45 lines
1.5 KiB
C
45 lines
1.5 KiB
C
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// ---
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void *obj_copy(void **dst, const void *src) {
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if(!*dst) return *dst = obj_clone(src);
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if( obj_typeeq(*dst, src) ) {
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return memcpy(*dst, src, obj_sizeof(src));
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}
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return NULL;
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}
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void *obj_mutate(void **dst_, const void *src) {
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// mutate a class. ie, convert a given object class into a different one,
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// while preserving the original metas and references as much as possible.
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//
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// @fixme: systems might be tracking objects in the future. the fact that we
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// can reallocate a pointer (and hence, change its address) seems way too dangerous,
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// as the tracking systems could crash when referencing a mutated object.
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// solutions: do not reallocate if sizeof(new_class) > sizeof(old_class) maybe? good enough?
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// also, optimization hint: no need to reallocate if both sizes matches, just copy contents.
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if(!*dst_) return *dst_ = obj_clone(src);
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void *dst = *dst_;
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dtor(dst);
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unsigned src_sz = obj_sizeof(src);
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unsigned src_id = obj_typeid(src);
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void *dst_ptr = *((void**)dst - 1);
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unsigned payload = (OBJPAYLOAD16(dst_ptr) & 255) | src_id << 8;
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FREE( OBJUNBOX(dst_ptr) );
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*((void**)dst - 1) = OBJBOX( STRDUP( OBJUNBOX(*((void**)src - 1)) ), payload);
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void *base = (void*)((void**)dst - 1);
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base = REALLOC(base, src_sz + sizeof(void*));
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*dst_ = (char*)base + sizeof(void*);
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dst = (char*)base + sizeof(void*);
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memcpy(dst, src, src_sz);
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ctor(dst);
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return dst;
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}
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