20 lines
709 B
TypeScript
20 lines
709 B
TypeScript
// Copyright 2017-2020 @polkadot/api-derive authors & contributors
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// This software may be modified and distributed under the terms
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// of the Apache-2.0 license. See the LICENSE file for details.
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import { BlockNumber } from '@polkadot/types/interfaces';
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import { DerivedSessionInfo } from '../types';
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import { Observable } from 'rxjs';
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import { map } from 'rxjs/operators';
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import { ApiInterfaceRx } from '@polkadot/api/types';
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import { memo } from '../util';
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export function eraLength (api: ApiInterfaceRx): () => Observable<BlockNumber> {
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return memo((): Observable<BlockNumber> =>
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api.derive.session.info().pipe(
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map(({ eraLength }: DerivedSessionInfo): BlockNumber => eraLength)
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));
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}
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