let extend-line respect range direction (#3046)

* let extend-line respect range direction

* fix extend above logic

* keep `x` existing binding

* Update book/src/keymap.md

Co-authored-by: Ivan Tham <pickfire@riseup.net>

Co-authored-by: Ivan Tham <pickfire@riseup.net>

3 files changed, 29 insertions, 7 deletions

diff --git a/book/src/keymap.md b/book/src/keymap.md
index f84393ac..a26fd7ea 100644
--- a/book/src/keymap.md
+++ b/book/src/keymap.md
@@ -125,7 +125,7 @@
 | `Alt-(`               | Rotate selection contents backward                                | `rotate_selection_contents_backward` |
 | `Alt-)`               | Rotate selection contents forward                                 | `rotate_selection_contents_forward`  |
 | `%`                   | Select entire file                                                | `select_all`                         |
-| `x`                   | Select current line, if already selected, extend to next line     | `extend_line`                        |
+| `x`                   | Select current line, if already selected, extend to next line     | `extend_line_below`                  |
 | `X`                   | Extend selection to line bounds (line-wise selection)             | `extend_to_line_bounds`              |
 | `Alt-x`               | Shrink selection to line bounds (line-wise selection)             | `shrink_to_line_bounds`              |
 | `J`                   | Join lines inside selection                                       | `join_selections`                    |
diff --git a/helix-term/src/commands.rs b/helix-term/src/commands.rs
index ffcccec3..885afa18 100644
--- a/helix-term/src/commands.rs
+++ b/helix-term/src/commands.rs
@@ -247,7 +247,8 @@ impl MappableCommand {
         extend_search_prev, "Add previous search match to selection",
         search_selection, "Use current selection as search pattern",
         global_search, "Global search in workspace folder",
-        extend_line, "Select current line, if already selected, extend to next line",
+        extend_line, "Select current line, if already selected, extend to another line based on the anchor",
+        extend_line_below, "Select current line, if already selected, extend to next line",
         extend_line_above, "Select current line, if already selected, extend to previous line",
         extend_to_line_bounds, "Extend selection to line bounds",
         shrink_to_line_bounds, "Shrink selection to line bounds",
@@ -1945,6 +1946,15 @@ enum Extend {
 }
 
 fn extend_line(cx: &mut Context) {
+    let (view, doc) = current_ref!(cx.editor);
+    let extend = match doc.selection(view.id).primary().direction() {
+        Direction::Forward => Extend::Below,
+        Direction::Backward => Extend::Above,
+    };
+    extend_line_impl(cx, extend);
+}
+
+fn extend_line_below(cx: &mut Context) {
     extend_line_impl(cx, Extend::Below);
 }
 
@@ -1960,20 +1970,32 @@ fn extend_line_impl(cx: &mut Context, extend: Extend) {
     let selection = doc.selection(view.id).clone().transform(|range| {
         let (start_line, end_line) = range.line_range(text.slice(..));
 
-        let start = text.line_to_char(start_line);
-        let end = text.line_to_char((end_line + count).min(text.len_lines()));
+        let start = text.line_to_char(match extend {
+            Extend::Above => start_line.saturating_sub(count),
+            Extend::Below => start_line,
+        });
+        let end = text.line_to_char(
+            match extend {
+                Extend::Above => end_line + 1, // the start of next line
+                Extend::Below => (end_line + count),
+            }
+            .min(text.len_lines()),
+        );
 
         // extend to previous/next line if current line is selected
         let (anchor, head) = if range.from() == start && range.to() == end {
             match extend {
-                Extend::Above => (end, text.line_to_char(start_line.saturating_sub(1))),
+                Extend::Above => (end, text.line_to_char(start_line.saturating_sub(count + 1))),
                 Extend::Below => (
                     start,
                     text.line_to_char((end_line + count + 1).min(text.len_lines())),
                 ),
             }
         } else {
-            (start, end)
+            match extend {
+                Extend::Above => (end, start),
+                Extend::Below => (start, end),
+            }
         };
 
         Range::new(anchor, head)
diff --git a/helix-term/src/keymap/default.rs b/helix-term/src/keymap/default.rs
index 8a16dc1b..fd7ea457 100644
--- a/helix-term/src/keymap/default.rs
+++ b/helix-term/src/keymap/default.rs
@@ -85,7 +85,7 @@ pub fn default() -> HashMap<Mode, Keymap> {
         "A-n" | "A-right" => select_next_sibling,
 
         "%" => select_all,
-        "x" => extend_line,
+        "x" => extend_line_below,
         "X" => extend_to_line_bounds,
         "A-x" => shrink_to_line_bounds,