commands: Implement expand_selection.

2 files changed, 33 insertions, 0 deletions

diff --git a/helix-core/src/lib.rs b/helix-core/src/lib.rs
index 14e58293..7b401557 100644
--- a/helix-core/src/lib.rs
+++ b/helix-core/src/lib.rs
@@ -5,6 +5,7 @@ pub mod graphemes;
 mod history;
 pub mod indent;
 pub mod macros;
+pub mod object;
 mod position;
 pub mod register;
 pub mod selection;
diff --git a/helix-core/src/object.rs b/helix-core/src/object.rs
new file mode 100644
index 00000000..19ff9d96
--- /dev/null
+++ b/helix-core/src/object.rs
@@ -0,0 +1,32 @@
+use crate::{Range, RopeSlice, Selection, Syntax};
+use smallvec::smallvec;
+
+// TODO: to contract_selection we'd need to store the previous ranges before expand.
+// Maybe just contract to the first child node?
+pub fn expand_selection(syntax: &Syntax, text: RopeSlice, selection: &Selection) -> Selection {
+    let tree = syntax.root_layer.tree.as_ref().unwrap();
+
+    selection.transform(|range| {
+        let from = text.char_to_byte(range.from());
+        let to = text.char_to_byte(range.to());
+
+        // find parent of a descendant that matches the range
+        let parent = match tree
+            .root_node()
+            .descendant_for_byte_range(from, to)
+            .and_then(|node| node.parent())
+        {
+            Some(parent) => parent,
+            None => return range,
+        };
+
+        let from = text.byte_to_char(parent.start_byte());
+        let to = text.byte_to_char(parent.end_byte());
+
+        if range.head < range.anchor {
+            Range::new(to, from)
+        } else {
+            Range::new(from, to)
+        }
+    })
+}