vuejs/node_modules/@vue/component-compiler-utils/lib/compileTemplate.ts

import {
  VueTemplateCompiler,
  VueTemplateCompilerOptions,
  ErrorWithRange
} from './types'

import assetUrlsModule, {
  AssetURLOptions
} from './templateCompilerModules/assetUrl'
import srcsetModule from './templateCompilerModules/srcset'

const consolidate = require('consolidate')
const transpile = require('vue-template-es2015-compiler')

export interface TemplateCompileOptions {
  source: string
  filename: string
  compiler: VueTemplateCompiler
  compilerOptions?: VueTemplateCompilerOptions
  transformAssetUrls?: AssetURLOptions | boolean
  preprocessLang?: string
  preprocessOptions?: any
  transpileOptions?: any
  isProduction?: boolean
  isFunctional?: boolean
  optimizeSSR?: boolean
  prettify?: boolean
}

export interface TemplateCompileResult {
  code: string
  source: string
  tips: (string | ErrorWithRange)[]
  errors: (string | ErrorWithRange)[]
}

export function compileTemplate(
  options: TemplateCompileOptions
): TemplateCompileResult {
  const { preprocessLang } = options
  const preprocessor = preprocessLang && consolidate[preprocessLang]
  if (preprocessor) {
    return actuallyCompile(
      Object.assign({}, options, {
        source: preprocess(options, preprocessor)
      })
    )
  } else if (preprocessLang) {
    return {
      code: `var render = function () {}\n` + `var staticRenderFns = []\n`,
      source: options.source,
      tips: [
        `Component ${
          options.filename
        } uses lang ${preprocessLang} for template. Please install the language preprocessor.`
      ],
      errors: [
        `Component ${
          options.filename
        } uses lang ${preprocessLang} for template, however it is not installed.`
      ]
    }
  } else {
    return actuallyCompile(options)
  }
}

function preprocess(
  options: TemplateCompileOptions,
  preprocessor: any
): string {
  const { source, filename, preprocessOptions } = options

  const finalPreprocessOptions = Object.assign(
    {
      filename
    },
    preprocessOptions
  )

  // Consolidate exposes a callback based API, but the callback is in fact
  // called synchronously for most templating engines. In our case, we have to
  // expose a synchronous API so that it is usable in Jest transforms (which
  // have to be sync because they are applied via Node.js require hooks)
  let res: any, err
  preprocessor.render(
    source,
    finalPreprocessOptions,
    (_err: Error | null, _res: string) => {
      if (_err) err = _err
      res = _res
    }
  )

  if (err) throw err
  return res
}

function actuallyCompile(
  options: TemplateCompileOptions
): TemplateCompileResult {
  const {
    source,
    compiler,
    compilerOptions = {},
    transpileOptions = {},
    transformAssetUrls,
    isProduction = process.env.NODE_ENV === 'production',
    isFunctional = false,
    optimizeSSR = false,
    prettify = true
  } = options

  const compile =
    optimizeSSR && compiler.ssrCompile ? compiler.ssrCompile : compiler.compile

  let finalCompilerOptions = compilerOptions
  if (transformAssetUrls) {
    const builtInModules = [
      transformAssetUrls === true
        ? assetUrlsModule()
        : assetUrlsModule(transformAssetUrls),
      srcsetModule()
    ]
    finalCompilerOptions = Object.assign({}, compilerOptions, {
      modules: [...builtInModules, ...(compilerOptions.modules || [])]
    })
  }

  const { render, staticRenderFns, tips, errors } = compile(
    source,
    finalCompilerOptions
  )

  if (errors && errors.length) {
    return {
      code: `var render = function () {}\n` + `var staticRenderFns = []\n`,
      source,
      tips,
      errors
    }
  } else {
    const finalTranspileOptions = Object.assign({}, transpileOptions, {
      transforms: Object.assign({}, transpileOptions.transforms, {
        stripWithFunctional: isFunctional
      })
    })

    const toFunction = (code: string): string => {
      return `function (${isFunctional ? `_h,_vm` : ``}) {${code}}`
    }

    // transpile code with vue-template-es2015-compiler, which is a forked
    // version of Buble that applies ES2015 transforms + stripping `with` usage
    let code =
      transpile(
        `var __render__ = ${toFunction(render)}\n` +
          `var __staticRenderFns__ = [${staticRenderFns.map(toFunction)}]`,
        finalTranspileOptions
      ) + `\n`

    // #23 we use __render__ to avoid `render` not being prefixed by the
    // transpiler when stripping with, but revert it back to `render` to
    // maintain backwards compat
    code = code.replace(/\s__(render|staticRenderFns)__\s/g, ' $1 ')

    if (!isProduction) {
      // mark with stripped (this enables Vue to use correct runtime proxy
      // detection)
      code += `render._withStripped = true`

      if (prettify) {
        code = require('prettier').format(code, {
          semi: false,
          parser: 'babel'
        })
      }
    }

    return {
      code,
      source,
      tips,
      errors
    }
  }
}