107 lines
3.1 KiB
JavaScript
107 lines
3.1 KiB
JavaScript
/*
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MIT License http://www.opensource.org/licenses/mit-license.php
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Author Tobias Koppers @sokra
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*/
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"use strict";
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const DescriptionFileUtils = require("./DescriptionFileUtils");
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/** @typedef {import("./Resolver")} Resolver */
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/** @typedef {import("./Resolver").JsonObject} JsonObject */
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/** @typedef {import("./Resolver").ResolveRequest} ResolveRequest */
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/** @typedef {import("./Resolver").ResolveStepHook} ResolveStepHook */
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const slashCode = "/".charCodeAt(0);
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// Sentinel stored in `_nameCache` when the description file either has no
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// exports field (so self-reference can't apply) or no string `name`.
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const NO_SELF_REF = Symbol("NoSelfRef");
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module.exports = class SelfReferencePlugin {
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/**
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* @param {string | ResolveStepHook} source source
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* @param {string | string[]} fieldNamePath name path
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* @param {string | ResolveStepHook} target target
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*/
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constructor(source, fieldNamePath, target) {
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this.source = source;
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this.target = target;
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this.fieldName = fieldNamePath;
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// Self-reference needs both an exports field and a `"name"` string.
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// Both are stable per description-file content, so cache the decision
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// in one WeakMap: the resolved name when self-reference is possible,
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// or `NO_SELF_REF` when it isn't. This skips the two per-resolve
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// `DescriptionFileUtils.getField` walks for hot packages.
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/** @type {WeakMap<JsonObject, string | typeof NO_SELF_REF>} */
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this._nameCache = new WeakMap();
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}
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/**
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* @param {Resolver} resolver the resolver
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* @returns {void}
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*/
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apply(resolver) {
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const target = resolver.ensureHook(this.target);
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resolver
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.getHook(this.source)
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.tapAsync("SelfReferencePlugin", (request, resolveContext, callback) => {
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if (!request.descriptionFileData) return callback();
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const req = request.request;
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if (!req) return callback();
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const { descriptionFileData } = request;
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let name = this._nameCache.get(descriptionFileData);
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if (name === undefined) {
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// Feature is only enabled when an exports field is present
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const exportsField = DescriptionFileUtils.getField(
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descriptionFileData,
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this.fieldName,
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);
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if (!exportsField) {
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this._nameCache.set(descriptionFileData, NO_SELF_REF);
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return callback();
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}
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const rawName = DescriptionFileUtils.getField(
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descriptionFileData,
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"name",
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);
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if (typeof rawName !== "string") {
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this._nameCache.set(descriptionFileData, NO_SELF_REF);
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return callback();
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}
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name = rawName;
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this._nameCache.set(descriptionFileData, name);
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} else if (name === NO_SELF_REF) {
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return callback();
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}
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if (
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req.startsWith(name) &&
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(req.length === name.length ||
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req.charCodeAt(name.length) === slashCode)
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) {
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const remainingRequest = `.${req.slice(name.length)}`;
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/** @type {ResolveRequest} */
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const obj = {
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...request,
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request: remainingRequest,
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path: /** @type {string} */ (request.descriptionFileRoot),
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relativePath: ".",
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};
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resolver.doResolve(
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target,
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obj,
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"self reference",
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resolveContext,
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callback,
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);
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} else {
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return callback();
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}
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});
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}
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};
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