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import { useSyncExternalStore } from 'react'
import type { SegmentNodeState } from '../userspace/app/segment-explorer-node'
/**
* Trie data structure for storing and searching paths
*
* This can be used to store app router paths and search for them efficiently.
* e.g.
*
* [trie root]
* ├── layout.js
* ├── page.js
* ├── blog
* ├── layout.js
* ├── page.js
* ├── [slug]
* ├── layout.js
* ├── page.js
**/
type TrieNode<Value = string> = {
value: Value | undefined
children: {
[key: string]: TrieNode<Value> | undefined
}
}
type Trie<Value = string> = {
insert: (value: Value) => void
remove: (value: Value) => void
getRoot: () => TrieNode<Value>
}
const listeners = new Set<() => void>()
const createSegmentTreeStore = (): {
subscribe: (callback: () => void) => () => void
getSnapshot: () => SegmentTrieNode
getServerSnapshot: () => SegmentTrieNode
} => {
// return a store that can be used by useSyncExternalStore
return {
subscribe: (callback) => {
listeners.add(callback)
return () => listeners.delete(callback)
},
getSnapshot: () => {
return trie.getRoot()
},
getServerSnapshot: () => {
return trie.getRoot()
},
}
}
// TODO: Move the Segment Tree into React State
const { subscribe, getSnapshot, getServerSnapshot } = createSegmentTreeStore()
function createTrie<Value = string>({
getCharacters = (item: Value) => [item] as string[],
compare = (a: Value | undefined, b: Value | undefined) => a === b,
}: {
getCharacters?: (item: Value) => string[]
compare?: (a: Value | undefined, b: Value | undefined) => boolean
}): Trie<Value> {
let root: TrieNode<Value> = {
value: undefined,
children: {},
}
function markUpdated() {
for (const listener of listeners) {
listener()
}
}
function insert(value: Value) {
let currentNode = root
const segments = getCharacters(value)
for (const segment of segments) {
if (!currentNode.children[segment]) {
currentNode.children[segment] = {
value: undefined,
// Skip value for intermediate nodes
children: {},
}
}
currentNode = currentNode.children[segment]
}
currentNode.value = value
root = { ...root }
markUpdated()
}
function remove(value: Value) {
let currentNode = root
const segments = getCharacters(value)
const stack: TrieNode<Value>[] = []
let found = true
for (const segment of segments) {
if (!currentNode.children[segment]) {
found = false
break
}
stack.push(currentNode)
currentNode = currentNode.children[segment]!
}
// If the value is not found, skip removal
if (!found || !compare(currentNode.value, value)) {
return
}
currentNode.value = undefined
for (let i = stack.length - 1; i >= 0; i--) {
const parentNode = stack[i]
const segment = segments[i]
if (Object.keys(parentNode.children[segment]!.children).length === 0) {
delete parentNode.children[segment]
}
}
root = { ...root }
markUpdated()
}
function getRoot(): TrieNode<Value> {
return root
}
return { insert, remove, getRoot }
}
export type SegmentTrie = Trie<SegmentNodeState>
export type SegmentTrieNode = TrieNode<SegmentNodeState>
const trie: SegmentTrie = createTrie({
compare: (a, b) => {
if (!a || !b) return false
return (
a.pagePath === b.pagePath &&
a.type === b.type &&
a.boundaryType === b.boundaryType
)
},
getCharacters: (item) => item.pagePath.split('/'),
})
export const insertSegmentNode = trie.insert
export const removeSegmentNode = trie.remove
export function useSegmentTree(): SegmentTrieNode {
const state = useSyncExternalStore(subscribe, getSnapshot, getServerSnapshot)
return state
}
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