105 lines
2.8 KiB
C
105 lines
2.8 KiB
C
/*
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references.h - strong and weak references
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Copyright (C) Lumiera.org
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2008, Christian Thaeter <ct@pipapo.org>
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#ifndef LUMIERA_REFERENCES_H
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#define LUMIERA_REFERENCES_H
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#include <nobug.h>
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/**
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* @file Strong and Weak references, header.
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*/
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typedef struct lumiera_reference_struct lumiera_reference;
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typedef lumiera_reference* LumieraReference;
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#include "lib/error.h"
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#include "lib/mutex.h"
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/* Implementation detail */
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struct lumiera_reftarget_struct
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{
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void* object;
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void (*dtor)(void*);
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unsigned strong_cnt; /*when strong becomes 0 obj is destroyed, if weak is 0 destroy target too*/
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unsigned weak_cnt; /*when weak becomes 0 and !obj and lock strong is 0, destroy target */
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lumiera_mutex lock;
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};
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typedef struct lumiera_reftarget_struct lumiera_reftarget;
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typedef lumiera_reftarget* LumieraReftarget;
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/**
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* A reference pointing to some other object
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*/
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struct lumiera_reference_struct
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{
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void* object; /*set for strong, NULL for weak*/
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LumieraReftarget target;
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};
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#define lumiera_reference \
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lumiera_reference NOBUG_CLEANUP(lumiera_reference_ensuredestroyed)
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/* helper function for nobug */
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static inline void
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lumiera_reference_ensuredestroyed (LumieraReference self)
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{
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ENSURE (!self->target, "forgot to destroy reference");
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}
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LumieraReference
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lumiera_reference_strong_init_once (LumieraReference self, void* obj, void (*dtor)(void*));
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LumieraReference
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lumiera_reference_destroy (LumieraReference self);
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/**
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* Get object from a strong reference.
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* @return pointer to object, NULL if applied to a weak reference
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*/
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static inline void*
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lumiera_reference_get (LumieraReference self)
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{
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ENSURE (self->target, "illegal reference (not initialized or already destroyed?)");
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return self->object;
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}
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LumieraReference
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lumiera_reference_strong_init (LumieraReference self, LumieraReference source);
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LumieraReference
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lumiera_reference_weak_init (LumieraReference self, LumieraReference source);
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LumieraReference
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lumiera_reference_weaken (restrict LumieraReference self);
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LumieraReference
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lumiera_reference_strengthen (LumieraReference self);
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#endif
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