Allocator abstraction that works for most use cases, according to Andrei Alexandrescu (+ Jon Blow)

allocator.h

#ifdef __cplusplus
extern "C" {
#endif

typedef struct Memory_Block {
    uint8_t *data;
    size_t num_bytes;
} Memory_Block;

typedef enum Allocator_Mode {
    Allocator_Mode_Get_Alignment,      /* size_t get_alignment(void); */
    Allocator_Mode_Get_Good_Size,      /* size_t get_good_size(size_t input_size); */
    Allocator_Mode_Allocate,           /* Memory_Block allocate(size_t size); */
    Allocator_Mode_Allocate_Aligned,   /* Memory_Block allocate_aligned(size_t size, size_t alignment); */
    Allocator_Mode_Allocate_All,       /* Memory_Block allocate_all(void); */
    Allocator_Mode_Expand_In_Place,    /* bool expand_in_place(Memory_Block *block, size_t delta); */
    Allocator_Mode_Reallocate,         /* bool reallocate(Memory_Block *block, size_t new_size); */
    Allocator_Mode_Reallocate_Aligned, /* bool reallocate_aligned(Memory_Block *block, size_t new_size, size_t alignment); */
    Allocator_Mode_Owns,               /* bool owns(Memory_Block block); */
    Allocator_Mode_Free,               /* void free(Memory_Block block); */
    Allocator_Mode_Free_All            /* void free_all(void); */
} Allocator_Mode;

typedef size_t Allocator_Proc(void *allocator_data, Memory_Block *block, Allocator_Mode mode, size_t size, size_t alignment, uintptr_t allocator_options);

typedef struct Allocator {
    Allocator_Proc *proc;
    void *data;
} Allocator;

#ifdef __cplusplus
}
#endif