mirror of https://github.com/webpack/webpack.git
122 lines
3.8 KiB
JavaScript
122 lines
3.8 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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const HarmonyExportImportedSpecifierDependency = require("../dependencies/HarmonyExportImportedSpecifierDependency");
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const HarmonyImportSideEffectDependency = require("../dependencies/HarmonyImportSideEffectDependency");
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const HarmonyImportSpecifierDependency = require("../dependencies/HarmonyImportSpecifierDependency");
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class SideEffectsFlagPlugin {
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apply(compiler) {
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compiler.hooks.normalModuleFactory.tap("SideEffectsFlagPlugin", (nmf) => {
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nmf.hooks.module.tap("SideEffectsFlagPlugin", (module, data) => {
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const resolveData = data.resourceResolveData;
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if(resolveData && resolveData.descriptionFileData && resolveData.relativePath) {
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const sideEffects = resolveData.descriptionFileData.sideEffects;
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const isSideEffectFree = sideEffects === false; // TODO allow more complex expressions
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if(isSideEffectFree) {
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module.factoryMeta.sideEffectFree = true;
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}
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}
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return module;
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});
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nmf.hooks.module.tap("SideEffectsFlagPlugin", (module, data) => {
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if(data.settings.sideEffects === false)
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module.factoryMeta.sideEffectFree = true;
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else if(data.settings.sideEffects === true)
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module.factoryMeta.sideEffectFree = false;
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});
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});
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compiler.hooks.compilation.tap("SideEffectsFlagPlugin", (compilation) => {
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compilation.hooks.optimizeDependencies.tap("SideEffectsFlagPlugin", (modules) => {
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const reexportMaps = new Map();
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// Capture reexports of sideEffectFree modules
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for(const module of modules) {
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const removeDependencies = [];
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for(const dep of module.dependencies) {
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if(dep instanceof HarmonyImportSideEffectDependency) {
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if(dep.module && dep.module.factoryMeta.sideEffectFree) {
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removeDependencies.push(dep);
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}
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} else if(dep instanceof HarmonyExportImportedSpecifierDependency) {
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if(module.factoryMeta.sideEffectFree) {
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const mode = dep.getMode(true);
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if(mode.type === "safe-reexport") {
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let map = reexportMaps.get(module);
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if(!map) {
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reexportMaps.set(module, map = new Map());
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}
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for(const pair of mode.map) {
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map.set(pair[0], {
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module: mode.module,
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exportName: pair[1]
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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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for(const dep of removeDependencies) {
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module.removeDependency(dep);
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dep.module.reasons = dep.module.reasons.filter(r => r.dependency !== dep);
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}
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}
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// Flatten reexports
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for(const map of reexportMaps.values()) {
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for(const pair of map) {
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let mapping = pair[1];
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while(mapping) {
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const innerMap = reexportMaps.get(mapping.module);
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if(!innerMap) break;
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const newMapping = innerMap.get(mapping.exportName);
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if(newMapping) {
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map.set(pair[0], newMapping);
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}
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mapping = newMapping;
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}
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}
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}
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// Update imports along the reexports from sideEffectFree modules
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const updates = [];
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for(const pair of reexportMaps) {
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const module = pair[0];
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const map = pair[1];
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for(const reason of module.reasons) {
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const dep = reason.dependency;
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if(dep instanceof HarmonyImportSpecifierDependency) {
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const mapping = map.get(dep.id);
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if(mapping) {
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updates.push({
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dep,
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mapping,
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module,
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reason
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});
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}
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}
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}
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}
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// Execute updates
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for(const update of updates) {
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const dep = update.dep;
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const mapping = update.mapping;
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const module = update.module;
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const reason = update.reason;
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dep.module = mapping.module;
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dep.id = mapping.exportName;
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module.removeReason(reason.module, dep);
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mapping.module.addReason(reason.module, dep);
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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 = SideEffectsFlagPlugin;
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