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import { AsyncAction } from './AsyncAction';
import { AsyncScheduler } from './AsyncScheduler';
export class AnimationFrameScheduler extends AsyncScheduler {
public flush(action?: AsyncAction<any>): void {
this._active = true;
// The async id that effects a call to flush is stored in _scheduled.
// Before executing an action, it's necessary to check the action's async
// id to determine whether it's supposed to be executed in the current
// flush.
// Previous implementations of this method used a count to determine this,
// but that was unsound, as actions that are unsubscribed - i.e. cancelled -
// are removed from the actions array and that can shift actions that are
// scheduled to be executed in a subsequent flush into positions at which
// they are executed within the current flush.
const flushId = this._scheduled;
this._scheduled = undefined;
const { actions } = this;
let error: any;
action = action || actions.shift()!;
do {
if ((error = action.execute(action.state, action.delay))) {
break;
}
} while ((action = actions[0]) && action.id === flushId && actions.shift());
this._active = false;
if (error) {
while ((action = actions[0]) && action.id === flushId && actions.shift()) {
action.unsubscribe();
}
throw error;
}
}
}
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