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