webpack/lib/dependencies/HarmonyExportExpressionDependency.js

Packs CommonJs/AMD modules for the browser. Allows to split your codebase into multiple bundles, which can be loaded on demand. Support 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 ConcatenationScope = require("../ConcatenationScope");
const RuntimeGlobals = require("../RuntimeGlobals");
const makeSerializable = require("../util/makeSerializable");
const HarmonyExportInitFragment = require("./HarmonyExportInitFragment");
const NullDependency = require("./NullDependency");

/** @typedef {import("webpack-sources").ReplaceSource} ReplaceSource */
/** @typedef {import("../Dependency")} Dependency */
/** @typedef {import("../Dependency").ExportsSpec} ExportsSpec */
/** @typedef {import("../DependencyTemplate").DependencyTemplateContext} DependencyTemplateContext */
/** @typedef {import("../ModuleGraph")} ModuleGraph */
/** @typedef {import("../ModuleGraphConnection").ConnectionState} ConnectionState */

class HarmonyExportExpressionDependency extends NullDependency {
	constructor(range, rangeStatement, prefix, declarationId) {
		super();
		this.range = range;
		this.rangeStatement = rangeStatement;
		this.prefix = prefix;
		this.declarationId = declarationId;
	}

	get type() {
		return "harmony export expression";
	}

	/**
	 * Returns the exported names
	 * @param {ModuleGraph} moduleGraph module graph
	 * @returns {ExportsSpec | undefined} export names
	 */
	getExports(moduleGraph) {
		return {
			exports: ["default"],
			priority: 1,
			terminalBinding: true,
			dependencies: undefined
		};
	}

	/**
	 * @param {ModuleGraph} moduleGraph the module graph
	 * @returns {ConnectionState} how this dependency connects the module to referencing modules
	 */
	getModuleEvaluationSideEffectsState(moduleGraph) {
		// The expression/declaration is already covered by SideEffectsFlagPlugin
		return false;
	}

	serialize(context) {
		const { write } = context;
		write(this.range);
		write(this.rangeStatement);
		write(this.prefix);
		write(this.declarationId);
		super.serialize(context);
	}

	deserialize(context) {
		const { read } = context;
		this.range = read();
		this.rangeStatement = read();
		this.prefix = read();
		this.declarationId = read();
		super.deserialize(context);
	}
}

makeSerializable(
	HarmonyExportExpressionDependency,
	"webpack/lib/dependencies/HarmonyExportExpressionDependency"
);

HarmonyExportExpressionDependency.Template = class HarmonyExportDependencyTemplate extends (
	NullDependency.Template
) {
	/**
	 * @param {Dependency} dependency the dependency for which the template should be applied
	 * @param {ReplaceSource} source the current replace source which can be modified
	 * @param {DependencyTemplateContext} templateContext the context object
	 * @returns {void}
	 */
	apply(
		dependency,
		source,
		{
			module,
			moduleGraph,
			runtimeTemplate,
			runtimeRequirements,
			initFragments,
			runtime,
			concatenationScope
		}
	) {
		const dep = /** @type {HarmonyExportExpressionDependency} */ (dependency);
		const { declarationId } = dep;
		const exportsName = module.exportsArgument;
		if (declarationId) {
			let name;
			if (typeof declarationId === "string") {
				name = declarationId;
			} else {
				name = ConcatenationScope.DEFAULT_EXPORT;
				source.replace(
					declarationId.range[0],
					declarationId.range[1] - 1,
					`${declarationId.prefix}${name}${declarationId.suffix}`
				);
			}

			if (concatenationScope) {
				concatenationScope.registerExport("default", name);
			} else {
				const used = moduleGraph
					.getExportsInfo(module)
					.getUsedName("default", runtime);
				if (used) {
					const map = new Map();
					map.set(used, `/* export default binding */ ${name}`);
					initFragments.push(new HarmonyExportInitFragment(exportsName, map));
				}
			}

			source.replace(
				dep.rangeStatement[0],
				dep.range[0] - 1,
				`/* harmony default export */ ${dep.prefix}`
			);
		} else {
			let content;
			const name = ConcatenationScope.DEFAULT_EXPORT;
			if (runtimeTemplate.supportsConst()) {
				content = `/* harmony default export */ const ${name} = `;
				if (concatenationScope) {
					concatenationScope.registerExport("default", name);
				} else {
					const used = moduleGraph
						.getExportsInfo(module)
						.getUsedName("default", runtime);
					if (used) {
						runtimeRequirements.add(RuntimeGlobals.exports);
						const map = new Map();
						map.set(used, name);
						initFragments.push(new HarmonyExportInitFragment(exportsName, map));
					} else {
						content = `/* unused harmony default export */ var ${name} = `;
					}
				}
			} else if (concatenationScope) {
				content = `/* harmony default export */ var ${name} = `;
				concatenationScope.registerExport("default", name);
			} else {
				const used = moduleGraph
					.getExportsInfo(module)
					.getUsedName("default", runtime);
				if (used) {
					runtimeRequirements.add(RuntimeGlobals.exports);
					// This is a little bit incorrect as TDZ is not correct, but we can't use const.
					content = `/* harmony default export */ ${exportsName}[${JSON.stringify(
						used
					)}] = `;
				} else {
					content = `/* unused harmony default export */ var ${name} = `;
				}
			}

			if (dep.range) {
				source.replace(
					dep.rangeStatement[0],
					dep.range[0] - 1,
					content + "(" + dep.prefix
				);
				source.replace(dep.range[1], dep.rangeStatement[1] - 0.5, ");");
				return;
			}

			source.replace(dep.rangeStatement[0], dep.rangeStatement[1] - 1, content);
		}
	}
};

module.exports = HarmonyExportExpressionDependency;