.25-浅析webpack源码之事件流compilation(3)

　　这一节跑下一批plugin。

compiler.apply(
    new EnsureChunkConditionsPlugin(),
    new RemoveParentModulesPlugin(),
    new RemoveEmptyChunksPlugin(),
    new MergeDuplicateChunksPlugin(),
    new FlagIncludedChunksPlugin(),
    new OccurrenceOrderPlugin(true),
    new FlagDependencyExportsPlugin(),
    new FlagDependencyUsagePlugin()
);

　　希望不要跟上一节一样，全是plugin。

　　流程如图(看看流程图就行了，后面也没有什么内容)：

EnsureChunkConditionsPlugin

class EnsureChunkConditionsPlugin {
    apply(compiler) {
        compiler.plugin("compilation", (compilation) => {
            const triesMap = new Map();
            compilation.plugin(["optimize-chunks-basic", "optimize-extracted-chunks-basic"], (chunks) => { /**/ });
        });
    }
}

　　这个看看就懂，不解释了。

RemoveParentModulesPlugin

class RemoveParentModulesPlugin {
    apply(compiler) {
        compiler.plugin("compilation", (compilation) => {
            compilation.plugin(["optimize-chunks-basic", "optimize-extracted-chunks-basic"], (chunks) => { /**/ });
        });
    }
}

　　难道又是另一批plugin么……

RemoveEmptyChunksPlugin

class RemoveEmptyChunksPlugin {
    apply(compiler) {
        compiler.plugin("compilation", (compilation) => {
            compilation.plugin(["optimize-chunks-basic", "optimize-extracted-chunks-basic"], (chunks) => { /**/ });
        });
    }
}

　　是的。

MergeDuplicateChunksPlugin

class MergeDuplicateChunksPlugin {
    apply(compiler) {
        compiler.plugin("compilation", (compilation) => {
            compilation.plugin("optimize-chunks-basic", (chunks) => { /**/ });
        });
    }
}

FlagIncludedChunksPlugin

class FlagIncludedChunksPlugin {
    apply(compiler) {
        compiler.plugin("compilation", (compilation) => {
            compilation.plugin("optimize-chunk-ids", (chunks) => { /**/ });
        });
    }
}

OccurrenceOrderPlugin

class OccurrenceOrderPlugin {
    // true
    constructor(preferEntry) {
        if (preferEntry !== undefined && typeof preferEntry !== "boolean") {
            throw new Error("Argument should be a boolean.\nFor more info on this plugin, see https://webpack.js.org/plugins/");
        }
        this.preferEntry = preferEntry;
    }
    apply(compiler) {
        const preferEntry = this.preferEntry;
        compiler.plugin("compilation", (compilation) => {
            compilation.plugin("optimize-module-order", (modules) => { /**/ });
            compilation.plugin("optimize-chunk-order", (chunks) => { /**/ });
        });
    }
}

　　看到那个错误提示就想笑，这个插件除了你自己谁会去调用啊。

FlagDependencyExportsPlugin

class FlagDependencyExportsPlugin {
    apply(compiler) {
        compiler.plugin("compilation", (compilation) => {
            compilation.plugin("finish-modules", (modules) => { /**/ });

            function addToSet(a, b) { /**/ }
        });
    }
}

FlagDependencyUsagePlugin

class FlagDependencyUsagePlugin {
    apply(compiler) {
        compiler.plugin("compilation", compilation => {
            compilation.plugin("optimize-modules-advanced", modules => { /**/ });

            function addToSet(a, b) { /**/ }

            function isSubset(biggerSet, subset) { /**/ }
        });
    }
}

　　总的来说，这一批plugin是针对模块的，不过仍然没有任何实际行为。

　　还剩下3个也一并过了吧。

TemplatedPathPlugin

class TemplatedPathPlugin {
    apply(compiler) {
        compiler.plugin("compilation", compilation => {
            const mainTemplate = compilation.mainTemplate;
            mainTemplate.plugin("asset-path", replacePathVariables);
            mainTemplate.plugin("global-hash", function(chunk, paths) { /**/ });
            mainTemplate.plugin("hash-for-chunk", function(hash, chunk) { /**/ });
        });
    }
}

RecordIdsPlugin

class RecordIdsPlugin {
    apply(compiler) {
        compiler.plugin("compilation", compilation => {
            compilation.plugin("record-modules", (modules, records) => { /**/ });
            compilation.plugin("revive-modules", (modules, records) => { /**/ });

            function getDepBlockIdent(chunk, block) { /**/ }
            compilation.plugin("record-chunks", (chunks, records) => { /**/ });
            compilation.plugin("revive-chunks", (chunks, records) => { /**/ });
        });
    }
}

WarnCaseSensitiveModulesPlugin

class WarnCaseSensitiveModulesPlugin {
    apply(compiler) {
        compiler.plugin("compilation", compilation => {
            compilation.plugin("seal", () => { /**/ });
        });
    }
}

　　这里把所有compilation事件流触发完后，也只是针对不同的阶段再次进行plugin，所以详细过程还需要继续跑流程。