gose.go

package gose

import (
	"fmt"
	"strings"
)

type Tree struct {
	Parent *Tree
	Child  []*Tree
	Value  string
}

func NewTree() *Tree {
	t := &Tree{}
	t.Parent = t
	return t
}

func Parse(s string) (*Tree, error) {
	if s[0] != '(' {
		return nil, fmt.Errorf("first letter must be '(', have '%s'", string(s[0]))
	}
	t := NewTree()

	t = t.Insert(s[1:])

	return t, nil
}

func (t *Tree) Insert(s string) *Tree {
	if s == "" {
		return t
	}
	s = strings.TrimSpace(s)

	switch s[0] {
	case '(':
		n := &Tree{Parent: t}
		n = n.Insert(s[1:])
		t.Child = append(t.Child, n)
	case ')':
		t.Parent = t.Parent.Insert(s[1:])
	default:
		for i := 0; i < len(s); i++ {
			if s[i] == '(' || s[i] == ')' {
				t.Value = s[:i]
				t = t.Insert(s[i:])
				break
			}
		}
	}
	return t
}

func (t *Tree) Walk() {
	fmt.Println("I am '", t.Value, "'")
	fmt.Println("my parent is '", t.Parent.Value, "'")
	fmt.Println("-------")

	for i := len(t.Child) - 1; i >= 0; i-- {
		t.Child[i].Walk()
	}
}