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Copy pathscan-iterator.ts
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139 lines (121 loc) · 3.67 KB
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import {Invoke, RPC, ScanRequest} from './repm-invoker.js';
import type {JSONValue} from './json.js';
import {throwIfClosed} from './transaction-closed-error.js';
import {ScanOptions, toRPC} from './scan-options.js';
interface IdCloser {
close(): void;
closed: boolean;
id: number;
}
const VALUE = 0;
const KEY = 1;
const ENTRY = 2;
type ScanIterableKind = typeof VALUE | typeof KEY | typeof ENTRY;
type Args = [
options: ScanOptions | undefined,
invoke: Invoke,
getTransaction: () => Promise<IdCloser> | IdCloser,
shouldCloseTransaction: boolean,
];
/**
* This class is used for the results of [[ReadTransaction.scan|scan]]. It
* implements `AsyncIterable<JSONValue>` which allows you to use it in a `for
* await` loop. There are also methods to iterate over the [[keys]],
* [[entries]] or [[values]].
*/
export class ScanResult<K> implements AsyncIterable<JSONValue> {
private readonly _args: Args;
/** @internal */
constructor(...args: Args) {
this._args = args;
}
/** The default AsyncIterable. This is the same as [[values]]. */
[Symbol.asyncIterator](): AsyncIterableIterator<JSONValue> {
return this.values();
}
/** Async iterator over the valus of the [[ReadTransaction.scan|scan]] call. */
values(): AsyncIterableIterator<JSONValue> {
return this._newIterator(VALUE);
}
/**
* Async iterator over the keys of the [[ReadTransaction.scan|scan]]
* call. If the [[ReadTransaction.scan|scan]] is over an index the key
* is a tuple of `[secondaryKey: string, primaryKey]`
*/
keys(): AsyncIterableIterator<K> {
return this._newIterator(KEY);
}
/**
* Async iterator over the entries of the [[ReadTransaction.scan|scan]]
* call. An entry is a tuple of key values. If the
* [[ReadTransaction.scan|scan]] is over an index the key is a tuple of
* `[secondaryKey: string, primaryKey]`
*/
entries(): AsyncIterableIterator<[K, JSONValue]> {
return this._newIterator(ENTRY);
}
private _newIterator<V>(kind: ScanIterableKind): AsyncIterableIterator<V> {
return scanIterator(kind, ...this._args);
}
}
async function* scanIterator<V>(
kind: ScanIterableKind,
options: ScanOptions | undefined,
invoke: Invoke,
getTransaction: () => Promise<IdCloser> | IdCloser,
shouldCloseTransaction: boolean,
): AsyncGenerator<V> {
const transaction = await getTransaction();
throwIfClosed(transaction);
const items = await load<V>(kind, options, transaction.id, invoke);
try {
for (const item of items) {
yield item;
}
} finally {
if (shouldCloseTransaction && !transaction.closed) {
transaction.close();
}
}
}
async function load<V>(
kind: ScanIterableKind,
options: ScanOptions | undefined,
transactionID: number,
invoke: Invoke,
): Promise<V[]> {
const items: V[] = [];
const decoder = new TextDecoder();
const parse = (v: Uint8Array) => JSON.parse(decoder.decode(v));
type MaybeIndexName = {indexName?: string};
const key = (primaryKey: string, secondaryKey: string | null) =>
(options as MaybeIndexName)?.indexName !== undefined
? [secondaryKey, primaryKey]
: primaryKey;
const receiver = (
primaryKey: string,
secondaryKey: string | null,
value: Uint8Array,
) => {
switch (kind) {
case VALUE:
items.push(parse(value));
return;
case KEY:
items.push((key(primaryKey, secondaryKey) as unknown) as V);
return;
case ENTRY:
items.push(([
key(primaryKey, secondaryKey),
parse(value),
] as unknown) as V);
}
};
const args: ScanRequest = {
transactionId: transactionID,
opts: toRPC(options),
receiver,
};
await invoke(RPC.Scan, args);
return items;
}