treeprint

Package treeprint provides a simple ASCII tree composing tool.

If you are familiar with the tree utility that is a recursive directory listing command that produces a depth indented listing of files, then you have the idea of what it would look like.

On my system the command yields the following

 $ tree
.
├── LICENSE
├── README.md
├── treeprint.go
└── treeprint_test.go

0 directories, 4 files

and I'd like to have the same format for my Go data structures when I print them.

Installation

$ go get github.com/xlab/treeprint

Concept of work

The general idea is that you initialise a new tree with treeprint.New() and then add nodes and branches into it. Use AddNode() when you want add a node on the same level as the target or use AddBranch() when you want to go a level deeper. So tree.AddBranch().AddNode().AddNode() would create a new level with two distinct nodes on it. So tree.AddNode().AddNode() is a flat thing and tree.AddBranch().AddBranch().AddBranch() is a high thing. Use String() or Bytes() on a branch to render a subtree, or use it on the root to print the whole tree.

The utility will yield Unicode-friendly trees. The output is predictable and there is no platform-dependent exceptions, so if you have issues with displaying the tree in the console, all platform-related transformations can be done after the tree has been rendered: an example for Asian locales.

Use cases

When you want to render a complex data structure:

func main() {
    // to add a custom root name use `treeprint.NewWithRoot()` instead
    tree := treeprint.New()

    // create a new branch in the root
    one := tree.AddBranch("one")

    // add some nodes
    one.AddNode("subnode1").AddNode("subnode2")

    // create a new sub-branch
    one.AddBranch("two").
        AddNode("subnode1").AddNode("subnode2"). // add some nodes
        AddBranch("three"). // add a new sub-branch
        AddNode("subnode1").AddNode("subnode2") // add some nodes too

    // add one more node that should surround the inner branch
    one.AddNode("subnode3")

    // add a new node to the root
    tree.AddNode("outernode")

    fmt.Println(tree.String())
}

Will give you:

.
├── one
│   ├── subnode1
│   ├── subnode2
│   ├── two
│   │   ├── subnode1
│   │   ├── subnode2
│   │   └── three
│   │       ├── subnode1
│   │       └── subnode2
│   └── subnode3
└── outernode

Another case, when you have to make a tree where any leaf may have some meta-data (as tree is capable of it):

func main {
    // to add a custom root name use `treeprint.NewWithRoot()` instead
    tree := treeprint.New()

    tree.AddNode("Dockerfile")
    tree.AddNode("Makefile")
    tree.AddNode("aws.sh")
    tree.AddMetaBranch(" 204", "bin").
        AddNode("dbmaker").AddNode("someserver").AddNode("testtool")
    tree.AddMetaBranch(" 374", "deploy").
        AddNode("Makefile").AddNode("bootstrap.sh")
    tree.AddMetaNode("122K", "testtool.a")

    fmt.Println(tree.String())
}

Output:

.
├── Dockerfile
├── Makefile
├── aws.sh
├── [ 204]  bin
│   ├── dbmaker
│   ├── someserver
│   └── testtool
├── [ 374]  deploy
│   ├── Makefile
│   └── bootstrap.sh
└── [122K]  testtool.a

Iterating over the tree nodes

tree := New()

one := tree.AddBranch("one")
one.AddNode("one-subnode1").AddNode("one-subnode2")
one.AddBranch("two").AddNode("two-subnode1").AddNode("two-subnode2").
    AddBranch("three").AddNode("three-subnode1").AddNode("three-subnode2")
tree.AddNode("outernode")

// if you need to iterate over the whole tree
// call `VisitAll` from your top root node.
tree.VisitAll(func(item *node) {
    if len(item.Nodes) > 0 {
        // branch nodes
        fmt.Println(item.Value) // will output one, two, three
    } else {
        // leaf nodes
        fmt.Println(item.Value) // will output one-*, two-*, three-* and outernode
    }
})

Yay! So it works.

License

MIT