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