/*
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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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class MergeDuplicateChunksPlugin {
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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.optimizeChunksBasic.tap(
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"MergeDuplicateChunksPlugin",
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chunks => {
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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 chunk.modulesIterable) {
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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 module.chunksIterable) {
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if (
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dup !== chunk &&
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chunk.getNumberOfModules() === dup.getNumberOfModules() &&
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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 (!dup.containsModule(module)) {
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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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for (const otherChunk of possibleDuplicates) {
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if (otherChunk.hasRuntime() !== chunk.hasRuntime()) continue;
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// merge them
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if (chunk.integrate(otherChunk, "duplicate")) {
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chunks.splice(chunks.indexOf(otherChunk), 1);
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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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