gecko-dev/xpcom/string/public/nsSharedString.h

204 lines
5.9 KiB
C++

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/*
* The contents of this file are subject to the Netscape 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/NPL/
*
* 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.org code.
*
* The Initial Developer of the Original Code is Netscape
* Communications Corporation. Portions created by Netscape are
* Copyright (C) 1998 Netscape Communications Corporation. All
* Rights Reserved.
*
* Original Author:
* Scott Collins <scc@mozilla.org>
*
* Contributor(s):
*/
#ifndef nsSharedString_h___
#define nsSharedString_h___
#ifndef nsAReadableString_h___
#include "nsAReadableString.h"
#endif
template <class CharT>
class basic_nsSharedString
: public basic_nsAReadableString<CharT>
/*
...
*/
{
public:
basic_nsSharedString( const CharT* data, size_t length )
: mRefCount(0), mData(data), mLength(length)
{
// nothing else to do here
}
private:
~basic_nsSharedString() { } // You can't sub-class me, or make an instance of me on the stack
// NOT TO BE IMPLEMENTED
// we're reference counted, remember. copying and passing by value are wrong
// basic_nsSharedString(); // we define at least one constructor, so the default constructor will not be auto-generated. It's wrong to create me with no data anyway
basic_nsSharedString( const basic_nsSharedString<CharT>& ); // copy-constructor, the auto generated one would reference somebody elses data
void operator=( const basic_nsSharedString<CharT>& ); // copy-assignment operator
// operator delete?
public:
virtual const CharT* GetReadableFragment( nsReadableFragment<CharT>&, nsFragmentRequest, PRUint32 ) const;
virtual
PRUint32
Length() const
{
return mLength;
}
nsrefcnt
AddRef() const
{
return ++mRefCount;
}
nsrefcnt
Release() const
{
nsrefcnt result = --mRefCount;
if ( !mRefCount )
{
// would have to call my destructor by hand here, if there was anything to destruct
operator delete(this); // form of |delete| should always match the |new|
}
return result;
}
private:
mutable nsrefcnt mRefCount;
const CharT* mData;
size_t mLength;
};
NS_DEF_TEMPLATE_STRING_COMPARISON_OPERATORS(basic_nsSharedString<CharT>, CharT)
template <class CharT>
const CharT*
basic_nsSharedString<CharT>::GetReadableFragment( nsReadableFragment<CharT>& aFragment, nsFragmentRequest aRequest, PRUint32 anOffset ) const
{
switch ( aRequest )
{
case kFirstFragment:
case kLastFragment:
case kFragmentAt:
aFragment.mEnd = (aFragment.mStart = mData) + mLength;
return aFragment.mStart + anOffset;
case kPrevFragment:
case kNextFragment:
default:
return 0;
}
}
template <class CharT>
class basic_nsSharedStringPtr
{
public:
// default constructor
basic_nsSharedStringPtr() : mRawPtr(0) { }
// copy-constructor
basic_nsSharedStringPtr( const basic_nsSharedStringPtr<CharT>& rhs )
: mRawPtr(rhs.mRawPtr)
{
mRawPtr->AddRef();
}
~basic_nsSharedStringPtr()
{
if ( mRawPtr )
mRawPtr->Release();
}
// copy-assignment operator
basic_nsSharedStringPtr<CharT>&
operator=( const basic_nsSharedStringPtr<CharT>& );
basic_nsSharedString<CharT>*
operator->() const
{
NS_PRECONDITION(mRawPtr != 0, "You can't dereference a NULL string pointer with operator->().");
return mRawPtr;
}
basic_nsSharedString<CharT>&
operator*() const
{
NS_PRECONDITION(mRawPtr != 0, "You can't dereference a NULL string pointer with operator->().");
return *mRawPtr;
}
private:
const basic_nsSharedString<CharT>* mRawPtr;
};
template <class CharT>
basic_nsSharedStringPtr<CharT>&
basic_nsSharedStringPtr<CharT>::operator=( const basic_nsSharedStringPtr<CharT>& rhs )
// Not |inline|
{
if ( rhs.mRawPtr )
rhs.mRawPtr->AddRef();
basic_nsSharedString<CharT>* oldPtr = mRawPtr;
mRawPtr = rhs.mRawPtr;
if ( oldPtr )
oldPtr->Release();
}
template <class CharT>
basic_nsSharedString<CharT>*
new_nsSharedString( const basic_nsAReadableString<CharT>& aReadable )
{
size_t object_size = ((sizeof(basic_nsSharedString<CharT>) + sizeof(CharT) - 1) / sizeof(CharT)) * sizeof(CharT);
size_t string_length = aReadable.Length();
size_t string_size = string_length * sizeof(CharT);
void* object_ptr = operator new(object_size + string_size);
if ( object_ptr )
{
typedef CharT* CharT_ptr;
CharT* string_ptr = CharT_ptr(NS_STATIC_CAST(unsigned char*, object_ptr) + object_size);
nsReadingIterator<CharT> fromBegin, fromEnd;
CharT* toBegin = string_ptr;
copy_string(aReadable.BeginReading(fromBegin), aReadable.EndReading(fromEnd), toBegin);
return new (object_ptr) basic_nsSharedString<CharT>(string_ptr, string_length);
}
return 0;
}
typedef basic_nsSharedString<PRUnichar> nsSharedString;
typedef basic_nsSharedString<char> nsSharedCString;
typedef basic_nsSharedStringPtr<PRUnichar> nsSharedStringPtr;
typedef basic_nsSharedStringPtr<char> nsSharedCStringPtr;
#endif // !defined(nsSharedString_h___)