steal a linked list implementation

engine/llist.c

@@ -0,0 +1,99 @@
+/* llist.c
+ * Generic Linked List implementation
+ */
+
+#include <stdlib.h>
+#include <stdio.h>
+#include "llist.h"
+
+llist *llist_create(TodoItem *new_item)
+{
+    TodoItemNode *new_node;
+
+    llist *new_list = (llist *)malloc(sizeof (llist));
+    *new_list = (TodoItemNode *)malloc(sizeof (TodoItemNode));
+    
+    new_node = *new_list;
+    new_node->item = new_item;
+    new_node->next = NULL;
+    return new_list;
+}
+
+void llist_free(llist *list)
+{
+    TodoItemNode *curr = *list;
+    TodoItemNode *next;
+
+    while (curr != NULL) {
+        next = curr->next;
+        free(curr);
+        curr = next;
+    }
+
+    free(list);
+}
+
+void llist_push(llist *list, TodoItem *item)
+{
+    TodoItemNode *head;
+    TodoItemNode *new_node;
+    if (list == NULL || *list == NULL) {
+        fprintf(stderr, "llist_add_inorder: list is null\n");
+    }
+
+    head = *list;
+    
+    // Head is empty node
+    if (head->item == NULL)
+        head->item = item;
+
+    // Head is not empty, add new node to front
+    else {
+        new_node = malloc(sizeof (TodoItemNode));
+        new_node->item = item;
+        new_node->next = head;
+        *list = new_node;
+    }
+}
+
+TodoItem *llist_pop(llist *list)
+{
+    TodoItem *popped_item;
+    TodoItemNode *head = *list;
+
+    if (list == NULL || head->item == NULL)
+        return NULL;
+    
+    popped_item = head->item;
+    *list = head->next;
+
+    free(head);
+
+    return popped_item;
+}
+
+void llist_print(llist *list, void (*print)(TodoItem *))
+{
+    TodoItemNode *curr = *list;
+    while (curr != NULL) {
+        print(curr->item);
+        printf(" ");
+        curr = curr->next;
+    }
+    putchar('\n');
+}
+
+unsigned int llist_length(llist *list) {
+  if (list == NULL) {
+    return 0;
+  }
+
+  TodoItemNode *curr = *list;
+  unsigned int length = 0;
+  while (curr != NULL) {
+    length++;
+    curr = curr->next;
+  }
+
+  return length;
+}

engine/llist.h

@@ -0,0 +1,21 @@
+#ifndef LLIST_H
+#define LLIST_H
+#include "todo.h"
+/* llist.h
+ * Generic Linked List
+ */
+
+typedef struct Node {
+    TodoItem *item;
+    struct Node *next;
+} TodoItemNode;
+
+typedef TodoItemNode *llist;
+
+llist *llist_create(TodoItem *item);
+void llist_free(llist *list);
+void llist_push(llist *list, TodoItem *item);
+TodoItem *llist_pop(llist *list);
+void llist_print(llist *list, void (*print)(TodoItem *item));
+unsigned int llist_length(llist *list);
+#endif