//////////////////////////////////////////////////////////////////////////
// //
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//////////////////////////////////////////////////////////////////////////
(function () {
/* Imports */
var Meteor = Package.meteor.Meteor;
var Tracker = Package.tracker.Tracker;
var Deps = Package.tracker.Deps;
/* Package-scope variables */
var ReactiveVar;
(function () {
//////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// //
// packages/reactive-var/reactive-var.js //
// //
//////////////////////////////////////////////////////////////////////////////////////////////////////////////////
//
/* // 1
* ## [new] ReactiveVar(initialValue, [equalsFunc]) // 2
* // 3
* A ReactiveVar holds a single value that can be get and set, // 4
* such that calling `set` will invalidate any Computations that // 5
* called `get`, according to the usual contract for reactive // 6
* data sources. // 7
* // 8
* A ReactiveVar is much like a Session variable -- compare `foo.get()` // 9
* to `Session.get("foo")` -- but it doesn't have a global name and isn't // 10
* automatically migrated across hot code pushes. Also, while Session // 11
* variables can only hold JSON or EJSON, ReactiveVars can hold any value. // 12
* // 13
* An important property of ReactiveVars, which is sometimes the reason // 14
* to use one, is that setting the value to the same value as before has // 15
* no effect, meaning ReactiveVars can be used to absorb extra // 16
* invalidations that wouldn't serve a purpose. However, by default, // 17
* ReactiveVars are extremely conservative about what changes they // 18
* absorb. Calling `set` with an object argument will *always* trigger // 19
* invalidations, because even if the new value is `===` the old value, // 20
* the object may have been mutated. You can change the default behavior // 21
* by passing a function of two arguments, `oldValue` and `newValue`, // 22
* to the constructor as `equalsFunc`. // 23
* // 24
* This class is extremely basic right now, but the idea is to evolve // 25
* it into the ReactiveVar of Geoff's Lickable Forms proposal. // 26
*/ // 27
// 28
/** // 29
* @class // 30
* @instanceName reactiveVar // 31
* @summary Constructor for a ReactiveVar, which represents a single reactive variable. // 32
* @locus Client // 33
* @param {Any} initialValue The initial value to set. `equalsFunc` is ignored when setting the initial value. // 34
* @param {Function} [equalsFunc] Optional. A function of two arguments, called on the old value and the new value whenever the ReactiveVar is set. If it returns true, no set is performed. If omitted, the default `equalsFunc` returns true if its arguments are `===` and are of type number, boolean, string, undefined, or null.
*/ // 36
ReactiveVar = function (initialValue, equalsFunc) { // 37
if (! (this instanceof ReactiveVar)) // 38
// called without `new` // 39
return new ReactiveVar(initialValue, equalsFunc); // 40
// 41
this.curValue = initialValue; // 42
this.equalsFunc = equalsFunc; // 43
this.dep = new Tracker.Dependency; // 44
}; // 45
// 46
ReactiveVar._isEqual = function (oldValue, newValue) { // 47
var a = oldValue, b = newValue; // 48
// Two values are "equal" here if they are `===` and are // 49
// number, boolean, string, undefined, or null. // 50
if (a !== b) // 51
return false; // 52
else // 53
return ((!a) || (typeof a === 'number') || (typeof a === 'boolean') || // 54
(typeof a === 'string')); // 55
}; // 56
// 57
/** // 58
* @summary Returns the current value of the ReactiveVar, establishing a reactive dependency. // 59
* @locus Client // 60
*/ // 61
ReactiveVar.prototype.get = function () { // 62
if (Tracker.active) // 63
this.dep.depend(); // 64
// 65
return this.curValue; // 66
}; // 67
// 68
/** // 69
* @summary Sets the current value of the ReactiveVar, invalidating the Computations that called `get` if `newValue` is different from the old value.
* @locus Client // 71
* @param {Any} newValue // 72
*/ // 73
ReactiveVar.prototype.set = function (newValue) { // 74
var oldValue = this.curValue; // 75
// 76
if ((this.equalsFunc || ReactiveVar._isEqual)(oldValue, newValue)) // 77
// value is same as last time // 78
return; // 79
// 80
this.curValue = newValue; // 81
this.dep.changed(); // 82
}; // 83
// 84
ReactiveVar.prototype.toString = function () { // 85
return 'ReactiveVar{' + this.get() + '}'; // 86
}; // 87
// 88
ReactiveVar.prototype._numListeners = function() { // 89
// Tests want to know. // 90
// Accesses a private field of Tracker.Dependency. // 91
var count = 0; // 92
for (var id in this.dep._dependentsById) // 93
count++; // 94
return count; // 95
}; // 96
// 97
//////////////////////////////////////////////////////////////////////////////////////////////////////////////////
}).call(this);
/* Exports */
if (typeof Package === 'undefined') Package = {};
Package['reactive-var'] = {
ReactiveVar: ReactiveVar
};
})();