Source/heap/Visitor.h

/*
 * Copyright (C) 2013 Google Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
 *     * Neither the name of Google Inc. nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef Visitor_h
#define Visitor_h

#define TRACE_GC_MARKING 0
#define TRACE_GC_FINALIZATION 0

#if TRACE_GC_MARKING || TRACE_GC_FINALIZATION
#define TRACE_GC_USING_CLASSOF 1
#else
#define TRACE_GC_USING_CLASSOF 0
#endif

namespace WebCore {

typedef void (*FinalizationCallback)(void*);

class Visitor;
typedef void (*VisitorCallback)(Visitor*, void* self);
typedef VisitorCallback TraceCallback;
typedef VisitorCallback WeakPointerCallback;

// GCInfo contains meta-data associated with objects allocated in the
// Blink heap. This meta-data consists of a function pointer used to
// trace the pointers in the object during garbage collection, an
// indication of whether or not the object needs a finalization
// callback, and a function pointer used to finalize the object when
// the garbage collector determines that the object is no longer
// reachable. There is a GCInfo struct for each class that directly
// inherits from GarbageCollected or GarbageCollectedFinalized.
struct GCInfo {
    bool hasFinalizer() const { return m_nonTrivialFinalizer; }
    const char* m_typeMarker;
    TraceCallback m_trace;
    FinalizationCallback m_finalize;
    bool m_nonTrivialFinalizer;
#if TRACE_GC_USING_CLASSOF
    ClassOfCallback m_classOf;
#endif
};

}

#endif