package main

/**
* A fairly simple implementation of a single linked list in Go
* Created: Sep 2023
* Author gtowell
 */

import "fmt"

// a struct for the Node of a linked list.
// The data item should be generic
type Node struct {
	next *Node
	data int
}

// A struct to hold the head and tail of a linked list.
// most LL methods will be from here
type LinkedList struct {
	head *Node
	tail *Node
}

// Add an item to the linked list. 
// This will change the tail, and may change the head
func (ll *LinkedList) add(dta int) {
	nnode := Node{data:dta}
	fmt.Printf("Add %v\n", nnode)
	if ll.head==nil {
		fmt.Println("Enpty list")
		ll.head=&nnode
		ll.tail=&nnode
	} else {
		ll.tail.next = &nnode
		ll.tail=&nnode
	}
}

// A function type, for easy reference later
type itrfunc func() *Node

// ask the linked list for an iterator
// this will give each node in the list 
// successively 
func (ll LinkedList) getIterator() itrfunc {
	var nxt *Node
	frst := true
	return func() *Node {
		if nxt==nil {
			if frst {
				nxt=ll.head
				return nxt
			} else {
				return nil;
			}
		} else {
			nxt = nxt.next
			return nxt
		}
	}
}


//Exercise the linked list
func main() {
	ll := LinkedList{}
	ll.add(1)
	fmt.Printf("HH %v\n", ll.head)
	ll.add(3)
	ll.add(5)
	ll.add(7)
	for getNext:=ll.getIterator();; {
		v:=getNext()
		if v==nil {
			break;
		}
		fmt.Printf("%v\n", v.data)
	}
}