Vim Mode

Overview

Optional modal editing mode that adds Vim-style keybindings to FerriteEditor. Disabled by default to preserve standard editing behavior. When enabled, provides Normal/Insert/Visual/Visual Line modes with essential Vim commands.

Key Files

• src/config/settings.rs - vim_mode: bool setting (default: false)
• src/editor/ferrite/vim.rs - VimState struct, VimMode enum, handle_key() dispatcher
• src/editor/ferrite/editor.rs - Event loop interception, set_vim_mode()/vim_mode() methods
• src/editor/widget.rs - vim_mode builder method, vim_mode_label on EditorOutput
• src/app/central_panel.rs - Propagates setting to EditorWidget, surfaces mode to UiState
• src/app/status_bar.rs - Renders [NORMAL]/[INSERT]/[VISUAL]/[V-LINE] indicator
• src/ui/settings.rs - Vim Mode checkbox in Editor settings section
• src/state.rs - vim_mode_indicator: Option<&'static str> on UiState

Architecture

Data Flow

Settings.vim_mode ──► EditorWidget.vim_mode() ──► FerriteEditor.set_vim_mode()
                                                        │
                                                   VimState.handle_key()
                                                        │
                                              VimMode (label: &'static str)
                                                        │
                                              EditorOutput.vim_mode_label
                                                        │
                                              UiState.vim_mode_indicator
                                                        │
                                              status_bar.rs (renders indicator)

Modal State Machine

VimState manages the current mode and pending operations:

• Normal: Default mode. Keys are interpreted as commands (motions, operators, mode switches).
• Insert: Text input mode. All keys pass through to normal editor handling. Esc returns to Normal.
• Visual: Character-wise selection. Motions extend selection. d/y operate on selection.
• Visual Line: Line-wise selection. Similar to Visual but selects full lines.

Event Loop Integration

In FerriteEditor::ui(), when vim_mode_enabled is true:

1. Event::Key events are intercepted by VimState::handle_key() before normal processing.
2. Returns VimKeyResult::Handled(result) if Vim consumed the key, Passthrough if not.
3. Event::Text events are suppressed in Normal/Visual modes via should_insert_text().
4. Standard egui shortcuts (Ctrl+C, Ctrl+V, etc.) are not intercepted by Vim.

Implemented Commands

Normal Mode

Key	Action
h/j/k/l	Left/down/up/right movement
w/b/e	Word forward/backward/end
0/$	Line start/end
gg/G	File start/end
i/a	Insert before/after cursor
I/A	Insert at line start/end
o/O	Open line below/above
x	Delete character
dd	Delete line
yy	Yank line
D	Delete to end of line
C	Change to end of line
p/P	Paste after/before
v/V	Enter Visual/Visual Line mode
u	Undo
Ctrl+R	Redo
{count}{motion}	Repeat count (e.g., 3j = move down 3)

Visual/Visual Line Mode

Key	Action
Motions	Extend selection
d	Delete selection
y	Yank selection
Esc	Return to Normal

Dependencies Used

No additional crates. Built entirely on existing TextBuffer, Cursor, and Selection types.

Usage

1. Open Settings (gear icon or Ctrl+,)
2. In the Editor section, check "Vim Mode"
3. Status bar shows [NORMAL] when active
4. Press i to enter Insert mode, Esc to return to Normal
5. Disable the checkbox to return to standard editing