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<template>
<ul>
<li v-for="(breadcrumb, index) in breadcrumbs" class="cw-ribbon-breadcrumb-item" :key="index">
<span v-if="breadcrumb.active">{{ breadcrumb.title }}</span>
<a v-else :href="breadcrumb.url">{{ breadcrumb.title }}</a>
</li>
</ul>
</template>
<script lang="ts">
import { defineComponent, PropType } from 'vue';
import { TOCItem, traverse } from './table-of-contents';
interface Breadcrumb {
title: string;
url: string;
active: boolean;
}
export default defineComponent({
name: 'ContentBarBreadcrumbs',
props: {
// The table of contents tree for the page that is currently open.
toc: {
type: Object as PropType<TOCItem>,
required: true,
},
},
computed: {
// Convert the nested TOCItem into a list of breadcrumbs we can iterate through
// in the template.
breadcrumbs(): Breadcrumb[] {
// First, clone the toc and add parent references to it.
// (The parent references are lost in serialization from PHP to JS.)
const tocClone = JSON.parse(JSON.stringify(this.toc));
this.addParentReferences(tocClone);
// Then, find the TOCItem corresponding to the page that is currently open.
const activeTocItem = this.findActiveTocItem(tocClone);
if (!activeTocItem) {
console.error('No TOCItem is marked as active. No breadcrumbs will be rendered.');
return [];
}
// Finally, iterate upwards from the active TOC Item, through its parent, grandparent, ...
// up to the root, generating a breadcrumb at each step of the way.
const breadcrumbs = [{ title: activeTocItem.title, url: activeTocItem.url, active: true }];
let current = activeTocItem;
while (current.parent) {
current = current.parent;
breadcrumbs.push({ title: current.title, url: current.url, active: false });
}
return breadcrumbs.reverse();
},
},
methods: {
// Find the TOCItem, if any, that is marked as active in the given toc tree.
findActiveTocItem(toc: TOCItem): TOCItem | undefined {
let activeItem: TOCItem | undefined;
traverse(toc, (item) => {
if (item.active) {
activeItem = item;
}
});
return activeItem;
},
// Augment each node in the given toc tree with a reference to its parent.
addParentReferences(tocItem: TOCItem, parent?: TOCItem): void {
if (parent) {
tocItem.parent = parent;
}
for (let child of tocItem.children) {
this.addParentReferences(child, tocItem);
}
},
},
});
</script>
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