Function depthFirst

depthFirst<A>(a: Zipper.Zipper<A>): Zipper.Zipper<A>

Navigate from a node to the next node in a depth-first pre-order traversal, where parents are visited before their children, and both are visited before the next sibling of the parent. For example:

For the tree:
                  ┌─┐
                  │1│
             ╭────┴─┴─────╮
           ┌─┴─┐        ┌─┴─┐
           │1.1│        │1.2│
         ╭─┴───┴╮      ╭┴───┴─╮
      ┌──┴──┐┌──┴──┐┌──┴──┐┌──┴──┐
      │1.1.1││1.1.2││1.2.1││1.2.2│
      └─────┘└─────┘└─────┘└─────┘

     depthFirst ┊ result of
    called on...┊ navigation
    ┈┈┈┈┈┈┈┈┈┈┈┈┼┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈
           “1”  ┊ “1.1”
         “1.1”  ┊ “1.2”
         “1.2”  ┊ “1.1.1”
       “1.1.1”  ┊ “1.1.2”
       “1.2.1”  ┊ “1.2.2”
       “1.2.2”  ┊ Exception thrown

Returns Option.none when the final node in the traversal has been reached.

This is the unsafe version of tryDepthFirst.

Type Parameters

A
The underlying type of the tree.

Parameters

a: Zipper.Zipper<A>

Returns Zipper.Zipper<A>

An updated zipper pointing at a new focus.

Example

import {Zipper, from, of} from 'effect-tree'

// ┬1
// ├┬2
// │├─3
// │└─4
// └┬5
//  ├─6
//  └─7
const tree = from(1, from(2, of(3), of(4)), from(5, of(6), of(7)))

const start = Zipper.fromTree(tree)

const hop1 = Zipper.depthFirst(start)
expect(Zipper.getValue(hop1)).toBe(2)

const hop2 = Zipper.depthFirst(hop1)
expect(Zipper.getValue(hop2)).toBe(3)

const hop3 = Zipper.depthFirst(hop2)
expect(Zipper.getValue(hop3)).toBe(4)

const hop4 = Zipper.depthFirst(hop3)
expect(Zipper.getValue(hop4)).toBe(5)

const hop5 = Zipper.depthFirst(hop4)
expect(Zipper.getValue(hop5)).toBe(6)

const hop6 = Zipper.depthFirst(hop5)
expect(Zipper.getValue(hop6)).toBe(7)

// Out-of-bounds exception when nowhere left to go.
expect(()  => Zipper.depthFirst(hop6)).toThrow(/getOrThrow/)