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import noop from 'lodash/noop';
import rest from './internal/rest';
import onlyOnce from './internal/onlyOnce';
/**
* The post-check version of [`during`]{@link module:ControlFlow.during}. To reflect the difference in
* the order of operations, the arguments `test` and `fn` are switched.
*
* Also a version of [`doWhilst`]{@link module:ControlFlow.doWhilst} with asynchronous `test` function.
* @name doDuring
* @static
* @memberOf module:ControlFlow
* @method
* @see [async.during]{@link module:ControlFlow.during}
* @category Control Flow
* @param {Function} fn - A function which is called each time `test` passes.
* The function is passed a `callback(err)`, which must be called once it has
* completed with an optional `err` argument. Invoked with (callback).
* @param {Function} test - asynchronous truth test to perform before each
* execution of `fn`. Invoked with (...args, callback), where `...args` are the
* non-error args from the previous callback of `fn`.
* @param {Function} [callback] - A callback which is called after the test
* function has failed and repeated execution of `fn` has stopped. `callback`
* will be passed an error if one occured, otherwise `null`.
*/
export default function doDuring(fn, test, callback) {
callback = onlyOnce(callback || noop);
var next = rest(function(err, args) {
if (err) return callback(err);
args.push(check);
test.apply(this, args);
});
function check(err, truth) {
if (err) return callback(err);
if (!truth) return callback(null);
fn(next);
}
check(null, true);
}
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