(function () {
/* Imports */
var Meteor = Package.meteor.Meteor;
var _ = Package.underscore._;
/* Package-scope variables */
var Hook;
(function () {
//////////////////////////////////////////////////////////////////////////////////
// //
// packages/callback-hook/hook.js //
// //
//////////////////////////////////////////////////////////////////////////////////
//
// XXX This pattern is under development. Do not add more callsites // 1
// using this package for now. See: // 2
// https://meteor.hackpad.com/Design-proposal-Hooks-YxvgEW06q6f // 3
// // 4
// Encapsulates the pattern of registering callbacks on a hook. // 5
// // 6
// The `each` method of the hook calls its iterator function argument // 7
// with each registered callback. This allows the hook to // 8
// conditionally decide not to call the callback (if, for example, the // 9
// observed object has been closed or terminated). // 10
// // 11
// Callbacks are bound with `Meteor.bindEnvironment`, so they will be // 12
// called with the Meteor environment of the calling code that // 13
// registered the callback. // 14
// // 15
// Registering a callback returns an object with a single `stop` // 16
// method which unregisters the callback. // 17
// // 18
// The code is careful to allow a callback to be safely unregistered // 19
// while the callbacks are being iterated over. // 20
// // 21
// If the hook is configured with the `exceptionHandler` option, the // 22
// handler will be called if a called callback throws an exception. // 23
// By default (if the exception handler doesn't itself throw an // 24
// exception, or if the iterator function doesn't return a falsy value // 25
// to terminate the calling of callbacks), the remaining callbacks // 26
// will still be called. // 27
// // 28
// Alternatively, the `debugPrintExceptions` option can be specified // 29
// as string describing the callback. On an exception the string and // 30
// the exception will be printed to the console log with // 31
// `Meteor._debug`, and the exception otherwise ignored. // 32
// // 33
// If an exception handler isn't specified, exceptions thrown in the // 34
// callback will propagate up to the iterator function, and will // 35
// terminate calling the remaining callbacks if not caught. // 36
// 37
Hook = function (options) { // 38
var self = this; // 39
options = options || {}; // 40
self.nextCallbackId = 0; // 41
self.callbacks = {}; // 42
// 43
if (options.exceptionHandler) // 44
self.exceptionHandler = options.exceptionHandler; // 45
else if (options.debugPrintExceptions) { // 46
if (! _.isString(options.debugPrintExceptions)) // 47
throw new Error("Hook option debugPrintExceptions should be a string"); // 48
self.exceptionHandler = options.debugPrintExceptions; // 49
} // 50
}; // 51
// 52
_.extend(Hook.prototype, { // 53
register: function (callback) { // 54
var self = this; // 55
// 56
callback = Meteor.bindEnvironment( // 57
callback, // 58
self.exceptionHandler || function (exception) { // 59
// Note: this relies on the undocumented fact that if bindEnvironment's // 60
// onException throws, and you are invoking the callback either in the // 61
// browser or from within a Fiber in Node, the exception is propagated. // 62
throw exception; // 63
} // 64
); // 65
// 66
var id = self.nextCallbackId++; // 67
self.callbacks[id] = callback; // 68
// 69
return { // 70
stop: function () { // 71
delete self.callbacks[id]; // 72
} // 73
}; // 74
}, // 75
// 76
// For each registered callback, call the passed iterator function // 77
// with the callback. // 78
// // 79
// The iterator function can choose whether or not to call the // 80
// callback. (For example, it might not call the callback if the // 81
// observed object has been closed or terminated). // 82
// // 83
// The iteration is stopped if the iterator function returns a falsy // 84
// value or throws an exception. // 85
// // 86
each: function (iterator) { // 87
var self = this; // 88
// 89
// Invoking bindEnvironment'd callbacks outside of a Fiber in Node doesn't // 90
// run them to completion (and exceptions thrown from onException are not // 91
// propagated), so we need to be in a Fiber. // 92
Meteor._nodeCodeMustBeInFiber(); // 93
// 94
var ids = _.keys(self.callbacks); // 95
for (var i = 0; i < ids.length; ++i) { // 96
var id = ids[i]; // 97
// check to see if the callback was removed during iteration // 98
if (_.has(self.callbacks, id)) { // 99
var callback = self.callbacks[id]; // 100
// 101
if (! iterator(callback)) // 102
break; // 103
} // 104
} // 105
} // 106
}); // 107
// 108
//////////////////////////////////////////////////////////////////////////////////
}).call(this);
/* Exports */
if (typeof Package === 'undefined') Package = {};
Package['callback-hook'] = {
Hook: Hook
};
})();
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