117 lines
3.4 KiB
JavaScript
117 lines
3.4 KiB
JavaScript
/*
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MIT License http://www.opensource.org/licenses/mit-license.php
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Author Tobias Koppers @sokra
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*/
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"use strict";
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/** @typedef {import("./Module")} Module */
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/** @typedef {import("./DependenciesBlock")} DependenciesBlock */
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/** @typedef {false | true | string[]} UsedExports */
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const addToSet = (a, b) => {
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for (const item of b) {
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if (!a.includes(item)) a.push(item);
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}
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return a;
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};
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const isSubset = (biggerSet, subset) => {
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if (biggerSet === true) return true;
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if (subset === true) return false;
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return subset.every(item => biggerSet.indexOf(item) >= 0);
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};
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class FlagDependencyUsagePlugin {
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apply(compiler) {
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compiler.hooks.compilation.tap("FlagDependencyUsagePlugin", compilation => {
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compilation.hooks.optimizeDependencies.tap(
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"FlagDependencyUsagePlugin",
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modules => {
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const processModule = (module, usedExports) => {
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module.used = true;
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if (module.usedExports === true) return;
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if (usedExports === true) {
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module.usedExports = true;
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} else if (Array.isArray(usedExports)) {
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const old = module.usedExports ? module.usedExports.length : -1;
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module.usedExports = addToSet(
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module.usedExports || [],
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usedExports
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);
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if (module.usedExports.length === old) {
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return;
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}
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} else if (Array.isArray(module.usedExports)) {
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return;
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} else {
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module.usedExports = false;
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}
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// for a module without side effects we stop tracking usage here when no export is used
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// This module won't be evaluated in this case
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if (module.factoryMeta.sideEffectFree) {
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if (module.usedExports === false) return;
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if (
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Array.isArray(module.usedExports) &&
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module.usedExports.length === 0
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)
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return;
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}
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queue.push([module, module, module.usedExports]);
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};
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const processDependenciesBlock = (module, depBlock, usedExports) => {
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for (const dep of depBlock.dependencies) {
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processDependency(module, dep);
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}
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for (const variable of depBlock.variables) {
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for (const dep of variable.dependencies) {
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processDependency(module, dep);
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}
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}
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for (const block of depBlock.blocks) {
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queue.push([module, block, usedExports]);
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}
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};
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const processDependency = (module, dep) => {
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const reference = compilation.getDependencyReference(module, dep);
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if (!reference) return;
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const referenceModule = reference.module;
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const importedNames = reference.importedNames;
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const oldUsed = referenceModule.used;
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const oldUsedExports = referenceModule.usedExports;
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if (
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!oldUsed ||
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(importedNames &&
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(!oldUsedExports || !isSubset(oldUsedExports, importedNames)))
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) {
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processModule(referenceModule, importedNames);
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}
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};
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for (const module of modules) {
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if (!module.used) module.used = false;
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}
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/** @type {[Module, DependenciesBlock, UsedExports][]} */
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const queue = [];
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for (const preparedEntrypoint of compilation._preparedEntrypoints) {
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if (preparedEntrypoint.module) {
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processModule(preparedEntrypoint.module, true);
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}
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}
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while (queue.length) {
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const queueItem = queue.pop();
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processDependenciesBlock(queueItem[0], queueItem[1], queueItem[2]);
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}
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}
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);
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});
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}
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}
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module.exports = FlagDependencyUsagePlugin;
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