Add a TreeCursor type that travels over injection layers

This uses the layer parentage information from the parent commit to
traverse the layers. It's a similar API to `tree_sitter:TreeCursor`
but internally it does not use a `tree_sitter::TreeCursor` currently
because that interface is behaving very unexpectedly. Using the
`next_sibling`/`prev_sibling`/`parent` API on `tree_sitter::Node`
reflects the previous code's behavior so this should result in no
surprising changes.

1 files changed, 13 insertions, 3 deletions

diff --git a/helix-core/src/syntax.rs b/helix-core/src/syntax.rs
index 6414f3ce..78abc0b0 100644
--- a/helix-core/src/syntax.rs
+++ b/helix-core/src/syntax.rs
@@ -1,3 +1,5 @@
+mod tree_cursor;
+
 use crate::{
     auto_pairs::AutoPairs,
     chars::char_is_line_ending,
@@ -32,6 +34,8 @@ use serde::{ser::SerializeSeq, Deserialize, Serialize};
 
 use helix_loader::grammar::{get_language, load_runtime_file};
 
+pub use tree_cursor::TreeCursor;
+
 fn deserialize_regex<'de, D>(deserializer: D) -> Result<Option<Regex>, D::Error>
 where
     D: serde::Deserializer<'de>,
@@ -1495,6 +1499,12 @@ impl Syntax {
             .descendant_for_byte_range(start, end)
     }
 
+    pub fn walk(&self) -> TreeCursor<'_> {
+        // data structure to find the smallest range that contains a point
+        // when some of the ranges in the structure can overlap.
+        TreeCursor::new(&self.layers, self.root)
+    }
+
     // Commenting
     // comment_strings_for_pos
     // is_commented
@@ -1723,7 +1733,7 @@ use std::sync::atomic::{AtomicUsize, Ordering};
 use std::{iter, mem, ops, str, usize};
 use tree_sitter::{
     Language as Grammar, Node, Parser, Point, Query, QueryCaptures, QueryCursor, QueryError,
-    QueryMatch, Range, TextProvider, Tree, TreeCursor,
+    QueryMatch, Range, TextProvider, Tree,
 };
 
 const CANCELLATION_CHECK_INTERVAL: usize = 100;
@@ -2657,7 +2667,7 @@ pub fn pretty_print_tree<W: fmt::Write>(fmt: &mut W, node: Node) -> fmt::Result
 
 fn pretty_print_tree_impl<W: fmt::Write>(
     fmt: &mut W,
-    cursor: &mut TreeCursor,
+    cursor: &mut tree_sitter::TreeCursor,
     depth: usize,
 ) -> fmt::Result {
     let node = cursor.node();
@@ -2967,7 +2977,7 @@ mod test {
         // rule but `name` and `body` belong to an unnamed helper `_method_rest`.
         // This can cause a bug with a pretty-printing implementation that
         // uses `Node::field_name_for_child` to determine field names but is
-        // fixed when using `TreeCursor::field_name`.
+        // fixed when using `tree_sitter::TreeCursor::field_name`.
         let source = "def self.method_name
           true
         end";