Implement no-yank delete/change (#1099)

3 files changed, 81 insertions, 59 deletions

diff --git a/book/src/keymap.md b/book/src/keymap.md
index fbe77267..4d542800 100644
--- a/book/src/keymap.md
+++ b/book/src/keymap.md
@@ -45,44 +45,46 @@
 
 ### Changes
 
-| Key         | Description                                     | Command               |
-| -----       | -----------                                     | -------               |
-| `r`         | Replace with a character                        | `replace`             |
-| `R`         | Replace with yanked text                        | `replace_with_yanked` |
-| `~`         | Switch case of the selected text                | `switch_case`         |
-| `` ` ``     | Set the selected text to lower case             | `switch_to_lowercase` |
-| `` Alt-` `` | Set the selected text to upper case             | `switch_to_uppercase` |
-| `i`         | Insert before selection                         | `insert_mode`         |
-| `a`         | Insert after selection (append)                 | `append_mode`         |
-| `I`         | Insert at the start of the line                 | `prepend_to_line`     |
-| `A`         | Insert at the end of the line                   | `append_to_line`      |
-| `o`         | Open new line below selection                   | `open_below`          |
-| `O`         | Open new line above selection                   | `open_above`          |
-| `.`         | Repeat last change                              | N/A                   |
-| `u`         | Undo change                                     | `undo`                |
-| `U`         | Redo change                                     | `redo`                |
-| `Alt-u`     | Move backward in history                        | `earlier`             |
-| `Alt-U`     | Move forward in history                         | `later`               |
-| `y`         | Yank selection                                  | `yank`                |
-| `p`         | Paste after selection                           | `paste_after`         |
-| `P`         | Paste before selection                          | `paste_before`        |
-| `"` `<reg>` | Select a register to yank to or paste from      | `select_register`     |
-| `>`         | Indent selection                                | `indent`              |
-| `<`         | Unindent selection                              | `unindent`            |
-| `=`         | Format selection (**LSP**)                      | `format_selections`   |
-| `d`         | Delete selection                                | `delete_selection`    |
-| `c`         | Change selection (delete and enter insert mode) | `change_selection`    |
-| `Ctrl-a`    | Increment object (number) under cursor          | `increment`           |
-| `Ctrl-x`    | Decrement object (number) under cursor          | `decrement`           |
+| Key         | Description                                                      | Command                   |
+| -----       | -----------                                                      | -------                   |
+| `r`         | Replace with a character                                         | `replace`                 |
+| `R`         | Replace with yanked text                                         | `replace_with_yanked`     |
+| `~`         | Switch case of the selected text                                 | `switch_case`             |
+| `` ` ``     | Set the selected text to lower case                              | `switch_to_lowercase`     |
+| `` Alt-` `` | Set the selected text to upper case                              | `switch_to_uppercase`     |
+| `i`         | Insert before selection                                          | `insert_mode`             |
+| `a`         | Insert after selection (append)                                  | `append_mode`             |
+| `I`         | Insert at the start of the line                                  | `prepend_to_line`         |
+| `A`         | Insert at the end of the line                                    | `append_to_line`          |
+| `o`         | Open new line below selection                                    | `open_below`              |
+| `O`         | Open new line above selection                                    | `open_above`              |
+| `.`         | Repeat last change                                               | N/A                       |
+| `u`         | Undo change                                                      | `undo`                    |
+| `U`         | Redo change                                                      | `redo`                    |
+| `Alt-u`     | Move backward in history                                         | `earlier`                 |
+| `Alt-U`     | Move forward in history                                          | `later`                   |
+| `y`         | Yank selection                                                   | `yank`                    |
+| `p`         | Paste after selection                                            | `paste_after`             |
+| `P`         | Paste before selection                                           | `paste_before`            |
+| `"` `<reg>` | Select a register to yank to or paste from                       | `select_register`         |
+| `>`         | Indent selection                                                 | `indent`                  |
+| `<`         | Unindent selection                                               | `unindent`                |
+| `=`         | Format selection (**LSP**)                                       | `format_selections`       |
+| `d`         | Delete selection                                                 | `delete_selection`        |
+| `Alt-d`     | Delete selection, without yanking                                | `delete_selection_noyank` |
+| `c`         | Change selection (delete and enter insert mode)                  | `change_selection`        |
+| `Alt-c`     | Change selection (delete and enter insert mode, without yanking) | `change_selection_noyank` |
+| `Ctrl-a`    | Increment object (number) under cursor                           | `increment`               |
+| `Ctrl-x`    | Decrement object (number) under cursor                           | `decrement`               |
 
 #### Shell
 
-| Key                   | Description                                                                      | Command               |
-| ------                | -----------                                                                      | -------               |
-| <code>&#124;</code>   | Pipe each selection through shell command, replacing with output                 | `shell_pipe`          |
-| <code>A-&#124;</code> | Pipe each selection into shell command, ignoring output                          | `shell_pipe_to`       |
-| `!`                   | Run shell command, inserting output before each selection                        | `shell_insert_output` |
-| `A-!`                 | Run shell command, appending output after each selection                         | `shell_append_output` |
+| Key                     | Description                                                      | Command               |
+| ------                  | -----------                                                      | -------               |
+| <code>&#124;</code>     | Pipe each selection through shell command, replacing with output | `shell_pipe`          |
+| <code>Alt-&#124;</code> | Pipe each selection into shell command, ignoring output          | `shell_pipe_to`       |
+| `!`                     | Run shell command, inserting output before each selection        | `shell_insert_output` |
+| `Alt-!`                 | Run shell command, appending output after each selection         | `shell_append_output` |
 
 
 ### Selection manipulation
diff --git a/helix-term/src/commands.rs b/helix-term/src/commands.rs
index 2c556281..b5b6ac6d 100644
--- a/helix-term/src/commands.rs
+++ b/helix-term/src/commands.rs
@@ -9,7 +9,6 @@ use helix_core::{
     numbers::NumberIncrementor,
     object, pos_at_coords,
     regex::{self, Regex, RegexBuilder},
-    register::Register,
     search, selection, surround, textobject,
     unicode::width::UnicodeWidthChar,
     LineEnding, Position, Range, Rope, RopeGraphemes, RopeSlice, Selection, SmallVec, Tendril,
@@ -232,7 +231,9 @@ impl Command {
         extend_line, "Select current line, if already selected, extend to next line",
         extend_to_line_bounds, "Extend 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)",
+        change_selection_noyank, "Change selection (delete and enter insert mode, without yanking)",
         collapse_selection, "Collapse selection onto a single cursor",
         flip_selections, "Flip selection cursor and anchor",
         insert_mode, "Insert before selection",
@@ -1693,19 +1694,42 @@ fn extend_to_line_bounds(cx: &mut Context) {
     );
 }
 
-fn delete_selection_impl(reg: &mut Register, doc: &mut Document, view_id: ViewId) {
+enum Operation {
+    Delete,
+    Change,
+}
+
+fn delete_selection_impl(cx: &mut Context, op: Operation) {
+    let (view, doc) = current!(cx.editor);
+
     let text = doc.text().slice(..);
-    let selection = doc.selection(view_id);
+    let selection = doc.selection(view.id);
 
-    // first yank the selection
-    let values: Vec<String> = selection.fragments(text).map(Cow::into_owned).collect();
-    reg.write(values);
+    if cx.register != Some('_') {
+        // first yank the selection
+        let values: Vec<String> = selection.fragments(text).map(Cow::into_owned).collect();
+        let reg_name = cx.register.unwrap_or('"');
+        let registers = &mut cx.editor.registers;
+        let reg = registers.get_mut(reg_name);
+        reg.write(values);
+    };
 
     // then delete
     let transaction = Transaction::change_by_selection(doc.text(), selection, |range| {
         (range.from(), range.to(), None)
     });
-    doc.apply(&transaction, view_id);
+    doc.apply(&transaction, view.id);
+
+    match op {
+        Operation::Delete => {
+            doc.append_changes_to_history(view.id);
+            // exit select mode, if currently in select mode
+            exit_select_mode(cx);
+        }
+        Operation::Change => {
+            enter_insert_mode(doc);
+        }
+    }
 }
 
 #[inline]
@@ -1720,25 +1744,21 @@ fn delete_selection_insert_mode(doc: &mut Document, view: &View, selection: &Sel
 }
 
 fn delete_selection(cx: &mut Context) {
-    let reg_name = cx.register.unwrap_or('"');
-    let (view, doc) = current!(cx.editor);
-    let registers = &mut cx.editor.registers;
-    let reg = registers.get_mut(reg_name);
-    delete_selection_impl(reg, doc, view.id);
-
-    doc.append_changes_to_history(view.id);
+    delete_selection_impl(cx, Operation::Delete);
+}
 
-    // exit select mode, if currently in select mode
-    exit_select_mode(cx);
+fn delete_selection_noyank(cx: &mut Context) {
+    cx.register = Some('_');
+    delete_selection_impl(cx, Operation::Delete);
 }
 
 fn change_selection(cx: &mut Context) {
-    let reg_name = cx.register.unwrap_or('"');
-    let (view, doc) = current!(cx.editor);
-    let registers = &mut cx.editor.registers;
-    let reg = registers.get_mut(reg_name);
-    delete_selection_impl(reg, doc, view.id);
-    enter_insert_mode(doc);
+    delete_selection_impl(cx, Operation::Change);
+}
+
+fn change_selection_noyank(cx: &mut Context) {
+    cx.register = Some('_');
+    delete_selection_impl(cx, Operation::Change);
 }
 
 fn collapse_selection(cx: &mut Context) {
diff --git a/helix-term/src/keymap.rs b/helix-term/src/keymap.rs
index 7f6d0c6b..0062e636 100644
--- a/helix-term/src/keymap.rs
+++ b/helix-term/src/keymap.rs
@@ -537,9 +537,9 @@ impl Default for Keymaps {
             "O" => open_above,
 
             "d" => delete_selection,
-            // TODO: also delete without yanking
+            "A-d" => delete_selection_noyank,
             "c" => change_selection,
-            // TODO: also change delete without yanking
+            "A-c" => change_selection_noyank,
 
             "C" => copy_selection_on_next_line,
             "A-C" => copy_selection_on_prev_line,