+static void
+item_init (item_t *item,
+ int count,
+ const char *challenge,
+ const char *response)
+{
+ item->count = count;
+
+ item->challenge = xmalloc (strlen (challenge) + 1 +
+ strlen (response) + 1);
+ item->response = item->challenge + strlen (challenge) + 1;
+
+ strcpy (item->challenge, challenge);
+ strcpy (item->response, response);
+}
+
+static void
+item_fini (item_t *item)
+{
+ /* item->response shares allocation with item->challenge, so
+ * doesn't require a separate call to free */
+ free (item->challenge);
+}
+
+static void
+category_init (category_t *category,
+ const char *name)
+{
+ category->name = xstrdup (name);
+
+ category->items_size = 0;
+ category->num_items = 0;
+ category->items = NULL;
+}
+
+static void
+category_fini (category_t *category)
+{
+ int i;
+
+ for (i = 0; i < category->num_items; i++)
+ item_fini (&category->items[i]);
+
+ free (category->items);
+
+ free (category->name);
+}
+
+static void
+category_grow (category_t *category)
+{
+ if (category->items_size)
+ category->items_size *= 2;
+ else
+ category->items_size = 1;
+
+ category->items = xrealloc (category->items,
+ category->items_size * sizeof (item_t));
+}
+
+static item_t *
+category_add_item (category_t *category,
+ int count,
+ const char *challenge,
+ const char *response)
+{
+ item_t *item;
+
+ if (category->num_items == category->items_size)
+ category_grow (category);
+
+ item = &category->items[category->num_items++];
+
+ item_init (item, count, challenge, response);
+
+ return item;
+}
+
+static void
+category_print (category_t *category,
+ FILE *file)
+{
+ int i;
+ item_t *item;
+
+ for (i = 0; i < category->num_items; i++) {
+ item = &category->items[i];
+ if (i != 0)
+ fprintf (file, "\n");
+ fprintf (file, "%d\n%s\n%s\n",
+ item->count,
+ item->challenge,
+ item->response);
+ }
+}
+
+static void
+bin_init (bin_t *bin,
+ int count)
+{
+ bin->count = count;
+
+ bin->items_size = 0;
+ bin->num_items = 0;
+ bin->items = NULL;
+}
+
+static void
+bin_fini (bin_t *bin)
+{
+ free (bin->items);
+}
+
+static void
+bin_grow (bin_t *bin)
+{
+ if (bin->items_size)
+ bin->items_size *= 2;
+ else
+ bin->items_size = 1;
+
+ bin->items = xrealloc (bin->items,
+ bin->items_size * sizeof (item_t*));
+}
+
+static void
+bin_add_item (bin_t *bin,
+ item_t *item)
+{
+ assert (item->count == bin->count);
+
+ if (bin->num_items == bin->items_size)
+ bin_grow (bin);
+
+ bin->items[bin->num_items++] = item;
+}
+
+static void
+mnemon_init (mnemon_t *mnemon)
+{
+ char *home;
+
+ home = getenv ("HOME");
+ if (home == NULL)
+ home = "";
+
+ xasprintf (&mnemon->dir_name, "%s/.mnemon", getenv ("HOME"));
+
+ mnemon->categories_size = 0;
+ mnemon->num_categories = 0;
+ mnemon->categories = NULL;
+
+ mnemon->bins_size = 0;
+ mnemon->num_bins = 0;
+ mnemon->bins = NULL;
+}
+
+static void
+mnemon_fini (mnemon_t *mnemon)
+{
+ int i;
+
+ for (i = 0; i < mnemon->num_bins; i++)
+ bin_fini (&mnemon->bins[i]);
+ free (mnemon->bins);
+
+ for (i = 0; i < mnemon->num_categories; i++)
+ category_fini (&mnemon->categories[i]);
+ free (mnemon->categories);
+
+ free (mnemon->dir_name);
+}
+
+static void
+mnemon_categories_grow (mnemon_t *mnemon)
+{
+ if (mnemon->categories_size)
+ mnemon->categories_size *= 2;
+ else
+ mnemon->categories_size = 1;
+
+ mnemon->categories = xrealloc (mnemon->categories,
+ mnemon->categories_size * sizeof (category_t));
+}
+
+static category_t *
+mnemon_get_category (mnemon_t *mnemon,
+ const char *name)
+{
+ int i;
+ category_t *category;
+
+ for (i = 0; i < mnemon->num_categories; i++)
+ if (strcmp (mnemon->categories[i].name, name) == 0)
+ return &mnemon->categories[i];
+
+ mnemon_categories_grow (mnemon);
+
+ category = &mnemon->categories[mnemon->num_categories++];
+
+ category_init (category, name);
+
+ return category;
+}
+
+static void
+mnemon_bins_grow (mnemon_t *mnemon)
+{
+ if (mnemon->bins_size)
+ mnemon->bins_size *= 2;
+ else
+ mnemon->bins_size = 1;
+
+ mnemon->bins = xrealloc (mnemon->bins,
+ mnemon->bins_size * sizeof (bin_t));
+}
+
+static bin_t *
+mnemon_get_bin (mnemon_t *mnemon,
+ int count)
+{
+ int i;
+ bin_t *bin;
+
+ for (i = 0; i < mnemon->num_bins; i++)
+ if (mnemon->bins[i].count == count)
+ return &mnemon->bins[i];
+
+ mnemon_bins_grow (mnemon);
+
+ bin = &mnemon->bins[mnemon->num_bins++];
+
+ bin_init (bin, count);
+
+ return bin;
+}
+
+static void
+mnemon_add_item (mnemon_t *mnemon,
+ category_t *category,
+ int count,
+ const char *challenge,
+ const char *response)
+{
+ item_t *item;
+ bin_t *bin;
+
+ item = category_add_item (category, count, challenge, response);
+
+ bin = mnemon_get_bin (mnemon, count);
+
+ bin_add_item (bin, item);
+}
+