first commit for Yuescript document site.

15 files changed, 1851 insertions, 0 deletions

diff --git a/doc/docs/.vuepress/theme/components/AlgoliaSearchBox.vue b/doc/docs/.vuepress/theme/components/AlgoliaSearchBox.vue
new file mode 100644
index 0000000..7071fb8
--- /dev/null
+++ b/doc/docs/.vuepress/theme/components/AlgoliaSearchBox.vue
@@ -0,0 +1,172 @@
+<template>
+  <form
+    id="search-form"
+    class="algolia-search-wrapper search-box"
+    role="search"
+  >
+    <input
+      id="algolia-search-input"
+      class="search-query"
+      :placeholder="placeholder"
+    >
+  </form>
+</template>
+
+<script>
+export default {
+  name: 'AlgoliaSearchBox',
+
+  props: ['options'],
+
+  data () {
+    return {
+      placeholder: undefined
+    }
+  },
+
+  watch: {
+    $lang (newValue) {
+      this.update(this.options, newValue)
+    },
+
+    options (newValue) {
+      this.update(newValue, this.$lang)
+    }
+  },
+
+  mounted () {
+    this.initialize(this.options, this.$lang)
+    this.placeholder = this.$site.themeConfig.searchPlaceholder || ''
+  },
+
+  methods: {
+    initialize (userOptions, lang) {
+      Promise.all([
+        import(/* webpackChunkName: "docsearch" */ 'docsearch.js/dist/cdn/docsearch.min.js'),
+        import(/* webpackChunkName: "docsearch" */ 'docsearch.js/dist/cdn/docsearch.min.css')
+      ]).then(([docsearch]) => {
+        docsearch = docsearch.default
+        const { algoliaOptions = {}} = userOptions
+        docsearch(Object.assign(
+          {},
+          userOptions,
+          {
+            inputSelector: '#algolia-search-input',
+            // #697 Make docsearch work well at i18n mode.
+            algoliaOptions: {
+              ...algoliaOptions,
+              facetFilters: [`lang:${lang}`].concat(algoliaOptions.facetFilters || [])
+            },
+            handleSelected: (input, event, suggestion) => {
+              const { pathname, hash } = new URL(suggestion.url)
+              const routepath = pathname.replace(this.$site.base, '/')
+              const _hash = decodeURIComponent(hash)
+              this.$router.push(`${routepath}${_hash}`)
+            }
+          }
+        ))
+      })
+    },
+
+    update (options, lang) {
+      this.$el.innerHTML = '<input id="algolia-search-input" class="search-query">'
+      this.initialize(options, lang)
+    }
+  }
+}
+</script>
+
+<style lang="stylus">
+.algolia-search-wrapper
+  & > span
+    vertical-align middle
+  .algolia-autocomplete
+    line-height normal
+    .ds-dropdown-menu
+      background-color #fff
+      border 1px solid #999
+      border-radius 4px
+      font-size 16px
+      margin 6px 0 0
+      padding 4px
+      text-align left
+      &:before
+        border-color #999
+      [class*=ds-dataset-]
+        border none
+        padding 0
+      .ds-suggestions
+        margin-top 0
+      .ds-suggestion
+        border-bottom 1px solid $borderColor
+    .algolia-docsearch-suggestion--highlight
+      color #2c815b
+    .algolia-docsearch-suggestion
+      border-color $borderColor
+      padding 0
+      .algolia-docsearch-suggestion--category-header
+        padding 5px 10px
+        margin-top 0
+        background $accentColor
+        color #fff
+        font-weight 600
+        .algolia-docsearch-suggestion--highlight
+          background rgba(255, 255, 255, 0.6)
+      .algolia-docsearch-suggestion--wrapper
+        padding 0
+      .algolia-docsearch-suggestion--title
+        font-weight 600
+        margin-bottom 0
+        color $textColor
+      .algolia-docsearch-suggestion--subcategory-column
+        vertical-align top
+        padding 5px 7px 5px 5px
+        border-color $borderColor
+        background #f1f3f5
+        &:after
+          display none
+      .algolia-docsearch-suggestion--subcategory-column-text
+        color #555
+    .algolia-docsearch-footer
+      border-color $borderColor
+    .ds-cursor .algolia-docsearch-suggestion--content
+      background-color #e7edf3 !important
+      color $textColor
+
+@media (min-width: $MQMobile)
+  .algolia-search-wrapper
+    .algolia-autocomplete
+      .algolia-docsearch-suggestion
+        .algolia-docsearch-suggestion--subcategory-column
+          float none
+          width 150px
+          min-width 150px
+          display table-cell
+        .algolia-docsearch-suggestion--content
+          float none
+          display table-cell
+          width 100%
+          vertical-align top
+        .ds-dropdown-menu
+          min-width 515px !important
+
+@media (max-width: $MQMobile)
+  .algolia-search-wrapper
+    .ds-dropdown-menu
+      min-width calc(100vw - 4rem) !important
+      max-width calc(100vw - 4rem) !important
+    .algolia-docsearch-suggestion--wrapper
+      padding 5px 7px 5px 5px !important
+    .algolia-docsearch-suggestion--subcategory-column
+      padding 0 !important
+      background white !important
+    .algolia-docsearch-suggestion--subcategory-column-text:after
+      content " > "
+      font-size 10px
+      line-height 14.4px
+      display inline-block
+      width 5px
+      margin -3px 3px 0
+      vertical-align middle
+
+</style>
diff --git a/doc/docs/.vuepress/theme/components/DropdownLink.vue b/doc/docs/.vuepress/theme/components/DropdownLink.vue
new file mode 100644
index 0000000..be6563f
--- /dev/null
+++ b/doc/docs/.vuepress/theme/components/DropdownLink.vue
@@ -0,0 +1,252 @@
+<template>
+  <div
+    class="dropdown-wrapper"
+    :class="{ open }"
+  >
+    <button
+      class="dropdown-title"
+      type="button"
+      :aria-label="dropdownAriaLabel"
+      @click="handleDropdown"
+    >
+      <span class="title">{{ item.text }}</span>
+      <span
+        class="arrow down"
+      />
+    </button>
+    <button
+      class="mobile-dropdown-title"
+      type="button"
+      :aria-label="dropdownAriaLabel"
+      @click="setOpen(!open)"
+    >
+      <span class="title">{{ item.text }}</span>
+      <span
+        class="arrow"
+        :class="open ? 'down' : 'right'"
+      />
+    </button>
+
+    <DropdownTransition>
+      <ul
+        v-show="open"
+        class="nav-dropdown"
+      >
+        <li
+          v-for="(subItem, index) in item.items"
+          :key="subItem.link || index"
+          class="dropdown-item"
+        >
+          <h4 v-if="subItem.type === 'links'">
+            {{ subItem.text }}
+          </h4>
+
+          <ul
+            v-if="subItem.type === 'links'"
+            class="dropdown-subitem-wrapper"
+          >
+            <li
+              v-for="childSubItem in subItem.items"
+              :key="childSubItem.link"
+              class="dropdown-subitem"
+            >
+              <NavLink
+                :item="childSubItem"
+                @focusout="
+                  isLastItemOfArray(childSubItem, subItem.items) &&
+                    isLastItemOfArray(subItem, item.items) &&
+                    setOpen(false)
+                "
+              />
+            </li>
+          </ul>
+
+          <NavLink
+            v-else
+            :item="subItem"
+            @focusout="isLastItemOfArray(subItem, item.items) && setOpen(false)"
+          />
+        </li>
+      </ul>
+    </DropdownTransition>
+  </div>
+</template>
+
+<script>
+import NavLink from '@theme/components/NavLink.vue'
+import DropdownTransition from '@theme/components/DropdownTransition.vue'
+import last from 'lodash/last'
+
+export default {
+  name: 'DropdownLink',
+
+  components: {
+    NavLink,
+    DropdownTransition
+  },
+
+  props: {
+    item: {
+      required: true
+    }
+  },
+
+  data () {
+    return {
+      open: false
+    }
+  },
+
+  computed: {
+    dropdownAriaLabel () {
+      return this.item.ariaLabel || this.item.text
+    }
+  },
+
+  watch: {
+    $route () {
+      this.open = false
+    }
+  },
+
+  methods: {
+    setOpen (value) {
+      this.open = value
+    },
+
+    isLastItemOfArray (item, array) {
+      return last(array) === item
+    },
+
+    /**
+     * Open the dropdown when user tab and click from keyboard.
+     *
+     * Use event.detail to detect tab and click from keyboard. Ref: https://developer.mozilla.org/en-US/docs/Web/API/UIEvent/detail
+     * The Tab + Click is UIEvent > KeyboardEvent, so the detail is 0.
+     */
+    handleDropdown () {
+      const isTriggerByTab = event.detail === 0
+      if (isTriggerByTab) this.setOpen(!this.open)
+    }
+  }
+}
+</script>
+
+<style lang="stylus">
+.dropdown-wrapper
+  cursor pointer
+  .dropdown-title
+    display block
+    font-size 0.9rem
+    font-family inherit
+    cursor inherit
+    padding inherit
+    line-height 1.4rem
+    background transparent
+    border none
+    font-weight 500
+    color $textColor
+    &:hover
+      border-color transparent
+    .arrow
+      vertical-align middle
+      margin-top -1px
+      margin-left 0.4rem
+  .mobile-dropdown-title
+    @extends .dropdown-title
+    display none
+    font-weight 600
+    font-size inherit
+      &:hover
+        color $accentColor
+  .nav-dropdown
+    .dropdown-item
+      color inherit
+      line-height 1.7rem
+      h4
+        margin 0.45rem 0 0
+        border-top 1px solid #eee
+        padding 1rem 1.5rem 0.45rem 1.25rem
+      .dropdown-subitem-wrapper
+        padding 0
+        list-style none
+        .dropdown-subitem
+          font-size 0.9em
+      a
+        display block
+        line-height 1.7rem
+        position relative
+        border-bottom none
+        font-weight 400
+        margin-bottom 0
+        padding 0 1.5rem 0 1.25rem
+        &:hover
+          color $accentColor
+        &.router-link-active
+          color $accentColor
+          &::after
+            content ""
+            width 0
+            height 0
+            border-left 5px solid $accentColor
+            border-top 3px solid transparent
+            border-bottom 3px solid transparent
+            position absolute
+            top calc(50% - 2px)
+            left 9px
+      &:first-child h4
+        margin-top 0
+        padding-top 0
+        border-top 0
+
+@media (max-width: $MQMobile)
+  .dropdown-wrapper
+    &.open .dropdown-title
+      margin-bottom 0.5rem
+    .dropdown-title
+      display: none
+    .mobile-dropdown-title
+      display: block
+    .nav-dropdown
+      transition height .1s ease-out
+      overflow hidden
+      .dropdown-item
+        h4
+          border-top 0
+          margin-top 0
+          padding-top 0
+        h4, & > a
+          font-size 15px
+          line-height 2rem
+        .dropdown-subitem
+          font-size 14px
+          padding-left 1rem
+
+@media (min-width: $MQMobile)
+  .dropdown-wrapper
+    height 1.8rem
+    &:hover .nav-dropdown,
+    &.open .nav-dropdown
+      // override the inline style.
+      display block !important
+    &.open:blur
+      display none
+    .nav-dropdown
+      display none
+      // Avoid height shaked by clicking
+      height auto !important
+      box-sizing border-box;
+      max-height calc(100vh - 2.7rem)
+      overflow-y auto
+      position absolute
+      top 100%
+      right 0
+      background-color #fff
+      padding 0.6rem 0
+      border 1px solid #ddd
+      border-bottom-color #ccc
+      text-align left
+      border-radius 0.25rem
+      white-space nowrap
+      margin 0
+</style>
diff --git a/doc/docs/.vuepress/theme/components/DropdownTransition.vue b/doc/docs/.vuepress/theme/components/DropdownTransition.vue
new file mode 100644
index 0000000..eeaf12b
--- /dev/null
+++ b/doc/docs/.vuepress/theme/components/DropdownTransition.vue
@@ -0,0 +1,33 @@
+<template>
+  <transition
+    name="dropdown"
+    @enter="setHeight"
+    @after-enter="unsetHeight"
+    @before-leave="setHeight"
+  >
+    <slot />
+  </transition>
+</template>
+
+<script>
+export default {
+  name: 'DropdownTransition',
+
+  methods: {
+    setHeight (items) {
+      // explicitly set height so that it can be transitioned
+      items.style.height = items.scrollHeight + 'px'
+    },
+
+    unsetHeight (items) {
+      items.style.height = ''
+    }
+  }
+}
+</script>
+
+<style lang="stylus">
+.dropdown-enter, .dropdown-leave-to
+  height 0 !important
+
+</style>
diff --git a/doc/docs/.vuepress/theme/components/Home.vue b/doc/docs/.vuepress/theme/components/Home.vue
new file mode 100644
index 0000000..acd8744
--- /dev/null
+++ b/doc/docs/.vuepress/theme/components/Home.vue
@@ -0,0 +1,175 @@
+<template>
+  <main
+    class="home"
+    :aria-labelledby="data.heroText !== null ? 'main-title' : null"
+  >
+    <header class="hero">
+      <img
+        v-if="data.heroImage"
+        :src="$withBase(data.heroImage)"
+        :alt="data.heroAlt || 'hero'"
+      >
+
+      <h1
+        v-if="data.heroText !== null"
+        id="main-title"
+      >
+        {{ data.heroText || $title || 'Hello' }}
+      </h1>
+
+      <p
+        v-if="data.tagline !== null"
+        class="description"
+      >
+        {{ data.tagline || $description || 'Welcome to your VuePress site' }}
+      </p>
+
+      <p
+        v-if="data.actionText && data.actionLink"
+        class="action"
+      >
+        <NavLink
+          class="action-button"
+          :item="actionLink"
+        />
+      </p>
+    </header>
+
+    <div
+      v-if="data.features && data.features.length"
+      class="features"
+    >
+      <div
+        v-for="(feature, index) in data.features"
+        :key="index"
+        class="feature"
+      >
+        <h2>{{ feature.title }}</h2>
+        <p>{{ feature.details }}</p>
+      </div>
+    </div>
+
+    <Content class="theme-default-content custom" />
+
+    <div
+      v-if="data.footer"
+      class="footer"
+    >
+      {{ data.footer }}
+    </div>
+  </main>
+</template>
+
+<script>
+import NavLink from '@theme/components/NavLink.vue'
+
+export default {
+  name: 'Home',
+
+  components: { NavLink },
+
+  computed: {
+    data () {
+      return this.$page.frontmatter
+    },
+
+    actionLink () {
+      return {
+        link: this.data.actionLink,
+        text: this.data.actionText
+      }
+    }
+  }
+}
+</script>
+
+<style lang="stylus">
+.home
+  padding $navbarHeight 2rem 0
+  max-width $homePageWidth
+  margin 0px auto
+  display block
+  .hero
+    text-align center
+    img
+      max-width: 100%
+      max-height 280px
+      display block
+      margin 3rem auto 1.5rem
+    h1
+      font-size 3rem
+    h1, .description, .action
+      margin 1.8rem auto
+    .description
+      max-width 35rem
+      font-size 1.6rem
+      line-height 1.3
+      color lighten($textColor, 40%)
+    .action-button
+      display inline-block
+      font-size 1.2rem
+      color #fff
+      background-color $accentColor
+      padding 0.8rem 1.6rem
+      border-radius 4px
+      transition background-color .1s ease
+      box-sizing border-box
+      border-bottom 1px solid darken($accentColor, 10%)
+      &:hover
+        background-color lighten($accentColor, 10%)
+  .features
+    border-top 1px solid $borderColor
+    padding 1.2rem 0
+    margin-top 2.5rem
+    display flex
+    flex-wrap wrap
+    align-items flex-start
+    align-content stretch
+    justify-content space-between
+  .feature
+    flex-grow 1
+    flex-basis 30%
+    max-width 30%
+    h2
+      font-size 1.4rem
+      font-weight 500
+      border-bottom none
+      padding-bottom 0
+      color lighten($textColor, 10%)
+    p
+      color lighten($textColor, 25%)
+  .footer
+    padding 2.5rem
+    border-top 1px solid $borderColor
+    text-align center
+    color lighten($textColor, 25%)
+
+@media (max-width: $MQMobile)
+  .home
+    .features
+      flex-direction column
+    .feature
+      max-width 100%
+      padding 0 2.5rem
+
+@media (max-width: $MQMobileNarrow)
+  .home
+    padding-left 1.5rem
+    padding-right 1.5rem
+    .hero
+      img
+        max-height 210px
+        margin 2rem auto 1.2rem
+      h1
+        font-size 2rem
+      h1, .description, .action
+        margin 1.2rem auto
+      .description
+        font-size 1.2rem
+      .action-button
+        font-size 1rem
+        padding 0.6rem 1.2rem
+    .feature
+      h2
+        font-size 1.25rem
+</style>
diff --git a/doc/docs/.vuepress/theme/components/NavLink.vue b/doc/docs/.vuepress/theme/components/NavLink.vue
new file mode 100644
index 0000000..f7e65a4
--- /dev/null
+++ b/doc/docs/.vuepress/theme/components/NavLink.vue
@@ -0,0 +1,90 @@
+<template>
+  <RouterLink
+    v-if="isInternal"
+    class="nav-link"
+    :to="link"
+    :exact="exact"
+    @focusout.native="focusoutAction"
+  >
+    {{ item.text }}
+  </RouterLink>
+  <a
+    v-else
+    :href="link"
+    class="nav-link external"
+    :target="target"
+    :rel="rel"
+    @focusout="focusoutAction"
+  >
+    {{ item.text }}
+    <OutboundLink v-if="isBlankTarget" />
+  </a>
+</template>
+
+<script>
+import { isExternal, isMailto, isTel, ensureExt } from '../util'
+
+export default {
+  name: 'NavLink',
+
+  props: {
+    item: {
+      required: true
+    }
+  },
+
+  computed: {
+    link () {
+      return ensureExt(this.item.link)
+    },
+
+    exact () {
+      if (this.$site.locales) {
+        return Object.keys(this.$site.locales).some(rootLink => rootLink === this.link)
+      }
+      return this.link === '/'
+    },
+
+    isNonHttpURI () {
+      return isMailto(this.link) || isTel(this.link)
+    },
+
+    isBlankTarget () {
+      return this.target === '_blank'
+    },
+
+    isInternal () {
+      return !isExternal(this.link) && !this.isBlankTarget
+    },
+
+    target () {
+      if (this.isNonHttpURI) {
+        return null
+      }
+      if (this.item.target) {
+        return this.item.target
+      }
+      return isExternal(this.link) ? '_blank' : ''
+    },
+
+    rel () {
+      if (this.isNonHttpURI) {
+        return null
+      }
+      if (this.item.rel === false) {
+        return null
+      }
+      if (this.item.rel) {
+        return this.item.rel
+      }
+      return this.isBlankTarget ? 'noopener noreferrer' : null
+    }
+  },
+
+  methods: {
+    focusoutAction () {
+      this.$emit('focusout')
+    }
+  }
+}
+</script>
diff --git a/doc/docs/.vuepress/theme/components/NavLinks.vue b/doc/docs/.vuepress/theme/components/NavLinks.vue
new file mode 100644
index 0000000..2656ae2
--- /dev/null
+++ b/doc/docs/.vuepress/theme/components/NavLinks.vue
@@ -0,0 +1,156 @@
+<template>
+  <nav
+    v-if="userLinks.length || repoLink"
+    class="nav-links"
+  >
+    <!-- user links -->
+    <div
+      v-for="item in userLinks"
+      :key="item.link"
+      class="nav-item"
+    >
+      <DropdownLink
+        v-if="item.type === 'links'"
+        :item="item"
+      />
+      <NavLink
+        v-else
+        :item="item"
+      />
+    </div>
+
+    <!-- repo link -->
+    <a
+      v-if="repoLink"
+      :href="repoLink"
+      class="repo-link"
+      target="_blank"
+      rel="noopener noreferrer"
+    >
+      {{ repoLabel }}
+      <OutboundLink />
+    </a>
+  </nav>
+</template>
+
+<script>
+import DropdownLink from '@theme/components/DropdownLink.vue'
+import { resolveNavLinkItem } from '../util'
+import NavLink from '@theme/components/NavLink.vue'
+
+export default {
+  name: 'NavLinks',
+
+  components: {
+    NavLink,
+    DropdownLink
+  },
+
+  computed: {
+    userNav () {
+      return this.$themeLocaleConfig.nav || this.$site.themeConfig.nav || []
+    },
+
+    nav () {
+      const { locales } = this.$site
+      if (locales && Object.keys(locales).length > 1) {
+        const currentLink = this.$page.path
+        const routes = this.$router.options.routes
+        const themeLocales = this.$site.themeConfig.locales || {}
+        const languageDropdown = {
+          text: this.$themeLocaleConfig.selectText || 'Languages',
+          ariaLabel: this.$themeLocaleConfig.ariaLabel || 'Select language',
+          items: Object.keys(locales).map(path => {
+            const locale = locales[path]
+            const text = themeLocales[path] && themeLocales[path].label || locale.lang
+            let link
+            // Stay on the current page
+            if (locale.lang === this.$lang) {
+              link = currentLink
+            } else {
+              // Try to stay on the same page
+              link = currentLink.replace(this.$localeConfig.path, path)
+              // fallback to homepage
+              if (!routes.some(route => route.path === link)) {
+                link = path
+              }
+            }
+            return { text, link }
+          })
+        }
+        return [...this.userNav, languageDropdown]
+      }
+      return this.userNav
+    },
+
+    userLinks () {
+      return (this.nav || []).map(link => {
+        return Object.assign(resolveNavLinkItem(link), {
+          items: (link.items || []).map(resolveNavLinkItem)
+        })
+      })
+    },
+
+    repoLink () {
+      const { repo } = this.$site.themeConfig
+      if (repo) {
+        return /^https?:/.test(repo)
+          ? repo
+          : `https://github.com/${repo}`
+      }
+      return null
+    },
+
+    repoLabel () {
+      if (!this.repoLink) return
+      if (this.$site.themeConfig.repoLabel) {
+        return this.$site.themeConfig.repoLabel
+      }
+
+      const repoHost = this.repoLink.match(/^https?:\/\/[^/]+/)[0]
+      const platforms = ['GitHub', 'GitLab', 'Bitbucket']
+      for (let i = 0; i < platforms.length; i++) {
+        const platform = platforms[i]
+        if (new RegExp(platform, 'i').test(repoHost)) {
+          return platform
+        }
+      }
+
+      return 'Source'
+    }
+  }
+}
+</script>
+
+<style lang="stylus">
+.nav-links
+  display inline-block
+  a
+    line-height 1.4rem
+    color inherit
+    &:hover, &.router-link-active
+      color $accentColor
+  .nav-item
+    position relative
+    display inline-block
+    margin-left 1.5rem
+    line-height 2rem
+    &:first-child
+      margin-left 0
+  .repo-link
+    margin-left 1.5rem
+
+@media (max-width: $MQMobile)
+  .nav-links
+    .nav-item, .repo-link
+      margin-left 0
+
+@media (min-width: $MQMobile)
+  .nav-links a
+    &:hover, &.router-link-active
+      color $textColor
+  .nav-item > a:not(.external)
+    &:hover, &.router-link-active
+      margin-bottom -2px
+      border-bottom 2px solid lighten($accentColor, 8%)
+</style>
diff --git a/doc/docs/.vuepress/theme/components/Navbar.vue b/doc/docs/.vuepress/theme/components/Navbar.vue
new file mode 100644
index 0000000..f8dd49c
--- /dev/null
+++ b/doc/docs/.vuepress/theme/components/Navbar.vue
@@ -0,0 +1,140 @@
+<template>
+  <header class="navbar">
+    <SidebarButton @toggle-sidebar="$emit('toggle-sidebar')" />
+
+    <RouterLink
+      :to="$localePath"
+      class="home-link"
+    >
+      <img
+        v-if="$site.themeConfig.logo"
+        class="logo"
+        :src="$withBase($site.themeConfig.logo)"
+        :alt="$siteTitle"
+      >
+      <span
+        v-if="$siteTitle"
+        ref="siteName"
+        class="site-name"
+        :class="{ 'can-hide': $site.themeConfig.logo }"
+      >{{ $siteTitle }}</span>
+    </RouterLink>
+
+    <div
+      class="links"
+      :style="linksWrapMaxWidth ? {
+        'max-width': linksWrapMaxWidth + 'px'
+      } : {}"
+    >
+      <AlgoliaSearchBox
+        v-if="isAlgoliaSearch"
+        :options="algolia"
+      />
+      <SearchBox v-else-if="$site.themeConfig.search !== false && $page.frontmatter.search !== false" />
+      <NavLinks class="can-hide" />
+    </div>
+  </header>
+</template>
+
+<script>
+import AlgoliaSearchBox from '@AlgoliaSearchBox'
+import SearchBox from '@SearchBox'
+import SidebarButton from '@theme/components/SidebarButton.vue'
+import NavLinks from '@theme/components/NavLinks.vue'
+
+export default {
+  name: 'Navbar',
+
+  components: {
+    SidebarButton,
+    NavLinks,
+    SearchBox,
+    AlgoliaSearchBox
+  },
+
+  data () {
+    return {
+      linksWrapMaxWidth: null
+    }
+  },
+
+  computed: {
+    algolia () {
+      return this.$themeLocaleConfig.algolia || this.$site.themeConfig.algolia || {}
+    },
+
+    isAlgoliaSearch () {
+      return this.algolia && this.algolia.apiKey && this.algolia.indexName
+    }
+  },
+
+  mounted () {
+    const MOBILE_DESKTOP_BREAKPOINT = 719 // refer to config.styl
+    const NAVBAR_VERTICAL_PADDING = parseInt(css(this.$el, 'paddingLeft')) + parseInt(css(this.$el, 'paddingRight'))
+    const handleLinksWrapWidth = () => {
+      if (document.documentElement.clientWidth < MOBILE_DESKTOP_BREAKPOINT) {
+        this.linksWrapMaxWidth = null
+      } else {
+        this.linksWrapMaxWidth = this.$el.offsetWidth - NAVBAR_VERTICAL_PADDING
+          - (this.$refs.siteName && this.$refs.siteName.offsetWidth || 0)
+      }
+    }
+    handleLinksWrapWidth()
+    window.addEventListener('resize', handleLinksWrapWidth, false)
+  }
+}
+
+function css (el, property) {
+  // NOTE: Known bug, will return 'auto' if style value is 'auto'
+  const win = el.ownerDocument.defaultView
+  // null means not to return pseudo styles
+  return win.getComputedStyle(el, null)[property]
+}
+</script>
+
+<style lang="stylus">
+$navbar-vertical-padding = 0.7rem
+$navbar-horizontal-padding = 1.5rem
+
+.navbar
+  padding $navbar-vertical-padding $navbar-horizontal-padding
+  line-height $navbarHeight - 1.4rem
+  a, span, img
+    display inline-block
+  .logo
+    height $navbarHeight - 1.4rem
+    min-width $navbarHeight - 1.4rem
+    margin-right 0.8rem
+    vertical-align top
+  .site-name
+    font-size 1.3rem
+    font-weight 600
+    color $textColor
+    position relative
+  .links
+    padding-left 1.5rem
+    box-sizing border-box
+    background-color white
+    white-space nowrap
+    font-size 0.9rem
+    position absolute
+    right $navbar-horizontal-padding
+    top $navbar-vertical-padding
+    display flex
+    .search-box
+      flex: 0 0 auto
+      vertical-align top
+
+@media (max-width: $MQMobile)
+  .navbar
+    padding-left 4rem
+    .can-hide
+      display none
+    .links
+      padding-left 1.5rem
+    .site-name
+      width calc(100vw - 9.4rem)
+      overflow hidden
+      white-space nowrap
+      text-overflow ellipsis
+</style>
diff --git a/doc/docs/.vuepress/theme/components/Page.vue b/doc/docs/.vuepress/theme/components/Page.vue
new file mode 100644
index 0000000..04ec7cb
--- /dev/null
+++ b/doc/docs/.vuepress/theme/components/Page.vue
@@ -0,0 +1,31 @@
+<template>
+  <main class="page">
+    <slot name="top" />
+
+    <Content class="theme-default-content" />
+    <PageEdit />
+
+    <PageNav v-bind="{ sidebarItems }" />
+
+    <slot name="bottom" />
+  </main>
+</template>
+
+<script>
+import PageEdit from '@theme/components/PageEdit.vue'
+import PageNav from '@theme/components/PageNav.vue'
+
+export default {
+  components: { PageEdit, PageNav },
+  props: ['sidebarItems']
+}
+</script>
+
+<style lang="stylus">
+@require '../styles/wrapper.styl'
+
+.page
+  padding-bottom 2rem
+  display block
+
+</style>
diff --git a/doc/docs/.vuepress/theme/components/PageEdit.vue b/doc/docs/.vuepress/theme/components/PageEdit.vue
new file mode 100644
index 0000000..cf9b2d2
--- /dev/null
+++ b/doc/docs/.vuepress/theme/components/PageEdit.vue
@@ -0,0 +1,155 @@
+<template>
+  <footer class="page-edit">
+    <div
+      v-if="editLink"
+      class="edit-link"
+    >
+      <a
+        :href="editLink"
+        target="_blank"
+        rel="noopener noreferrer"
+      >{{ editLinkText }}</a>
+      <OutboundLink />
+    </div>
+
+    <div
+      v-if="lastUpdated"
+      class="last-updated"
+    >
+      <span class="prefix">{{ lastUpdatedText }}:</span>
+      <span class="time">{{ lastUpdated }}</span>
+    </div>
+  </footer>
+</template>
+
+<script>
+import isNil from 'lodash/isNil'
+import { endingSlashRE, outboundRE } from '../util'
+
+export default {
+  name: 'PageEdit',
+
+  computed: {
+    lastUpdated () {
+      return this.$page.lastUpdated
+    },
+
+    lastUpdatedText () {
+      if (typeof this.$themeLocaleConfig.lastUpdated === 'string') {
+        return this.$themeLocaleConfig.lastUpdated
+      }
+      if (typeof this.$site.themeConfig.lastUpdated === 'string') {
+        return this.$site.themeConfig.lastUpdated
+      }
+      return 'Last Updated'
+    },
+
+    editLink () {
+      const showEditLink = isNil(this.$page.frontmatter.editLink)
+        ? this.$site.themeConfig.editLinks
+        : this.$page.frontmatter.editLink
+
+      const {
+        repo,
+        docsDir = '',
+        docsBranch = 'master',
+        docsRepo = repo
+      } = this.$site.themeConfig
+
+      if (showEditLink && docsRepo && this.$page.relativePath) {
+        return this.createEditLink(
+          repo,
+          docsRepo,
+          docsDir,
+          docsBranch,
+          this.$page.relativePath
+        )
+      }
+      return null
+    },
+
+    editLinkText () {
+      return (
+        this.$themeLocaleConfig.editLinkText
+        || this.$site.themeConfig.editLinkText
+        || `Edit this page`
+      )
+    }
+  },
+
+  methods: {
+    createEditLink (repo, docsRepo, docsDir, docsBranch, path) {
+      const bitbucket = /bitbucket.org/
+      if (bitbucket.test(docsRepo)) {
+        const base = docsRepo
+        return (
+          base.replace(endingSlashRE, '')
+          + `/src`
+          + `/${docsBranch}/`
+          + (docsDir ? docsDir.replace(endingSlashRE, '') + '/' : '')
+          + path
+          + `?mode=edit&spa=0&at=${docsBranch}&fileviewer=file-view-default`
+        )
+      }
+
+      const gitlab = /gitlab.com/
+      if (gitlab.test(docsRepo)) {
+        const base = docsRepo
+        return (
+          base.replace(endingSlashRE, '')
+          + `/-/edit`
+          + `/${docsBranch}/`
+          + (docsDir ? docsDir.replace(endingSlashRE, '') + '/' : '')
+          + path
+        )
+      }
+
+      const base = outboundRE.test(docsRepo)
+        ? docsRepo
+        : `https://github.com/${docsRepo}`
+      return (
+        base.replace(endingSlashRE, '')
+        + '/edit'
+        + `/${docsBranch}/`
+        + (docsDir ? docsDir.replace(endingSlashRE, '') + '/' : '')
+        + path
+      )
+    }
+  }
+}
+</script>
+
+<style lang="stylus">
+@require '../styles/wrapper.styl'
+
+.page-edit
+  @extend $wrapper
+  padding-top 1rem
+  padding-bottom 1rem
+  overflow auto
+
+  .edit-link
+    display inline-block
+    a
+      color lighten($textColor, 25%)
+      margin-right 0.25rem
+  .last-updated
+    float right
+    font-size 0.9em
+    .prefix
+      font-weight 500
+      color lighten($textColor, 25%)
+    .time
+      font-weight 400
+      color #767676
+
+@media (max-width: $MQMobile)
+  .page-edit
+    .edit-link
+      margin-bottom 0.5rem
+    .last-updated
+      font-size 0.8em
+      float none
+      text-align left
+
+</style>
diff --git a/doc/docs/.vuepress/theme/components/PageNav.vue b/doc/docs/.vuepress/theme/components/PageNav.vue
new file mode 100644
index 0000000..4c19aae
--- /dev/null
+++ b/doc/docs/.vuepress/theme/components/PageNav.vue
@@ -0,0 +1,163 @@
+<template>
+  <div
+    v-if="prev || next"
+    class="page-nav"
+  >
+    <p class="inner">
+      <span
+        v-if="prev"
+        class="prev"
+      >
+        ←
+        <a
+          v-if="prev.type === 'external'"
+          class="prev"
+          :href="prev.path"
+          target="_blank"
+          rel="noopener noreferrer"
+        >
+          {{ prev.title || prev.path }}
+
+          <OutboundLink />
+        </a>
+
+        <RouterLink
+          v-else
+          class="prev"
+          :to="prev.path"
+        >
+          {{ prev.title || prev.path }}
+        </RouterLink>
+      </span>
+
+      <span
+        v-if="next"
+        class="next"
+      >
+        <a
+          v-if="next.type === 'external'"
+          :href="next.path"
+          target="_blank"
+          rel="noopener noreferrer"
+        >
+          {{ next.title || next.path }}
+
+          <OutboundLink />
+        </a>
+
+        <RouterLink
+          v-else
+          :to="next.path"
+        >
+          {{ next.title || next.path }}
+        </RouterLink>
+        →
+      </span>
+    </p>
+  </div>
+</template>
+
+<script>
+import { resolvePage } from '../util'
+import isString from 'lodash/isString'
+import isNil from 'lodash/isNil'
+
+export default {
+  name: 'PageNav',
+
+  props: ['sidebarItems'],
+
+  computed: {
+    prev () {
+      return resolvePageLink(LINK_TYPES.PREV, this)
+    },
+
+    next () {
+      return resolvePageLink(LINK_TYPES.NEXT, this)
+    }
+  }
+}
+
+function resolvePrev (page, items) {
+  return find(page, items, -1)
+}
+
+function resolveNext (page, items) {
+  return find(page, items, 1)
+}
+
+const LINK_TYPES = {
+  NEXT: {
+    resolveLink: resolveNext,
+    getThemeLinkConfig: ({ nextLinks }) => nextLinks,
+    getPageLinkConfig: ({ frontmatter }) => frontmatter.next
+  },
+  PREV: {
+    resolveLink: resolvePrev,
+    getThemeLinkConfig: ({ prevLinks }) => prevLinks,
+    getPageLinkConfig: ({ frontmatter }) => frontmatter.prev
+  }
+}
+
+function resolvePageLink (
+  linkType,
+  { $themeConfig, $page, $route, $site, sidebarItems }
+) {
+  const { resolveLink, getThemeLinkConfig, getPageLinkConfig } = linkType
+
+  // Get link config from theme
+  const themeLinkConfig = getThemeLinkConfig($themeConfig)
+
+  // Get link config from current page
+  const pageLinkConfig = getPageLinkConfig($page)
+
+  // Page link config will overwrite global theme link config if defined
+  const link = isNil(pageLinkConfig) ? themeLinkConfig : pageLinkConfig
+
+  if (link === false) {
+    return
+  } else if (isString(link)) {
+    return resolvePage($site.pages, link, $route.path)
+  } else {
+    return resolveLink($page, sidebarItems)
+  }
+}
+
+function find (page, items, offset) {
+  const res = []
+  flatten(items, res)
+  for (let i = 0; i < res.length; i++) {
+    const cur = res[i]
+    if (cur.type === 'page' && cur.path === decodeURIComponent(page.path)) {
+      return res[i + offset]
+    }
+  }
+}
+
+function flatten (items, res) {
+  for (let i = 0, l = items.length; i < l; i++) {
+    if (items[i].type === 'group') {
+      flatten(items[i].children || [], res)
+    } else {
+      res.push(items[i])
+    }
+  }
+}
+</script>
+
+<style lang="stylus">
+@require '../styles/wrapper.styl'
+
+.page-nav
+  @extend $wrapper
+  padding-top 1rem
+  padding-bottom 0
+  .inner
+    min-height 2rem
+    margin-top 0
+    border-top 1px solid $borderColor
+    padding-top 1rem
+    overflow auto // clear float
+  .next
+    float right
+</style>
diff --git a/doc/docs/.vuepress/theme/components/Sidebar.vue b/doc/docs/.vuepress/theme/components/Sidebar.vue
new file mode 100644
index 0000000..e70e333
--- /dev/null
+++ b/doc/docs/.vuepress/theme/components/Sidebar.vue
@@ -0,0 +1,64 @@
+<template>
+  <aside class="sidebar">
+    <NavLinks />
+
+    <slot name="top" />
+
+    <SidebarLinks
+      :depth="0"
+      :items="items"
+    />
+    <slot name="bottom" />
+  </aside>
+</template>
+
+<script>
+import SidebarLinks from '@theme/components/SidebarLinks.vue'
+import NavLinks from '@theme/components/NavLinks.vue'
+
+export default {
+  name: 'Sidebar',
+
+  components: { SidebarLinks, NavLinks },
+
+  props: ['items']
+}
+</script>
+
+<style lang="stylus">
+.sidebar
+  ul
+    padding 0
+    margin 0
+    list-style-type none
+  a
+    display inline-block
+  .nav-links
+    display none
+    border-bottom 1px solid $borderColor
+    padding 0.5rem 0 0.75rem 0
+    a
+      font-weight 600
+    .nav-item, .repo-link
+      display block
+      line-height 1.25rem
+      font-size 1.1em
+      padding 0.5rem 0 0.5rem 1.5rem
+  & > .sidebar-links
+    padding 1.5rem 0
+    & > li > a.sidebar-link
+      font-size 1.1em
+      line-height 1.7
+      font-weight bold
+    & > li:not(:first-child)
+      margin-top .75rem
+
+@media (max-width: $MQMobile)
+  .sidebar
+    .nav-links
+      display block
+      .dropdown-wrapper .nav-dropdown .dropdown-item a.router-link-active::after
+        top calc(1rem - 2px)
+    & > .sidebar-links
+      padding 1rem 0
+</style>
diff --git a/doc/docs/.vuepress/theme/components/SidebarButton.vue b/doc/docs/.vuepress/theme/components/SidebarButton.vue
new file mode 100644
index 0000000..3f54afd
--- /dev/null
+++ b/doc/docs/.vuepress/theme/components/SidebarButton.vue
@@ -0,0 +1,40 @@
+<template>
+  <div
+    class="sidebar-button"
+    @click="$emit('toggle-sidebar')"
+  >
+    <svg
+      class="icon"
+      xmlns="http://www.w3.org/2000/svg"
+      aria-hidden="true"
+      role="img"
+      viewBox="0 0 448 512"
+    >
+      <path
+        fill="currentColor"
+        d="M436 124H12c-6.627 0-12-5.373-12-12V80c0-6.627 5.373-12 12-12h424c6.627 0 12 5.373 12 12v32c0 6.627-5.373 12-12 12zm0 160H12c-6.627 0-12-5.373-12-12v-32c0-6.627 5.373-12 12-12h424c6.627 0 12 5.373 12 12v32c0 6.627-5.373 12-12 12zm0 160H12c-6.627 0-12-5.373-12-12v-32c0-6.627 5.373-12 12-12h424c6.627 0 12 5.373 12 12v32c0 6.627-5.373 12-12 12z"
+        class=""
+      />
+    </svg>
+  </div>
+</template>
+
+<style lang="stylus">
+.sidebar-button
+  cursor pointer
+  display none
+  width 1.25rem
+  height 1.25rem
+  position absolute
+  padding 0.6rem
+  top 0.6rem
+  left 1rem
+  .icon
+    display block
+    width 1.25rem
+    height 1.25rem
+
+@media (max-width: $MQMobile)
+  .sidebar-button
+    display block
+</style>
diff --git a/doc/docs/.vuepress/theme/components/SidebarGroup.vue b/doc/docs/.vuepress/theme/components/SidebarGroup.vue
new file mode 100644
index 0000000..d7f1929
--- /dev/null
+++ b/doc/docs/.vuepress/theme/components/SidebarGroup.vue
@@ -0,0 +1,141 @@
+<template>
+  <section
+    class="sidebar-group"
+    :class="[
+      {
+        collapsable,
+        'is-sub-group': depth !== 0
+      },
+      `depth-${depth}`
+    ]"
+  >
+    <RouterLink
+      v-if="item.path"
+      class="sidebar-heading clickable"
+      :class="{
+        open,
+        'active': isActive($route, item.path)
+      }"
+      :to="item.path"
+      @click.native="$emit('toggle')"
+    >
+      <span>{{ item.title }}</span>
+      <span
+        v-if="collapsable"
+        class="arrow"
+        :class="open ? 'down' : 'right'"
+      />
+    </RouterLink>
+
+    <p
+      v-else
+      class="sidebar-heading"
+      :class="{ open }"
+      @click="$emit('toggle')"
+    >
+      <span>{{ item.title }}</span>
+      <span
+        v-if="collapsable"
+        class="arrow"
+        :class="open ? 'down' : 'right'"
+      />
+    </p>
+
+    <DropdownTransition>
+      <SidebarLinks
+        v-if="open || !collapsable"
+        class="sidebar-group-items"
+        :items="item.children"
+        :sidebar-depth="item.sidebarDepth"
+        :initial-open-group-index="item.initialOpenGroupIndex"
+        :depth="depth + 1"
+      />
+    </DropdownTransition>
+  </section>
+</template>
+
+<script>
+import { isActive } from '../util'
+import DropdownTransition from '@theme/components/DropdownTransition.vue'
+
+export default {
+  name: 'SidebarGroup',
+
+  components: {
+    DropdownTransition
+  },
+
+  props: [
+    'item',
+    'open',
+    'collapsable',
+    'depth'
+  ],
+
+  // ref: https://vuejs.org/v2/guide/components-edge-cases.html#Circular-References-Between-Components
+  beforeCreate () {
+    this.$options.components.SidebarLinks = require('@theme/components/SidebarLinks.vue').default
+  },
+
+  methods: { isActive }
+}
+</script>
+
+<style lang="stylus">
+.sidebar-group
+  .sidebar-group
+    padding-left 0.5em
+  &:not(.collapsable)
+    .sidebar-heading:not(.clickable)
+      cursor auto
+      color inherit
+  // refine styles of nested sidebar groups
+  &.is-sub-group
+    padding-left 0
+    & > .sidebar-heading
+      font-size 0.95em
+      line-height 1.4
+      font-weight normal
+      padding-left 2rem
+      &:not(.clickable)
+        opacity 0.5
+    & > .sidebar-group-items
+      padding-left 1rem
+      & > li > .sidebar-link
+        font-size: 0.95em;
+        border-left none
+  &.depth-2
+    & > .sidebar-heading
+      border-left none
+
+.sidebar-heading
+  color $textColor
+  transition color .15s ease
+  cursor pointer
+  font-size 1.1em
+  font-weight bold
+  // text-transform uppercase
+  padding 0.35rem 1.5rem 0.35rem 1.25rem
+  width 100%
+  box-sizing border-box
+  margin 0
+  border-left 0.25rem solid transparent
+  &.open, &:hover
+    color inherit
+  .arrow
+    position relative
+    top -0.12em
+    left 0.5em
+  &.clickable
+    &.active
+      font-weight 600
+      color $accentColor
+      border-left-color $accentColor
+    &:hover
+      color $accentColor
+
+.sidebar-group-items
+  transition height .1s ease-out
+  font-size 0.95em
+  overflow hidden
+</style>
diff --git a/doc/docs/.vuepress/theme/components/SidebarLink.vue b/doc/docs/.vuepress/theme/components/SidebarLink.vue
new file mode 100644
index 0000000..4cd7665
--- /dev/null
+++ b/doc/docs/.vuepress/theme/components/SidebarLink.vue
@@ -0,0 +1,133 @@
+<script>
+import { isActive, hashRE, groupHeaders } from '../util'
+
+export default {
+  functional: true,
+
+  props: ['item', 'sidebarDepth'],
+
+  render (h,
+    {
+      parent: {
+        $page,
+        $site,
+        $route,
+        $themeConfig,
+        $themeLocaleConfig
+      },
+      props: {
+        item,
+        sidebarDepth
+      }
+    }) {
+    // use custom active class matching logic
+    // due to edge case of paths ending with / + hash
+    const selfActive = isActive($route, item.path)
+    // for sidebar: auto pages, a hash link should be active if one of its child
+    // matches
+    const active = item.type === 'auto'
+      ? selfActive || item.children.some(c => isActive($route, item.basePath + '#' + c.slug))
+      : selfActive
+    const link = item.type === 'external'
+      ? renderExternal(h, item.path, item.title || item.path)
+      : renderLink(h, item.path, item.title || item.path, active)
+
+    const maxDepth = [
+      $page.frontmatter.sidebarDepth,
+      sidebarDepth,
+      $themeLocaleConfig.sidebarDepth,
+      $themeConfig.sidebarDepth,
+      1
+    ].find(depth => depth !== undefined)
+
+    const displayAllHeaders = $themeLocaleConfig.displayAllHeaders
+      || $themeConfig.displayAllHeaders
+
+    if (item.type === 'auto') {
+      return [link, renderChildren(h, item.children, item.basePath, $route, maxDepth)]
+    } else if ((active || displayAllHeaders) && item.headers && !hashRE.test(item.path)) {
+      const children = groupHeaders(item.headers)
+      return [link, renderChildren(h, children, item.path, $route, maxDepth)]
+    } else {
+      return link
+    }
+  }
+}
+
+function renderLink (h, to, text, active, level) {
+  const component = {
+    props: {
+      to,
+      activeClass: '',
+      exactActiveClass: ''
+    },
+    class: {
+      active,
+      'sidebar-link': true
+    }
+  }
+
+  if (level > 2) {
+    component.style = {
+      'padding-left': level + 'rem'
+    }
+  }
+
+  return h('RouterLink', component, text)
+}
+
+function renderChildren (h, children, path, route, maxDepth, depth = 1) {
+  if (!children || depth > maxDepth) return null
+  return h('ul', { class: 'sidebar-sub-headers' }, children.map(c => {
+    const active = isActive(route, path + '#' + c.slug)
+    return h('li', { class: 'sidebar-sub-header' }, [
+      renderLink(h, path + '#' + c.slug, c.title, active, c.level - 1),
+      renderChildren(h, c.children, path, route, maxDepth, depth + 1)
+    ])
+  }))
+}
+
+function renderExternal (h, to, text) {
+  return h('a', {
+    attrs: {
+      href: to,
+      target: '_blank',
+      rel: 'noopener noreferrer'
+    },
+    class: {
+      'sidebar-link': true
+    }
+  }, [text, h('OutboundLink')])
+}
+</script>
+
+<style lang="stylus">
+.sidebar .sidebar-sub-headers
+  padding-left 1rem
+  font-size 0.95em
+
+a.sidebar-link
+  font-size 1em
+  font-weight 400
+  display inline-block
+  color $textColor
+  border-left 0.25rem solid transparent
+  padding 0.35rem 1rem 0.35rem 1.25rem
+  line-height 1.4
+  width: 100%
+  box-sizing: border-box
+  &:hover
+    color $accentColor
+  &.active
+    font-weight 600
+    color $accentColor
+    border-left-color $accentColor
+  .sidebar-group &
+    padding-left 2rem
+  .sidebar-sub-headers &
+    padding-top 0.25rem
+    padding-bottom 0.25rem
+    border-left none
+    &.active
+      font-weight 500
+</style>
diff --git a/doc/docs/.vuepress/theme/components/SidebarLinks.vue b/doc/docs/.vuepress/theme/components/SidebarLinks.vue
new file mode 100644
index 0000000..55e6288
--- /dev/null
+++ b/doc/docs/.vuepress/theme/components/SidebarLinks.vue
@@ -0,0 +1,106 @@
+<template>
+  <ul
+    v-if="items.length"
+    class="sidebar-links"
+  >
+    <li
+      v-for="(item, i) in items"
+      :key="i"
+    >
+      <SidebarGroup
+        v-if="item.type === 'group'"
+        :item="item"
+        :open="i === openGroupIndex"
+        :collapsable="item.collapsable || item.collapsible"
+        :depth="depth"
+        @toggle="toggleGroup(i)"
+      />
+      <SidebarLink
+        v-else
+        :sidebar-depth="sidebarDepth"
+        :item="item"
+      />
+    </li>
+  </ul>
+</template>
+
+<script>
+import SidebarGroup from '@theme/components/SidebarGroup.vue'
+import SidebarLink from '@theme/components/SidebarLink.vue'
+import { isActive } from '../util'
+
+export default {
+  name: 'SidebarLinks',
+
+  components: { SidebarGroup, SidebarLink },
+
+  props: [
+    'items',
+    'depth',  // depth of current sidebar links
+    'sidebarDepth', // depth of headers to be extracted
+    'initialOpenGroupIndex'
+  ],
+
+  data () {
+    return {
+      openGroupIndex: this.initialOpenGroupIndex || 0
+    }
+  },
+
+  watch: {
+    '$route' () {
+      this.refreshIndex()
+    }
+  },
+
+  created () {
+    this.refreshIndex()
+  },
+
+  methods: {
+    refreshIndex () {
+      const index = resolveOpenGroupIndex(
+        this.$route,
+        this.items
+      )
+      if (index > -1) {
+        this.openGroupIndex = index
+      }
+    },
+
+    toggleGroup (index) {
+      this.openGroupIndex = index === this.openGroupIndex ? -1 : index
+    },
+
+    isActive (page) {
+      return isActive(this.$route, page.regularPath)
+    }
+  }
+}
+
+function resolveOpenGroupIndex (route, items) {
+  for (let i = 0; i < items.length; i++) {
+    const item = items[i]
+    if (descendantIsActive(route, item)) {
+      return i
+    }
+  }
+  return -1
+}
+
+function descendantIsActive (route, item) {
+  if (item.type === 'group') {
+    const childIsActive = item.path && isActive(route, item.path)
+    const grandChildIsActive = item.children.some(child => {
+      if (child.type === 'group') {
+        return descendantIsActive(route, child)
+      } else {
+        return child.type === 'page' && isActive(route, child.path)
+      }
+    })
+
+    return childIsActive || grandChildIsActive
+  }
+  return false
+}
+</script>