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go-to-line.md

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Go to Line Dialog

Overview

The Go to Line feature (Ctrl+G) provides a modal dialog for navigating directly to a specific line number in the editor. The cursor moves to the target line and the viewport is centered on it.

Key Files

  • src/ui/dialogs.rs - GoToLineDialog struct and GoToLineResult enum
  • src/ui/mod.rs - Public exports for dialog types
  • src/state.rs - UiState.go_to_line_dialog field
  • src/app.rs - Keyboard shortcut handling and navigation logic

Implementation Details

Dialog Component (src/ui/dialogs.rs)

pub struct GoToLineDialog {
    pub line_input: String,      // User input text
    pub current_line: usize,     // Shown as placeholder (1-indexed)
    pub max_line: usize,         // Document line count
    pub error_message: Option<String>,
}

pub enum GoToLineResult {
    None,                        // Dialog still open
    Cancelled,                   // User cancelled (Escape)
    GoToLine(usize),            // Navigate to line (1-indexed)
}

Key Design Decisions

  1. Global Enter key handling - Enter key is checked at the start of show() before window rendering to ensure it works regardless of TextEdit focus state.

  2. Input validation - Only numeric input accepted; empty input defaults to current line.

  3. Line clamping - Target line is clamped to valid range [1, max_line] to handle out-of-bounds input gracefully.

  4. Viewport centering - Uses existing pending_scroll_to_line mechanism to center the target line approximately 1/3 from the top of the viewport.

Keyboard Shortcut (src/app.rs)

enum KeyboardAction {
    // ...
    GoToLine,  // Ctrl+G
}

// In handle_keyboard_shortcuts():
if i.modifiers.ctrl && !i.modifiers.shift && i.key_pressed(egui::Key::G) {
    return Some(KeyboardAction::GoToLine);
}

Navigation Logic

fn handle_go_to_line(&mut self, target_line: usize) {
    // 1. Calculate character index for line start
    // 2. Update cursor position via Tab.cursors
    // 3. Set pending_scroll_to_line for viewport centering
}

Dependencies Used

  • egui - Window, TextEdit, layout, key handling

Usage

  1. Press Ctrl+G to open the dialog
  2. Enter a line number (or leave empty to use current line)
  3. Press Enter or click Go to navigate
  4. Press Escape or click Cancel to close without navigating

UI Appearance

  • Modal window centered on screen
  • Single-line text input with current line as placeholder
  • "Range: 1 - N" hint showing valid line numbers
  • Go and Cancel buttons

Tests

Unit test in src/ui/dialogs.rs:

#[test]
fn test_go_to_line_dialog() {
    let dialog = GoToLineDialog::new(10, 100);
    assert_eq!(dialog.current_line, 10);
    assert_eq!(dialog.max_line, 100);
    assert!(dialog.line_input.is_empty());
}

Run tests:

cargo test go_to_line

Related Features

  • Outline Panel navigation (click heading to scroll)
  • Search result navigation (F3/Shift+F3)
  • scroll_to_line in EditorWidget