TODO.md

Teapot — Status and Roadmap

Completed

Core Engine

• Token, Scanner, Parser (recursive descent evaluator, no AST)
• 42 built-in functions (math, string, cell refs, aggregates, utility)
• 3D sparse HashMap-based sheet with lazy on-demand evaluation
• Type-safe arithmetic with promotion rules matching C original

File I/O

• Portable ASCII format (.tp) — load/save
• Compressed format (.tpz) — load/save
• CSV — load/save
• XLSX — load/save (via calamine/rust_xlsxwriter)
• ODS/XLS — load (via calamine)
• HTML export
• LaTeX export
• ConTeXt export
• Plain text export

Terminal UI (ratatui/crossterm)

• Spreadsheet grid with column/row headers
• Sheet tabs with navigation
• Cell editing with formula pre-fill
• vim-style navigation (hjkl, HJKL page, Home/End, PgUp/PgDn)
• Command mode (: prefix)
• Block operations: mark, copy, move, clear, sort, yank/paste
• Insert/delete rows and columns
• Column width adjustment (+/-)
• Cell formatting: alignment, precision, bold, underline, lock, ignore
• Block-scoped formatting (applies to marked block when set)
• Undo/redo (50 levels)
• Batch mode (stdin commands)
• Help screen (?)

Modern TUI Features

• Smart entry keys: = for formula, ' for text (auto-quotes), 0-9 for numbers
• Full readline-style editing (Left/Right, Home/End, Ctrl+A/E/K/U/W/F/B, Delete)
• Command history (Up/Down, max 100 entries)
• Tab completion for commands
• @ cell picker (highlight on sheet, insert reference)
• Sheet navigation: [/] keys, Z picker popup, :sheet/:sheet-add/:sheet-del
• Mirror block (:mirror-x/y/z)
• Fill/tile block (:fill cols rows [layers])
• Multi-axis sort (:sort-x, :sort-y, :sort-z)
• Clocked cells — three-phase commit (C key, :clock, :clock-run)
• Command palette (/ or F1) with fuzzy filtering
• Search/replace with regex (n/N navigate, :search, :replace, y/n/a/q confirmation)
• Cell reference and dependency highlighting (g/d/r keys, colored refs in status bar)
• Label-based cell references — @("labelName"), :label, :labels picker
• eval() function — re-evaluates a cell's formula (with recursion protection)
• Export marked block only (all export commands respect mark range)
• @/& partial coordinate support — @(), @(x), @(x,y), &(), &(x), &(x,y)
• log(x, base) two-argument form
• rnd() zero-argument random [0,1)
• strftime() with chrono — format string + optional timestamp
• Status bar: modified indicator (*), mark range display

Remaining Work

File Formats

• XDR binary format (original native format) — load/save
• SC (Spreadsheet Calculator) format — load
• WK1 (Lotus 1-2-3) format — load

UI Polish

• Mouse support (click to select cell, scroll)
• Theming / color schemes
• Resizable column widths by dragging
• Status bar: show mark range, modified indicator
• Configurable key bindings

Missing C Features

• Internationalization (message catalogs) — deferred (C code has no actual translations)

Future Ideas

• Undo descriptions (show what each undo step reverts)
• Search/replace within cells
• Conditional formatting
• Charts (sparklines in terminal)
• Lua/Rhai scripting extension
• Web-based viewer