first commit

app_vue/node_modules/@vue/component-compiler-utils/lib/templateCompilerModules/srcset.ts

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+// vue compiler module for transforming `img:srcset` to a number of `require`s
+
+import { urlToRequire, ASTNode } from './utils'
+import { TransformAssetUrlsOptions } from './assetUrl'
+
+interface ImageCandidate {
+  require: string
+  descriptor: string
+}
+
+export default (transformAssetUrlsOptions?: TransformAssetUrlsOptions) => ({
+  postTransformNode: (node: ASTNode) => {
+    transform(node, transformAssetUrlsOptions)
+  }
+})
+
+// http://w3c.github.io/html/semantics-embedded-content.html#ref-for-image-candidate-string-5
+const escapedSpaceCharacters = /( |\\t|\\n|\\f|\\r)+/g
+
+function transform(
+  node: ASTNode,
+  transformAssetUrlsOptions?: TransformAssetUrlsOptions
+) {
+  const tags = ['img', 'source']
+
+  if (tags.indexOf(node.tag) !== -1 && node.attrs) {
+    node.attrs.forEach(attr => {
+      if (attr.name === 'srcset') {
+        // same logic as in transform-require.js
+        const value = attr.value
+        const isStatic =
+          value.charAt(0) === '"' && value.charAt(value.length - 1) === '"'
+        if (!isStatic) {
+          return
+        }
+
+        const imageCandidates: ImageCandidate[] = value
+          .substr(1, value.length - 2)
+          .split(',')
+          .map(s => {
+            // The attribute value arrives here with all whitespace, except
+            // normal spaces, represented by escape sequences
+            const [url, descriptor] = s
+              .replace(escapedSpaceCharacters, ' ')
+              .trim()
+              .split(' ', 2)
+            return {
+              require: urlToRequire(url, transformAssetUrlsOptions),
+              descriptor
+            }
+          })
+
+        // "require(url1)"
+        // "require(url1) 1x"
+        // "require(url1), require(url2)"
+        // "require(url1), require(url2) 2x"
+        // "require(url1) 1x, require(url2)"
+        // "require(url1) 1x, require(url2) 2x"
+        const code = imageCandidates
+          .map(
+            ({ require, descriptor }) =>
+              `${require} + "${descriptor ? ' ' + descriptor : ''}, " + `
+          )
+          .join('')
+          .slice(0, -6)
+          .concat('"')
+          .replace(/ \+ ""$/, '')
+
+        attr.value = code
+      }
+    })
+  }
+}