loader.js

const NodeTargetPlugin = require('webpack/lib/node/NodeTargetPlugin')
const EntryPlugin = require('webpack/lib/EntryPlugin')
const LazySet = require('webpack/lib/util/LazySet')
const LimitChunkCountPlugin = require('webpack/lib/optimize/LimitChunkCountPlugin')
const FlagEntryExportAsUsedPlugin = require('webpack/lib/FlagEntryExportAsUsedPlugin')
const path = require('path')
const WxsPlugin = require('./WxsPlugin')
const RecordResourceMapDependency = require('../dependencies/RecordResourceMapDependency')
const parseRequest = require('../utils/parse-request')
const toPosix = require('../utils/to-posix')
const fixRelative = require('../utils/fix-relative')
const addQuery = require('../utils/add-query')
const config = require('../config')

module.exports = content => content

module.exports.pitch = function (remainingRequest) {
  const nativeCallback = this.async()
  const moduleGraph = this._compilation.moduleGraph
  const mpx = this.getMpx()
  const mode = mpx.mode
  const getOutputPath = mpx.getOutputPath
  let { resourcePath, queryObj, rawResourcePath } = parseRequest(this.resource)
  const issuer = moduleGraph.getIssuer(this._module)
  const { resourcePath: issuerResourcePath, queryObj: issuerQueryObj } = parseRequest(queryObj.issuerResource || issuer.resource)
  const issuerPackageName = issuerQueryObj.packageRoot || 'main'
  const pagesMap = mpx.pagesMap
  const componentsMap = mpx.componentsMap[issuerPackageName]
  const staticResourcesMap = mpx.staticResourcesMap[issuerPackageName]
  const issuerName = pagesMap[issuerResourcePath] || componentsMap[issuerResourcePath] || staticResourcesMap[issuerResourcePath]
  const issuerDir = path.dirname(issuerName)

  const getName = (raw) => {
    const match = /^(.*?)(\.[^.]*)?$/.exec(raw)
    return match[1]
  }

  const wxsModule = queryObj.wxsModule
  if (wxsModule) {
    resourcePath = `${rawResourcePath}~${wxsModule}`
  }
  const packageRoot = queryObj.packageRoot || ''
  const ext = config[mode].wxs.ext
  const filename = toPosix(path.join(packageRoot, getOutputPath(resourcePath, ext.slice(1), { ext })))
  this._module.addPresentationalDependency(new RecordResourceMapDependency(resourcePath, 'staticResource', filename, packageRoot))

  const callback = (err) => {
    if (err) return nativeCallback(err)
    let relativePath = toPosix(path.relative(issuerDir, filename))
    relativePath = fixRelative(relativePath, mode)
    nativeCallback(null, `module.exports = ${JSON.stringify(relativePath)};`)
  }

  // 清空issuerResource query避免文件内容输出报错并进行子编译缓存优化
  const request = '!!' + addQuery(remainingRequest, {}, false, ['issuerResource'])

  // request中已经包含全量构成filename的信息，故可以直接使用request作为key来进行缓存
  if (!mpx.wxsAssetsCache.has(request)) {
    mpx.wxsAssetsCache.set(request, new Promise((resolve, reject) => {
      const outputOptions = {
        filename,
        // 避免输出的wxs中包含es语法
        environment: {
          // The environment supports arrow functions ('() => { ... }').
          arrowFunction: false,
          // The environment supports BigInt as literal (123n).
          bigIntLiteral: false,
          // The environment supports const and let for variable declarations.
          const: false,
          // The environment supports destructuring ('{ a, b } = obj').
          destructuring: false,
          // The environment supports an async import() function to import EcmaScript modules.
          dynamicImport: false,
          // The environment supports 'for of' iteration ('for (const x of array) { ... }').
          forOf: false,
          // The environment supports ECMAScript Module syntax to import ECMAScript modules (import ... from '...').
          module: false
        }
      }

      const plugins = [
        new WxsPlugin({ mode }),
        new NodeTargetPlugin(),
        new EntryPlugin(this.context, request, { name: getName(filename) }),
        new LimitChunkCountPlugin({ maxChunks: 1 }),
        new FlagEntryExportAsUsedPlugin(true, 'entry')
      ]

      const childCompiler = this._compilation.createChildCompiler(resourcePath, outputOptions, plugins)

      let assets = []

      childCompiler.hooks.afterCompile.tap('MpxWebpackPlugin', (compilation) => {
        // 持久化缓存，使用module.buildInfo.assets来输出文件
        assets = compilation.getAssets()
        compilation.clearAssets()
      })

      childCompiler.runAsChild((err, entries, compilation) => {
        if (err) return reject(err)
        const fileDependencies = new LazySet()
        const contextDependencies = new LazySet()
        const missingDependencies = new LazySet()
        const buildDependencies = new LazySet()
        compilation.modules.forEach((module) => {
          module.addCacheDependencies(
            fileDependencies,
            contextDependencies,
            missingDependencies,
            buildDependencies
          )
        })
        resolve({
          assets,
          fileDependencies,
          contextDependencies,
          missingDependencies,
          buildDependencies
        })
      })
    }))
  }

  mpx.wxsAssetsCache.get(request).then(({ assets, fileDependencies, contextDependencies, missingDependencies, buildDependencies }) => {
    assets.forEach(({ name, source, info }) => {
      this.emitFile(name, source.source(), undefined, info)
    })
    fileDependencies.forEach((dep) => {
      this.addDependency(dep)
    })
    contextDependencies.forEach((dep) => {
      this.addContextDependency(dep)
    })
    missingDependencies.forEach((dep) => {
      this.addMissingDependency(dep)
    })
    buildDependencies.forEach((dep) => {
      this.addBuildDependency(dep)
    })
    callback()
  }).catch(callback)
}