nosqlite.js

const sqlite = require('sqlite');
const msgpack = require('msgpack-lite');
const fs = require('fs');
const pathlib = require('path');
const zoneToFilename = (zone) => zone.replace(/[^\p{L}\p{N}_\-]+/gu, '') || '_';
const separator = '\x1f';
const mangle = (key) => {
  if (typeof key === 'string') return key + separator;
  else return key.join(separator) + separator;
};
const unmangle = (mangled) => {
  let keys = mangled.slice(0, mangled.length - 1).split('\x1f'); // remove the last dot
  if (keys.length === 0) return '';
  else if (keys.length === 1) return keys[0];
  else return keys;
};
class DB {
  constructor(dir) {
    try { fs.mkdirSync(dir); } catch (err) { }
    this.dir = dir;
    this.zones = new Map;
  }
  zone(name) {
    let zone = this.zones.get(name);
    if (zone) return zone;
    zone = new Zone(pathlib.join(this.dir, zoneToFilename(name)));
    this.zones.set(name, zone);
    return zone;
  }
}
class Zone {
  constructor(path) {
    this.path = path;
    this._dbPromise = sqlite.open(this.path);
    this._dbPromise.then(db => {
      this._db = db;
      db.exec(`CREATE TABLE IF NOT EXISTS keys (id INTEGER PRIMARY KEY, key TEXT UNIQUE NOT NULL, value BLOB NOT NULL)`);
    });
  }
  async get(key) {
    if (!this._db) this._db = await this._dbPromise;
    let result = await this._db.get(`SELECT value FROM keys WHERE key = ?`, mangle(key));
    return result ? result.value : undefined;
  }
  async set(key, val) {
    if (!this._db) this._db = await this._dbPromise;
    await this._db.all(`INSERT OR REPLACE INTO keys (id, key, value) VALUES ((SELECT id FROM keys WHERE key = ?), ?, ?)`,
      mangle(key), mangle(key), msgpack.encode(val));
  }
  async delete(key, val) {
    if (!this._db) this._db = await this._dbPromise;
    await this._db.all(`DELETE FROM keys WHERE key = ?`, mangle(key));
  }
  async has(key) {
    if (!this._db) this._db = await this._dbPromise;
    let result = await this._db.get(`SELECT COUNT(*) FROM keys WHERE key = ?`, mangle(key));
    return 1 === result['COUNT(*)'];
  }
  async all() {
    if (!this._db) this._db = await this._dbPromise;
    let result = await this._db.all(`SELECT key, value FROM keys ORDER BY id`);
    return result.map(kv => [unmangle(kv.key), msgpack.decode(kv.value)]);
  }
}
module.exports = { DB, Zone };