Implement m / match_brackets (using tree sitter).

3 files changed, 37 insertions, 0 deletions

diff --git a/helix-core/src/auto_pairs.rs b/helix-core/src/auto_pairs.rs
index 52a45075..e6b8f667 100644
--- a/helix-core/src/auto_pairs.rs
+++ b/helix-core/src/auto_pairs.rs
@@ -1,6 +1,8 @@
 use crate::{Range, Rope, Selection, Tendril, Transaction};
 use smallvec::SmallVec;
 
+// Heavily based on https://github.com/codemirror/closebrackets/
+
 const PAIRS: &[(char, char)] = &[
     ('(', ')'),
     ('{', '}'),
diff --git a/helix-core/src/lib.rs b/helix-core/src/lib.rs
index a8a449ca..30b3d37f 100644
--- a/helix-core/src/lib.rs
+++ b/helix-core/src/lib.rs
@@ -6,6 +6,7 @@ pub mod graphemes;
 mod history;
 pub mod indent;
 pub mod macros;
+pub mod match_brackets;
 pub mod movement;
 pub mod object;
 mod position;
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
+}