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      1 /*
      2  * Copyright (C) 2013 Google Inc. All rights reserved.
      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions are
      6  * met:
      7  *
      8  *     * Redistributions of source code must retain the above copyright
      9  * notice, this list of conditions and the following disclaimer.
     10  *     * Redistributions in binary form must reproduce the above
     11  * copyright notice, this list of conditions and the following disclaimer
     12  * in the documentation and/or other materials provided with the
     13  * distribution.
     14  *     * Neither the name of Google Inc. nor the names of its
     15  * contributors may be used to endorse or promote products derived from
     16  * this software without specific prior written permission.
     17  *
     18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     19  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     20  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     21  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     22  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     23  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
     24  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     28  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     29  */
     30 
     31 #ifndef Visitor_h
     32 #define Visitor_h
     33 
     34 #define TRACE_GC_MARKING 0
     35 #define TRACE_GC_FINALIZATION 0
     36 
     37 #if TRACE_GC_MARKING || TRACE_GC_FINALIZATION
     38 #define TRACE_GC_USING_CLASSOF 1
     39 #else
     40 #define TRACE_GC_USING_CLASSOF 0
     41 #endif
     42 
     43 namespace WebCore {
     44 
     45 typedef void (*FinalizationCallback)(void*);
     46 
     47 class Visitor;
     48 typedef void (*VisitorCallback)(Visitor*, void* self);
     49 typedef VisitorCallback TraceCallback;
     50 typedef VisitorCallback WeakPointerCallback;
     51 
     52 // GCInfo contains meta-data associated with objects allocated in the
     53 // Blink heap. This meta-data consists of a function pointer used to
     54 // trace the pointers in the object during garbage collection, an
     55 // indication of whether or not the object needs a finalization
     56 // callback, and a function pointer used to finalize the object when
     57 // the garbage collector determines that the object is no longer
     58 // reachable. There is a GCInfo struct for each class that directly
     59 // inherits from GarbageCollected or GarbageCollectedFinalized.
     60 struct GCInfo {
     61     bool hasFinalizer() const { return m_nonTrivialFinalizer; }
     62     const char* m_typeMarker;
     63     TraceCallback m_trace;
     64     FinalizationCallback m_finalize;
     65     bool m_nonTrivialFinalizer;
     66 #if TRACE_GC_USING_CLASSOF
     67     ClassOfCallback m_classOf;
     68 #endif
     69 };
     70 
     71 }
     72 
     73 #endif
     74