Add support for Unicode input

ref: helix-editor/helix#1438
ref: helix-editor/helix#2852

book/src/configuration.md

@@ -412,3 +412,16 @@ Sets explorer side width and style.
 | -------------- | ------------------------------------------- | ------- |
 | `column-width` | explorer side width                         | 30      |
 | `position`     | explorer widget position, `left` or `right` | `left`  |
+
+
+### `[editor.digraphs]` Section
+
+By default, special characters can be input using the `insert_digraphs` command, bound to `\` in normal mode.
+Custom digraphs can be added to the `editor.digraphs` section of the config.
+
+```toml
+[editor.digraphs]
+ka = "か"
+ku = { symbols = "く", description = "The japanese character Ku" }
+shrug = "¯\\_(ツ)_/¯"
+```

book/src/keymap.md

@@ -73,6 +73,7 @@ Normal mode is the default mode when you launch helix. You can return to it from
 | `a`         | Insert after selection (append)                                      | `append_mode`             |
 | `I`         | Insert at the start of the line                                      | `insert_at_line_start`    |
 | `A`         | Insert at the end of the line                                        | `insert_at_line_end`      |
+| `\`         | Insert digraphs                                                      | `insert_digraph`          |
 | `o`         | Open new line below selection                                        | `open_below`              |
 | `O`         | Open new line above selection                                        | `open_above`              |
 | `.`         | Repeat last insert                                                   | N/A                       |

helix-term/src/commands.rs

@@ -511,6 +511,7 @@ impl MappableCommand {
         extend_to_word, "Extend to a two-character label",
         open_or_focus_explorer, "Open or focus explorer",
         reveal_current_file, "Reveal current file in explorer",
+        insert_digraph, "Insert Unicode characters with prompt",
     );
 }
 
@@ -6268,3 +6269,50 @@ fn jump_to_word(cx: &mut Context, behaviour: Movement) {
     }
     jump_to_label(cx, words, behaviour)
 }
+
+fn insert_digraph(cx: &mut Context) {
+    ui::prompt(
+        cx,
+        "digraph:".into(),
+        Some('K'), // todo: decide on register to use
+        move |editor, input| {
+            editor
+                .config()
+                .digraphs
+                .search(input)
+                .take(10)
+                .map(|entry| {
+                    // todo: Prompt does not currently allow additional text as part
+                    // of it's suggestions. Show the user the symbol and description
+                    // once prompt has been made more robust
+                    #[allow(clippy::useless_format)]
+                    ((0..), Cow::from(format!("{}", entry.sequence)))
+                })
+                .collect()
+        },
+        move |cx, input, event| {
+            match event {
+                PromptEvent::Validate => (),
+                _ => return,
+            }
+            let config = cx.editor.config();
+            let symbols = if let Some(entry) = config.digraphs.get(input) {
+                &entry.symbols
+            } else {
+                cx.editor.set_error("Digraph not found");
+                return;
+            };
+
+            let (view, doc) = current!(cx.editor);
+            let selection = doc.selection(view.id);
+            let mut changes = Vec::with_capacity(selection.len());
+
+            for range in selection.ranges() {
+                changes.push((range.from(), range.from(), Some(symbols.clone().into())));
+            }
+            let trans = Transaction::change(doc.text(), changes.into_iter());
+            doc.apply(&trans, view.id);
+            doc.append_changes_to_history(view);
+        },
+    )
+}

helix-term/src/keymap/default.rs

@@ -138,6 +138,8 @@ pub fn default() -> HashMap<Mode, KeyTrie> {
         "N" => search_prev,
         "*" => search_selection,
 
+        "\\" => insert_digraph,
+
         "u" => undo,
         "U" => redo,
         "A-u" => earlier,