dirv / martian-robots

martian-robots

An implementation of Martian Robots using functional JavaScript.

How to run

1. You'll need to install Node version 13 or greater.
2. At a shell prompt, pipe your input data into the Node command, like this:

node src/index.js < test/sampleInput.txt

You should then see the program results printed on screen.

Sample test data

Sample input (this is in the repo as test/sampleInput.txt):

5 3
1 1 E
RFRFRFRF
3 2 N
FRRFLLFFRRFLL
0 3 W
LLFFFLFLFL

Which will return:

1 1 E
3 3 N LOST
2 3 S

How to add a new instruction

To add a new instruction, you'll need to do the following.

1. In src/instructions.js (or in another file if you wish), define a function that takes two arguments: the robot state (e.g. { x: 3, y: 3, orientation: "WS" }) and the world state (e.g. { maxX: 5, maxY: 5 }). This function should return the new transformed robot state.

2. Add the instruction to the instructionLookup at the bottom of the same file. You'll need to give the instruction a single character keycode which is the used in the program input.

You can use the existing commands moveForward, turnRight, and turnLeft as references for how to implement a command.

Running the automated tests

This package uses the Vitest test runner. To run the tests you can use the following commands:

npm install
npm test

Description of code

There are four modules:

Module	Description
index.js	Reads stdin and invokes the application. This code has no automated tests.
io.js	Parsing input and formatting output.
processor.js	Runs each instruction on each robot, and passes any collected scents between robots.
instructions.js	Houses the individudal instructions that can affect the robot state.

Todo

Here's what I'd do if I had more time.

• The io module was a bit rushed - I'd probably split out some more tests, move in some of the code from src/index.js for reading stdin and also possibly rename the module itself.
• The scents array with functions hasScents and addScent code could be extended to use a more performant data structure, and possibly live in its own module
• Instructions don't get passed scents. It might make sense to move scents into the world context object, so that they can make use of that data.