webpack/lib/dependencies/HarmonyDetectionParserPlugin.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 HarmonyCompatibilityDependency = require("./HarmonyCompatibilityDependency");
const HarmonyInitDependency = require("./HarmonyInitDependency");

module.exports = class HarmonyDetectionParserPlugin {
	apply(parser) {
		parser.hooks.program.tap("HarmonyDetectionParserPlugin", ast => {
			const isStrictHarmony = parser.state.module.type === "javascript/esm";
			const isHarmony =
				isStrictHarmony ||
				ast.body.some(
					statement =>
						statement.type === "ImportDeclaration" ||
						statement.type === "ExportDefaultDeclaration" ||
						statement.type === "ExportNamedDeclaration" ||
						statement.type === "ExportAllDeclaration"
				);
			if (isHarmony) {
				const module = parser.state.module;
				const compatDep = new HarmonyCompatibilityDependency(module);
				compatDep.loc = {
					start: {
						line: -1,
						column: 0
					},
					end: {
						line: -1,
						column: 0
					},
					index: -3
				};
				module.addDependency(compatDep);
				const initDep = new HarmonyInitDependency(module);
				initDep.loc = {
					start: {
						line: -1,
						column: 0
					},
					end: {
						line: -1,
						column: 0
					},
					index: -2
				};
				module.addDependency(initDep);
				parser.state.harmonyParserScope = parser.state.harmonyParserScope || {};
				parser.scope.isStrict = true;
				module.buildMeta.exportsType = "namespace";
				module.buildInfo.strict = true;
				module.buildInfo.exportsArgument = "__webpack_exports__";
				if (isStrictHarmony) {
					module.buildMeta.strictHarmonyModule = true;
					module.buildInfo.moduleArgument = "__webpack_module__";
				}
			}
		});

		const skipInHarmony = () => {
			const module = parser.state.module;
			if (module && module.buildMeta && module.buildMeta.exportsType) {
				return true;
			}
		};

		const nullInHarmony = () => {
			const module = parser.state.module;
			if (module && module.buildMeta && module.buildMeta.exportsType) {
				return null;
			}
		};

		const nonHarmonyIdentifiers = ["define", "exports"];
		for (const identifer of nonHarmonyIdentifiers) {
			parser.hooks.evaluateTypeof
				.for(identifer)
				.tap("HarmonyDetectionParserPlugin", nullInHarmony);
			parser.hooks.typeof
				.for(identifer)
				.tap("HarmonyDetectionParserPlugin", skipInHarmony);
			parser.hooks.evaluate
				.for(identifer)
				.tap("HarmonyDetectionParserPlugin", nullInHarmony);
			parser.hooks.expression
				.for(identifer)
				.tap("HarmonyDetectionParserPlugin", skipInHarmony);
			parser.hooks.call
				.for(identifer)
				.tap("HarmonyDetectionParserPlugin", skipInHarmony);
		}
	}
};