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/*
* QEMU Object Model
*
* Copyright IBM, Corp. 2011
*
* Authors:
* Anthony Liguori <aliguori@us.ibm.com>
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*
*/
#ifndef QEMU_OBJECT_H
#define QEMU_OBJECT_H
#include <glib.h>
#include <stdint.h>
#include <stdbool.h>
struct TypeImpl;
typedef struct TypeImpl *Type;
typedef struct ObjectClass ObjectClass;
typedef struct Object Object;
typedef struct TypeInfo TypeInfo;
typedef struct InterfaceClass InterfaceClass;
typedef struct InterfaceInfo InterfaceInfo;
#define TYPE_OBJECT NULL
/**
* SECTION:object.h
* @title:Base Object Type System
* @short_description: interfaces for creating new types and objects
*
* The QEMU Object Model provides a framework for registering user creatable
* types and instantiating objects from those types. QOM provides the following
* features:
*
* - System for dynamically registering types
* - Support for single-inheritance of types
* - Multiple inheritance of stateless interfaces
*
* <example>
* <title>Creating a minimal type</title>
* <programlisting>
* #include "qdev.h"
*
* #define TYPE_MY_DEVICE "my-device"
*
* typedef struct MyDevice
* {
* DeviceState parent;
*
* int reg0, reg1, reg2;
* } MyDevice;
*
* static TypeInfo my_device_info = {
* .name = TYPE_MY_DEVICE,
* .parent = TYPE_DEVICE,
* .instance_size = sizeof(MyDevice),
* };
*
* static void my_device_module_init(void)
* {
* type_register_static(&my_device_info);
* }
*
* device_init(my_device_module_init);
* </programlisting>
* </example>
*
* In the above example, we create a simple type that is described by #TypeInfo.
* #TypeInfo describes information about the type including what it inherits
* from, the instance and class size, and constructor/destructor hooks.
*
* Every type has an #ObjectClass associated with it. #ObjectClass derivatives
* are instantiated dynamically but there is only ever one instance for any
* given type. The #ObjectClass typically holds a table of function pointers
* for the virtual methods implemented by this type.
*
* Using object_new(), a new #Object derivative will be instantiated. You can
* cast an #Object to a subclass (or base-class) type using
* object_dynamic_cast(). You typically want to define a macro wrapper around
* object_dynamic_cast_assert() to make it easier to convert to a specific type.
*
* # Class Initialization #
*
* Before an object is initialized, the class for the object must be
* initialized. There is only one class object for all instance objects
* that is created lazily.
*
* Classes are initialized by first initializing any parent classes (if
* necessary). After the parent class object has initialized, it will be
* copied into the current class object and any additional storage in the
* class object is zero filled.
*
* The effect of this is that classes automatically inherit any virtual
* function pointers that the parent class has already initialized. All
* other fields will be zero filled.
*
* Once all of the parent classes have been initialized, #TypeInfo::class_init
* is called to let the class being instantiated provide default initialize for
* it's virtual functions.
*
* # Interfaces #
*
* Interfaces allow a limited form of multiple inheritance. Instances are
* similar to normal types except for the fact that are only defined by
* their classes and never carry any state. You can dynamically cast an object
* to one of its #Interface types and vice versa.
*/
/**
* ObjectClass:
*
* The base for all classes. The only thing that #ObjectClass contains is an
* integer type handle.
*/
struct ObjectClass
{
/*< private >*/
Type type;
};
/**
* Object:
*
* The base for all objects. The first member of this object is a pointer to
* a #ObjectClass. Since C guarantees that the first member of a structure
* always begins at byte 0 of that structure, as long as any sub-object places
* its parent as the first member, we can cast directly to a #Object.
*
* As a result, #Object contains a reference to the objects type as its
* first member. This allows identification of the real type of the object at
* run time.
*
* #Object also contains a list of #Interfaces that this object
* implements.
*/
struct Object
{
/*< private >*/
ObjectClass *class;
GSList *interfaces;
};
/**
* TypeInfo:
* @name: The name of the type.
* @parent: The name of the parent type.
* @instance_size: The size of the object (derivative of #Object). If
* @instance_size is 0, then the size of the object will be the size of the
* parent object.
* @instance_init: This function is called to initialize an object. The parent
* class will have already been initialized so the type is only responsible
* for initializing its own members.
* @instance_finalize: This function is called during object destruction. This
* is called before the parent @instance_finalize function has been called.
* An object should only free the members that are unique to its type in this
* function.
* @abstract: If this field is true, then the class is considered abstract and
* cannot be directly instantiated.
* @class_size: The size of the class object (derivative of #ObjectClass)
* for this object. If @class_size is 0, then the size of the class will be
* assumed to be the size of the parent class. This allows a type to avoid
* implementing an explicit class type if they are not adding additional
* virtual functions.
* @class_init: This function is called after all parent class initialization
* has occured to allow a class to set its default virtual method pointers.
* This is also the function to use to override virtual methods from a parent
* class.
* @class_finalize: This function is called during class destruction and is
* meant to release and dynamic parameters allocated by @class_init.
* @class_data: Data to pass to the @class_init and @class_finalize functions.
* This can be useful when building dynamic classes.
* @interfaces: The list of interfaces associated with this type. This
* should point to a static array that's terminated with a zero filled
* element.
*/
struct TypeInfo
{
const char *name;
const char *parent;
size_t instance_size;
void (*instance_init)(Object *obj);
void (*instance_finalize)(Object *obj);
bool abstract;
size_t class_size;
void (*class_init)(ObjectClass *klass, void *data);
void (*class_finalize)(ObjectClass *klass, void *data);
void *class_data;
InterfaceInfo *interfaces;
};
/**
* OBJECT:
* @obj: A derivative of #Object
*
* Converts an object to a #Object. Since all objects are #Objects,
* this function will always succeed.
*/
#define OBJECT(obj) \
((Object *)(obj))
/**
* OBJECT_CHECK:
* @type: The C type to use for the return value.
* @obj: A derivative of @type to cast.
* @name: The QOM typename of @type
*
* A type safe version of @object_dynamic_cast_assert. Typically each class
* will define a macro based on this type to perform type safe dynamic_casts to
* this object type.
*
* If an invalid object is passed to this function, a run time assert will be
* generated.
*/
#define OBJECT_CHECK(type, obj, name) \
((type *)object_dynamic_cast_assert((Object *)(obj), (name)))
/**
* OBJECT_CLASS_CHECK:
* @class: The C type to use for the return value.
* @obj: A derivative of @type to cast.
* @name: the QOM typename of @class.
*
* A type safe version of @object_check_class. This macro is typically wrapped
* by each type to perform type safe casts of a class to a specific class type.
*/
#define OBJECT_CLASS_CHECK(class, obj, name) \
((class *)object_class_dynamic_cast_assert((ObjectClass *)(obj), (name)))
/**
* OBJECT_GET_CLASS:
* @class: The C type to use for the return value.
* @obj: The object to obtain the class for.
* @name: The QOM typename of @obj.
*
* This function will return a specific class for a given object. Its generally
* used by each type to provide a type safe macro to get a specific class type
* from an object.
*/
#define OBJECT_GET_CLASS(class, obj, name) \
OBJECT_CLASS_CHECK(class, object_get_class(OBJECT(obj)), name)
#define OBJECT_CLASS(class) \
((ObjectClass *)(class))
/**
* InterfaceClass:
* @parent_class: the base class
*
* The class for all interfaces. Subclasses of this class should only add
* virtual methods.
*/
struct InterfaceClass
{
ObjectClass parent_class;
};
/**
* InterfaceInfo:
* @type: The name of the interface.
* @interface_initfn: This method is called during class initialization and is
* used to initialize an interface associated with a class. This function
* should initialize any default virtual functions for a class and/or override
* virtual functions in a parent class.
*
* The information associated with an interface.
*/
struct InterfaceInfo
{
const char *type;
void (*interface_initfn)(ObjectClass *class, void *data);
};
#define TYPE_INTERFACE "interface"
/**
* object_new:
* @typename: The name of the type of the object to instantiate.
*
* This function will initialize a new object using heap allocated memory. This
* function should be paired with object_delete() to free the resources
* associated with the object.
*
* Returns: The newly allocated and instantiated object.
*/
Object *object_new(const char *typename);
/**
* object_new_with_type:
* @type: The type of the object to instantiate.
*
* This function will initialize a new object using heap allocated memory. This
* function should be paired with object_delete() to free the resources
* associated with the object.
*
* Returns: The newly allocated and instantiated object.
*/
Object *object_new_with_type(Type type);
/**
* object_delete:
* @obj: The object to free.
*
* Finalize an object and then free the memory associated with it. This should
* be paired with object_new() to free the resources associated with an object.
*/
void object_delete(Object *obj);
/**
* object_initialize_with_type:
* @obj: A pointer to the memory to be used for the object.
* @type: The type of the object to instantiate.
*
* This function will initialize an object. The memory for the object should
* have already been allocated.
*/
void object_initialize_with_type(void *data, Type type);
/**
* object_initialize:
* @obj: A pointer to the memory to be used for the object.
* @typename: The name of the type of the object to instantiate.
*
* This function will initialize an object. The memory for the object should
* have already been allocated.
*/
void object_initialize(void *obj, const char *typename);
/**
* object_finalize:
* @obj: The object to finalize.
*
* This function destroys and object without freeing the memory associated with
* it.
*/
void object_finalize(void *obj);
/**
* object_dynamic_cast:
* @obj: The object to cast.
* @typename: The @typename to cast to.
*
* This function will determine if @obj is-a @typename. @obj can refer to an
* object or an interface associated with an object.
*
* Returns: This function returns @obj on success or #NULL on failure.
*/
Object *object_dynamic_cast(Object *obj, const char *typename);
/**
* @object_dynamic_cast_assert:
*
* See object_dynamic_cast() for a description of the parameters of this
* function. The only difference in behavior is that this function asserts
* instead of returning #NULL on failure.
*/
Object *object_dynamic_cast_assert(Object *obj, const char *typename);
/**
* object_get_class:
* @obj: A derivative of #Object
*
* Returns: The #ObjectClass of the type associated with @obj.
*/
ObjectClass *object_get_class(Object *obj);
/**
* object_get_typename:
* @obj: A derivative of #Object.
*
* Returns: The QOM typename of @obj.
*/
const char *object_get_typename(Object *obj);
/**
* type_register_static:
* @info: The #TypeInfo of the new type.
*
* @info and all of the strings it points to should exist for the life time
* that the type is registered.
*
* Returns: 0 on failure, the new #Type on success.
*/
Type type_register_static(const TypeInfo *info);
/**
* type_register:
* @info: The #TypeInfo of the new type
*
* Unlike type_register_static(), this call does not require @info or it's
* string members to continue to exist after the call returns.
*
* Returns: 0 on failure, the new #Type on success.
*/
Type type_register(const TypeInfo *info);
/**
* object_class_dynamic_cast_assert:
* @klass: The #ObjectClass to attempt to cast.
* @typename: The QOM typename of the class to cast to.
*
* Returns: This function always returns @klass and asserts on failure.
*/
ObjectClass *object_class_dynamic_cast_assert(ObjectClass *klass,
const char *typename);
ObjectClass *object_class_dynamic_cast(ObjectClass *klass,
const char *typename);
/**
* object_class_get_name:
* @klass: The class to obtain the QOM typename for.
*
* Returns: The QOM typename for @klass.
*/
const char *object_class_get_name(ObjectClass *klass);
ObjectClass *object_class_by_name(const char *typename);
void object_class_foreach(void (*fn)(ObjectClass *klass, void *opaque),
const char *implements_type, bool include_abstract,
void *opaque);
#endif
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