Add a list.

include/mx/list.h

@@ -0,0 +1,97 @@
+/**
+ * @file list.h Array List
+ * This is an array list implementation inspired by the stb data structures
+ * single header library. The list itself works like any C pointer, except
+ * the real base pointer is before the pointer you will see.
+ */
+#ifndef _MX_LIST_H_
+#define _MX_LIST_H_
+
+#include "mx/base.h"
+#include "mx/assert.h"
+#include <stdlib.h>
+#include <string.h>
+
+struct mx_list_self_t {
+    int count;
+};
+
+/**
+ * @brief Internal function for retreiving the list header.
+ * @param list The list.
+ * @returns The list header.
+ */
+#define mx_list_self(list) (((struct mx_list_self_t*)(list))-1)
+
+/**
+ * @brief The number of items in the list.
+ * @param list The list.
+ * @returns The number of items in the list.
+*/
+#define mx_list_count(list) (((list) == NULL) ? 0 : mx_list_self(list)->count)
+
+#define mx_list_resize(list, count) do { \
+    struct mx_list_self_t *self = (list == NULL) ? NULL : mx_list_self(list); \
+    self = realloc(self, sizeof(*self) + sizeof(*(list)) * (count)); \
+    if (self != NULL) { \
+        self->count = (count); \
+        (list) = (void*)(self+1); \
+    } \
+} while (0)
+
+/**
+ * @brief Insert an item into the list (with assignment)
+ * @param list The list.
+ * @param index The index to insert the item into.
+ * @param item The item to insert.
+ * @remarks This overload is for things that can be assigned, like base types. Useful for rvalues.
+ */
+#define mx_list_insert(list, index, item) do { \
+    int idx = (index); \
+    if (list == NULL) { \
+        MX_ASSERT(idx == 0, "mx_list_insert() can only insert at 0 for an empty list."); \
+        mx_list_resize(list, 1); \
+        list[0] = item; \
+    } else { \
+        int count = mx_list_count(list) \
+        MX_ASSERT(idx > 0 && idx <= count, "mx_list_insert() expected a range between 0 and mx_list_count()."); \
+        mx_list_resize(list, count + 1); \
+        memmove(&list[idx]+1, &list[idx], (count - idx) * sizeof(*list)); \
+        list[idx] = item; \
+    } \
+} while(0)
+
+/**
+ * @brief Insert an item into the list (with copy)
+ * @param list The list.
+ * @param index The index to insert the item into.
+ * @param item The item to insert.
+ * @remarks This overload is for things that can be copied, like structs. Item must be an addressable lvalue.
+ */
+#define mx_list_insert_copy(list, index, item) do { \
+    int idx = (index); \
+    if (list == NULL) { \
+        MX_ASSERT(idx == 0, "mx_list_insert() can only insert at 0 for an empty list."); \
+        mx_list_resize(list, 1); \
+        memcpy(&list[0], &item, sizeof(*item)); \
+    } else { \
+        int count = mx_list_count(list) \
+        MX_ASSERT(idx > 0 && idx <= count, "mx_list_insert() expected a range between 0 and mx_list_count()."); \
+        mx_list_resize(list, count + 1); \
+        memmove(&list[idx]+1, &list[idx], (count - idx) * sizeof(*list)); \
+        memcpy(&list[idx], &item, sizeof(*item)); \
+    } \
+} while(0)
+
+/**
+ * @brief Free the list, completely destroying any associated memory.
+ * @param list The list to free.
+ */
+#define mx_list_free(list) do { \
+    if (list != NULL) { \
+        free(mx_list_self(list)); \
+        list = NULL; \
+    } \
+} while(0)
+
+#endif