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/**
* Creates an iterator function which calls the next function in the `tasks`
* array, returning a continuation to call the next one after that. It's also
* possible to “peek” at the next iterator with `iterator.next()`.
*
* This function is used internally by the `async` module, but can be useful
* when you want to manually control the flow of functions in series.
*
* @name iterator
* @static
* @memberOf async
* @category Control Flow
* @param {Array} tasks - An array of functions to run.
* @returns The next function to run in the series.
* @example
*
* var iterator = async.iterator([
* function() { sys.p('one'); },
* function() { sys.p('two'); },
* function() { sys.p('three'); }
* ]);
*
* node> var iterator2 = iterator();
* 'one'
* node> var iterator3 = iterator2();
* 'two'
* node> iterator3();
* 'three'
* node> var nextfn = iterator2.next();
* node> nextfn();
* 'three'
*/
export default function(tasks) {
function makeCallback(index) {
function fn() {
if (tasks.length) {
tasks[index].apply(null, arguments);
}
return fn.next();
}
fn.next = function() {
return (index < tasks.length - 1) ? makeCallback(index + 1) : null;
};
return fn;
}
return makeCallback(0);
}
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