gecko-dev/string/public/nsBufferHandleUtils.h

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/*
* The contents of this file are subject to the Mozilla Public
* License Version 1.1 (the "License"); you may not use this file
* except in compliance with the License. You may obtain a copy of
* the License at http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS
* IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
* implied. See the License for the specific language governing
* rights and limitations under the License.
*
* The Original Code is Mozilla strings.
*
* The Initial Developer of the Original Code is Netscape
* Communications Corporation. Portions created by Netscape are
* Copyright (C) 2000 Netscape Communications Corporation. All
* Rights Reserved.
*
* Contributor(s):
* Scott Collins <scc@mozilla.org> (original author)
*
*/
#ifndef nsBufferHandleUtils_h___
#define nsBufferHandleUtils_h___
#ifndef nsAString_h___
#include "nsAString.h"
#endif
#ifndef nsStringTraits_h___
#include "nsStringTraits.h"
#endif
#include <new.h>
// for placement |new|
template <class CharT>
class nsAutoBufferHandle
{
public:
nsAutoBufferHandle() : mHandle(0) { }
nsAutoBufferHandle( const nsAutoBufferHandle<CharT>& aOther )
: mHandle(aOther.get())
{
if ( mHandle )
mHandle->AcquireReference();
}
explicit
nsAutoBufferHandle( const nsSharedBufferHandle<CharT>* aHandle )
: mHandle( NS_CONST_CAST(nsSharedBufferHandle<CharT>*, aHandle) )
{
if ( mHandle )
mHandle->AcquireReference();
}
~nsAutoBufferHandle()
{
if ( mHandle )
mHandle->ReleaseReference();
}
nsAutoBufferHandle<CharT>&
operator=( const nsSharedBufferHandle<CharT>* rhs )
{
nsSharedBufferHandle<CharT>* old_handle = mHandle;
if ( (mHandle = NS_CONST_CAST(nsSharedBufferHandle<CharT>*, rhs)) )
mHandle->AcquireReference();
if ( old_handle )
old_handle->ReleaseReference();
return *this;
}
nsAutoBufferHandle<CharT>&
operator=( const nsAutoBufferHandle<CharT>& rhs )
{
return operator=(rhs.get());
}
nsSharedBufferHandle<CharT>*
get() const
{
return mHandle;
}
operator nsSharedBufferHandle<CharT>*() const
{
return get();
}
nsSharedBufferHandle<CharT>*
operator->() const
{
return get();
}
private:
nsSharedBufferHandle<CharT>* mHandle;
};
template <class HandleT, class CharT>
inline
size_t
NS_AlignedHandleSize( const HandleT*, const CharT* )
{
// figure out the number of bytes needed the |HandleT| part, including padding to correctly align the data part
return ((sizeof(HandleT) + sizeof(CharT) - 1) / sizeof(CharT)) * sizeof(CharT);
}
template <class HandleT, class CharT>
inline
const CharT*
NS_DataAfterHandle( const HandleT* aHandlePtr, const CharT* aDummyCharTPtr )
{
typedef const CharT* CharT_ptr;
return CharT_ptr(NS_STATIC_CAST(const unsigned char*, aHandlePtr) + NS_AlignedHandleSize(aHandlePtr, aDummyCharTPtr));
}
template <class HandleT, class CharT>
inline
CharT*
NS_DataAfterHandle( HandleT* aHandlePtr, const CharT* aDummyCharTPtr )
{
typedef CharT* CharT_ptr;
return CharT_ptr(NS_STATIC_CAST(unsigned char*, aHandlePtr) + NS_AlignedHandleSize(aHandlePtr, aDummyCharTPtr));
}
template <class HandleT, class StringT>
HandleT*
NS_AllocateContiguousHandleWithData( const HandleT* aDummyHandlePtr, PRUint32 aAdditionalCapacity, const StringT* aDataSource )
{
typedef typename StringT::char_type char_type;
typedef char_type* char_ptr;
// figure out the number of bytes needed the |HandleT| part, including padding to correctly align the data part
size_t handle_size = NS_AlignedHandleSize(aDummyHandlePtr, char_ptr(0));
// figure out how many |char_type|s wee need to fit in the data part
size_t data_length = aDataSource? aDataSource->Length() : 0;
size_t buffer_length = data_length + aAdditionalCapacity;
// how many bytes is that (including a zero-terminator so we can claim to be flat)?
size_t buffer_size = buffer_length * sizeof(char_type);
HandleT* result = 0;
void* handle_ptr = ::operator new(handle_size + buffer_size);
if ( handle_ptr )
{
char_ptr data_start_ptr = char_ptr(NS_STATIC_CAST(unsigned char*, handle_ptr) + handle_size);
char_ptr data_end_ptr = data_start_ptr + data_length;
char_ptr buffer_end_ptr = data_start_ptr + buffer_length;
char_ptr toBegin = data_start_ptr;
if ( data_length )
{
typename StringT::const_iterator fromBegin, fromEnd;
copy_string(aDataSource->BeginReading(fromBegin), aDataSource->EndReading(fromEnd), toBegin);
}
// and if the caller bothered asking for a buffer bigger than their string, we'll zero-terminate
if ( aAdditionalCapacity > 0 )
*toBegin = char_type(0);
result = new (handle_ptr) HandleT(data_start_ptr, data_end_ptr, data_start_ptr, buffer_end_ptr, PR_TRUE);
}
return result;
}
template <class HandleT, class StringT>
inline
HandleT*
NS_AllocateContiguousHandleWithData( const HandleT* aDummyHandlePtr, const StringT& aDataSource, PRUint32 aAdditionalCapacity )
{
return NS_AllocateContiguousHandleWithData(aDummyHandlePtr, aAdditionalCapacity, &aDataSource);
}
#endif // !defined(nsBufferHandleUtils_h___)