Adding derives for election sets and approval flags. (#1141)

* Adding derives for election sets and approval flags.

* Bugfixes to derived election functions.

* Attempting linter fix.

* Fixing typing error.

* Another eslint fix.

* Adding explicit types to api calls.

packages/api-derive/src/elections/approvalsOf.ts

@@ -0,0 +1,30 @@
+import BN from 'bn.js';
+import { Observable } from 'rxjs';
+import { switchMap, map } from 'rxjs/operators';
+import { ApiInterfaceRx } from '@polkadot/api/types';
+import { AccountId, Vector, SetIndex, ApprovalFlag } from '@polkadot/types';
+import { drr } from '../util/drr';
+
+export function approvalFlagToBool (flags: Vector<ApprovalFlag>): boolean[] {
+  const bools: boolean[] = [];
+  for (const flag of flags) {
+    for (const bit of Array(flag.bitLength()).map((_, i): number => i)) {
+      bools.push(!flag.toBn().uand((new BN(1)).shln(bit)).isZero());
+    }
+  }
+  return bools;
+}
+
+export function approvalsOf (api: ApiInterfaceRx): (who: AccountId) => Observable<Vector<ApprovalFlag>> {
+  return (who: AccountId): Observable<Vector<ApprovalFlag>> =>
+    api.query.elections.nextVoterSet<SetIndex>().pipe(
+      switchMap((nextVoterSet: SetIndex): Observable<Vector<ApprovalFlag>[]> =>
+        api.query.elections.approvalsOf.multi(
+          [...Array(+nextVoterSet + 1)].map((_, i): [AccountId, number] => [who, i])
+        )
+      ),
+      map((votes: Vector<ApprovalFlag>[]): Vector<ApprovalFlag> =>
+        votes.find((v): boolean => v.length > 0) || new Vector(ApprovalFlag, [])),
+      drr()
+    );
+}

packages/api-derive/src/elections/voters.ts

@@ -0,0 +1,19 @@
+import { Observable } from 'rxjs';
+import { switchMap, map } from 'rxjs/operators';
+import { ApiInterfaceRx } from '@polkadot/api/types';
+import { AccountId, Vector, Option, SetIndex } from '@polkadot/types';
+import { drr } from '../util/drr';
+
+export function voters (api: ApiInterfaceRx): () => Observable<Option<AccountId>[]> {
+  return (): Observable<Option<AccountId>[]> =>
+    api.query.elections.nextVoterSet<SetIndex>().pipe(
+      switchMap((nextVoterSet: SetIndex): Observable<Vector<Option<AccountId>>[]> =>
+        api.query.elections.voters.multi<Vector<Option<AccountId>>>(
+          [...Array(+nextVoterSet + 1)].map((_, i): number => i)
+        )
+      ),
+      map((voters: Vector<Option<AccountId>>[]): Option<AccountId>[] =>
+        Array.prototype.concat.apply([], voters)),
+      drr()
+    );
+}