From ab2a0f325b906574698933824b381ed65c7482a3 Mon Sep 17 00:00:00 2001
From: Gokul Soumya <gokulps15@gmail.com>
Date: Fri, 11 Feb 2022 09:01:52 +0530
Subject: [PATCH] Add object.movement for tree-sitter navigation

---
 book/src/guides/textobject.md | 15 +++++++++++++++
 book/src/usage.md             |  2 +-
 helix-core/src/movement.rs    | 10 +++++++---
 helix-core/src/syntax.rs      | 16 +++++++++++++++-
 helix-core/src/textobject.rs  |  5 +++++
 5 files changed, 43 insertions(+), 5 deletions(-)

diff --git a/book/src/guides/textobject.md b/book/src/guides/textobject.md
index dd726b7c9..7200a5144 100644
--- a/book/src/guides/textobject.md
+++ b/book/src/guides/textobject.md
@@ -24,7 +24,22 @@ The following [captures][tree-sitter-captures] are recognized:
 
 [Example query files][textobject-examples] can be found in the helix GitHub repository.
 
+## Queries for Textobject Based Navigation
+
+[Tree-sitter based navigation][textobjects-nav] is done using captures in the
+following order:
+
+- `object.movement`
+- `object.around`
+- `object.inside`
+
+For example if a `function.around` capture has been already defined for a language
+in it's `textobjects.scm` file, function navigation should also work automatically.
+`function.movement` should be defined only if the node captured by `function.around`
+doesn't make sense in a navigation context.
+
 [textobjects]: ../usage.md#textobjects
+[textobjects-nav]: ../usage.md#tree-sitter-textobject-based-navigation
 [tree-sitter-queries]: https://tree-sitter.github.io/tree-sitter/using-parsers#query-syntax
 [tree-sitter-captures]: https://tree-sitter.github.io/tree-sitter/using-parsers#capturing-nodes
 [textobject-examples]: https://github.com/search?q=repo%3Ahelix-editor%2Fhelix+filename%3Atextobjects.scm&type=Code&ref=advsearch&l=&l=
diff --git a/book/src/usage.md b/book/src/usage.md
index 3f9499ca4..039628bf8 100644
--- a/book/src/usage.md
+++ b/book/src/usage.md
@@ -75,7 +75,7 @@ document and a special tree-sitter query file to work properly. [Only
 some grammars][lang-support] currently have the query file implemented.
 Contributions are welcome!
 
-## Tree-sitter Based Navigation
+## Tree-sitter Textobject Based Navigation
 
 Navigating between functions, classes, parameters, etc is made
 possible by leveraging tree-sitter and textobjects queries. For
diff --git a/helix-core/src/movement.rs b/helix-core/src/movement.rs
index e9cd299bc..e559f1ea6 100644
--- a/helix-core/src/movement.rs
+++ b/helix-core/src/movement.rs
@@ -321,10 +321,14 @@ pub fn goto_treesitter_object(
     let get_range = move || -> Option<Range> {
         let byte_pos = slice.char_to_byte(range.cursor(slice));
 
-        let capture_name = format!("{}.{}", object_name, TextObject::Around);
+        let cap_name = |t: TextObject| format!("{}.{}", object_name, t);
         let mut cursor = QueryCursor::new();
-        let nodes = lang_config.textobject_query()?.capture_nodes(
-            &capture_name,
+        let nodes = lang_config.textobject_query()?.capture_nodes_any(
+            &[
+                &cap_name(TextObject::Movement),
+                &cap_name(TextObject::Around),
+                &cap_name(TextObject::Inside),
+            ],
             slice_tree,
             slice,
             &mut cursor,
diff --git a/helix-core/src/syntax.rs b/helix-core/src/syntax.rs
index a5c5e4983..ccf91100f 100644
--- a/helix-core/src/syntax.rs
+++ b/helix-core/src/syntax.rs
@@ -188,7 +188,21 @@ impl TextObjectQuery {
         slice: RopeSlice<'a>,
         cursor: &'a mut QueryCursor,
     ) -> Option<impl Iterator<Item = Node<'a>>> {
-        let capture_idx = self.query.capture_index_for_name(capture_name)?;
+        self.capture_nodes_any(&[capture_name], node, slice, cursor)
+    }
+
+    /// Find the first capture that exists out of all given `capture_names`
+    /// and return sub nodes that match this capture.
+    pub fn capture_nodes_any<'a>(
+        &'a self,
+        capture_names: &[&str],
+        node: Node<'a>,
+        slice: RopeSlice<'a>,
+        cursor: &'a mut QueryCursor,
+    ) -> Option<impl Iterator<Item = Node<'a>>> {
+        let capture_idx = capture_names
+            .iter()
+            .find_map(|cap| self.query.capture_index_for_name(cap))?;
         let captures = cursor.captures(&self.query, node, RopeProvider(slice));
 
         captures
diff --git a/helix-core/src/textobject.rs b/helix-core/src/textobject.rs
index 21ceec04f..5a55a6f1d 100644
--- a/helix-core/src/textobject.rs
+++ b/helix-core/src/textobject.rs
@@ -53,6 +53,8 @@ fn find_word_boundary(slice: RopeSlice, mut pos: usize, direction: Direction, lo
 pub enum TextObject {
     Around,
     Inside,
+    /// Used for moving between objects.
+    Movement,
 }
 
 impl Display for TextObject {
@@ -60,6 +62,7 @@ impl Display for TextObject {
         f.write_str(match self {
             Self::Around => "around",
             Self::Inside => "inside",
+            Self::Movement => "movement",
         })
     }
 }
@@ -104,6 +107,7 @@ pub fn textobject_word(
                 Range::new(word_start - whitespace_count_left, word_end)
             }
         }
+        TextObject::Movement => unreachable!(),
     }
 }
 
@@ -118,6 +122,7 @@ pub fn textobject_surround(
         .map(|(anchor, head)| match textobject {
             TextObject::Inside => Range::new(next_grapheme_boundary(slice, anchor), head),
             TextObject::Around => Range::new(anchor, next_grapheme_boundary(slice, head)),
+            TextObject::Movement => unreachable!(),
         })
         .unwrap_or(range)
 }