From 6dc0caceeb8d5ade6014cd5853dff0716f4f6d20 Mon Sep 17 00:00:00 2001
From: Ivar Fatland <fatland99@hotmail.com>
Date: Tue, 25 Nov 2025 22:18:54 +0100
Subject: [PATCH] wrote with_arena macro

---
 arena_allocator.c      |  3 ++-
 cig.h                  | 13 +++++++++++--
 test_arena_allocator.c | 21 +++++++++++++++++++++
 3 files changed, 34 insertions(+), 3 deletions(-)
 create mode 100644 test_arena_allocator.c

diff --git a/arena_allocator.c b/arena_allocator.c
index 6b0168e..ac321ce 100644
--- a/arena_allocator.c
+++ b/arena_allocator.c
@@ -26,7 +26,7 @@ void *arena_allocator_alloc_func(
     return NULL;
 }
 
-void arena_allocator_reset(arena_allocator_t *this, const char *file, int line) {
+void arena_allocator_reset_func(arena_allocator_t *this, const char *file, int line) {
     borrow_allocator_free_all(&this->borrow_allocator);
     if (this->bytes == NULL) {
         this->bytes = dyn_array_create_non_crashing_func(
@@ -72,6 +72,7 @@ void arena_allocator_reset(arena_allocator_t *this, const char *file, int line)
 void arena_allocator_destroy(arena_allocator_t *this) {
     borrow_allocator_free_all(&this->borrow_allocator);
     dyn_array_destroy(this->bytes);
+    *this = arena_allocator_create();
 }
 
 static void *arena_allocator_alloc_impl(void *this, size_t bytes, const char *file, int line) {
diff --git a/cig.h b/cig.h
index 820c43d..e818eb6 100644
--- a/cig.h
+++ b/cig.h
@@ -101,7 +101,7 @@ allocator_t borrow_allocator_interface(borrow_allocator_t *this);
            borrow_allocator_interface(&borrow_allocator_create());             \
        !((borrow_allocator_t *)NAME.this)->head;                               \
        ((borrow_allocator_t *)NAME.this)->head =                               \
-           (borrow_allocator_free_all(((borrow_allocator_t *)NAME.this)),         \
+           (borrow_allocator_free_all(((borrow_allocator_t *)NAME.this)),      \
             (linked_allocation_node_t *)1))                                    \
     for (int UNIQUE = 0; UNIQUE < 1; UNIQUE++)
 
@@ -145,10 +145,19 @@ void *arena_allocator_alloc_func(
 #define arena_allocator_alloc(THIS, BYTES)                                     \
   arena_allocator_alloc_func(THIS, BYTES, __FILE__, __LINE__)
 
-void arena_allocator_reset(arena_allocator_t *this, const char *file, int line);
+void arena_allocator_reset_func(arena_allocator_t *this, const char *file, int line);
+#define arena_allocator_reset(THIS)                                            \
+  arena_allocator_reset_func(THIS, __FILE__, __LINE__)
 void arena_allocator_destroy(arena_allocator_t *this);
 allocator_t arena_allocator_interface(arena_allocator_t *this);
 
+#define with_arena(ARENA, ALLOCATOR_NAME)                                      \
+  for (allocator_t ALLOCATOR_NAME = arena_allocator_interface(ARENA);          \
+       ALLOCATOR_NAME.vtbl != NULL;                                            \
+       ALLOCATOR_NAME.vtbl =                                                   \
+           (arena_allocator_reset_func(ARENA, __FILE__, __LINE__), NULL))      \
+    for (int UNIQUE = 0; UNIQUE < 1; UNIQUE++)
+
 // dynamic arrays //////////////////////////////////////////////////////////////
 
 typedef struct dyn_array_header {
diff --git a/test_arena_allocator.c b/test_arena_allocator.c
new file mode 100644
index 0000000..4b3dd25
--- /dev/null
+++ b/test_arena_allocator.c
@@ -0,0 +1,21 @@
+#include <criterion/criterion.h>
+#include "cig.h"
+
+Test(arena_allocator, repeated_allocations) {
+    arena_allocator_t aalloc = arena_allocator_create();
+
+    for ( int i = 0; i < 10; i++ ) {
+        with_arena(&aalloc, allocator) {
+            allocator_alloc(allocator, 10);
+        }
+    }
+
+    cr_assert_eq(aalloc.total_allocated, 10);
+    cr_assert_eq(borrow_allocator_count_allocations(&aalloc.borrow_allocator), 0);
+    cr_assert_eq(dyn_array_capacity(aalloc.bytes), 10);
+
+    arena_allocator_destroy(&aalloc);
+    cr_assert_eq(aalloc.total_allocated, 0);
+}
+
+// TODO somehow test reallocations