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