cef/libcef_dll/ctocpp/ctocpp_ref_counted.h
2017-07-28 18:30:34 -04:00

178 lines
5.8 KiB
C++

// Copyright (c) 2009 The Chromium Embedded Framework Authors. All rights
// reserved. Use of this source code is governed by a BSD-style license that
// can be found in the LICENSE file.
#ifndef CEF_LIBCEF_DLL_CTOCPP_CTOCPP_REF_COUNTED_H_
#define CEF_LIBCEF_DLL_CTOCPP_CTOCPP_REF_COUNTED_H_
#pragma once
#include "include/base/cef_atomic_ref_count.h"
#include "include/base/cef_logging.h"
#include "include/base/cef_macros.h"
#include "include/capi/cef_base_capi.h"
#include "include/cef_base.h"
#include "libcef_dll/wrapper_types.h"
// Wrap a C structure with a C++ class. This is used when the implementation
// exists on the other side of the DLL boundary but will have methods called on
// this side of the DLL boundary.
template <class ClassName, class BaseName, class StructName>
class CefCToCppRefCounted : public BaseName {
public:
// Create a new wrapper instance for a structure reference received from the
// other side.
static CefRefPtr<BaseName> Wrap(StructName* s);
// Retrieve the underlying structure reference from a wrapper instance for
// return back to the other side.
static StructName* Unwrap(CefRefPtr<BaseName> c);
// CefBaseRefCounted methods increment/decrement reference counts on both this
// object and the underlying wrapped structure.
void AddRef() const {
UnderlyingAddRef();
ref_count_.AddRef();
}
bool Release() const;
bool HasOneRef() const { return UnderlyingHasOneRef(); }
#if DCHECK_IS_ON()
// Simple tracking of allocated objects.
static base::AtomicRefCount DebugObjCt;
#endif
protected:
CefCToCppRefCounted() {
#if DCHECK_IS_ON()
base::AtomicRefCountInc(&DebugObjCt);
#endif
}
virtual ~CefCToCppRefCounted() {
#if DCHECK_IS_ON()
base::AtomicRefCountDec(&DebugObjCt);
#endif
}
// If returning the structure across the DLL boundary use Unwrap() instead.
StructName* GetStruct() const {
WrapperStruct* wrapperStruct = GetWrapperStruct(this);
// Verify that the wrapper offset was calculated correctly.
DCHECK_EQ(kWrapperType, wrapperStruct->type_);
return wrapperStruct->struct_;
}
private:
// Used to associate this wrapper object and the structure reference received
// from the other side.
struct WrapperStruct;
static WrapperStruct* GetWrapperStruct(const BaseName* obj);
// Unwrap as the derived type.
static StructName* UnwrapDerived(CefWrapperType type, BaseName* c);
// Increment/decrement reference counts on only the underlying class.
void UnderlyingAddRef() const {
cef_base_ref_counted_t* base =
reinterpret_cast<cef_base_ref_counted_t*>(GetStruct());
if (base->add_ref)
base->add_ref(base);
}
bool UnderlyingRelease() const {
cef_base_ref_counted_t* base =
reinterpret_cast<cef_base_ref_counted_t*>(GetStruct());
if (!base->release)
return false;
return base->release(base) ? true : false;
}
bool UnderlyingHasOneRef() const {
cef_base_ref_counted_t* base =
reinterpret_cast<cef_base_ref_counted_t*>(GetStruct());
if (!base->has_one_ref)
return false;
return base->has_one_ref(base) ? true : false;
}
CefRefCount ref_count_;
static CefWrapperType kWrapperType;
DISALLOW_COPY_AND_ASSIGN(CefCToCppRefCounted);
};
template <class ClassName, class BaseName, class StructName>
struct CefCToCppRefCounted<ClassName, BaseName, StructName>::WrapperStruct {
CefWrapperType type_;
StructName* struct_;
ClassName wrapper_;
};
template <class ClassName, class BaseName, class StructName>
CefRefPtr<BaseName> CefCToCppRefCounted<ClassName, BaseName, StructName>::Wrap(
StructName* s) {
if (!s)
return NULL;
// Wrap their structure with the CefCToCppRefCounted object.
WrapperStruct* wrapperStruct = new WrapperStruct;
wrapperStruct->type_ = kWrapperType;
wrapperStruct->struct_ = s;
// Put the wrapper object in a smart pointer.
CefRefPtr<BaseName> wrapperPtr(&wrapperStruct->wrapper_);
// Release the reference that was added to the CefCppToC wrapper object on
// the other side before their structure was passed to us.
wrapperStruct->wrapper_.UnderlyingRelease();
// Return the smart pointer.
return wrapperPtr;
}
template <class ClassName, class BaseName, class StructName>
StructName* CefCToCppRefCounted<ClassName, BaseName, StructName>::Unwrap(
CefRefPtr<BaseName> c) {
if (!c.get())
return NULL;
WrapperStruct* wrapperStruct = GetWrapperStruct(c.get());
// If the type does not match this object then we need to unwrap as the
// derived type.
if (wrapperStruct->type_ != kWrapperType)
return UnwrapDerived(wrapperStruct->type_, c.get());
// Add a reference to the CefCppToC wrapper object on the other side that
// will be released once the structure is received.
wrapperStruct->wrapper_.UnderlyingAddRef();
// Return their original structure.
return wrapperStruct->struct_;
}
template <class ClassName, class BaseName, class StructName>
bool CefCToCppRefCounted<ClassName, BaseName, StructName>::Release() const {
UnderlyingRelease();
if (ref_count_.Release()) {
WrapperStruct* wrapperStruct = GetWrapperStruct(this);
// Verify that the wrapper offset was calculated correctly.
DCHECK_EQ(kWrapperType, wrapperStruct->type_);
delete wrapperStruct;
return true;
}
return false;
}
template <class ClassName, class BaseName, class StructName>
typename CefCToCppRefCounted<ClassName, BaseName, StructName>::WrapperStruct*
CefCToCppRefCounted<ClassName, BaseName, StructName>::GetWrapperStruct(
const BaseName* obj) {
// Offset using the WrapperStruct size instead of individual member sizes to
// avoid problems due to platform/compiler differences in structure padding.
return reinterpret_cast<WrapperStruct*>(
reinterpret_cast<char*>(const_cast<BaseName*>(obj)) -
(sizeof(WrapperStruct) - sizeof(ClassName)));
}
#endif // CEF_LIBCEF_DLL_CTOCPP_CTOCPP_REF_COUNTED_H_