Pattern Matching

pattern-matching.js

import flatten from 'flat';
import objPath from 'object-path';


const _matchKeys = (matchOn, matchWith) => {
    const matchWithPaths = Object.keys(flatten(matchWith));
    const matchWithValues = matchWithPaths.map(path => {
        return objPath.get(matchWith, path);
    })
    const matchOnValues = matchWithPaths.map(path => {
        return objPath.get(matchOn, path);
    })

    return matchOnValues.every((value, index) => {
        return value === matchWithValues[index];
    })
}


const _with = matchOn => (matchWith, onMatch) => {
    const jsonMatchOn = JSON.stringify(matchOn);
    const jsonMatchWith = JSON.stringify(matchWith);
    // If the whole object matches
    if (jsonMatchOn === jsonMatchWith) {
        return onMatch();
    }

    if (_matchKeys(matchOn, matchWith)) {
        return onMatch();
    }

}


const match = (matchOn) => {
    return {
        with: _with(matchOn)
    }
}

//Main useage
const myObj = {
    name: 'chris'
};

match(myObj)
    .with({name: 'chris'}, () => console.log('matched with Chris'));
//matched with Chris

match(myObj)
    .with({name: 'john'}, () => console.log('matched with John'));
//no match

const myObj1 = {
    status: '200',
    response: {
        data: 'hello drunk world',
        headers: [
            'Content-Type: text/plain'
        ],
        forward: false,
        foo: {
            bar: {
                baz: 'hello'
            }
        }
    }
}

match(myObj1).with(
    { 
        response: { 
            foo: {
                bar: {
                    baz: 'hello'
                }
            }
        } 
    },
    () => console.log('matched'),
);
//matched