cig/cig.h

#ifndef ALLOCATOR_H
#define ALLOCATOR_H

#include <stddef.h>
#include <stdint.h>
#include <stdlib.h>

typedef union any_align { char c; int i; long l; long long ll; float f; double d; void *p; } any_align_t;
#define MAX_ALIGN (sizeof(any_align_t))
#define KB (1024)
#define MB (KB * KB)
#define GB (KB * KB * KB)
#define OFFSET(STRUCT, FIELD) ((size_t) (&((STRUCT*) NULL)->FIELD))
#define PTR_FROM_FIELD_PTR(STRUCT, FIELD, PTR) ((STRUCT *) (((char *) PTR) - OFFSET(STRUCT, FIELD)))


// 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__)

// std_allocator ///////////////////////////////////////////////////////////////
allocator_t allocator_stdlib();
// buffer_allocator ////////////////////////////////////////////////////////////
typedef struct buffer_allocator {
    size_t size, capacity;
    uint8_t *data;
} buffer_allocator_t;

#define buffer_allocator_create(CAPACITY) \
  ((buffer_allocator_t){ \
      .size = 0, .capacity = CAPACITY, .data = (uint8_t[CAPACITY]){0}})

allocator_t buffer_allocator_interface(buffer_allocator_t *this);
void *buffer_allocator_alloc(buffer_allocator_t *this, size_t bytes);
// Very simple resize. Does not free any memory, nor does it keep track of the
// previously allocated size of the old_pointer, just copies over as few bytes
// as it can with the information it has to a new allocation.
void *buffer_allocator_resize(buffer_allocator_t *this, void *old_ptr, size_t bytes);
void buffer_allocator_reset(buffer_allocator_t *this);

// borrow_allocator ////////////////////////////////////////////////////////////
typedef struct linked_allocation_node {
    struct linked_allocation_node *next;
    struct linked_allocation_node *prev;
    const char *file;
    int line;
    any_align_t data[];
} linked_allocation_node_t;

typedef struct borrow_allocator {
    linked_allocation_node_t *head;
} borrow_allocator_t;

#define borrow_allocator_create() ((borrow_allocator_t){.head=NULL})

void *borrow_allocator_alloc_func(borrow_allocator_t *this, size_t bytes, const char *file, int line);
#define borrow_allocator_alloc(this, bytes) borrow_allocator_alloc_func(this, bytes, __FILE__, __LINE__)
void *borrow_allocator_resize_func(borrow_allocator_t *this, void *old_ptr, size_t bytes, const char *file, int line);
#define borrow_allocator_resize(this, old_ptr, bytes) borrow_allocator_resize_func(this, old_ptr, bytes, __FILE__, __LINE__)
void borrow_allocator_free(borrow_allocator_t *this, void *old_ptr);
// Free all allocations done by this allocator.
void borrow_allocator_reset(borrow_allocator_t *this);
size_t borrow_allocator_count_allocations(borrow_allocator_t *this);
// Check that all allocations have been freed, or print a list of files and
// lines where made that haven't been freed to stderr and then exit the program
// with 1 as the return value.
void borrow_allocator_assert_all_freed(borrow_allocator_t *this);
allocator_t borrow_allocator_interface(borrow_allocator_t *this);

// Some text that can be used as an identifier (no, not by you), so that I can
// use a variable that won't collide with yours inside macros.
#define UNIQUE __macro_internal_34bba35b8b9b20a75f9881e3795630e25d36e620d9c9741e2e9141ba82ec6ef6__

// Can be used to mimic rust borrow semantics. with_borrow(foos_allocator) {
// foo(foos_allocator); }. If a function should return ownership assume that
// my_allocator was passed in by an outer function void *bar;
// with_borrow(foos_allocator) {bar = foo(foos_allocator, my_allocator); } Using
// the return a keyword in the statement following this macro will cause a
// guaranteed memory leak.
#define with_borrow(NAME) \
    for (allocator_t NAME = borrow_allocator_interface(&borrow_allocator_create()); !((borrow_allocator_t*)NAME.this)->head; ((borrow_allocator_t*)NAME.this)->head = (borrow_allocator_reset(((borrow_allocator_t*)NAME.this)), (linked_allocation_node_t*) 1)) \
    for (int UNIQUE = 0; UNIQUE < 1; UNIQUE++)

// dynamic arrays //////////////////////////////////////////////////////////////
typedef struct dyn_array_header {
    size_t size, capacity, itemsize;
    allocator_t allocator;
    uint8_t bytes[];
} dyn_array_header_t;

typedef struct dyn_array_create_func_args {
    allocator_t allocator;
    size_t itemsize;
    size_t initial_capacity;
} dyn_array_create_func_args_t;
void *dyn_array_create_func(dyn_array_create_func_args_t args);
#define dyn_array_create(ALLOCATOR, TYPE, ...) ((TYPE*) dyn_array_create_func((dyn_array_create_func_args_t){.allocator=ALLOCATOR, .itemsize=sizeof(TYPE), __VA_ARGS__}))

#ifdef ALLOCATOR_IMPLEMENTATION

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);
}

#include "std_allocator.c"
#include "buffer_allocator.c"
#include "borrow_allocator.c"

#endif // ALLOCATOR_IMPLEMENTATION
#endif // ALLOCATOR_H