Auto-close Brackets & Quotes

Overview

Task 4 implements automatic insertion of closing brackets and quotes while typing, with selection wrapping and skip-over behavior.

Features

1. Auto-pair Insertion

When typing an opener character without a selection, automatically insert the closing pair:

• ( → ()
• [ → []
• { → {}
• " → ""
• ' → ''
• ` → ``

Cursor is positioned between the pair.

2. Selection Wrapping

When text is selected and an opener is typed, wrap the selection:

• Select "hello", type ( → (hello)
• Select "world", type " → "world"

Cursor moves to after the closing bracket.

3. Skip-over Behavior

When typing a closer and the next character is the same closer, move cursor forward instead of inserting a duplicate:

• text|) + type ) → text)| (skipped over)

4. Smart Quote Handling

Quotes are not auto-closed after alphanumeric characters to avoid interference with contractions:

• can't won't trigger auto-close after the apostrophe

Implementation

Settings

• Settings.auto_close_brackets: bool - Default: true
• UI toggle in Settings → Editor → "Auto-close Brackets & Quotes"

Key Files

• src/config/settings.rs - Setting definition
• src/ui/settings.rs - Settings UI checkbox
• src/app.rs - Core auto-close logic

Architecture

The implementation uses a two-phase approach:

Pre-render Phase (handle_auto_close_pre_render):

1. Scan egui input events for bracket/quote characters
2. Handle skip-over: Consume closer events when next char matches
3. Handle selection wrapping: Consume opener events, modify content manually

Post-render Phase (handle_auto_close_post_render):

1. Detect if single opener character was just typed
2. Insert closing bracket at cursor position
3. Use pending_cursor_restore to keep cursor between brackets

Helper Functions

fn get_closing_bracket(opener: char) -> Option<char>
fn is_closing_bracket(ch: char) -> bool
fn get_opening_bracket(closer: char) -> Option<char>

Testing

Scenario	Expected
Type ( with no selection	() inserted, cursor between
Type ( with "hello" selected	(hello) with cursor after )
Cursor before ), type )	Cursor jumps over )
Disable setting, type (	Only ( inserted
Type ' after "can"	Only ' inserted (apostrophe)
Undo after auto-close	Restores to before

Undo Behavior

• Selection wrapping: Undo removes both brackets
• Auto-pair insertion: TextEdit's internal undo may handle this differently
• Skip-over: No undo needed (just cursor movement)

Future Enhancements

• Multi-char pairs: **, __ for markdown emphasis
• Triple backticks for code blocks
• Configurable pair mapping