1 files changed, 225 insertions, 0 deletions
diff --git a/Algorithms/lists.c b/Algorithms/lists.c
new file mode 100644
index 0000000..0e73801
--- /dev/null
+++ b/Algorithms/lists.c
@@ -0,0 +1,225 @@
+/*
+ * Linked lists implementation
+*/
+
+#include <stdlib.h>
+#include <string.h>
+
+#include "lists.h"
+
+/* SINGLY LINKED LIST */
+
+void list_init(List *list, void (*destroy)(void *data))
+{
+	list->size = 0;
+	list->destroy = destroy;
+	list->head = NULL;
+	list-tail = NULL;
+
+	return;
+}
+
+void list_destroy(List *list)
+{
+	void	*data = NULL;
+
+	while (list_size(list) > 0) {
+		/* list_rem_next removes head's element if passed NULL */
+		if (list_rem_next(list, NULL, (void **)&data) == 0 &&
+		    list->destroy != NULL)
+			list->destroy(data);
+	}
+
+	memset(list, 0, sizeof(List));
+	return;
+}
+
+int list_ins_next(List *list, ListElmt *element, const void *data)
+{
+	ListElmt	*new_element;
+
+	if ((new_element = (ListElmt *)malloc(sizeof(ListElmt))) == NULL)
+		return -1;
+
+	new_element->data = (void *)data;
+
+	if (element == NULL) {
+		if (list_size(list) == 0)
+			list->tail = new_element;
+
+		new_element->next = list->head;
+		list->head = new_element;
+	} else {
+		if (element->next == NULL)
+			list->tail = new_element;
+
+		new_element->next = element->next;
+		element->next = new_element
+	}
+
+	list->size++;
+	return 0;
+}
+
+int list_rem_next(List *list, ListElmt *element, void **data) {
+	ListElmt	*old_element;
+
+	if (list_size(list) == 0)
+		return -1;
+
+	if (element == NULL) {
+		*data = list->head->data;
+		old_element = list->head;
+		list->head = list->head->next;
+
+		if (list_size(list) == 1)
+			list->tail = NULL;
+
+	} else {
+		if (element->next == NULL)
+			return -1;
+
+		*data = element->next->data;
+		old_element = element->next;
+		element->next = element->next->next;
+
+		if (element->next == NULL)
+			list->tail = element;
+	}
+
+	free(old_element);
+	list->size--;
+	return 0;
+}
+
+/* SINGLY LINKED LIST -- END */
+
+/* DOUBLY LINKED LIST */
+
+void dlist_init(struct DList *list, void (*destroy)(void *data)) {
+
+	/* Initialize list */
+	list->size = 0;
+	list->destroy = destroy;
+	list->head = NULL;
+	list->tail = NULL;
+	return;
+}
+
+void dlist_destroy(struct DList *list) {
+	void *data;
+
+	/* Remove elements */
+	while (dlist_size(list) > 0) {
+		if (dlist_remove(list, dlist_tail(list), (void **)&data) == 0
+		    && list->destroy != NULL)
+			list->destroy(data);
+	}
+
+	/* clear list struct just in case */
+	memset(list, 0, sizeof(DList));
+	return;
+}
+
+int dlist_ins_next(struct DList *list,
+		   struct DListElmt *element,
+		   const void *data)
+{
+	struct DListElmt	*new;
+
+	/* No NULL elements allowed */
+	if (element == NULL && dlist_size(list) != 0)
+		return -1;
+
+	if ((new = (struct DListElmt *)malloc(sizeof(struct DListElmt))) == NULL)
+		return -1;
+
+	new->data = (void *)data;
+
+	if (dlist_size(list) == 0) {
+		list->head = new;
+		list->head->prev = NULL;
+		list->head->next = NULL;
+		list->tail = new;
+	} else {
+		new->next = element->next;
+		new->prev = element;
+
+		if (new->next == NULL)
+			list->tail = new;
+		else
+			new->next->prev = new;
+
+		element->next = new;
+	}
+
+	list->size++;
+	return 0
+}
+
+int dlist_ins_prev(struct DList *list,
+		   struct DListElmt *element,
+		   const void *data)
+{
+	struct DListElmt	*new;
+
+	/* No NULL elements allowed */
+	if (element == NULL && dlist_size(list) != 0)
+		return -1;
+
+	if ((new = (struct DListElmt *)malloc(sizeof(struct DListElmt))) == NULL)
+		return -1;
+
+	new->data = (void *)data;
+
+	if (dlist_size(list) == 0) {
+		/* insert on head */
+		list->head = new;
+		list->head->prev = NULL;
+		list->head->next = NULL;
+		list->tail = new;
+	} else {
+		new->next = element;
+		new->prev = element->prev;
+
+		if (new->prev == NULL)
+			list->head = new;
+		else
+			element->prev->next = new;
+
+		element->prev = new;
+	}
+
+	list_size++;
+	return 0;
+}
+
+int dlist_remove(struct DList *list, struct DListElmt *element, void **data)
+{
+	/* No NULL element allowed or removal from empty */
+	if (element == NULL || dlist_size(list == 0))
+		return -1;
+
+	/* Remove element */
+	*data = element->data;
+
+	if (element == list->head) {
+		list->head = element->next;
+
+		if (list->head == NULL)
+			list->tail = NULL;
+		else
+			list->head->prev = NULL;
+	} else {
+		element->prev->next = element->next;
+
+		if (element->next == NULL)
+			list->tail = element->prev;
+		else
+			element->next->prev = element->prev;
+	}
+
+	free(element);
+	list->size--;
+	return 0;
+}