core/packages/compiler-sfc/src/compileTemplate.ts

import {
  CompilerOptions,
  CodegenResult,
  CompilerError,
  NodeTransform,
  ParserOptions,
  RootNode
} from '@vue/compiler-core'
import { SourceMapConsumer, SourceMapGenerator, RawSourceMap } from 'source-map'
import {
  transformAssetUrl,
  AssetURLOptions,
  createAssetUrlTransformWithOptions,
  AssetURLTagConfig,
  normalizeOptions
} from './templateTransformAssetUrl'
import {
  transformSrcset,
  createSrcsetTransformWithOptions
} from './templateTransformSrcset'
import { isObject } from '@vue/shared'
import * as CompilerDOM from '@vue/compiler-dom'
import * as CompilerSSR from '@vue/compiler-ssr'
import consolidate from 'consolidate'

export interface TemplateCompiler {
  compile(template: string, options: CompilerOptions): CodegenResult
  parse(template: string, options: ParserOptions): RootNode
}

export interface SFCTemplateCompileResults {
  code: string
  source: string
  tips: string[]
  errors: (string | CompilerError)[]
  map?: RawSourceMap
}

export interface SFCTemplateCompileOptions {
  source: string
  filename: string
  ssr?: boolean
  inMap?: RawSourceMap
  compiler?: TemplateCompiler
  compilerOptions?: CompilerOptions
  preprocessLang?: string
  preprocessOptions?: any
  /**
   * In some cases, compiler-sfc may not be inside the project root (e.g. when
   * linked or globally installed). In such cases a custom `require` can be
   * passed to correctly resolve the preprocessors.
   */
  preprocessCustomRequire?: (id: string) => any
  /**
   * Configure what tags/attributes to trasnform into asset url imports,
   * or disable the transform altogether with `false`.
   */
  transformAssetUrls?: AssetURLOptions | AssetURLTagConfig | boolean
}

interface PreProcessor {
  render(
    source: string,
    options: any,
    cb: (err: Error | null, res: string) => void
  ): void
}

function preprocess(
  { source, filename, preprocessOptions }: SFCTemplateCompileOptions,
  preprocessor: PreProcessor
): string {
  // 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: string = ''
  let err: Error | null = null

  preprocessor.render(
    source,
    { filename, ...preprocessOptions },
    (_err, _res) => {
      if (_err) err = _err
      res = _res
    }
  )

  if (err) throw err
  return res
}

export function compileTemplate(
  options: SFCTemplateCompileOptions
): SFCTemplateCompileResults {
  const { preprocessLang, preprocessCustomRequire } = options

  if (
    (__ESM_BROWSER__ || __GLOBAL__) &&
    preprocessLang &&
    !preprocessCustomRequire
  ) {
    throw new Error(
      `[@vue/compiler-sfc] Template preprocessing in the browser build must ` +
        `provide the \`preprocessCustomRequire\` option to return the in-browser ` +
        `version of the preprocessor in the shape of { render(): string }.`
    )
  }

  const preprocessor = preprocessLang
    ? preprocessCustomRequire
      ? preprocessCustomRequire(preprocessLang)
      : require('consolidate')[preprocessLang as keyof typeof consolidate]
    : false
  if (preprocessor) {
    try {
      return doCompileTemplate({
        ...options,
        source: preprocess(options, preprocessor)
      })
    } catch (e) {
      return {
        code: `export default function render() {}`,
        source: options.source,
        tips: [],
        errors: [e]
      }
    }
  } else if (preprocessLang) {
    return {
      code: `export default function render() {}`,
      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 doCompileTemplate(options)
  }
}

function doCompileTemplate({
  filename,
  inMap,
  source,
  ssr = false,
  compiler = ssr ? (CompilerSSR as TemplateCompiler) : CompilerDOM,
  compilerOptions = {},
  transformAssetUrls
}: SFCTemplateCompileOptions): SFCTemplateCompileResults {
  const errors: CompilerError[] = []

  let nodeTransforms: NodeTransform[] = []
  if (isObject(transformAssetUrls)) {
    const assetOptions = normalizeOptions(transformAssetUrls)
    nodeTransforms = [
      createAssetUrlTransformWithOptions(assetOptions),
      createSrcsetTransformWithOptions(assetOptions)
    ]
  } else if (transformAssetUrls !== false) {
    nodeTransforms = [transformAssetUrl, transformSrcset]
  }

  let { code, map } = compiler.compile(source, {
    mode: 'module',
    prefixIdentifiers: true,
    hoistStatic: true,
    cacheHandlers: true,
    ...compilerOptions,
    nodeTransforms: nodeTransforms.concat(compilerOptions.nodeTransforms || []),
    filename,
    sourceMap: true,
    onError: e => errors.push(e)
  })

  // inMap should be the map produced by ./parse.ts which is a simple line-only
  // mapping. If it is present, we need to adjust the final map and errors to
  // reflect the original line numbers.
  if (inMap) {
    if (map) {
      map = mapLines(inMap, map)
    }
    if (errors.length) {
      patchErrors(errors, source, inMap)
    }
  }

  return { code, source, errors, tips: [], map }
}

function mapLines(oldMap: RawSourceMap, newMap: RawSourceMap): RawSourceMap {
  if (!oldMap) return newMap
  if (!newMap) return oldMap

  const oldMapConsumer = new SourceMapConsumer(oldMap)
  const newMapConsumer = new SourceMapConsumer(newMap)
  const mergedMapGenerator = new SourceMapGenerator()

  newMapConsumer.eachMapping(m => {
    if (m.originalLine == null) {
      return
    }

    const origPosInOldMap = oldMapConsumer.originalPositionFor({
      line: m.originalLine,
      column: m.originalColumn
    })

    if (origPosInOldMap.source == null) {
      return
    }

    mergedMapGenerator.addMapping({
      generated: {
        line: m.generatedLine,
        column: m.generatedColumn
      },
      original: {
        line: origPosInOldMap.line, // map line
        // use current column, since the oldMap produced by @vue/compiler-sfc
        // does not
        column: m.originalColumn
      },
      source: origPosInOldMap.source,
      name: origPosInOldMap.name
    })
  })

  // source-map's type definition is incomplete
  const generator = mergedMapGenerator as any
  ;(oldMapConsumer as any).sources.forEach((sourceFile: string) => {
    generator._sources.add(sourceFile)
    const sourceContent = oldMapConsumer.sourceContentFor(sourceFile)
    if (sourceContent != null) {
      mergedMapGenerator.setSourceContent(sourceFile, sourceContent)
    }
  })

  generator._sourceRoot = oldMap.sourceRoot
  generator._file = oldMap.file
  return generator.toJSON()
}

function patchErrors(
  errors: CompilerError[],
  source: string,
  inMap: RawSourceMap
) {
  const originalSource = inMap.sourcesContent![0]
  const offset = originalSource.indexOf(source)
  const lineOffset = originalSource.slice(0, offset).split(/\r?\n/).length - 1
  errors.forEach(err => {
    if (err.loc) {
      err.loc.start.line += lineOffset
      err.loc.start.offset += offset
      if (err.loc.end !== err.loc.start) {
        err.loc.end.line += lineOffset
        err.loc.end.offset += offset
      }
    }
  })
}