98 lines
2.6 KiB
TypeScript
98 lines
2.6 KiB
TypeScript
import { uuid1 } from "./deps.ts";
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/**
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* Standard interface for the simplest key-value store
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*/
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export interface KeyValueStorage {
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get(key: string): Promise<string | null>;
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set(key: string, value: string | null): Promise<void>;
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}
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/**
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* Basic memory implementation
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*/
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export class MemoryStorage implements KeyValueStorage {
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private store: { [key: string]: string } = {};
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async get(key: string): Promise<string | null> {
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const result = this.store[key];
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return (typeof result == "undefined") ? null : result;
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}
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async set(key: string, value: string | null): Promise<void> {
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if (value === null) {
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delete this.store[key];
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} else {
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this.store[key] = value;
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}
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}
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}
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type StorageDelegate = KeyValueStorage | (() => KeyValueStorage);
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function fromDelegate(delegate: StorageDelegate): KeyValueStorage {
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return (typeof delegate === "function") ? delegate() : delegate;
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}
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/**
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* Wrap a storage, scoping the keys using a suffix
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*/
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export class ScopedStorage implements KeyValueStorage {
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private readonly target: KeyValueStorage;
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constructor(target: StorageDelegate, private readonly suffix: string) {
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this.target = fromDelegate(target);
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}
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async get(key: string): Promise<string | null> {
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return await this.target.get(`${key}#${this.suffix}`);
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}
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async set(key: string, value: string | null): Promise<void> {
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return await this.target.set(`${key}#${this.suffix}`, value);
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}
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}
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/**
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* Use a target unscoped storage, scoping the keys in a virtual random namespace
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*
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* The namespace is persisted in a reference storage (used unscoped)
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*/
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export class RefScopedStorage implements KeyValueStorage {
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private readonly reference: KeyValueStorage;
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private readonly target: KeyValueStorage;
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private inner?: KeyValueStorage;
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constructor(reference: StorageDelegate, target: StorageDelegate) {
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this.reference = fromDelegate(reference);
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this.target = fromDelegate(target);
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}
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private async init(): Promise<KeyValueStorage> {
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const refkey = "tk-storage-scope-ref";
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const suffix = await this.reference.get(refkey);
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if (suffix) {
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return new ScopedStorage(this.target, suffix);
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} else {
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const suffix = uuid1.generate().toString();
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await this.reference.set(refkey, suffix);
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return new ScopedStorage(this.target, suffix);
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}
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}
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async get(key: string): Promise<string | null> {
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if (!this.inner) {
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this.inner = await this.init();
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}
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return await this.inner.get(key);
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}
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async set(key: string, value: string | null): Promise<void> {
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if (!this.inner) {
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this.inner = await this.init();
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}
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return await this.inner.set(key, value);
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}
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}
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