data-holder

data-holder

A NodeJS package that provides asynchronous implementations for some data structures, with the flexibility needed in this cruel world divided by callbacks and promises.

You can find the complete docs in here.

Implemented structures

• Linked list
• Double linked list
• Ordered List
• Stack
• Queue

A little introduction

Let's start simple, say you want a semi synchronous process (recommended mostly for short lived experiments and tests).

let structures = require(data-holder)('Sync');
let List = structures.List;

//Blah, blah, blah...

let l = new List();                                        // []
l.add(13);                                                 // [13]

//Another important thing

l.unshift(42);                                             // [42, 13]

//Here you must put code that is definitively not going to crash.

console.log(l.pop());                                      // [42]

But... what about callbacks?

let structures = require(data-holder)();
let List = structures.List;

//Blah, blah, blah...

//You simply pass the callback as an extra parameter.
let l = new List();                                        // []
l.add(13, () => {                                          // [42, 13]
    l.unshift(42, () => {
      l.pop((err, element) => {                            // [42]
        console.log(element);
      });                                      
    });
});

And do not panic, I won't forget about promises. If you want to use the ones implemented by default on Node, this example is for you.

let structures = require(data-holder)();
let List = structures.List;

//Blah, blah, blah...

//You simply pass the callback as an extra parameter.
let l = new List();                                        // []
let p1 = l.add(13);                                        // [13]
let p2 = p1.then(() => {
  return l.unshift(42);                                    // [42, 13]
});
let p3 = p2.then(() => {
  return l.pop();                                          // [42]
});

p3
  .then((element) => {
    console.log(element);
  })
  .catch(() => {
    console.log("):");
  });

Just as a pro-tip, you can also pass the string default or Default and get the same behaviour (callbacks and Node's promise).

But maybe, you are already using a promise library, then send the function through parameter. Don't worry, I'm pretty bad at explaining, let's see it it action (with Bluebird)

let Promise = require('bluebird');
let structures = require(data-holder)(Promise);
let List = structures.List;

//Blah, blah, blah...

//You simply pass the callback as an extra parameter.
let l = new List();                                        // []
let p1 = l.add(13);                                        // [13]
let p2 = p1.then(() => {
  return l.unshift(42);                                    // [42, 13]
});
let p3 = p2.then(() => {
  return l.pop();                                          // [42]
});

p3
  .then((element) => {
    console.log(element);
  })
  .catch(() => {
    console.log("):");
  });

And that's how you use it with Bluebird. And, yes, I didn't bothered to change the example.

Also, you don't need to import all of the structures (which we have been doing on the previous examples). Let's say you only need a list with callbacks; the second parameter must be a string with the name of the structure. Be careful, this returns the structure directly.

let List = require(data-holder)('Default', 'List');

//Blah, blah, bla

//You simply pass the callback as an extra parameter.
let l = new List();                                        // []
l.add(13, () => {                                          // [42, 13]
    l.unshift(42, () => {
      l.pop((err, element) => {                            // [42]
        console.log(element);
      });                                      
    });
});

Also, you might need more than one structure at the same time, to require them is as simple as passing an array of strings. It gives you the same arrangement as if you imported all of the structures available.

let data-holder = require(data-holder)('Default', 'List', 'OrderedList');
let List = structures.List;
let OrderedList = structures.OrderedList;

//Blah, blah, blah...

//You simply pass the callback as an extra parameter.
let l = new List();                                        // []
let l2 = new OrderedList();                                // []
l.add(13, () => {                                          // [42, 13]
    l.unshift(42, () => {
      l.pop((err, element) => {                            // [42]
        console.log(element);
      });                                      
    });
});