tree.Print: "Hash of unhashable type main.Node" error

[godstanis]

Hi, I try to print my simple tree but I get the mentioned error, here is my code:

package main

import (
	"fmt"
	"github.com/shivamMg/ppds/tree"
)

type Node struct {
	data  string
	depth int
	c     []*Node
}

func (n Node) Data() interface{} {
	return n.data
}

func (n Node) Children() (children []tree.Node) {
	for _, c := range n.c {
		children = append(children, tree.Node(c))
	}
	return
}

func main() {
	parent := Node{"Test", 0, nil}
	buildBinaryTreeFromNode(&parent, 3, 0)

	fmt.Println(parent)
	tree.Print(parent)
}

func buildBinaryTreeFromNode(node *Node, maxDepth int, curDepth int) {
	if curDepth >= maxDepth {
		return
	}

	curDepth++

	if node.c == nil {
		node.c = []*Node{{"Element", curDepth, nil}, {"Element", curDepth, nil}}
	}

	for idx, _ := range []int{0, 1} {
		buildBinaryTreeFromNode(node.c[idx], maxDepth, curDepth)
	}
}

[shivamMg]

Slices in go are unhashable. So if you've a struct with one of the fields as a slice it will also be unhashable. See: https://play.golang.org/p/u2xb1fxVt3d

The library counts on your Node type to be hashable. I will suggest using pointer to Node everywhere - which will make it hashable.

Here's your snippet where I've made Data() and Children() receivers to be pointer to Node: https://play.golang.org/p/3Q3KKzaLliU

package main

import (
	"fmt"
	"github.com/shivamMg/ppds/tree"
)

type Node struct {
	data  string
	depth int
	c     []*Node
}

func (n *Node) Data() interface{} {
	return n.data
}

func (n *Node) Children() (children []tree.Node) {
	for _, c := range n.c {
		children = append(children, tree.Node(c))
	}
	return
}

func main() {
	parent := Node{"Test", 0, nil}
	buildBinaryTreeFromNode(&parent, 3, 0)

	fmt.Println(parent)
	tree.Print(&parent)
}

func buildBinaryTreeFromNode(node *Node, maxDepth int, curDepth int) {
	if curDepth >= maxDepth {
		return
	}

	curDepth++

	if node.c == nil {
		node.c = []*Node{{"Element", curDepth, nil}, {"Element", curDepth, nil}}
	}

	for idx, _ := range []int{0, 1} {
		buildBinaryTreeFromNode(node.c[idx], maxDepth, curDepth)
	}
}

Hope this helps.

[godstanis]

Yeah, right. Ok, thanks)