How do you perform a deep copy of a struct in Go?

问题:

I'm attempting to perform a deep copy of the following struct:

// Ternary Tree
type Tree struct {
    Left  *Tree
    Mid *Tree
    Right *Tree
    Value interface{}
    Parent *Tree
    Orientation string
    IsTerminal bool
    Type string
}

The following is my sorry attempt. It looks like I'm creating a new tree at the root but it's children are still pointing to the same address in memory.

func (tree *Tree) CopyTree() *Tree {
    if (tree == nil) {
        return nil
    } else {
        copiedTree := &Tree {
            tree.Left.CopyTree(),
            tree.Mid.CopyTree(),
            tree.Right.CopyTree(),
            tree.Value,
            tree.Parent.CopyTree(),
            tree.Orientation,
            tree.IsTerminal,
            tree.Type}
        return copiedTree
    }
}

Are there any useful constructs in go that assist with deep copying a struct? If not, how would I perform this deep copy myself? Note, the "deepcopy" package no longer works as it uses a few functions that were deprecated with the release of Go 1

回答1:

I was close. I should have assigned the copiedTree to the parent property.

func (tree *Tree) CopyTree() *Tree {
    if (tree == nil) {
        return nil
    } else {
        copiedTree := &Tree {
            tree.Left.CopyTree(),
            tree.Mid.CopyTree(),
            tree.Right.CopyTree(),
            tree.Value,
            nil,
            tree.Orientation,
            tree.IsTerminal,
            tree.Type,
        }

        if copiedTree.Left != nil {
            copiedTree.Left.Parent = copiedTree
        }
        if copiedTree.Right != nil {
            copiedTree.Right.Parent = copiedTree
        }
        if copiedTree.Mid != nil {
            copiedTree.Mid.Parent = copiedTree
        }
        return copiedTree
    }
}

回答2:

How about json.Marshal and json.Unmarshal. If performance is critical, I perfer to use protobuf.