Viscous

serialisable appliable state differ

Usage

var viscous = require('viscous');

var state1 = {},
    differ1 = viscous(state1);

var state2 = {},
    differ2 = viscous(state2);

state1.x = 10; // assign a value
state1.y = state1; // assign an instance (in this case cyclic)

var changes = differ1.changes(); // -> unreadble arrays and stuff.

differ2.apply(changes);

// Now state2 is deepEqual to state1.

Methods

viscous.changes()

Returns a set of changes since the last time it was called.

viscous.apply()

Applies a set of changes

viscous.state()

Returns a set of changes that describes the current state.

viscous.getId(instance)

returns the internal id of the instance, or undefined if the instance does not exist in state

viscous.getInstance(id)

returns the instance for the given id, assuming it exists.

viscous.describe(anything)

returns a description of anything, including information about ids of tracked instances.

viscous.inflate(description)

inflates a description into whever was described, including instances that exist in state

Extending serialisation

extended functionality can be added via the serialiser and deserialiser settings:

function serialise(value){
    if(value instanceof EventEmitter){
        return [{}, 'emitter']; // MUST return an array of [anything, string type]
    }
}

function deserialise(definition){
    if(definition[1] === 'e'){
        return new EventEmitter();
    }
}

var a = {x: new EventEmitter()},
    primary = viscous(a, {
        serialiser: serialise,
        deserialiser: deserialise
    });

var b = {},
    replicant = viscous(b, {
        serialiser: serialise,
        deserialiser: deserialise
    });

replicant.apply(primary.state());

b.x instanceof EventEmitter; // -> true

Avoiding instance collisions.

You can pass a viscousId via settings, and all internal instance IDs will be prefixed with that.

I'm not super happy with this solution at the moment.

Good luck!

Goals

Fast. instance-tracked. Serialisable. Small serialised diff-size.

Caveats

viscous only looks at own properties, but if you need to handle prototypical properties, you can always use custom serialise/deserialisers