add with-next-layouts example

examples/with-next-layouts/layouts/AppLayout.js

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+import React from 'react'
+import delay from '../modules/delay'
+
+export default class AppLayout extends React.Component {
+  static async getInitialProps () {
+    return {
+      delay: await delay(1000)
+    }
+  }
+
+  render () {
+    return (
+      <div>
+        <h1>App header</h1>
+        {this.props.children}
+      </div>
+    )
+  }
+}

examples/with-next-layouts/layouts/ContentLayout.js

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+import React from 'react'
+import delay from '../modules/delay'
+import AppLayout from './AppLayout'
+
+export default class ContentLayout extends React.Component {
+  static parentLayout = AppLayout
+  static async getInitialProps () {
+    return {
+      delay: await delay(2000)
+    }
+  }
+
+  render () {
+    return (
+      <div>
+        <hr />
+        {this.props.children}
+        <hr />
+      </div>
+    )
+  }
+}

examples/with-next-layouts/modules/delay.js

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+export default function delay (ms) {
+  return new Promise(resolve => setTimeout(() => {
+    console.log(`sleep ${ms} ms.`)
+    resolve(ms)
+  }, ms))
+}

examples/with-next-layouts/modules/next-layouts.js

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+import React from 'react'
+const defaultOptions = {
+  getInitialPropsMode: 'sequential'
+}
+
+export default function applyLayout (PageComponent, options) {
+  options = Object.assign({}, defaultOptions, options)
+
+  if (!isFunction(PageComponent.layout)) {
+    warn('Missing static property "layout" of page component.')
+    return PageComponent
+  }
+
+  if (isFunction(PageComponent.renderPage)) {
+    warn('You should not define static property "renderPage" of page component when the layout is applying')
+    return PageComponent
+  }
+
+  // collect layouts & getInitialProps
+  let layouts = [PageComponent.layout]
+  while (isFunction(layouts[0].parentLayout)) {
+    layouts.unshift(layouts[0].parentLayout)
+  }
+  const layoutGetInitialPropsList = layouts.map(Layout => isFunction(Layout.getInitialProps) ? Layout.getInitialProps : () => ({}))
+  const pageGetInitialProps = isFunction(PageComponent.getInitialProps) ? PageComponent.getInitialProps : () => ({})
+
+  PageComponent.getInitialProps = async(ctx) => {
+    let layoutPropsList = []
+    let pageProps
+
+    if (options.getInitialPropsMode === 'sequential') {
+      for (const layoutGetInitialProps of layoutGetInitialPropsList) {
+        const layoutProps = await layoutGetInitialProps(ctx)
+        layoutPropsList.push(layoutProps)
+      }
+      pageProps = await pageGetInitialProps(ctx)
+    } else if (options.getInitialPropsMode === 'concurrent') {
+      const promises = layoutGetInitialPropsList.map(layoutGetInitialProps => layoutGetInitialProps(ctx))
+      promises.push(pageGetInitialProps(ctx))
+      const promiseResults = await Promise.all(promises)
+      pageProps = promiseResults.pop()
+      layoutPropsList = promiseResults
+    }
+
+    return { layoutPropsList, pageProps }
+  }
+
+  PageComponent.renderPage = ({ Component, props: { layoutPropsList, pageProps }, url }) => {
+    return renderLayout({ Component, layouts, pageProps, layoutPropsList, url })
+  }
+
+  return PageComponent
+}
+
+function renderLayout ({ Component, layouts, pageProps, layoutPropsList, url }) {
+  const Layout = layouts[0]
+  const layoutProps = layoutPropsList[0]
+  return (Layout) ? (
+    <Layout {...layoutProps} pageProps={pageProps} url={url}>
+      {renderLayout({
+        Component,
+        layouts: layouts.slice(1, layouts.length),
+        pageProps,
+        layoutPropsList: layoutPropsList.slice(1, layoutPropsList.length),
+        url
+      })}
+    </Layout>
+  ) : (
+    <Component {...pageProps} url={url} />
+  )
+}
+
+function isFunction (func) {
+  return typeof func === 'function'
+}
+
+function warn (message) {
+  if (process.env.NODE_ENV !== 'production') {
+    console.error(message)
+  }
+}

examples/with-next-layouts/package.json

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+{
+  "name": "with-next-layouts",
+  "version": "1.0.0",
+  "scripts": {
+    "dev": "next",
+    "build": "next build",
+    "start": "next start"
+  },
+  "dependencies": {
+    "next": "latest",
+    "react": "^16.0.0",
+    "react-dom": "^16.0.0"
+  },
+  "license": "ISC"
+}

examples/with-next-layouts/pages/about.js

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+import React from 'react'
+import delay from '../modules/delay'
+import applyLayout from '../modules/next-layouts'
+import ContentLayout from '../components/ContentLayout'
+
+class AboutPage extends React.Component {
+  static layout = ContentLayout
+  static async getInitialProps () {
+    return {
+      delay: await delay(3000)
+    }
+  }
+
+  render () {
+    return (
+      <p>about</p>
+    )
+  }
+}
+
+export default applyLayout(AboutPage, {
+  getInitialPropsMode: 'concurrent'
+})

examples/with-next-layouts/pages/index.js

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+import React from 'react'
+import Link from 'next/link'
+import delay from '../modules/delay'
+import applyLayout from '../modules/next-layouts'
+import ContentLayout from '../components/ContentLayout'
+
+class IndexPage extends React.Component {
+  static layout = ContentLayout
+  static async getInitialProps () {
+    return {
+      delay: await delay(3000)
+    }
+  }
+
+  render () {
+    return (
+      <div>
+        index
+        <Link href='/about'>
+          <a>about</a>
+        </Link>
+      </div>
+    )
+  }
+}
+
+export default applyLayout(IndexPage)