Therapy Assignment

This is an implementation of an assignment to convert inputs into outputs using the corresponding expressions.

Installation

Use cargo to run the application and create a server listening on localhost port 8080

cargo run

Usage

We can send a POST request to http://127.0.0.1:8080/eval with the values of A, B, C, D, E, F and receive the value of H and K

curl -i -d '{"A":true, "B":true, "C":true, "D":76.5, "E":2, "F":1}' -H 'Content-Type: application/json' http://127.0.0.1:8080/eval

Architecture

It was decided that hard codding the corresponding expressions for substitutions is not very flexible because in a real case scenario the code would need to be rewritten constantly, whenever an expression changes or is overridden.

The approach chosen was to divide the expressions in two categories, those who alter H and those who alter K. Then create a small parser for such expressions, this way we can handle the case when a new expression is added or overridden, easily.

This code is written in Rust and contains Unit Tests for the ExpressionProcessor (Parser) and for the H and K substitutions, which can be run using cargo test. For the porpouse of this assignment it's assumed that the expressions for substitutions are valid.

A single endpoint in /eval is provided, this was implemented using minimal functionality provided by actix-web and serde. The logic to evaluate an expression is provided by evalexpr.