🧮 Calculator (executable)

The calculator executable provides a scientific-expression evaluation UI primarily for WASM targets.

Role

• Owns calculator expression language pipeline (lexer/parser/evaluator) and button-matrix UI bindings.
• Serves as a target-specific application (interactive on wasm32, informational fallback on non-wasm targets).

Startup and lifecycle

• wasm32 target: creates interface window and enters event loop (Interface::run).
• non-wasm32 target: prints localized informational message and exits.

Runtime integration points

• WASM graphics/UI API (wasm crate guest graphics functions) for window, labels, button matrix, and events.
• Internationalization for UI labels/messages.
• Internal parser/evaluator modules for expression execution.

Data and control flow / VFS touchpoints

• Primary flow: button event -> expression text mutation -> parse -> evaluate -> display update.
• Constants/functions are translated to parser-friendly textual forms before evaluation.
• No direct VFS touchpoint in executable runtime path.

Concurrency and event-loop model

• Single synchronous UI event loop in Interface::run.
• No separate worker tasks; computations run inline on event handling.

Failure semantics

• Expression parse/evaluation failures are rendered as localized Error: ... display output.
• UI creation failures abort startup (Interface::new().unwrap() in wasm main path).

Contract vs implementation

• Contract: calculator executable computes expressions from UI/user input and renders result text.
• Current implementation: wasm-focused LVGL-like button matrix, direct string-based expression assembly, and inline parser/evaluator execution.

Operational limitations

• Intended runtime is wasm32; native targets only print fallback message.
• Event loop currently runs forever on wasm path and relies on host environment behavior.

References

• executables/calculator
• 🌍 WASM