RosettaCodeData/Task/Visualize-a-tree/Elena/visualize-a-tree.elena

/// a program to produce a visual representation of some tree.

import system'routines;
import extensions;

class Node
{
    string theValue;
    Node[] theChildren;

    constructor new(string value, Node[] children)
    {
        theValue := value;

        theChildren := children;
    }

    constructor new(string value)
        <= new(value, new Node[](0));

    constructor new(Node[] children)
        <= new(emptyString, children);

    get() = theValue;

    Children = theChildren;
}

extension treeOp
{
    writeTree(node, prefix)
    {
        var children := node.Children;
        var length := children.Length;

        children.zipForEach(new Range(1, length), (child,index)
        {
            self.printLine(prefix,"|");
            self.printLine(prefix,"+---",child.get());

            var nodeLine := prefix + (index==length).iif("    ","|   ");

            self.writeTree(child,nodeLine);
        });

        ^ self
    }

    writeTree(node)
        = self.writeTree(node,"");
}

public program()
{
    var tree := Node.new(
                 new Node[]::(
                    Node.new("a", new Node[]::
                    (
                        Node.new("b", new Node[]::(Node.new("c"))),
                        Node.new("d")
                    )),
                    Node.new("e")
                 ));

    console.writeTree(tree).readChar()
}