Design a Spreadsheet Application

Designing a spreadsheet application tests virtualized rendering, formula evaluation, complex state, and handling large datasets. Here's a structured approach.

Requirements Clarification

Functional Requirements

• Grid: Display cells in rows and columns; support thousands of rows/columns.
• Editing: Inline cell editing with formula support (e.g., =SUM(A1:A10)).
• Selection: Single cell, ranges, multi-select; keyboard navigation (arrow keys, Shift+arrows).
• Operations: Copy, paste, cut; undo/redo.
• Layout: Resizable columns and rows; frozen rows/columns.
• References: Cell references (A1, $A$1), range references (A1:B5).

Non-Functional Requirements

• Smooth scrolling and editing with 10,000+ cells visible in the viewport.
• Sub-100ms feedback for cell edits and formula recalculation.
• Offline-capable (optional); collaborative editing (optional).

High-Level Architecture

┌────────────────────────────────────────────────────────────┐
│                     SpreadsheetRoot                          │
├─────────────┬──────────────────────────────────────────────┤
│  HeaderBar  │  VirtualizedGrid (viewport only)              │
│  - Toolbar  │  - RowHeaders (virtualized)                   │
│  - Formula  │  - ColumnHeaders (virtualized)                │
│    Bar      │  - CellMatrix (virtualized rows × columns)    │
├─────────────┴──────────────────────────────────────────────┤
│  State: cells, selection, undoStack, formulas               │
└────────────────────────────────────────────────────────────┘