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