webpack/lib/FlagDependencyExportsPlugin.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 Queue = require("./util/Queue");

const addToSet = (a, b) => {
	let changed = false;
	for (const item of b) {
		if (!a.has(item)) {
			a.add(item);
			changed = true;
		}
	}
	return changed;
};

class FlagDependencyExportsPlugin {
	apply(compiler) {
		compiler.hooks.compilation.tap(
			"FlagDependencyExportsPlugin",
			compilation => {
				compilation.hooks.finishModules.tap(
					"FlagDependencyExportsPlugin",
					modules => {
						const dependencies = new Map();

						const queue = new Queue();

						let module;
						let moduleWithExports;
						let moduleProvidedExports;
						let providedExportsAreTemporary;

						const processDependenciesBlock = depBlock => {
							for (const dep of depBlock.dependencies) {
								if (processDependency(dep)) return true;
							}
							for (const variable of depBlock.variables) {
								for (const dep of variable.dependencies) {
									if (processDependency(dep)) return true;
								}
							}
							for (const block of depBlock.blocks) {
								if (processDependenciesBlock(block)) return true;
							}
							return false;
						};

						const processDependency = dep => {
							const exportDesc = dep.getExports && dep.getExports();
							if (!exportDesc) return;
							moduleWithExports = true;
							const exports = exportDesc.exports;
							// break early if it's only in the worst state
							if (module.buildMeta.providedExports === true) {
								return true;
							}
							// break if it should move to the worst state
							if (exports === true) {
								module.buildMeta.providedExports = true;
								notifyDependencies();
								return true;
							}
							// merge in new exports
							if (Array.isArray(exports)) {
								if (addToSet(moduleProvidedExports, exports)) {
									notifyDependencies();
								}
							}
							// store dependencies
							const exportDeps = exportDesc.dependencies;
							if (exportDeps) {
								providedExportsAreTemporary = true;
								for (const exportDependency of exportDeps) {
									// add dependency for this module
									const set = dependencies.get(exportDependency);
									if (set === undefined) {
										dependencies.set(exportDependency, new Set([module]));
									} else {
										set.add(module);
									}
								}
							}
							return false;
						};

						const notifyDependencies = () => {
							const deps = dependencies.get(module);
							if (deps !== undefined) {
								for (const dep of deps) {
									queue.enqueue(dep);
								}
							}
						};

						// Start with all modules without provided exports
						for (const module of modules) {
							if (module.buildInfo.temporaryProvidedExports) {
								// Clear exports when they are temporary
								// and recreate them
								module.buildMeta.providedExports = null;
								queue.enqueue(module);
							} else if (!module.buildMeta.providedExports) {
								queue.enqueue(module);
							}
						}

						while (queue.length > 0) {
							module = queue.dequeue();

							if (module.buildMeta.providedExports !== true) {
								moduleWithExports =
									module.buildMeta && module.buildMeta.exportsType;
								moduleProvidedExports = Array.isArray(
									module.buildMeta.providedExports
								)
									? new Set(module.buildMeta.providedExports)
									: new Set();
								providedExportsAreTemporary = false;
								processDependenciesBlock(module);
								module.buildInfo.temporaryProvidedExports = providedExportsAreTemporary;
								if (!moduleWithExports) {
									module.buildMeta.providedExports = true;
									notifyDependencies();
								} else if (module.buildMeta.providedExports !== true) {
									module.buildMeta.providedExports = Array.from(
										moduleProvidedExports
									);
								}
							}
						}
					}
				);
				const providedExportsCache = new WeakMap();
				compilation.hooks.rebuildModule.tap(
					"FlagDependencyExportsPlugin",
					module => {
						providedExportsCache.set(module, module.buildMeta.providedExports);
					}
				);
				compilation.hooks.finishRebuildingModule.tap(
					"FlagDependencyExportsPlugin",
					module => {
						module.buildMeta.providedExports = providedExportsCache.get(module);
					}
				);
			}
		);
	}
}

module.exports = FlagDependencyExportsPlugin;