FlagDependencyExportsPlugin.js

/*
	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;

				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.providedExports === true) {
						return true;
					}
					// break if it should move to the worst state
					if(exports === true) {
						module.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) {
						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.providedExports) {
						queue.enqueue(module);
					}
				}

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

					if(module.providedExports !== true) {
						moduleWithExports = module.buildMeta && module.buildMeta.harmonyModule;
						moduleProvidedExports = Array.isArray(module.providedExports) ? new Set(module.providedExports) : new Set();
						processDependenciesBlock(module);
						if(!moduleWithExports) {
							module.providedExports = true;
							notifyDependencies();
						} else if(module.providedExports !== true) {
							module.providedExports = Array.from(moduleProvidedExports);
						}
					}
				}
			});
		});
	}
}

module.exports = FlagDependencyExportsPlugin;