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/**
* @fileoverview `Map` to load rules lazily.
* @author Toru Nagashima <https://github.com/mysticatea>
*/
"use strict";
const debug = require("debug")("eslint:rules");
/** @typedef {import("./types").Rule} Rule */
/**
* The `Map` object that loads each rule when it's accessed.
* @example
* const rules = new LazyLoadingRuleMap([
* ["eqeqeq", () => require("eqeqeq")],
* ["semi", () => require("semi")],
* ["no-unused-vars", () => require("no-unused-vars")]
* ]);
*
* rules.get("semi"); // call `() => require("semi")` here.
*
* @extends {Map<string, () => Rule>}
*/
class LazyLoadingRuleMap extends Map {
/**
* Initialize this map.
* @param {Array<[string, function(): Rule]>} loaders The rule loaders.
*/
constructor(loaders) {
let remaining = loaders.length;
super(
debug.enabled
? loaders.map(([ruleId, load]) => {
let cache = null;
return [
ruleId,
() => {
if (!cache) {
debug("Loading rule %o (remaining=%d)", ruleId, --remaining);
cache = load();
}
return cache;
}
];
})
: loaders
);
// `super(...iterable)` uses `this.set()`, so disable it here.
Object.defineProperty(LazyLoadingRuleMap.prototype, "set", {
configurable: true,
value: void 0
});
}
/**
* Get a rule.
* Each rule will be loaded on the first access.
* @param {string} ruleId The rule ID to get.
* @returns {Rule|undefined} The rule.
*/
get(ruleId) {
const load = super.get(ruleId);
return load && load();
}
/**
* Iterate rules.
* @returns {IterableIterator<Rule>} Rules.
*/
*values() {
for (const load of super.values()) {
yield load();
}
}
/**
* Iterate rules.
* @returns {IterableIterator<[string, Rule]>} Rules.
*/
*entries() {
for (const [ruleId, load] of super.entries()) {
yield [ruleId, load()];
}
}
/**
* Call a function with each rule.
* @param {Function} callbackFn The callback function.
* @param {any} [thisArg] The object to pass to `this` of the callback function.
* @returns {void}
*/
forEach(callbackFn, thisArg) {
for (const [ruleId, load] of super.entries()) {
callbackFn.call(thisArg, load(), ruleId, this);
}
}
}
// Forbid mutation.
Object.defineProperties(LazyLoadingRuleMap.prototype, {
clear: { configurable: true, value: void 0 },
delete: { configurable: true, value: void 0 },
[Symbol.iterator]: {
configurable: true,
writable: true,
value: LazyLoadingRuleMap.prototype.entries
}
});
module.exports = { LazyLoadingRuleMap };