node.go

package main

// This file implements the Nodes of a filesystem tree.

import (
	"fmt"
	"io"
)

// Node in the Library's file tree.
type Node struct {
	payload  interface{}
	parent   *Node
	children []*Node
}

// Walks through the tree and applies function f to each Node.
func (this *Node) Walk(f func(*Node)) {
	f(this)
	for _, c := range this.children {
		c.Walk(f)
	}
}

// Construct new node with given parent
// and link the parent-child pointers.
func (parent *Node) NewChild(file string) (child *Node) {
	child = &Node{file, parent, nil}
	parent.children = append(parent.children, child)
	return
}

// Returns full path represented by this node.
func (n *Node) String() string {
	str := fmt.Sprint(n.payload)
	for p := n.parent; p != nil; p = p.parent {
		str = fmt.Sprint(p.payload, str)
	}
	return str
}

// Write full path to out.
func (this *Node) WriteTo(out io.Writer) (n int, err error) {
	n, err = fmt.Fprintln(out, this)
	return
}

// Get a child by its file string.
func (n *Node) Child(file string) *Node {
	for _, c := range n.children {
		if c.payload == file {
			return c
		}
	}
	return nil
}