logically group modules into folders

src/server/$meta.js

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+import inject from './inject'
+
+/**
+ * Returns an injector for server-side rendering.
+ * @this {Object} - the Vue instance (a root component)
+ * @return {Object} - injector
+ */
+export default function $meta () {
+  // bind inject method to this component
+  return { inject: inject.bind(this) }
+}

src/server/generateServerInjector.js

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+import titleGenerator from './generators/titleGenerator'
+import attrsGenerator from './generators/attrsGenerator'
+
+/**
+ * Converts a meta info property to one that can be stringified on the server
+ *
+ * @param  {String} type - the type of data to convert
+ * @param  {(String|Object|Array<Object>)} data - the data value
+ * @return {Object} - the new injector
+ */
+export default function generateServerInjector (type, data) {
+  switch (type) {
+    case 'title':
+      return titleGenerator(type, data)
+    case 'htmlAttrs':
+    case 'bodyAttrs':
+      return attrsGenerator(type, data)
+  }
+}

src/server/generators/attrsGenerator.js

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+import { VUE_META_ATTRIBUTE } from '../../shared/constants'
+
+/**
+ * Generates tag attributes for use on the server.
+ *
+ * @param  {('bodyAttrs'|'htmlAttrs')} type - the type of attributes to generate
+ * @param  {Object} data - the attributes to generate
+ * @return {Object} - the attribute generator
+ */
+export default function attrsGenerator (type, data) {
+  return {
+    text () {
+      let attributeStr = ''
+      let watchedAttrs = []
+      for (let attr in data) {
+        if (data.hasOwnProperty(attr)) {
+          watchedAttrs.push(attr)
+          attributeStr += `${
+            typeof data[attr] !== 'undefined'
+              ? `${attr}="${data[attr]}"`
+              : attr
+          } `
+        }
+      }
+      attributeStr += `${VUE_META_ATTRIBUTE}="${watchedAttrs.join(',')}"`
+      return attributeStr.trim()
+    }
+  }
+}

src/server/generators/titleGenerator.js

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+import { VUE_META_ATTRIBUTE } from '../../shared/constants'
+
+/**
+ * Generates title output for the server
+ *
+ * @param  {'title'} type - the string "title"
+ * @param  {String} data - the title text
+ * @return {Object} - the title generator
+ */
+export default function titleGenerator (type, data) {
+  return {
+    text () {
+      return `<${type} ${VUE_META_ATTRIBUTE}="true">${data}</${type}>`
+    }
+  }
+}

src/server/inject.js

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+import getMetaInfo from '../shared/getMetaInfo'
+import generateServerInjector from './generateServerInjector'
+
+/**
+ * Converts the state of the meta info object such that each item
+ * can be compiled to a tag string on the server
+ *
+ * @this {Object} - Vue instance - ideally the root component
+ * @return {Object} - server meta info with `toString` methods
+ */
+export default function inject () {
+  const Vue = this.constructor
+
+  // get meta info with sensible defaults
+  const info = Vue.util.extend({
+    title: '',
+    htmlAttrs: {},
+    bodyAttrs: {}
+  }, getMetaInfo(this.$root))
+
+  // generate server injectors
+  for (let key in info) {
+    if (info.hasOwnProperty(key) && key !== 'titleTemplate') {
+      info[key] = generateServerInjector(key, info[key])
+    }
+  }
+
+  return info
+}