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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
const gKeyValueService = Cc["@mozilla.org/key-value-service;1"].getService(
Ci.nsIKeyValueService
);
function promisify(fn, ...args) {
return new Promise((resolve, reject) => {
fn({ resolve, reject }, ...args);
});
}
/**
* This module wraps the nsIKeyValue* interfaces in a Promise-based API.
* To use it, import it, then call the KeyValueService.getOrCreate() method
* with a database's path and (optionally) its name:
*
* ```
* let { keyValueService } =
* let database = await KeyValueService.getOrCreate(path, name);
* ```
*
* See the documentation in nsIKeyValue.idl for more information about the API
* for key/value storage.
*/
export class KeyValueService {
static RecoveryStrategy = {
ERROR: gKeyValueService.ERROR,
DISCARD: gKeyValueService.DISCARD,
RENAME: gKeyValueService.RENAME,
};
static async getOrCreate(dir, name) {
return new KeyValueDatabase(
await promisify(gKeyValueService.getOrCreate, dir, name)
);
}
static async getOrCreateWithOptions(
dir,
name,
{ strategy = gKeyValueService.RENAME } = {}
) {
return new KeyValueDatabase(
await promisify(
gKeyValueService.getOrCreateWithOptions,
dir,
name,
strategy
)
);
}
}
/**
* A class that wraps an nsIKeyValueDatabase in a Promise-based API.
*
* This class isn't exported, so you can't instantiate it directly, but you
* can retrieve an instance of this class via KeyValueService.getOrCreate():
*
* ```
* const database = await KeyValueService.getOrCreate(path, name);
* ```
*
* You can then call its put(), get(), has(), and delete() methods to access
* and manipulate key/value pairs:
*
* ```
* await database.put("foo", 1);
* await database.get("foo") === 1; // true
* await database.has("foo"); // true
* await database.delete("foo");
* await database.has("foo"); // false
* ```
*
* You can also call writeMany() to put/delete multiple key/value pairs:
*
* ```
* await database.writeMany({
* key1: "value1",
* key2: "value2",
* key3: "value3",
* key4: null, // delete
* });
* ```
*
* And you can call its enumerate() method to retrieve a KeyValueEnumerator,
* which is described below.
*/
class KeyValueDatabase {
constructor(database) {
this.database = database;
}
put(key, value) {
return promisify(this.database.put, key, value);
}
/**
* Writes multiple key/value pairs to the database.
*
* Note:
* * Each write could be either put or delete.
* * Given multiple values with the same key, only the last value will be stored.
* * If the same key gets put and deleted for multiple times, the final state
* of that key is subject to the ordering of the put(s) and delete(s).
*
* @param pairs Pairs could be any of following types:
* * An Object, all its properties and the corresponding values will
* be used as key value pairs. A property with null or undefined indicating
* a deletion.
* * An Array or an iterable whose elements are key-value pairs. such as
* [["key1", "value1"], ["key2", "value2"]]. Use a pair with value null
* to delete a key-value pair, e.g. ["delete-key", null].
* * A Map. A key with null or undefined value indicating a deletion.
* @return A promise that is fulfilled when all the key/value pairs are written
* to the database.
*/
writeMany(pairs) {
if (!pairs) {
throw new Error("writeMany(): unexpected argument.");
}
let entries;
if (
pairs instanceof Map ||
pairs instanceof Array ||
typeof pairs[Symbol.iterator] === "function"
) {
try {
// Let Map constructor validate the argument. Note that Map remembers
// the original insertion order of the keys, which satisfies the ordering
// premise of this function.
const map = pairs instanceof Map ? pairs : new Map(pairs);
entries = Array.from(map, ([key, value]) => ({ key, value }));
} catch (error) {
throw new Error("writeMany(): unexpected argument.");
}
} else if (typeof pairs === "object") {
entries = Array.from(Object.entries(pairs), ([key, value]) => ({
key,
value,
}));
} else {
throw new Error("writeMany(): unexpected argument.");
}
if (entries.length) {
return promisify(this.database.writeMany, entries);
}
return Promise.resolve();
}
has(key) {
return promisify(this.database.has, key);
}
get(key, defaultValue) {
return promisify(this.database.get, key, defaultValue);
}
delete(key) {
return promisify(this.database.delete, key);
}
clear() {
return promisify(this.database.clear);
}
async enumerate(from_key, to_key) {
return new KeyValueEnumerator(
await promisify(this.database.enumerate, from_key, to_key)
);
}
}
/**
* A class that wraps an nsIKeyValueEnumerator in a Promise-based API.
*
* This class isn't exported, so you can't instantiate it directly, but you
* can retrieve an instance of this class by calling enumerate() on an instance
* of KeyValueDatabase:
*
* ```
* const database = await KeyValueService.getOrCreate(path, name);
* const enumerator = await database.enumerate();
* ```
*
* And then iterate pairs via its hasMoreElements() and getNext() methods:
*
* ```
* while (enumerator.hasMoreElements()) {
* const { key, value } = enumerator.getNext();
* …
* }
* ```
*
* Or with a `for...of` statement:
*
* ```
* for (const { key, value } of enumerator) {
* …
* }
* ```
*/
class KeyValueEnumerator {
constructor(enumerator) {
this.enumerator = enumerator;
}
hasMoreElements() {
return this.enumerator.hasMoreElements();
}
getNext() {
return this.enumerator.getNext();
}
*[Symbol.iterator]() {
while (this.enumerator.hasMoreElements()) {
yield this.enumerator.getNext();
}
}
}