Implement m / match_brackets (using tree sitter).

1 files changed, 34 insertions, 0 deletions

diff --git a/helix-core/src/match_brackets.rs b/helix-core/src/match_brackets.rs
new file mode 100644
index 00000000..bacd764f
--- /dev/null
+++ b/helix-core/src/match_brackets.rs
@@ -0,0 +1,34 @@
+use crate::{Range, Rope, Selection, Syntax};
+
+// const PAIRS: &[(char, char)] = &[('(', ')'), ('{', '}'), ('[', ']')];
+// limit matching pairs to only ( ) { } [ ] < >
+
+pub fn find(syntax: &Syntax, doc: &Rope, pos: usize) -> Option<usize> {
+    let tree = syntax.root_layer.tree.as_ref().unwrap();
+
+    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 mut node = match tree
+        .root_node()
+        .named_descendant_for_byte_range(byte_pos, byte_pos)
+    {
+        Some(node) => node,
+        None => return None,
+    };
+
+    let start_byte = node.start_byte();
+    let end_byte = node.end_byte() - 1; // it's end exclusive
+
+    if start_byte == byte_pos {
+        return Some(doc.byte_to_char(end_byte));
+    }
+
+    if end_byte == byte_pos {
+        return Some(doc.byte_to_char(start_byte));
+    }
+
+    None
+}