dohjon / calculator Goto Github PK

• Unix

$ node -v
v14.2.0

$ npm -v
6.14.4

// not a requirement, only info
$ docker -v
Docker version 19.03.9, build 9d988398e7

git clone https://github.com/dohjon/calculator.git

npm install

npm test

Docker support

// Step 1. change code
...

// Step 2. build
docker build -t calculator:latest .

// Step 3. run

// arguments
docker run \
    --rm \
    -it \
    --workdir /usr/src/app \
    --volume $(pwd):/usr/src/app \
    --init \
    calculator:latest x add 3 print x

// interactive
docker run \
    --rm \
    -it \
    --workdir /usr/src/app \
    --volume $(pwd):/usr/src/app \
    --init \
    calculator:latest

// file
docker run \
    --rm \
    -it \
    --workdir /usr/src/app \
    --volume $(pwd):/usr/src/app \
    --init \
    calculator:latest test.txt

// link bin to path 
sudo npm link

// or use path
$ lib/calculator.js

// arguments
$ calculator x add 3 print x

// interactive
$ calculator

// file
$ calculator text.txt

• Assumption: Cross platform support is not needed.

• Assumption: data does not need to be saved after application exits

• Assumption: no advanced error handling

• Assumption: only synchronous code

• Assumption: no need to handle signals (SIGINT, SIGTERM, etc) in interactive mode

• Assumption: no need to optimize by using steams (read file content into memory)

• Assumption: process should exit with 0 even when invalid tokens.

• Assumption: no special characters needs to be supported

• Assumption: operations words cannot be valid register word

• Assumption: quit, print cannot be valid register word

• Assumption: Beacuse this is a test I avoided using external libraries except for linting, formatting and testing. In the real world I would use existing libraries for everything.

• Assumption: Circular dependency is not implemenented. Input using below examples will cause endless recursion.

  x => y

  y => x

  And

  x => y

  y => y

Scan => Parse => Evaluate => Calculate

Converts a string to tokens.

'x add 3'

To

['x', 'add', '3']

Converts tokens to AST (abstract syntax tree)

['x', 'add', '3', 'print', 'x']

To

[
    {
        val: 'x',
        type: REGISTER,
        children: [
            {
                val: 'add',
                type: OPERATION,
                children: [
                    {
                        val: 3,
                        type: VALUE,
                        children: [],
                    },
                ],
            },
        ],
    },
    {
        val: 'print',
        type: PRINT,
        children: [
            {
                val: 'x',
                type: REGISTER,
                children: [],
            },
        ],
    }
]

Add new operation handler in operations.js

function division(a, b) {
  return a / b;
}

Add handler to operations in operations.js

const operations = {
  division: division,
  ...
};

Add name of handler to operation in parser/rules.js

const operation = `^division$`;

• eslint - Linter
• prettier - Formatter
• riteway - Testing