initial

an interface definition of an allocator, along with a simple
implementation that just re-exposes the default malloc, realloc and free
functions

allocator.h

@@ -0,0 +1,70 @@
+#ifndef ALLOCATOR_H
+#define ALLOCATOR_H
+
+#include <stddef.h>
+#include <stdlib.h>
+
+// Contains all operations an allocator can do. Similar interface to sdtlibs
+// malloc, realloc and free.
+typedef struct allocator_vtbl {
+	void *(*alloc)(void *this, size_t bytes, const char *file, int line);
+	void *(*resize)(void *this, void *old_ptr, size_t bytes, const char *file, int line);
+	void (*free)(void *this, void *ptr, const char *file, int line);
+} allocator_vtbl_t;
+
+// An instance of an allocator.
+typedef struct allocator {
+	// pointer to the behind-the-scenes data that an allocator may store.
+	void *const this;
+	// pointer to the method implementations of an allocator.
+	const allocator_vtbl_t *const vtbl;
+} allocator_t;
+
+void *allocator_alloc_func(allocator_t this, size_t bytes, const char *file, int line);
+void *allocator_resize_func(allocator_t this, void *old_ptr, size_t bytes, const char *file, int line);
+void allocator_free_func(allocator_t this, void *ptr, const char *file, int line);
+#define allocator_alloc(this, bytes) allocator_alloc_func(this, bytes, __FILE__, __LINE__)
+#define allocator_resize(this, old_ptr, bytes) allocator_resize_func(this, old_ptr, bytes, __FILE__, __LINE__)
+#define allocator_free(this, ptr) allocator_free_func(this, ptr, __FILE__, __LINE__)
+
+extern const allocator_t allocator_stdlib;
+
+#ifdef ALLOCATOR_IMPLEMENTATION
+
+// convenience functions ///////////////////////////////////////////////////////
+
+void *allocator_alloc_func(allocator_t this, size_t bytes, const char *file, int line) {
+	return this.vtbl->alloc(this.this, bytes, file, line);
+}
+void *allocator_resize_func(allocator_t this, void *old_ptr, size_t bytes, const char *file, int line) {
+	return this.vtbl->resize(this.this, old_ptr, bytes, file, line);
+}
+void allocator_free_func(allocator_t this, void *ptr, const char *file, int line) {
+	this.vtbl->free(this.this, ptr, file, line);
+}
+
+// allocator_stdlib ////////////////////////////////////////////////////////////
+
+static void *stdlib_alloc(void *_, size_t bytes, const char *_, int _) {
+	return malloc(bytes);
+}
+static void *stdlib_resize(void *_, void *old_ptr, size_t bytes, const char *_, int _) {
+	return realloc(old_ptr, bytes);
+}
+static void stdlib_free(void *_, void *ptr, const char *_, int _) {
+	free(ptr);
+}
+
+static const allocator_vtbl_t stdlib_vtbl = {
+	.alloc = stdlib_alloc,
+	.resize = stdlib_resize,
+	.free = stdlib_free,
+};
+
+const allocator_t allocator_stdlib = (allocator_t) {
+	.this=NULL,
+	.vtbl=&stdlib_vtbl,
+};
+
+#endif // ALLOCATOR_IMPLEMENTATION
+#endif // ALLOCATOR_H