源码5

来看下/bin/convert-argv文件，这个文件主要是对命令参数的解析。

先看开头：
var path = require("path");
var fs = require("fs");
fs.existsSync = fs.existsSync || path.existsSync;
var interpret = require("interpret");
var prepareOptions = require("../lib/prepareOptions");

引入interpret模块，这是一个文件后缀集合的模块，
还有prepareOptions文件：内容如下，主要是对导出模块的处理，首先对是否是es6支持的export defalut支持还是module.export导出的，
然后判断导出的是否是数组进入判断，返回导出内容

module.exports = function prepareOptions(options, argv) {
	argv = argv || {};

	options = handleExport(options);

	if(Array.isArray(options)) {
		options = options.map(_options => handleFunction(_options, argv));
	} else {
		options = handleFunction(options, argv);
	}
	return options;
};

function handleExport(options) {
	const isES6DefaultExported = (
		typeof options === "object" && options !== null && typeof options.default !== "undefined"
	);
	options = isES6DefaultExported ? options.default : options;
	return options;
}

function handleFunction(options, argv) {
	if(typeof options === "function") {
		options = options(argv.env, argv);
	}
	return options;
}

文件正文：

// 文件作为一个函数导出
module.exports = function(yargs, argv, convertOptions) { 
 // 其中yargs带表 配置参数，argv：命令解析组成的对象，convertOptions带表输出对象
  options为一个初始数组
	var options = [];
  // 是否带有d参数,代表是否debug
	// Shortcuts
	if(argv.d) {
		argv.debug = true;
		argv["output-pathinfo"] = true;
		if(!argv.devtool) {
			argv.devtool = "eval-cheap-module-source-map";
		}
	}
  // 参数p,是否压缩
	if(argv.p) {
		argv["optimize-minimize"] = true;
		argv["define"] = [].concat(argv["define"] || []).concat("process.env.NODE_ENV=\"production\"");
	}
  // 设置configFileLoaded 为false,等文件调用并解析完之后设为true
	var configFileLoaded = false;
  // 参数文件设置空数组
	var configFiles = [];
  // 对各种扩展文件进行排序，js在前
	var extensions = Object.keys(interpret.extensions).sort(function(a, b) {
		return a === ".js" ? -1 : b === ".js" ? 1 : a.length - b.length;
	});
  // webpack默人的两个文件webpack.config webpackfile进行扩展的匹配，defaultConfigFiles带表webpack配置文件和扩展名组合的数组
	var defaultConfigFiles = ["webpack.config", "webpackfile"].map(function(filename) {
		return extensions.map(function(ext) {
			return {
				path: path.resolve(filename + ext),
				ext: ext
			};
		});
	}).reduce(function(a, i) {
		return a.concat(i);
	}, []);

	var i;
  // argv.config 带表是否webpack命令中有--config参数，后面是配置文件的相对路径 如：build/webpack.dev.conf.js
	if(argv.config) {
    // 获取配置文件的后缀
		var getConfigExtension = function getConfigExtension(configPath) {
			for(i = extensions.length - 1; i >= 0; i--) {
				var tmpExt = extensions[i];
				if(configPath.indexOf(tmpExt, configPath.length - tmpExt.length) > -1) {
					return tmpExt;
				}
			}
			return path.extname(configPath);
		};
    // 将相对路径转化为绝对路径，返回绝对路径和扩展名的对象
		var mapConfigArg = function mapConfigArg(configArg) {
			var resolvedPath = path.resolve(configArg);
			var extension = getConfigExtension(resolvedPath);
			return {
				path: resolvedPath,
				ext: extension
			};
		};

		var configArgList = Array.isArray(argv.config) ? argv.config : [argv.config];
    配置文件绝对路径和扩展名的对象的数组
		configFiles = configArgList.map(mapConfigArg);
	} else {
    // 如果没有配置文件，就可默人的两个配置文件名和扩展名的组合逐一进行匹配
		for(i = 0; i < defaultConfigFiles.length; i++) {
			var webpackConfig = defaultConfigFiles[i].path;
			if(fs.existsSync(webpackConfig)) {
				configFiles.push({
					path: webpackConfig,
					ext: defaultConfigFiles[i].ext
				});
				break;
			}
		}
	}
  // 如果找到配置文件
	if(configFiles.length > 0) {
		var registerCompiler = function registerCompiler(moduleDescriptor) {
			if(moduleDescriptor) {
				if(typeof moduleDescriptor === "string") {
					require(moduleDescriptor);
				} else if(!Array.isArray(moduleDescriptor)) {
					moduleDescriptor.register(require(moduleDescriptor.module));
				} else {
					for(var i = 0; i < moduleDescriptor.length; i++) {
						try {
							registerCompiler(moduleDescriptor[i]);
							break;
						} catch(e) {
							// do nothing
						}
					}
				}
			}
		};

		var requireConfig = function requireConfig(configPath) {
			var options = require(configPath);
			options = prepareOptions(options, argv);
			return options;
		};
    // options加入文件path
		configFiles.forEach(function(file) {
			registerCompiler(interpret.extensions[file.ext]);
			options.push(requireConfig(file.path));
		});
		configFileLoaded = true;
	}
  
	if(!configFileLoaded) {
		return processConfiguredOptions({});
	} else if(options.length === 1) {
		return processConfiguredOptions(options[0]);
	} else {
		return processConfiguredOptions(options);
	}
  // 执行回调
	function processConfiguredOptions(options) {
    // 如果返回为空或者不为对象，报错
		if(options === null || typeof options !== "object") {
			console.error("Config did not export an object or a function returning an object.");
			process.exit(-1); // eslint-disable-line
		}

		// process Promise
    // 支持票promise
		if(typeof options.then === "function") {
			return options.then(processConfiguredOptions);
		}

		// process ES6 default
    // 支持es6
		if(typeof options === "object" && typeof options.default === "object") {
			return processConfiguredOptions(options.default);
		}
    // options多个，并且有config-name参数
		// filter multi-config by name
		if(Array.isArray(options) && argv["config-name"]) {
			var namedOptions = options.filter(function(opt) {
				return opt.name === argv["config-name"];
			});
			if(namedOptions.length === 0) {
				console.error("Configuration with name '" + argv["config-name"] + "' was not found.");
				process.exit(-1); // eslint-disable-line
			} else if(namedOptions.length === 1) {
				return processConfiguredOptions(namedOptions[0]);
			}
			options = namedOptions;
		}
    // 数组
		if(Array.isArray(options)) {
			options.forEach(processOptions);
		} else {
			processOptions(options);
		}
    // 绝对路径
		if(argv.context) {
			options.context = path.resolve(argv.context);
		}
		if(!options.context) {
			options.context = process.cwd();
		}
    // 是否监听
		if(argv.watch) {
			options.watch = true;
		}
    // 监听间隔时间
		if(argv["watch-aggregate-timeout"]) {
			options.watchOptions = options.watchOptions || {};
			options.watchOptions.aggregateTimeout = +argv["watch-aggregate-timeout"];
		}

		if(typeof argv["watch-poll"] !== "undefined") {
			options.watchOptions = options.watchOptions || {};
			if(argv["watch-poll"] === "true" || argv["watch-poll"] === "")
				options.watchOptions.poll = true;
			else if(!isNaN(argv["watch-poll"]))
				options.watchOptions.poll = +argv["watch-poll"];
		}

		if(argv["watch-stdin"]) {
			options.watchOptions = options.watchOptions || {};
			options.watchOptions.stdin = true;
			options.watch = true;
		}

		return options;
	}
  // process options的各种参数格式处理
	function processOptions(options) {
		var noOutputFilenameDefined = !options.output || !options.output.filename;

		function ifArg(name, fn, init, finalize) {
			if(Array.isArray(argv[name])) {
				if(init) {
					init();
				}
				argv[name].forEach(fn);
				if(finalize) {
					finalize();
				}
			} else if(typeof argv[name] !== "undefined" && argv[name] !== null) {
				if(init) {
					init();
				}
				fn(argv[name], -1);
				if(finalize) {
					finalize();
				}
			}
		}

		function ifArgPair(name, fn, init, finalize) {
			ifArg(name, function(content, idx) {
				var i = content.indexOf("=");
				if(i < 0) {
					return fn(null, content, idx);
				} else {
					return fn(content.substr(0, i), content.substr(i + 1), idx);
				}
			}, init, finalize);
		}

		function ifBooleanArg(name, fn) {
			ifArg(name, function(bool) {
				if(bool) {
					fn();
				}
			});
		}

		function mapArgToBoolean(name, optionName) {
			ifArg(name, function(bool) {
				if(bool === true)
					options[optionName || name] = true;
				else if(bool === false)
					options[optionName || name] = false;
			});
		}
                // 这里特别指出，加载插件plugin，是找到路径，然后require,在new Plugin()
		function loadPlugin(name) {
			var loadUtils = require("loader-utils");
			var args;
			try {
				var p = name && name.indexOf("?");
				if(p > -1) {
					args = loadUtils.parseQuery(name.substring(p));
					name = name.substring(0, p);
				}
			} catch(e) {
				console.log("Invalid plugin arguments " + name + " (" + e + ").");
				process.exit(-1); // eslint-disable-line
			}

			var path;
			try {
				var resolve = require("enhanced-resolve");
				path = resolve.sync(process.cwd(), name);
			} catch(e) {
				console.log("Cannot resolve plugin " + name + ".");
				process.exit(-1); // eslint-disable-line
			}
			var Plugin;
			try {
				Plugin = require(path);
			} catch(e) {
				console.log("Cannot load plugin " + name + ". (" + path + ")");
				throw e;
			}
			try {
				return new Plugin(args);
			} catch(e) {
				console.log("Cannot instantiate plugin " + name + ". (" + path + ")");
				throw e;
			}
		}

		function ensureObject(parent, name) {
			if(typeof parent[name] !== "object" || parent[name] === null) {
				parent[name] = {};
			}
		}

		function ensureArray(parent, name) {
			if(!Array.isArray(parent[name])) {
				parent[name] = [];
			}
		}

		ifArgPair("entry", function(name, entry) {
			if(typeof options.entry[name] !== "undefined" && options.entry[name] !== null) {
				options.entry[name] = [].concat(options.entry[name]).concat(entry);
			} else {
				options.entry[name] = entry;
			}
		}, function() {
			ensureObject(options, "entry");
		});

		function bindRules(arg) {
			ifArgPair(arg, function(name, binding) {
				if(name === null) {
					name = binding;
					binding += "-loader";
				}
				var rule = {
					test: new RegExp("\\." + name.replace(/[\-\[\]\/\{\}\(\)\*\+\?\.\\\^\$\|]/g, "\\$&") + "$"), // eslint-disable-line no-useless-escape
					loader: binding
				};
				if(arg === "module-bind-pre") {
					rule.enforce = "pre";
				} else if(arg === "module-bind-post") {
					rule.enforce = "post";
				}
				options.module.rules.push(rule);
			}, function() {
				ensureObject(options, "module");
				ensureArray(options.module, "rules");
			});
		}
		bindRules("module-bind");
		bindRules("module-bind-pre");
		bindRules("module-bind-post");

		var defineObject;
		ifArgPair("define", function(name, value) {
			if(name === null) {
				name = value;
				value = true;
			}
			defineObject[name] = value;
		}, function() {
			defineObject = {};
		}, function() {
			ensureArray(options, "plugins");
			var DefinePlugin = require("../lib/DefinePlugin");
			options.plugins.push(new DefinePlugin(defineObject));
		});

		ifArg("output-path", function(value) {
			ensureObject(options, "output");
			options.output.path = path.resolve(value);
		});

		ifArg("output-filename", function(value) {
			ensureObject(options, "output");
			options.output.filename = value;
			noOutputFilenameDefined = false;
		});

		ifArg("output-chunk-filename", function(value) {
			ensureObject(options, "output");
			options.output.chunkFilename = value;
		});

		ifArg("output-source-map-filename", function(value) {
			ensureObject(options, "output");
			options.output.sourceMapFilename = value;
		});

		ifArg("output-public-path", function(value) {
			ensureObject(options, "output");
			options.output.publicPath = value;
		});

		ifArg("output-jsonp-function", function(value) {
			ensureObject(options, "output");
			options.output.jsonpFunction = value;
		});

		ifBooleanArg("output-pathinfo", function() {
			ensureObject(options, "output");
			options.output.pathinfo = true;
		});

		ifArg("output-library", function(value) {
			ensureObject(options, "output");
			options.output.library = value;
		});

		ifArg("output-library-target", function(value) {
			ensureObject(options, "output");
			options.output.libraryTarget = value;
		});

		ifArg("records-input-path", function(value) {
			options.recordsInputPath = path.resolve(value);
		});

		ifArg("records-output-path", function(value) {
			options.recordsOutputPath = path.resolve(value);
		});

		ifArg("records-path", function(value) {
			options.recordsPath = path.resolve(value);
		});

		ifArg("target", function(value) {
			options.target = value;
		});

		mapArgToBoolean("cache");

		ifBooleanArg("hot", function() {
			ensureArray(options, "plugins");
			var HotModuleReplacementPlugin = require("../lib/HotModuleReplacementPlugin");
			options.plugins.push(new HotModuleReplacementPlugin());
		});

		ifBooleanArg("debug", function() {
			ensureArray(options, "plugins");
			var LoaderOptionsPlugin = require("../lib/LoaderOptionsPlugin");
			options.plugins.push(new LoaderOptionsPlugin({
				debug: true
			}));
		});

		ifArg("devtool", function(value) {
			options.devtool = value;
		});

		function processResolveAlias(arg, key) {
			ifArgPair(arg, function(name, value) {
				if(!name) {
					throw new Error("--" + arg + " <string>=<string>");
				}
				ensureObject(options, key);
				ensureObject(options[key], "alias");
				options[key].alias[name] = value;
			});
		}
		processResolveAlias("resolve-alias", "resolve");
		processResolveAlias("resolve-loader-alias", "resolveLoader");

		ifArg("resolve-extensions", function(value) {
			ensureObject(options, "resolve");
			if(Array.isArray(value)) {
				options.resolve.extensions = value;
			} else {
				options.resolve.extensions = value.split(/,\s*/);
			}
		});

		ifArg("optimize-max-chunks", function(value) {
			ensureArray(options, "plugins");
			var LimitChunkCountPlugin = require("../lib/optimize/LimitChunkCountPlugin");
			options.plugins.push(new LimitChunkCountPlugin({
				maxChunks: parseInt(value, 10)
			}));
		});

		ifArg("optimize-min-chunk-size", function(value) {
			ensureArray(options, "plugins");
			var MinChunkSizePlugin = require("../lib/optimize/MinChunkSizePlugin");
			options.plugins.push(new MinChunkSizePlugin({
				minChunkSize: parseInt(value, 10)
			}));
		});

		ifBooleanArg("optimize-minimize", function() {
			ensureArray(options, "plugins");
			var UglifyJsPlugin = require("../lib/optimize/UglifyJsPlugin");
			var LoaderOptionsPlugin = require("../lib/LoaderOptionsPlugin");
			options.plugins.push(new UglifyJsPlugin({
				sourceMap: options.devtool && (options.devtool.indexOf("sourcemap") >= 0 || options.devtool.indexOf("source-map") >= 0)
			}));
			options.plugins.push(new LoaderOptionsPlugin({
				minimize: true
			}));
		});

		ifArg("prefetch", function(request) {
			ensureArray(options, "plugins");
			var PrefetchPlugin = require("../lib/PrefetchPlugin");
			options.plugins.push(new PrefetchPlugin(request));
		});

		ifArg("provide", function(value) {
			ensureArray(options, "plugins");
			var idx = value.indexOf("=");
			var name;
			if(idx >= 0) {
				name = value.substr(0, idx);
				value = value.substr(idx + 1);
			} else {
				name = value;
			}
			var ProvidePlugin = require("../lib/ProvidePlugin");
			options.plugins.push(new ProvidePlugin(name, value));
		});

		ifArg("plugin", function(value) {
			ensureArray(options, "plugins");
			options.plugins.push(loadPlugin(value));
		});

		mapArgToBoolean("bail");

		mapArgToBoolean("profile");

		if(noOutputFilenameDefined) {
			ensureObject(options, "output");
			if(convertOptions && convertOptions.outputFilename) {
				options.output.path = path.resolve(path.dirname(convertOptions.outputFilename));
				options.output.filename = path.basename(convertOptions.outputFilename);
			} else if(argv._.length > 0) {
				options.output.filename = argv._.pop();
				options.output.path = path.resolve(path.dirname(options.output.filename));
				options.output.filename = path.basename(options.output.filename);
			} else if(configFileLoaded) {
				throw new Error("'output.filename' is required, either in config file or as --output-filename");
			} else {
				console.error("No configuration file found and no output filename configured via CLI option.");
				console.error("A configuration file could be named 'webpack.config.js' in the current directory.");
				console.error("Use --help to display the CLI options.");
				process.exit(-1); // eslint-disable-line
			}
		}

		if(argv._.length > 0) {
			if(Array.isArray(options.entry) || typeof options.entry === "string") {
				options.entry = {
					main: options.entry
				};
			}
			ensureObject(options, "entry");

			var addTo = function addTo(name, entry) {
				if(options.entry[name]) {
					if(!Array.isArray(options.entry[name])) {
						options.entry[name] = [options.entry[name]];
					}
					options.entry[name].push(entry);
				} else {
					options.entry[name] = entry;
				}
			};
			argv._.forEach(function(content) {
				var i = content.indexOf("=");
				var j = content.indexOf("?");
				if(i < 0 || (j >= 0 && j < i)) {
					var resolved = path.resolve(content);
					if(fs.existsSync(resolved)) {
						addTo("main", `${resolved}${fs.statSync(resolved).isDirectory() ? path.sep : ""}`);
					} else {
						addTo("main", content);
					}
				} else {
					addTo(content.substr(0, i), content.substr(i + 1));
				}
			});
		}

		if(!options.entry) {
			if(configFileLoaded) {
				console.error("Configuration file found but no entry configured.");
			} else {
				console.error("No configuration file found and no entry configured via CLI option.");
				console.error("When using the CLI you need to provide at least two arguments: entry and output.");
				console.error("A configuration file could be named 'webpack.config.js' in the current directory.");
			}
			console.error("Use --help to display the CLI options.");
			process.exit(-1); // eslint-disable-line
		}
	}
};