75 lines
3.1 KiB
TypeScript
75 lines
3.1 KiB
TypeScript
import webpack from 'webpack'
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import { RawSource } from 'webpack-sources'
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import { join, relative, dirname } from 'path'
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import { IS_BUNDLED_PAGE_REGEX } from 'next-server/constants'
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const SSR_MODULE_CACHE_FILENAME = 'ssr-module-cache.js'
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// By default webpack keeps initialized modules per-module.
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// This means that if you have 2 entrypoints loaded into the same app
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// they will *not* share the same instance
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// This creates many issues when developers / libraries rely on the singleton pattern
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// As this pattern assumes every module will have 1 instance
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// This plugin overrides webpack's code generation step to replace `installedModules`
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// The replacement is a require for a file that's also generated here that only exports an empty object
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// Because of Node.js's single instance modules this makes webpack share all initialized instances
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// Do note that this module is only geared towards the `node` compilation target.
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// For the client side compilation we use `runtimeChunk: 'single'`
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export default class NextJsSsrImportPlugin {
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private options: { outputPath: string }
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constructor(options: { outputPath: string }) {
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this.options = options
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}
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apply(compiler: webpack.Compiler) {
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const { outputPath } = this.options
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compiler.hooks.emit.tapAsync(
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'NextJsSSRModuleCache',
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(compilation, callback) => {
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compilation.assets[SSR_MODULE_CACHE_FILENAME] = new RawSource(`
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/* This cache is used by webpack for instantiated modules */
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module.exports = {}
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`)
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callback()
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}
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)
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compiler.hooks.compilation.tap(
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'NextJsSSRModuleCache',
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(compilation: any) => {
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compilation.mainTemplate.hooks.localVars.intercept({
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register(tapInfo: any) {
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if (tapInfo.name === 'MainTemplate') {
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const originalFn = tapInfo.fn
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tapInfo.fn = (source: any, chunk: any) => {
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// If the chunk is not part of the pages directory we have to keep the original behavior,
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// otherwise webpack will error out when the file is used before the compilation finishes
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// this is the case with mini-css-extract-plugin
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if (!IS_BUNDLED_PAGE_REGEX.exec(chunk.name)) {
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return originalFn(source, chunk)
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}
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const pagePath = join(outputPath, dirname(chunk.name))
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let relativePathToBaseDir = relative(
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pagePath,
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join(outputPath, SSR_MODULE_CACHE_FILENAME)
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)
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// Make sure even in windows, the path looks like in unix
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// Node.js require system will convert it accordingly
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const relativePathToBaseDirNormalized = relativePathToBaseDir.replace(
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/\\/g,
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'/'
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)
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return (webpack as any).Template.asString([
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source,
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'// The module cache',
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`var installedModules = require('${relativePathToBaseDirNormalized}');`,
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])
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}
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}
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return tapInfo
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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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