:tada: extend selection

2 files changed, 63 insertions, 2 deletions

diff --git a/libeditor/src/extend_selection.rs b/libeditor/src/extend_selection.rs
new file mode 100644
index 000000000..16d4bc084
--- /dev/null
+++ b/libeditor/src/extend_selection.rs
@@ -0,0 +1,36 @@
+use libsyntax2::{
+    TextRange, SyntaxNodeRef,
+    SyntaxKind::WHITESPACE,
+    algo::{find_leaf_at_offset, find_covering_node, ancestors},
+};
+
+
+pub(crate) fn extend_selection(root: SyntaxNodeRef, range: TextRange) -> Option<TextRange> {
+    if range.is_empty() {
+        let offset = range.start();
+        let mut leaves = find_leaf_at_offset(root, offset);
+        if let Some(leaf) = leaves.clone().find(|node| node.kind() != WHITESPACE) {
+            return Some(leaf.range());
+        }
+        let ws = leaves.next()?;
+//        let ws_suffix = file.text().slice(
+//            TextRange::from_to(offset, ws.range().end())
+//        );
+//        if ws.text().contains("\n") && !ws_suffix.contains("\n") {
+//            if let Some(line_end) = file.text()
+//                .slice(TextSuffix::from(ws.range().end()))
+//                .find("\n")
+//            {
+//                let range = TextRange::from_len(ws.range().end(), line_end);
+//                return Some(find_covering_node(file.root(), range).range());
+//            }
+//        }
+        return Some(ws.range());
+    };
+    let node = find_covering_node(root, range);
+
+    match ancestors(node).skip_while(|n| n.range() == range).next() {
+        None => None,
+        Some(parent) => Some(parent.range()),
+    }
+}
diff --git a/libeditor/src/lib.rs b/libeditor/src/lib.rs
index 091aed125..a0c003fb5 100644
--- a/libeditor/src/lib.rs
+++ b/libeditor/src/lib.rs
@@ -1,12 +1,13 @@
 extern crate libsyntax2;
-extern crate text_unit;
+
+mod extend_selection;
 
 use libsyntax2::{
     SyntaxNodeRef,
     algo::walk,
     SyntaxKind::*,
 };
-use text_unit::TextRange;
+pub use libsyntax2::{TextRange, TextUnit};
 
 pub struct File {
     inner: libsyntax2::File
@@ -71,6 +72,11 @@ impl File {
             .collect();
         res // NLL :-(
     }
+
+    pub fn extend_selection(&self, range: TextRange) -> Option<TextRange> {
+        let syntax = self.inner.syntax();
+        extend_selection::extend_selection(syntax.as_ref(), range)
+    }
 }
 
 
@@ -96,3 +102,22 @@ impl<'f> Declaration<'f> {
         self.0.range()
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_extend_selection() {
+        let text = r#"fn foo() {
+    1 + 1
+}
+"#;
+        let file = File::new(text);
+        let range = TextRange::offset_len(18.into(), 0.into());
+        let range = file.extend_selection(range).unwrap();
+        assert_eq!(range, TextRange::from_to(17.into(), 18.into()));
+        let range = file.extend_selection(range).unwrap();
+        assert_eq!(range, TextRange::from_to(15.into(), 20.into()));
+    }
+}