@aureooms/js-pubsub
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Publish-subscribe data structures for JavaScript
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JavaScript
/**
* pubsub node that only notifies clients whose stamp is less than
* the currently published stamp.
*
* @param {dict} subscriptions a ( key, stamp ) python-style dict
* @param {comparable} stamp
* @param {comparator} compare the comparison function used to compare stamps
*/
export const StampNode = function ( subscriptions, stamp, compare ) {
this.subscriptions = subscriptions;
this.stamp = stamp;
this.compare = compare;
} ;
/**
* Subscribes client with key *key* and stamp *stamp*. If
* *stamp* < current stamp then we forward the current stamp
* to client with key *key*.
*
* @param {key} key key of the subscriber
* @param {comparable} stamp most up to date stamp the subscriber has
* @param {callback} forward the function to call when the stamp for a client
* is outdated
*/
StampNode.prototype.subscribe = function ( key, stamp, forward ) {
this.subscriptions.set( key, this.update( forward )( key, stamp ) );
};
StampNode.prototype.unsubscribe = function ( key ) {
this.subscriptions.unset( key );
};
StampNode.prototype.publish = function ( stamp, forward ) {
this.stamp = stamp;
this.subscriptions.update( this.update( forward ) );
};
StampNode.prototype.update = function ( forward ) {
const that = this;
return function ( key, stamp ) {
if ( that.compare( that.stamp, stamp ) > 0 ) {
forward( key, that.stamp );
return that.stamp;
}
else {
return stamp;
}
};
};