/*
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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 { STAGE_BASIC } = require("../OptimizationStages");
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const { runtimeEqual } = require("../util/runtime");
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/** @typedef {import("../Compiler")} Compiler */
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class MergeDuplicateChunksPlugin {
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/**
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* @param {Compiler} compiler the compiler
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* @returns {void}
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*/
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apply(compiler) {
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compiler.hooks.compilation.tap(
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"MergeDuplicateChunksPlugin",
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compilation => {
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compilation.hooks.optimizeChunks.tap(
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{
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name: "MergeDuplicateChunksPlugin",
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stage: STAGE_BASIC
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},
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chunks => {
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const { chunkGraph, moduleGraph } = compilation;
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// remember already tested chunks for performance
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const notDuplicates = new Set();
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// for each chunk
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for (const chunk of chunks) {
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// track a Set of all chunk that could be duplicates
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let possibleDuplicates;
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for (const module of chunkGraph.getChunkModulesIterable(chunk)) {
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if (possibleDuplicates === undefined) {
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// when possibleDuplicates is not yet set,
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// create a new Set from chunks of the current module
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// including only chunks with the same number of modules
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for (const dup of chunkGraph.getModuleChunksIterable(
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module
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)) {
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if (
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dup !== chunk &&
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chunkGraph.getNumberOfChunkModules(chunk) ===
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chunkGraph.getNumberOfChunkModules(dup) &&
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!notDuplicates.has(dup)
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) {
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// delay allocating the new Set until here, reduce memory pressure
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if (possibleDuplicates === undefined) {
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possibleDuplicates = new Set();
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}
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possibleDuplicates.add(dup);
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}
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}
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// when no chunk is possible we can break here
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if (possibleDuplicates === undefined) break;
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} else {
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// validate existing possible duplicates
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for (const dup of possibleDuplicates) {
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// remove possible duplicate when module is not contained
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if (!chunkGraph.isModuleInChunk(module, dup)) {
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possibleDuplicates.delete(dup);
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}
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}
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// when all chunks has been removed we can break here
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if (possibleDuplicates.size === 0) break;
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}
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}
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// when we found duplicates
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if (
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possibleDuplicates !== undefined &&
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possibleDuplicates.size > 0
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) {
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outer: for (const otherChunk of possibleDuplicates) {
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if (otherChunk.hasRuntime() !== chunk.hasRuntime()) continue;
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if (chunkGraph.getNumberOfEntryModules(chunk) > 0) continue;
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if (chunkGraph.getNumberOfEntryModules(otherChunk) > 0)
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continue;
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if (!runtimeEqual(chunk.runtime, otherChunk.runtime)) {
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for (const module of chunkGraph.getChunkModulesIterable(
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chunk
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)) {
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const exportsInfo = moduleGraph.getExportsInfo(module);
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if (
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!exportsInfo.isEquallyUsed(
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chunk.runtime,
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otherChunk.runtime
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)
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) {
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continue outer;
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}
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}
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}
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// merge them
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if (chunkGraph.canChunksBeIntegrated(chunk, otherChunk)) {
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chunkGraph.integrateChunks(chunk, otherChunk);
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compilation.chunks.delete(otherChunk);
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}
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}
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}
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// don't check already processed chunks twice
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notDuplicates.add(chunk);
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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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}
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module.exports = MergeDuplicateChunksPlugin;
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