+static void
+item_init (item_t *item,
+ int score,
+ const char *challenge,
+ const char *response)
+{
+ item->score = score;
+
+ 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;
+ category->order = CATEGORY_ORDER_RANDOM;
+ category->bin_zero_head = 0;
+}
+
+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 score,
+ 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, score, challenge, response);
+
+ return item;
+}
+
+static item_t *
+category_next_bin_zero_item (category_t *category)
+{
+ int *i = &category->bin_zero_head;
+
+ for ( ; *i < category->num_items; *i = *i + 1)
+ if (category->items[*i].score == 0)
+ return &category->items[*i];
+
+ return NULL;
+}
+
+static void
+category_print (category_t *category,
+ FILE *file)
+{
+ int i;
+ item_t *item;
+
+ fprintf (file, "order = %s\n\n",
+ category->order == CATEGORY_ORDER_RANDOM ? "random" : "sequential");
+
+ 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->score,
+ item->challenge,
+ item->response);
+ }
+}
+
+static void
+bin_init (bin_t *bin,
+ int score)
+{
+ bin->score = score;
+
+ 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->score == bin->score);
+
+ if (bin->num_items == bin->items_size)
+ bin_grow (bin);
+
+ bin->items[bin->num_items++] = item;
+}
+
+static void
+bin_remove_item (bin_t *bin,
+ int item_index)
+{
+ /* Replace the current item with the last item, (no need to shift
+ * any more than that since we don't care about the order of the
+ * items within a bin). */
+ bin->num_items--;
+ if (bin->num_items)
+ bin->items[item_index] = bin->items[bin->num_items];
+}
+
+/* Find the index for an item within a bin.
+ *
+ * XXX: This is currently a linear search, so is a potential
+ * performance problem.
+ */
+static int
+bin_item_index (bin_t *bin,
+ item_t *item)
+{
+ int i;
+
+ for (i = 0; i < bin->num_items; i++)
+ if (bin->items[i] == item)
+ return i;
+
+ assert (0);
+}
+
+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;
+
+ mnemon->to_introduce = 3;
+ mnemon->to_master = 0;
+ mnemon->unlearned = 0;
+ mnemon->mastered = -1;
+}
+
+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 score)
+{
+ int i;
+ bin_t *bin;
+
+ for (i = 0; i < mnemon->num_bins; i++)
+ if (mnemon->bins[i].score == score)
+ return &mnemon->bins[i];
+ else if (mnemon->bins[i].score > score)
+ break;
+
+ if (mnemon->num_bins == mnemon->bins_size)
+ mnemon_bins_grow (mnemon);
+
+ bin = &mnemon->bins[i];
+
+ /* Make room to insert new bin at its sorted location. */
+ if (i < mnemon->num_bins)
+ memmove (bin + 1, bin, (mnemon->num_bins - i) * sizeof (bin_t));
+ mnemon->num_bins++;
+
+ bin_init (bin, score);
+
+ return bin;
+}
+
+static void
+mnemon_remove_bin (mnemon_t *mnemon,
+ bin_t *bin)
+{
+ int i = bin - mnemon->bins;
+
+ bin_fini (bin);
+
+ memmove (bin, bin + 1, (mnemon->num_bins - i) * sizeof (bin_t));
+ mnemon->num_bins--;
+}
+