@gmod/jbrowse/src/JBrowse/Util/RejectableFastPromise.js

JBrowse - client-side genome browser

/**
 * Fast implementation of a promise, used in performance-critical code
 * that still needs to be able to reject promises.  Dojo Deferred is
 * too heavy for some uses.
 */

define([
       ],
       function(
       ) {

var fastpromise = function() {
    this.callbacks = [];
    this.errbacks = [];
};

fastpromise.prototype.then = function( callback, errback ) {
    if( 'value' in this )
        callback( this.value );
    else if( 'error' in this )
        errback( this.error );
    else {
        this.callbacks.push( callback );
        this.errbacks.push( errback );
    }
};

fastpromise.prototype.resolve = function( value ) {
    this.value = value;
    delete this.errbacks;
    var c = this.callbacks;
    delete this.callbacks;
    for( var i = 0; i<c.length; i++ )
        c[i]( this.value );
};

fastpromise.prototype.reject = function( error ) {
    this.error = error;
    delete this.callbacks;
    var c = this.errbacks;
    delete this.errbacks;
    for( var i = 0; i<c.length; i++ )
        c[i]( error );
};

return fastpromise;
});