forked from crowetic/commerce
68 lines
2.0 KiB
TypeScript
68 lines
2.0 KiB
TypeScript
export type HasParent = { id: string; parent?: { id: string } | null }
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export type TreeNode<T extends HasParent> = T & {
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children: Array<TreeNode<T>>
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expanded: boolean
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}
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export type RootNode<T extends HasParent> = {
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id?: string
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children: Array<TreeNode<T>>
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}
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export function arrayToTree<T extends HasParent>(
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nodes: T[],
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currentState?: RootNode<T>
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): RootNode<T> {
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const topLevelNodes: Array<TreeNode<T>> = []
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const mappedArr: { [id: string]: TreeNode<T> } = {}
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const currentStateMap = treeToMap(currentState)
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// First map the nodes of the array to an object -> create a hash table.
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for (const node of nodes) {
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mappedArr[node.id] = { ...(node as any), children: [] }
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}
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for (const id of nodes.map((n) => n.id)) {
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if (mappedArr.hasOwnProperty(id)) {
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const mappedElem = mappedArr[id]
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mappedElem.expanded = currentStateMap.get(id)?.expanded ?? false
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const parent = mappedElem.parent
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if (!parent) {
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continue
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}
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// If the element is not at the root level, add it to its parent array of children.
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const parentIsRoot = !mappedArr[parent.id]
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if (!parentIsRoot) {
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if (mappedArr[parent.id]) {
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mappedArr[parent.id].children.push(mappedElem)
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} else {
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mappedArr[parent.id] = { children: [mappedElem] } as any
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}
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} else {
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topLevelNodes.push(mappedElem)
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}
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}
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}
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// tslint:disable-next-line:no-non-null-assertion
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const rootId = topLevelNodes.length ? topLevelNodes[0].parent!.id : undefined
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return { id: rootId, children: topLevelNodes }
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}
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/**
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* Converts an existing tree (as generated by the arrayToTree function) into a flat
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* Map. This is used to persist certain states (e.g. `expanded`) when re-building the
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* tree.
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*/
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function treeToMap<T extends HasParent>(
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tree?: RootNode<T>
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): Map<string, TreeNode<T>> {
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const nodeMap = new Map<string, TreeNode<T>>()
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function visit(node: TreeNode<T>) {
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nodeMap.set(node.id, node)
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node.children.forEach(visit)
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}
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if (tree) {
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visit(tree as TreeNode<T>)
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}
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return nodeMap
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}
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