105 lines
2.9 KiB
TypeScript
105 lines
2.9 KiB
TypeScript
'use strict';
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import { Provider } from './provider';
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import { Network } from '../utils/types';
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import * as errors from '../utils/errors';
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// Returns:
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// - true is all networks match
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// - false if any network is null
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// - throws if any 2 networks do not match
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function checkNetworks(networks: Array<Network>): boolean {
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var result = true;
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let check: Network = null;
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networks.forEach((network) => {
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// Null
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if (network == null) {
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result = false;
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return;
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}
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// Have nothing to compre to yet
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if (check == null) {
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check = network;
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return;
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}
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// Matches!
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if (check.name === network.name &&
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check.chainId === network.chainId &&
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check.ensAddress === network.ensAddress) { return; }
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errors.throwError(
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'provider mismatch',
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errors.INVALID_ARGUMENT,
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{ arg: 'networks', value: networks }
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);
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});
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return result;
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}
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export class FallbackProvider extends Provider {
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private _providers: Array<Provider>;
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constructor(providers: Array<Provider>) {
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if (providers.length === 0) { throw new Error('no providers'); }
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// All networks are ready, we can know the network for certain
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let ready = checkNetworks(providers.map((p) => p.network));
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if (ready) {
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super(providers[0].network);
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} else {
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// The network won't be known until all child providers know
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let ready = Promise.all(providers.map((p) => p.getNetwork())).then((networks) => {
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if (!checkNetworks(networks)) {
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errors.throwError('getNetwork returned null', errors.UNKNOWN_ERROR, { })
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}
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return networks[0];
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});
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super(ready);
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}
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errors.checkNew(this, FallbackProvider);
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// Preserve a copy, so we don't get mutated
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this._providers = providers.slice(0);
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}
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get providers(): Array<Provider> {
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// Return a copy, so we don't get mutated
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return this._providers.slice(0);
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}
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perform(method: string, params: any): any {
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// Creates a copy of the providers array
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var providers = this.providers;
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return new Promise((resolve, reject) => {
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var firstError: Error = null;
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function next() {
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if (!providers.length) {
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reject(firstError);
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return;
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}
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var provider = providers.shift();
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provider.perform(method, params).then((result) => {
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return resolve(result);
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}).catch((error) => {
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if (!firstError) { firstError = error; }
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setTimeout(next, 0);
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});
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}
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next();
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});
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}
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}
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