typedef struct objc_object *id;

/// Represents an instance of a class.
struct objc_object {
    Class isa  OBJC_ISA_AVAILABILITY;
};

typedef struct objc_class *Class;

struct objc_class {
    Class isa  OBJC_ISA_AVAILABILITY;

#if !__OBJC2__
    Class super_class;
    const char *name;
    long version;
    long info;
    long instance_size;
    struct objc_ivar_list *ivars;
    struct objc_method_list **methodLists;
    struct objc_cache *cache;
    struct objc_protocol_list *protocols;
#endif

} OBJC2_UNAVAILABLE;
/* Use `Class` instead of `struct objc_class *` */

typedef struct property_t *objc_property_t;

struct property_t {
    const char *name;
    const char *attributes;
};

/// Defines a property attribute
typedef struct {
    const char *name;           /**< The name of the attribute */
    const char *value;          /**< The value of the attribute (usually empty) */
} objc_property_attribute_t;

struct property_list_t : entsize_list_tt<property_t, property_list_t, 0> {
};

/// An opaque type that represents an instance variable.
typedef struct ivar_t *Ivar;

struct ivar_t {
#if __x86_64__
    // *offset was originally 64-bit on some x86_64 platforms.
    // We read and write only 32 bits of it.
    // Some metadata provides all 64 bits. This is harmless for unsigned 
    // little-endian values.
    // Some code uses all 64 bits. class_addIvar() over-allocates the 
    // offset for their benefit.
#endif
    int32_t *offset;
    const char *name;
    const char *type;
    // alignment is sometimes -1; use alignment() instead
    uint32_t alignment_raw;
    uint32_t size;
};


struct ivar_list_t : entsize_list_tt<ivar_t, ivar_list_t, 0> {
    bool containsIvar(Ivar ivar) const {
        return (ivar >= (Ivar)&*begin()  &&  ivar < (Ivar)&*end());
    }
};

typedef struct method_t *Method;

struct method_t {
    SEL name;
    const char *types;
    MethodListIMP imp;
};

// Two bits of entsize are used for fixup markers.
struct method_list_t : entsize_list_tt<method_t, method_list_t, 0x3> {
    bool isUniqued() const;
    bool isFixedUp() const;
    void setFixedUp();

    uint32_t indexOfMethod(const method_t *meth) const {
        uint32_t i = 
            (uint32_t)(((uintptr_t)meth - (uintptr_t)this) / entsize());
        ASSERT(i < count);
        return i;
    }
};