vue hello world项目
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/*
MIT License http://www.opensource.org/licenses/mit-license.php
Author Tobias Koppers @sokra
*/
"use strict";
const { STAGE_BASIC } = require("../OptimizationStages");
const Queue = require("../util/Queue");
const { intersect } = require("../util/SetHelpers");
/** @typedef {import("../Compiler")} Compiler */
class RemoveParentModulesPlugin {
/**
* @param {Compiler} compiler the compiler
* @returns {void}
*/
apply(compiler) {
compiler.hooks.compilation.tap("RemoveParentModulesPlugin", compilation => {
const handler = (chunks, chunkGroups) => {
const chunkGraph = compilation.chunkGraph;
const queue = new Queue();
const availableModulesMap = new WeakMap();
for (const chunkGroup of compilation.entrypoints.values()) {
// initialize available modules for chunks without parents
availableModulesMap.set(chunkGroup, new Set());
for (const child of chunkGroup.childrenIterable) {
queue.enqueue(child);
}
}
for (const chunkGroup of compilation.asyncEntrypoints) {
// initialize available modules for chunks without parents
availableModulesMap.set(chunkGroup, new Set());
for (const child of chunkGroup.childrenIterable) {
queue.enqueue(child);
}
}
while (queue.length > 0) {
const chunkGroup = queue.dequeue();
let availableModules = availableModulesMap.get(chunkGroup);
let changed = false;
for (const parent of chunkGroup.parentsIterable) {
const availableModulesInParent = availableModulesMap.get(parent);
if (availableModulesInParent !== undefined) {
// If we know the available modules in parent: process these
if (availableModules === undefined) {
// if we have not own info yet: create new entry
availableModules = new Set(availableModulesInParent);
for (const chunk of parent.chunks) {
for (const m of chunkGraph.getChunkModulesIterable(chunk)) {
availableModules.add(m);
}
}
availableModulesMap.set(chunkGroup, availableModules);
changed = true;
} else {
for (const m of availableModules) {
if (
!chunkGraph.isModuleInChunkGroup(m, parent) &&
!availableModulesInParent.has(m)
) {
availableModules.delete(m);
changed = true;
}
}
}
}
}
if (changed) {
// if something changed: enqueue our children
for (const child of chunkGroup.childrenIterable) {
queue.enqueue(child);
}
}
}
// now we have available modules for every chunk
for (const chunk of chunks) {
const availableModulesSets = Array.from(
chunk.groupsIterable,
chunkGroup => availableModulesMap.get(chunkGroup)
);
if (availableModulesSets.some(s => s === undefined)) continue; // No info about this chunk group
const availableModules =
availableModulesSets.length === 1
? availableModulesSets[0]
: intersect(availableModulesSets);
const numberOfModules = chunkGraph.getNumberOfChunkModules(chunk);
const toRemove = new Set();
if (numberOfModules < availableModules.size) {
for (const m of chunkGraph.getChunkModulesIterable(chunk)) {
if (availableModules.has(m)) {
toRemove.add(m);
}
}
} else {
for (const m of availableModules) {
if (chunkGraph.isModuleInChunk(m, chunk)) {
toRemove.add(m);
}
}
}
for (const module of toRemove) {
chunkGraph.disconnectChunkAndModule(chunk, module);
}
}
};
compilation.hooks.optimizeChunks.tap(
{
name: "RemoveParentModulesPlugin",
stage: STAGE_BASIC
},
handler
);
});
}
}
module.exports = RemoveParentModulesPlugin;