mirror of https://github.com/webpack/webpack.git
				
				
				
			
		
			
				
	
	
		
			93 lines
		
	
	
		
			2.2 KiB
		
	
	
	
		
			JavaScript
		
	
	
	
			
		
		
	
	
			93 lines
		
	
	
		
			2.2 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 { STAGE_ADVANCED } = require("../OptimizationStages");
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/** @typedef {import("../Chunk")} Chunk */
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/** @typedef {import("../Compiler")} Compiler */
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class AggressiveMergingPlugin {
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	constructor(options) {
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		if (
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			(options !== undefined && typeof options !== "object") ||
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			Array.isArray(options)
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		) {
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			throw new Error(
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				"Argument should be an options object. To use defaults, pass in nothing.\nFor more info on options, see https://webpack.js.org/plugins/"
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			);
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		}
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		this.options = options || {};
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	}
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	/**
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	 * Apply the plugin
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	 * @param {Compiler} compiler the compiler instance
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	 * @returns {void}
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	 */
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	apply(compiler) {
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		const options = this.options;
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		const minSizeReduce = options.minSizeReduce || 1.5;
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		compiler.hooks.thisCompilation.tap(
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			"AggressiveMergingPlugin",
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			compilation => {
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				compilation.hooks.optimizeChunks.tap(
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					{
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						name: "AggressiveMergingPlugin",
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						stage: STAGE_ADVANCED
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					},
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					chunks => {
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						const chunkGraph = compilation.chunkGraph;
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						/** @type {{a: Chunk, b: Chunk, improvement: number}[]} */
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						let combinations = [];
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						for (const a of chunks) {
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							if (a.canBeInitial()) continue;
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							for (const b of chunks) {
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								if (b.canBeInitial()) continue;
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								if (b === a) break;
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								if (!chunkGraph.canChunksBeIntegrated(a, b)) {
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									continue;
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								}
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								const aSize = chunkGraph.getChunkSize(b, {
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									chunkOverhead: 0
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								});
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								const bSize = chunkGraph.getChunkSize(a, {
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									chunkOverhead: 0
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								});
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								const abSize = chunkGraph.getIntegratedChunksSize(b, a, {
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									chunkOverhead: 0
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								});
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								const improvement = (aSize + bSize) / abSize;
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								combinations.push({
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									a,
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									b,
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									improvement
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								});
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							}
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						}
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						combinations.sort((a, b) => {
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							return b.improvement - a.improvement;
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						});
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						const pair = combinations[0];
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						if (!pair) return;
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						if (pair.improvement < minSizeReduce) return;
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						chunkGraph.integrateChunks(pair.b, pair.a);
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						compilation.chunks.delete(pair.a);
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						return true;
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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 = AggressiveMergingPlugin;
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