Design Raw and Computed Spreadsheet Views

Design a spreadsheet object model that can display both a cell's raw content and its computed value. A raw value may be a literal or a formula; changing a cell from one kind to the other must correctly update dependencies and cached values.

Constraints & Assumptions

• Preserve the user's raw expression for editing, separately from the parsed expression and computed result.
• Dependent cells must reflect changes to their inputs, including formula-to-literal and literal-to-formula replacements.
• This is an object/API design exercise. Choose and state a formula grammar and error policy only as needed to illustrate the design; the report does not give a complete callable contract.
• Begin with one writer and an in-memory sheet. Persistence, undo/redo, and concurrent editing are possible extensions, not assumed product requirements.

Clarifying Questions to Ask

• Should getRaw preserve exact user formatting or a normalized expression?
• Should an invalid or cyclic edit be rejected, or stored and shown with a computed error?
• Do reads need to be constant time, or can values be evaluated lazily?