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node_modules/webpack/lib/FlagDependencyUsagePlugin.js 2.33 KB
2a09d1a4   liuqimichale   添加宜春 天水 宣化
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  /*
  	MIT License http://www.opensource.org/licenses/mit-license.php
  	Author Tobias Koppers @sokra
  */
  "use strict";
  
  class FlagDependencyUsagePlugin {
  	apply(compiler) {
  		compiler.plugin("compilation", compilation => {
  			compilation.plugin("optimize-modules-advanced", modules => {
  
  				modules.forEach(module => module.used = false);
  
  				const queue = [];
  				compilation.chunks.forEach(chunk => {
  					if(chunk.entryModule) {
  						processModule(chunk.entryModule, true);
  					}
  				});
  
  				while(queue.length) {
  					const queueItem = queue.pop();
  					processDependenciesBlock(queueItem[0], queueItem[1]);
  				}
  
  				function processModule(module, usedExports) {
  					module.used = true;
  					if(module.usedExports === true)
  						return;
  					else if(usedExports === true)
  						module.usedExports = true;
  					else if(Array.isArray(usedExports)) {
  						const old = module.usedExports ? module.usedExports.length : -1;
  						module.usedExports = addToSet(module.usedExports || [], usedExports);
  						if(module.usedExports.length === old)
  							return;
  					} else if(Array.isArray(module.usedExports))
  						return;
  					else
  						module.usedExports = false;
  
  					queue.push([module, module.usedExports]);
  				}
  
  				function processDependenciesBlock(depBlock, usedExports) {
  					depBlock.dependencies.forEach(dep => processDependency(dep));
  					depBlock.variables.forEach(variable => variable.dependencies.forEach(dep => processDependency(dep)));
  					depBlock.blocks.forEach(block => queue.push([block, usedExports]));
  				}
  
  				function processDependency(dep) {
  					const reference = dep.getReference && dep.getReference();
  					if(!reference) return;
  					const module = reference.module;
  					const importedNames = reference.importedNames;
  					const oldUsed = module.used;
  					const oldUsedExports = module.usedExports;
  					if(!oldUsed || (importedNames && (!oldUsedExports || !isSubset(oldUsedExports, importedNames)))) {
  						processModule(module, importedNames);
  					}
  				}
  
  			});
  
  			function addToSet(a, b) {
  				b.forEach(item => {
  					if(a.indexOf(item) < 0)
  						a.push(item);
  				});
  				return a;
  			}
  
  			function isSubset(biggerSet, subset) {
  				if(biggerSet === true) return true;
  				if(subset === true) return false;
  				return subset.every(item => biggerSet.indexOf(item) >= 0);
  			}
  		});
  	}
  }
  module.exports = FlagDependencyUsagePlugin;