Add shrink equivalent of extend_to_line_bounds (#2450)

* Add shrink equivalent of extend_to_line_bounds

* Add a check for being past rope end in end position calc

* Include the EOL character in calculations

* Bind to `A-x` for now

* Document new keybind

3 files changed, 44 insertions, 1 deletions

diff --git a/book/src/keymap.md b/book/src/keymap.md
index e56eeefc..25280d71 100644
--- a/book/src/keymap.md
+++ b/book/src/keymap.md
@@ -107,6 +107,7 @@
 | `%`                   | Select entire file                                                | `select_all`                         |
 | `x`                   | Select current line, if already selected, extend to next line     | `extend_line`                        |
 | `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`                    |
 | `K`                   | Keep selections matching the regex                                | `keep_selections`                    |
 | `Alt-K`               | Remove selections matching the regex                              | `remove_selections`                  |
diff --git a/helix-term/src/commands.rs b/helix-term/src/commands.rs
index 2839f495..8024e3f0 100644
--- a/helix-term/src/commands.rs
+++ b/helix-term/src/commands.rs
@@ -247,6 +247,7 @@ impl MappableCommand {
         extend_line, "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 (line-wise selection)",
+        shrink_to_line_bounds, "Shrink selection to line bounds (line-wise selection)",
         delete_selection, "Delete selection",
         delete_selection_noyank, "Delete selection, without yanking",
         change_selection, "Change selection (delete and enter insert mode)",
@@ -1942,6 +1943,47 @@ fn extend_to_line_bounds(cx: &mut Context) {
     );
 }
 
+fn shrink_to_line_bounds(cx: &mut Context) {
+    let (view, doc) = current!(cx.editor);
+
+    doc.set_selection(
+        view.id,
+        doc.selection(view.id).clone().transform(|range| {
+            let text = doc.text();
+
+            let (start_line, end_line) = range.line_range(text.slice(..));
+
+            // Do nothing if the selection is within one line to prevent
+            // conditional logic for the behavior of this command
+            if start_line == end_line {
+                return range;
+            }
+
+            let mut start = text.line_to_char(start_line);
+
+            // line_to_char gives us the start position of the line, so
+            // we need to get the start position of the next line. In
+            // the editor, this will correspond to the cursor being on
+            // the EOL whitespace charactor, which is what we want.
+            let mut end = text.line_to_char((end_line + 1).min(text.len_lines()));
+
+            if start != range.from() {
+                start = text.line_to_char((start_line + 1).min(text.len_lines()));
+            }
+
+            if end != range.to() {
+                end = text.line_to_char(end_line);
+            }
+
+            if range.anchor <= range.head {
+                Range::new(start, end)
+            } else {
+                Range::new(end, start)
+            }
+        }),
+    );
+}
+
 enum Operation {
     Delete,
     Change,
diff --git a/helix-term/src/keymap/default.rs b/helix-term/src/keymap/default.rs
index a887f4b3..0f0b09dd 100644
--- a/helix-term/src/keymap/default.rs
+++ b/helix-term/src/keymap/default.rs
@@ -87,7 +87,7 @@ pub fn default() -> HashMap<Mode, Keymap> {
         "%" => select_all,
         "x" => extend_line,
         "X" => extend_to_line_bounds,
-        // crop_to_whole_line
+        "A-x" => shrink_to_line_bounds,
 
         "m" => { "Match"
             "m" => match_brackets,