package.lib.util.chainedImports.js Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of webpack Show documentation
Packs ECMAScript/CommonJs/AMD modules for the browser. Allows you to split your codebase into multiple bundles, which can be loaded on demand. Supports loaders to preprocess files, i.e. json, jsx, es7, css, less, ... and your custom stuff.
The newest version!
/*
	MIT License http://www.opensource.org/licenses/mit-license.php
	Author Tobias Koppers @sokra
*/

"use strict";

/** @typedef {import("../Dependency")} Dependency */
/** @typedef {import("../Module")} Module */
/** @typedef {import("../ModuleGraph")} ModuleGraph */
/** @typedef {import("../javascript/JavascriptParser").Range} Range */

/**
 * @summary Get the subset of ids and their corresponding range in an id chain that should be re-rendered by webpack.
 * Only those in the chain that are actually referring to namespaces or imports should be re-rendered.
 * Deeper member accessors on the imported object should not be re-rendered.  If deeper member accessors are re-rendered,
 * there is a potential loss of meaning with rendering a quoted accessor as an unquoted accessor, or vice versa,
 * because minifiers treat quoted accessors differently.  e.g. import { a } from "./module"; a["b"] vs a.b
 * @param {string[]} untrimmedIds chained ids
 * @param {Range} untrimmedRange range encompassing allIds
 * @param {Range[] | undefined} ranges cumulative range of ids for each of allIds
 * @param {ModuleGraph} moduleGraph moduleGraph
 * @param {Dependency} dependency dependency
 * @returns {{trimmedIds: string[], trimmedRange: Range}} computed trimmed ids and cumulative range of those ids
 */
exports.getTrimmedIdsAndRange = (
	untrimmedIds,
	untrimmedRange,
	ranges,
	moduleGraph,
	dependency
) => {
	let trimmedIds = trimIdsToThoseImported(
		untrimmedIds,
		moduleGraph,
		dependency
	);
	let trimmedRange = untrimmedRange;
	if (trimmedIds.length !== untrimmedIds.length) {
		// The array returned from dep.idRanges is right-aligned with the array returned from dep.names.
		// Meaning, the two arrays may not always have the same number of elements, but the last element of
		// dep.idRanges corresponds to [the expression fragment to the left of] the last element of dep.names.
		// Use this to find the correct replacement range based on the number of ids that were trimmed.
		const idx =
			ranges === undefined
				? -1 /* trigger failure case below */
				: ranges.length + (trimmedIds.length - untrimmedIds.length);
		if (idx < 0 || idx >= /** @type {Range[]} */ (ranges).length) {
			// cspell:ignore minifiers
			// Should not happen but we can't throw an error here because of backward compatibility with
			// external plugins in wp5.  Instead, we just disable trimming for now.  This may break some minifiers.
			trimmedIds = untrimmedIds;
			// TODO webpack 6 remove the "trimmedIds = ids" above and uncomment the following line instead.
			// throw new Error("Missing range starts data for id replacement trimming.");
		} else {
			trimmedRange = /** @type {Range[]} */ (ranges)[idx];
		}
	}

	return { trimmedIds, trimmedRange };
};

/**
 * @summary Determine which IDs in the id chain are actually referring to namespaces or imports,
 * and which are deeper member accessors on the imported object.
 * @param {string[]} ids untrimmed ids
 * @param {ModuleGraph} moduleGraph moduleGraph
 * @param {Dependency} dependency dependency
 * @returns {string[]} trimmed ids
 */
function trimIdsToThoseImported(ids, moduleGraph, dependency) {
	/** @type {string[]} */
	let trimmedIds = [];
	let currentExportsInfo = moduleGraph.getExportsInfo(
		/** @type {Module} */ (moduleGraph.getModule(dependency))
	);
	for (let i = 0; i < ids.length; i++) {
		if (i === 0 && ids[i] === "default") {
			continue; // ExportInfo for the next level under default is still at the root ExportsInfo, so don't advance currentExportsInfo
		}
		const exportInfo = currentExportsInfo.getExportInfo(ids[i]);
		if (exportInfo.provided === false) {
			// json imports have nested ExportInfo for elements that things that are not actually exported, so check .provided
			trimmedIds = ids.slice(0, i);
			break;
		}
		const nestedInfo = exportInfo.getNestedExportsInfo();
		if (!nestedInfo) {
			// once all nested exports are traversed, the next item is the actual import so stop there
			trimmedIds = ids.slice(0, i + 1);
			break;
		}
		currentExportsInfo = nestedInfo;
	}
	// Never trim to nothing.  This can happen for invalid imports (e.g. import { notThere } from "./module", or import { anything } from "./missingModule")
	return trimmedIds.length ? trimmedIds : ids;
}