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tree-fns

tree-fns provides simple utility functions for tree structure.

Each transformation function is non-destructive, making it suitable for working with immutable tree structures.

Development

Prerequisite

  • deno >= 1.20

Model

const tree: TreeNode = {
  id: "root",
  children: [
    {
      id: "1",
      children: [],
    },
    {
      id: "2",
      children: [],
    },
  ],
};
const tree: TreeNode<{ data: string }> = {
  id: "root",
  data: "yay",
  children: [],
};

Functions

walk(tree, visit)

Only pre-order traversing is supported.

walk(
  {
    id: "root",
    children: [
      {
        id: "1",
        children: [{ id: "1-1", children: [] }],
      },
      {
        id: "2",
        children: [{ id: "2-1", children: [] }],
      },
    ],
  },
  (node, location) => {
    console.log(node.id); // "root" -> "1" -> "1-1" -> "2" -> "2-1"
    if (node.id === "1") {
      console.log(location); // { parentPath: ["root"], index: 0 }
    }
  },
);

findNode(tree, test) | findNodeById(tree, id)

const tree: TreeNode = {
  id: "root",
  children: [
    {
      id: "1",
      children: [{ id: "1-1", children: [] }],
    },
    {
      id: "2",
      children: [{ id: "2-1", children: [] }],
    },
  ],
};

const node = findNode(tree, (node) => node.id === "1");
// [
//   {
//     id: '1',
//     children: [{ id: '1-1', children: [] }],
//   },
//   {
//     parentPath: ['root'],
//     index: 0,
//   },
// ]

findNode(tree, (node) => node.id === "x"); // undefined

or

const node = findNodeById(tree, "1");

map(tree, mapNode)

const tree: TreeNode<{ data: string }> = {
  id: "1",
  data: "foo",
  children: [
    {
      id: "2",
      data: "bar",
      children: [],
    },
  ],
};

const mapped = map<{ data: string }>(tree, (node) => ({
  ...node,
  data: `#${node.data}`,
}));
// {
//   id: '1',
//   data: '#foo',
//   children: [
//     {
//       id: '2',
//       data: '#bar',
//       children: [],
//     },
//   ],
// }

copy(tree)

const tree = {
  id: "1",
  children: [{ id: "2", children: [] }],
};

const copied = copy(tree);
// {
//   id: '1',
//   children: [{ id: '2', children: [] }],
// }

console.log(tree === copied); // false

addNode(tree, nodeToBeAdded, dest)

const srcTree = {
  id: "1",
  children: [{ id: "2", children: [] }],
};

const nodeToBeAdded = { id: "3", children: [] };

const destTree = addNode(srcTree, nodeToBeAdded, { parentId: "1", index: 0 });
// {
//   id: '1',
//   children: [
//     { id: '3', children: [] },
//     { id: '2', children: [] },
//   ],
// }

removeNode(tree, id)

const srcTree = {
  id: "1",
  children: [
    { id: "2", children: [] },
    { id: "3", children: [] },
  ],
};
const [destTree, removedNode] = removeNode(srcTree, "3");

console.log(removedNode); // { id: '3', children: [] }
console.log(destTree);
// {
//   id: '1',
//   children: [
//     { id: '2', children: [] },
//   ],
// }

removeNode(srcTree, "x"); // undefined

moveNode(tree, id, dest)

const srcTree = {
  id: "1",
  children: [
    { id: "2", children: [] },
    { id: "3", children: [] },
  ],
};

const destTree = moveNode(srcTree, "2", { parentId: "3", index: 0 });
// {
//   id: '1',
//   children: [
//     { id: '3', children: [
//       { id: '2', children: [] }
//     ] }
//   ],
// }

flatten(tree)

const tree = {
  id: "1",
  children: [
    { id: "2", children: [] },
    { id: "3", children: [] },
  ],
};

const flattened = flatten(tree);
// [
//   [
//     {
//       id: '1',
//       children: [
//         { id: '2', children: [] },
//         { id: '3', children: [] },
//       ],
//     },
//     { parentPath: [], index: 0 },
//   ],
//   [{ id: '2', children: [] }, { parentPath: ['1'], index: 0 }],
//   [{ id: '3', children: [] }, { parentPath: ['1'], index: 1 }],
// ]