webpack/lib/dependencies/processExportInfo.js

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.

/*
	MIT License http://www.opensource.org/licenses/mit-license.php
	Author Tobias Koppers @sokra
*/

"use strict";

const { UsageState } = require("../ExportsInfo");

/** @typedef {import("../Dependency").RawReferencedExports} RawReferencedExports */
/** @typedef {import("../ExportsInfo").ExportInfo} ExportInfo */
/** @typedef {import("../util/runtime").RuntimeSpec} RuntimeSpec */

/**
 * Process export info.
 * @param {RuntimeSpec} runtime the runtime
 * @param {RawReferencedExports} referencedExports list of referenced exports, will be added to
 * @param {string[]} prefix export prefix
 * @param {ExportInfo=} exportInfo the export info
 * @param {boolean} defaultPointsToSelf when true, using default will reference itself
 * @param {Set<ExportInfo>=} alreadyVisited already visited export info (to handle circular reexports)
 */
const processExportInfo = (
	runtime,
	referencedExports,
	prefix,
	exportInfo,
	defaultPointsToSelf = false,
	alreadyVisited = undefined
) => {
	if (!exportInfo) {
		referencedExports.push(prefix);
		return;
	}
	const used = exportInfo.getUsed(runtime);
	if (used === UsageState.Unused) return;
	if (alreadyVisited !== undefined && alreadyVisited.has(exportInfo)) {
		referencedExports.push(prefix);
		return;
	}
	// Terminal case: not recursing, so no need to track visited here
	if (
		used !== UsageState.OnlyPropertiesUsed ||
		!exportInfo.exportsInfo ||
		exportInfo.exportsInfo.otherExportsInfo.getUsed(runtime) !==
			UsageState.Unused
	) {
		referencedExports.push(prefix);
		return;
	}
	// Only the recursive path needs the visited set; allocate it lazily
	const visited = alreadyVisited !== undefined ? alreadyVisited : new Set();
	visited.add(exportInfo);
	const exportsInfo = exportInfo.exportsInfo;
	for (const childExportInfo of exportsInfo.orderedExports) {
		processExportInfo(
			runtime,
			referencedExports,
			defaultPointsToSelf && childExportInfo.name === "default"
				? prefix
				: [...prefix, childExportInfo.name],
			childExportInfo,
			false,
			visited
		);
	}
	visited.delete(exportInfo);
};

module.exports = processExportInfo;