feat(compiler-sfc): support transforming absolute asset urls

BREAKING CHANGE: `@vue/compiler-sfc`'s `transformAssetUrlsBase` option
has been removed. It is merged into `trasnformAssetUrls` which now also
accepts the format of

  ```ts
  {
    base?: string
    includeAbsolute?: string
    tags?: { [name: string]: string[] }
  }
  ```

packages/compiler-sfc/src/compileTemplate.ts

@@ -10,9 +10,14 @@ import { SourceMapConsumer, SourceMapGenerator, RawSourceMap } from 'source-map'
 import {
   transformAssetUrl,
   AssetURLOptions,
-  createAssetUrlTransformWithOptions
+  createAssetUrlTransformWithOptions,
+  AssetURLTagConfig,
+  normalizeOptions
 } from './templateTransformAssetUrl'
-import { transformSrcset } from './templateTransformSrcset'
+import {
+  transformSrcset,
+  createSrcsetTransformWithOptions
+} from './templateTransformSrcset'
 import { isObject } from '@vue/shared'
 import * as CompilerDOM from '@vue/compiler-dom'
 import * as CompilerSSR from '@vue/compiler-ssr'
@@ -47,16 +52,10 @@ export interface SFCTemplateCompileOptions {
    */
   preprocessCustomRequire?: (id: string) => any
   /**
-   * Configure what tags/attributes to trasnform into relative asset url imports
-   * in the form of `{ [tag: string]: string[] }`, or disable the transform with
-   * `false`.
+   * Configure what tags/attributes to trasnform into asset url imports,
+   * or disable the transform altogether with `false`.
    */
-  transformAssetUrls?: AssetURLOptions | boolean
-  /**
-   * If base is provided, instead of transforming relative asset urls into
-   * imports, they will be directly rewritten to absolute urls.
-   */
-  transformAssetUrlsBase?: string
+  transformAssetUrls?: AssetURLOptions | AssetURLTagConfig | boolean
 }
 
 function preprocess(
@@ -144,24 +143,19 @@ function doCompileTemplate({
   ssr = false,
   compiler = ssr ? (CompilerSSR as TemplateCompiler) : CompilerDOM,
   compilerOptions = {},
-  transformAssetUrls,
-  transformAssetUrlsBase
+  transformAssetUrls
 }: SFCTemplateCompileOptions): SFCTemplateCompileResults {
   const errors: CompilerError[] = []
 
   let nodeTransforms: NodeTransform[] = []
-  if (transformAssetUrls !== false) {
-    if (transformAssetUrlsBase || isObject(transformAssetUrls)) {
-      nodeTransforms = [
-        createAssetUrlTransformWithOptions({
-          base: transformAssetUrlsBase,
-          tags: isObject(transformAssetUrls) ? transformAssetUrls : undefined
-        }),
-        transformSrcset
-      ]
-    } else {
-      nodeTransforms = [transformAssetUrl, transformSrcset]
-    }
+  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, {

packages/compiler-sfc/src/templateTransformAssetUrl.ts

@@ -8,18 +8,28 @@ import {
   TransformContext
 } from '@vue/compiler-core'
 import { isRelativeUrl, parseUrl } from './templateUtils'
+import { isArray } from '@vue/shared'
 
-export interface AssetURLOptions {
+export interface AssetURLTagConfig {
   [name: string]: string[]
 }
 
-export interface NormlaizedAssetURLOptions {
+export interface AssetURLOptions {
+  /**
+   * If base is provided, instead of transforming relative asset urls into
+   * imports, they will be directly rewritten to absolute urls.
+   */
   base?: string | null
-  tags?: AssetURLOptions
+  /**
+   * If true, also processes absolute urls.
+   */
+  includeAbsolute?: boolean
+  tags?: AssetURLTagConfig
 }
 
-const defaultAssetUrlOptions: Required<NormlaizedAssetURLOptions> = {
+export const defaultAssetUrlOptions: Required<AssetURLOptions> = {
   base: null,
+  includeAbsolute: false,
   tags: {
     video: ['src', 'poster'],
     source: ['src'],
@@ -29,15 +39,27 @@ const defaultAssetUrlOptions: Required<NormlaizedAssetURLOptions> = {
   }
 }
 
-export const createAssetUrlTransformWithOptions = (
-  options: NormlaizedAssetURLOptions
-): NodeTransform => {
-  const mergedOptions = {
+export const normalizeOptions = (
+  options: AssetURLOptions | AssetURLTagConfig
+): Required<AssetURLOptions> => {
+  if (Object.keys(options).some(key => isArray((options as any)[key]))) {
+    // legacy option format which directly passes in tags config
+    return {
+      ...defaultAssetUrlOptions,
+      tags: options as any
+    }
+  }
+  return {
     ...defaultAssetUrlOptions,
     ...options
   }
+}
+
+export const createAssetUrlTransformWithOptions = (
+  options: Required<AssetURLOptions>
+): NodeTransform => {
   return (node, context) =>
-    (transformAssetUrl as Function)(node, context, mergedOptions)
+    (transformAssetUrl as Function)(node, context, options)
 }
 
 /**
@@ -56,7 +78,7 @@ export const createAssetUrlTransformWithOptions = (
 export const transformAssetUrl: NodeTransform = (
   node,
   context,
-  options: NormlaizedAssetURLOptions = defaultAssetUrlOptions
+  options: AssetURLOptions = defaultAssetUrlOptions
 ) => {
   if (node.type === NodeTypes.ELEMENT) {
     const tags = options.tags || defaultAssetUrlOptions.tags
@@ -69,16 +91,21 @@ export const transformAssetUrl: NodeTransform = (
               attr.type !== NodeTypes.ATTRIBUTE ||
               attr.name !== name ||
               !attr.value ||
-              !isRelativeUrl(attr.value.content)
+              (!options.includeAbsolute && !isRelativeUrl(attr.value.content))
             ) {
               return
             }
+
             const url = parseUrl(attr.value.content)
+
             if (options.base) {
               // explicit base - directly rewrite the url into absolute url
-              // does not apply to url that starts with `@` since they are
-              // aliases
-              if (attr.value.content[0] !== '@') {
+              // does not apply to absolute urls or urls that start with `@`
+              // since they are aliases
+              if (
+                attr.value.content[0] !== '@' &&
+                isRelativeUrl(attr.value.content)
+              ) {
                 // when packaged in the browser, path will be using the posix-
                 // only version provided by rollup-plugin-node-builtins.
                 attr.value.content = (path.posix || path).join(
@@ -86,24 +113,25 @@ export const transformAssetUrl: NodeTransform = (
                   url.path + (url.hash || '')
                 )
               }
-            } else {
-              // otherwise, transform the url into an import.
-              // this assumes a bundler will resolve the import into the correct
-              // absolute url (e.g. webpack file-loader)
-              const exp = getImportsExpressionExp(
-                url.path,
-                url.hash,
-                attr.loc,
-                context
-              )
-              node.props[index] = {
-                type: NodeTypes.DIRECTIVE,
-                name: 'bind',
-                arg: createSimpleExpression(name, true, attr.loc),
-                exp,
-                modifiers: [],
-                loc: attr.loc
-              }
+              return
+            }
+
+            // otherwise, transform the url into an import.
+            // this assumes a bundler will resolve the import into the correct
+            // absolute url (e.g. webpack file-loader)
+            const exp = getImportsExpressionExp(
+              url.path,
+              url.hash,
+              attr.loc,
+              context
+            )
+            node.props[index] = {
+              type: NodeTypes.DIRECTIVE,
+              name: 'bind',
+              arg: createSimpleExpression(name, true, attr.loc),
+              exp,
+              modifiers: [],
+              loc: attr.loc
             }
           })
         })

packages/compiler-sfc/src/templateTransformSrcset.ts

@@ -1,3 +1,4 @@
+import path from 'path'
 import {
   createCompoundExpression,
   createSimpleExpression,
@@ -5,7 +6,11 @@ import {
   NodeTypes,
   SimpleExpressionNode
 } from '@vue/compiler-core'
-import { isRelativeUrl, parseUrl } from './templateUtils'
+import { isRelativeUrl, parseUrl, isExternalUrl } from './templateUtils'
+import {
+  AssetURLOptions,
+  defaultAssetUrlOptions
+} from './templateTransformAssetUrl'
 
 const srcsetTags = ['img', 'source']
 
@@ -17,13 +22,23 @@ interface ImageCandidate {
 // http://w3c.github.io/html/semantics-embedded-content.html#ref-for-image-candidate-string-5
 const escapedSpaceCharacters = /( |\\t|\\n|\\f|\\r)+/g
 
-export const transformSrcset: NodeTransform = (node, context) => {
+export const createSrcsetTransformWithOptions = (
+  options: Required<AssetURLOptions>
+): NodeTransform => {
+  return (node, context) =>
+    (transformSrcset as Function)(node, context, options)
+}
+
+export const transformSrcset: NodeTransform = (
+  node,
+  context,
+  options: Required<AssetURLOptions> = defaultAssetUrlOptions
+) => {
   if (node.type === NodeTypes.ELEMENT) {
     if (srcsetTags.includes(node.tag) && node.props.length) {
       node.props.forEach((attr, index) => {
         if (attr.name === 'srcset' && attr.type === NodeTypes.ATTRIBUTE) {
           if (!attr.value) return
-          // same logic as in transform-require.js
           const value = attr.value.content
 
           const imageCandidates: ImageCandidate[] = value.split(',').map(s => {
@@ -37,11 +52,34 @@ export const transformSrcset: NodeTransform = (node, context) => {
           })
 
           // When srcset does not contain any relative URLs, skip transforming
-          if (!imageCandidates.some(({ url }) => isRelativeUrl(url))) return
+          if (
+            !options.includeAbsolute &&
+            !imageCandidates.some(({ url }) => isRelativeUrl(url))
+          ) {
+            return
+          }
+
+          if (options.base) {
+            const base = options.base
+            const set: string[] = []
+            imageCandidates.forEach(({ url, descriptor }, index) => {
+              descriptor = descriptor ? ` ${descriptor}` : ``
+              if (isRelativeUrl(url)) {
+                set.push((path.posix || path).join(base, url) + descriptor)
+              } else {
+                set.push(url + descriptor)
+              }
+            })
+            attr.value.content = set.join(', ')
+            return
+          }
 
           const compoundExpression = createCompoundExpression([], attr.loc)
           imageCandidates.forEach(({ url, descriptor }, index) => {
-            if (isRelativeUrl(url)) {
+            if (
+              !isExternalUrl(url) &&
+              (options.includeAbsolute || isRelativeUrl(url))
+            ) {
               const { path } = parseUrl(url)
               let exp: SimpleExpressionNode
               if (path) {

packages/compiler-sfc/src/templateUtils.ts

@@ -6,6 +6,11 @@ export function isRelativeUrl(url: string): boolean {
   return firstChar === '.' || firstChar === '~' || firstChar === '@'
 }
 
+const externalRE = /^https?:\/\//
+export function isExternalUrl(url: string): boolean {
+  return externalRE.test(url)
+}
+
 /**
  * Parses string url into URL object.
  */