1 files changed, 62 insertions, 0 deletions
diff --git a/prism/internal/list.h b/prism/internal/list.h
new file mode 100644
index 0000000000..0ab59ef32a
--- /dev/null
+++ b/prism/internal/list.h
@@ -0,0 +1,62 @@
+#ifndef PRISM_INTERNAL_LIST_H
+#define PRISM_INTERNAL_LIST_H
+
+#include <stddef.h>
+
+/*
+ * This struct represents an abstract linked list that provides common
+ * functionality. It is meant to be used any time a linked list is necessary to
+ * store data.
+ *
+ * The linked list itself operates off a set of pointers. Because the pointers
+ * are not necessarily sequential, they can be of any size. We use this fact to
+ * allow the consumer of this linked list to extend the node struct to include
+ * any data they want. This is done by using the pm_list_node_t as the first
+ * member of the struct.
+ *
+ * For example, if we want to store a list of integers, we can do the following:
+ *
+ * ```c
+ * typedef struct {
+ *     pm_list_node_t node;
+ *     int value;
+ * } pm_int_node_t;
+ *
+ * pm_list_t list = { 0 };
+ * pm_int_node_t *node = xmalloc(sizeof(pm_int_node_t));
+ * node->value = 5;
+ *
+ * pm_list_append(&list, &node->node);
+ * ```
+ *
+ * The pm_list_t struct is used to represent the overall linked list. It
+ * contains a pointer to the head and tail of the list. This allows for easy
+ * iteration and appending of new nodes.
+ */
+typedef struct pm_list_node {
+    /* A pointer to the next node in the list. */
+    struct pm_list_node *next;
+} pm_list_node_t;
+
+/*
+ * This represents the overall linked list. It keeps a pointer to the head and
+ * tail so that iteration is easy and pushing new nodes is easy.
+ */
+typedef struct {
+    /* The size of the list. */
+    size_t size;
+
+    /* A pointer to the head of the list. */
+    pm_list_node_t *head;
+
+    /* A pointer to the tail of the list. */
+    pm_list_node_t *tail;
+} pm_list_t;
+
+/* Returns the size of the list. */
+size_t pm_list_size(pm_list_t *list);
+
+/* Append a node to the given list. */
+void pm_list_append(pm_list_t *list, pm_list_node_t *node);
+
+#endif