', '>')];
// limit matching pairs to only ( ) { } [ ] < >
#[must_use]
pub fn find(syntax: &Syntax, doc: &Rope, pos: usize) -> Option<usize> {
let tree = syntax.tree();
let byte_pos = doc.char_to_byte(pos);
// most naive implementation: find the innermost syntax node, if we're at the edge of a node,
// return the other edge.
let node = match tree
.root_node()
.named_descendant_for_byte_range(byte_pos, byte_pos)
{
Some(node) => node,
None => return None,
};
if node.is_error() {
return None;
}
let len = doc.len_bytes();
let start_byte = node.start_byte();
let end_byte = node.end_byte().saturating_sub(1); // it's end exclusive
if start_byte >= len || end_byte >= len {
return None;
}
let start_char = doc.byte_to_char(start_byte);
let end_char = doc.byte_to_char(end_byte);
if PAIRS.contains(&(doc.char(start_char), doc.char(end_char))) {
if start_byte == byte_pos {
return Some(end_char);
}
if end_byte == byte_pos {
return Some(start_char);
}
}
None
}
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