// Laboratorio 7 - Esercizio 2 - Diagonali.c
// Matteo Schiff - s295565

#include <stdlib.h>
#include "Elementi.h"
#include "Diagonali.h"

typedef struct node_s *link;

typedef struct node_s {
    Diagonale diag;
    link next;
} node;

typedef struct diagonali
{
    link head;
    int N;
} *Diagonali;

link new_node(Diagonale diag, link next) {
    link t = malloc(sizeof(node));
    if (t == NULL) {
        printf("Errore: impossibile allocare memoria");
        exit(2);
    }
    t->diag = diag;
    t->next = next;

    return t;
}

void free_node(link p) {
    free(p);
}

/* creatore e distruttore */
Diagonali DiagionaliInit() {
    Diagonali new = malloc(sizeof(struct diagonali));
    new->head = NULL;
    new->N = 0;
    return new;
}

void DiagonaliFree(Diagonali diags) {
    link p, x;
    for (p = diags->head, x = diags->head->next; x != NULL; p = x, x = x->next){
        free_node(p);
    }
    free(diags);
}

void DiagonaliInsert(Diagonali diags, Diagonale newDiag) {
    link nd = new_node(newDiag, diags->head);
    diags->head = nd;
    diags->N++;
} 

link DiagonaliTraverse(Diagonali diags, link prev, Diagonale ** elem) {
    link next;

    if (prev == NULL) {
        next = diags->head;
    } else {
        next = prev->next;
    }

    if (next == NULL)
        return NULL;

    *elem = &next->diag;
    return next;
}