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359 lines
12 KiB
C++
Executable File
359 lines
12 KiB
C++
Executable File
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/*
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* The contents of this file are subject to the Mozilla Public
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* License Version 1.1 (the "License"); you may not use this file
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* except in compliance with the License. You may obtain a copy of
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* the License at http://www.mozilla.org/MPL/
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*
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* Software distributed under the License is distributed on an "AS
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* IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
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* implied. See the License for the specific language governing
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* rights and limitations under the License.
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*
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* The Original Code is Mozilla strings.
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*
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* The Initial Developer of the Original Code is Netscape
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* Communications Corporation. Portions created by Netscape are
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* Copyright (C) 2000 Netscape Communications Corporation. All
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* Rights Reserved.
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*
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* Contributor(s):
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* Scott Collins <scc@mozilla.org> (original author)
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*
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*/
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/* nsBufferHandle.h --- the collection of classes that describe the atomic hunks of strings */
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#ifndef nsBufferHandle_h___
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#define nsBufferHandle_h___
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#include <stddef.h>
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// for |ptrdiff_t|
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#include "prtypes.h"
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// for |PRBool|
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#include "nsDebug.h"
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// for |NS_ASSERTION|
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#include "nscore.h"
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// for |PRUnichar|, |NS_REINTERPRET_CAST|
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#ifdef XP_WIN
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// VC++ erroneously warns about incompatible linkage in these templates
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// It's a lie, and it's bothersome. This |#pragma| quiets the warning.
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#pragma warning( disable: 4251 )
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#endif
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/**
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The classes in this file are collectively called `buffer handles'.
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All buffer handles begin with a pointer-tuple that delimits the useful content of a
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hunk of string. A buffer handle that points to a sharable hunk of string data
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additionally has a field which multiplexes some flags and a reference count.
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ns[Const]BufferHandle nsSharedBufferHandle mFlexBufferHandle
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+-----+-----+-----+-----+ +-----+-----+-----+-----+ +-----+-----+-----+-----+
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| mDataStart | | mDataStart | | mDataStart |
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+-----+-----+-----+-----+ +-----+-----+-----+-----+ +-----+-----+-----+-----+
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| mDataEnd | | mDataEnd | | mDataEnd |
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+-----+-----+-----+-----+ +-----+-----+-----+-----+ +-----+-----+-----+-----+
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| mFlags | | mFlags |
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+-----+-----+-----+-----+ +-----+-----+-----+-----+
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. mAllocator . | mStorageStart |
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......................... +-----+-----+-----+-----+
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| mStorageEnd |
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+-----+-----+-----+-----+
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. mAllocator .
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.........................
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Given only a |ns[Const]BufferHandle|, there is no legal way to tell if it is sharable.
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In all cases, the data might immediately follow the handle in the same allocated block.
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From the |mFlags| field, you can tell exactly what configuration of a handle you
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actually have.
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*/
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/**
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*
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*/
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template <class CharT>
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class nsBufferHandle
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{
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public:
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nsBufferHandle( CharT* aDataStart, CharT* aDataEnd ) : mDataStart(aDataStart), mDataEnd(aDataEnd) { }
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void DataStart( CharT* aNewDataStart ) { mDataStart = aNewDataStart; }
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CharT* DataStart() { return mDataStart; }
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const CharT* DataStart() const { return mDataStart; }
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void DataEnd( CharT* aNewDataEnd ) { mDataEnd = aNewDataEnd; }
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CharT* DataEnd() { return mDataEnd; }
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const CharT* DataEnd() const { return mDataEnd; }
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ptrdiff_t DataLength() const { return mDataEnd - mDataStart; }
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protected:
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CharT* mDataStart;
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CharT* mDataEnd;
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};
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template <class CharT>
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class nsConstBufferHandle
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{
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public:
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nsConstBufferHandle( const CharT* aDataStart, const CharT* aDataEnd ) : mDataStart(aDataStart), mDataEnd(aDataEnd) { }
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const CharT* DataStart() const { return mDataStart; }
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const CharT* DataEnd() const { return mDataEnd; }
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ptrdiff_t DataLength() const { return mDataEnd - mDataStart; }
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protected:
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const CharT* mDataStart;
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const CharT* mDataEnd;
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};
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/**
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* string allocator stuff needs to move to its own file
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* also see http://bugzilla.mozilla.org/show_bug.cgi?id=70087
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*/
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template <class CharT>
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class nsStringAllocator
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{
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public:
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// more later
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virtual void Deallocate( CharT* ) const = 0;
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};
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/**
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* the following two routines must be provided by the client embedding strings
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*/
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NS_COM nsStringAllocator<char>& StringAllocator_char();
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NS_COM nsStringAllocator<PRUnichar>& StringAllocator_wchar_t();
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/**
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* this traits class lets templated clients pick the appropriate non-template global allocator
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*/
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template <class T>
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struct nsStringAllocatorTraits
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{
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};
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NS_SPECIALIZE_TEMPLATE
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struct nsStringAllocatorTraits<char>
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{
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static nsStringAllocator<char>& global_string_allocator() { return StringAllocator_char(); }
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};
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NS_SPECIALIZE_TEMPLATE
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struct nsStringAllocatorTraits<PRUnichar>
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{
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static nsStringAllocator<PRUnichar>& global_string_allocator() { return StringAllocator_wchar_t(); }
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};
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// end of string allocator stuff that needs to move
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/**
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*
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*/
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template <class CharT>
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class nsSharedBufferHandle
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: public nsBufferHandle<CharT>
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{
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protected:
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enum
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{
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kIsShared = 0x08000000, // one reason _not_ to set this is for a stack based handle that wants to express `NULL'-ness et al
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kIsSingleAllocationWithBuffer = 0x04000000, // handle and buffer are one piece, no separate deallocation is possible for the buffer
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kIsStorageDefinedSeparately = 0x02000000, // i.e., we're using the ``flex'' structure defined below
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kIsUserAllocator = 0x01000000, // can't |delete|, call a hook instead
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// the following flags are opaque to the string library itself
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kIsNULL = 0x80000000, // the most common request of external clients is a scheme by which they can express `NULL'-ness
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kImplementationFlagsMask = 0xF0000000, // 4 bits for use by site-implementations, e.g., for `NULL'-ness
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kFlagsMask = 0xFF000000,
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kRefCountMask = 0x00FFFFFF
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};
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public:
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nsSharedBufferHandle( CharT* aDataStart, CharT* aDataEnd )
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: nsBufferHandle<CharT>(aDataStart, aDataEnd)
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{
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mFlags = kIsShared;
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}
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nsSharedBufferHandle( CharT* aDataStart, CharT* aDataEnd, CharT*, CharT*, PRBool isSingleAllocation )
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: nsBufferHandle<CharT>(aDataStart, aDataEnd)
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{
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mFlags = kIsShared;
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if ( isSingleAllocation )
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mFlags |= kIsSingleAllocationWithBuffer;
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}
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~nsSharedBufferHandle();
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void
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AcquireReference() const
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{
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nsSharedBufferHandle<CharT>* mutable_this = NS_CONST_CAST(nsSharedBufferHandle<CharT>*, this);
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mutable_this->set_refcount( get_refcount()+1 );
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}
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void
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ReleaseReference() const
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{
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nsSharedBufferHandle<CharT>* mutable_this = NS_CONST_CAST(nsSharedBufferHandle<CharT>*, this);
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if ( !mutable_this->set_refcount( get_refcount()-1 ) )
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delete mutable_this;
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// hmm, what if |kIsUserAllocator| and |kIsSingleAllocationWithBuffer|?
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}
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PRBool
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IsReferenced() const
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{
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return get_refcount() != 0;
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}
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PRUint32
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GetImplementationFlags() const
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{
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return mFlags & kImplementationFlagsMask;
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}
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void
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SetImplementationFlags( PRUint32 aNewFlags )
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{
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mFlags = (mFlags & ~kImplementationFlagsMask) | (aNewFlags & kImplementationFlagsMask);
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}
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protected:
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PRUint32 mFlags;
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PRUint32
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get_refcount() const
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{
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return mFlags & kRefCountMask;
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}
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PRUint32
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set_refcount( PRUint32 aNewRefCount )
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{
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NS_ASSERTION(aNewRefCount <= kRefCountMask, "aNewRefCount <= kRefCountMask");
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mFlags = (mFlags & kFlagsMask) | aNewRefCount;
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return aNewRefCount;
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}
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nsStringAllocator<CharT>& get_allocator() const;
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};
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template <class CharT>
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class nsFlexBufferHandle
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: public nsSharedBufferHandle<CharT>
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{
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public:
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nsFlexBufferHandle( CharT* aDataStart, CharT* aDataEnd, CharT* aStorageStart, CharT* aStorageEnd )
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: nsSharedBufferHandle<CharT>(aDataStart, aDataEnd),
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mStorageStart(aStorageStart),
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mStorageEnd(aStorageEnd)
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{
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this->mFlags |= this->kIsStorageDefinedSeparately;
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}
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void StorageStart( CharT* aNewStorageStart ) { mStorageStart = aNewStorageStart; }
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CharT* StorageStart() { return mStorageStart; }
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const CharT* StorageStart() const { return mStorageStart; }
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void StorageEnd( CharT* aNewStorageEnd ) { mStorageEnd = aNewStorageEnd; }
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CharT* StorageEnd() { return mStorageEnd; }
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const CharT* StorageEnd() const { return mStorageEnd; }
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ptrdiff_t StorageLength() const { return mStorageEnd - mStorageStart; }
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protected:
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CharT* mStorageStart;
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CharT* mStorageEnd;
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};
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template <class CharT>
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class nsSharedBufferHandleWithAllocator
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: public nsSharedBufferHandle<CharT>
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{
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public:
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nsSharedBufferHandleWithAllocator( CharT* aDataStart, CharT* aDataEnd, nsStringAllocator<CharT>& aAllocator )
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: nsSharedBufferHandle<CharT>(aDataStart, aDataEnd),
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mAllocator(aAllocator)
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{
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this->mFlags |= this->kIsUserAllocator;
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}
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nsStringAllocator<CharT>& get_allocator() const { return mAllocator; }
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protected:
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nsStringAllocator<CharT>& mAllocator;
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};
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template <class CharT>
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class nsFlexBufferHandleWithAllocator
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: public nsFlexBufferHandle<CharT>
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{
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public:
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nsFlexBufferHandleWithAllocator( CharT* aDataStart, CharT* aDataEnd,
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CharT* aStorageStart, CharT* aStorageEnd,
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nsStringAllocator<CharT>& aAllocator )
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: nsFlexBufferHandle<CharT>(aDataStart, aDataEnd, aStorageStart, aStorageEnd),
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mAllocator(aAllocator)
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{
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this->mFlags |= this->kIsUserAllocator;
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}
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nsStringAllocator<CharT>& get_allocator() const { return mAllocator; }
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protected:
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nsStringAllocator<CharT>& mAllocator;
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};
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template <class CharT>
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nsStringAllocator<CharT>&
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nsSharedBufferHandle<CharT>::get_allocator() const
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// really don't want this to be |inline|
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{
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if ( mFlags & kIsUserAllocator )
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{
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if ( mFlags & kIsStorageDefinedSeparately )
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return NS_REINTERPRET_CAST(const nsFlexBufferHandleWithAllocator<CharT>*, this)->get_allocator();
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else
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return NS_REINTERPRET_CAST(const nsSharedBufferHandleWithAllocator<CharT>*, this)->get_allocator();
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}
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return nsStringAllocatorTraits<CharT>::global_string_allocator();
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}
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template <class CharT>
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nsSharedBufferHandle<CharT>::~nsSharedBufferHandle()
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// really don't want this to be |inline|
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{
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NS_ASSERTION(!IsReferenced(), "!IsReferenced()");
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if ( !(mFlags & kIsSingleAllocationWithBuffer) )
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{
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CharT* string_storage = this->mDataStart;
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if ( mFlags & kIsStorageDefinedSeparately )
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string_storage = NS_REINTERPRET_CAST(nsFlexBufferHandle<CharT>*, this)->StorageStart();
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get_allocator().Deallocate(string_storage);
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}
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}
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#endif // !defined(nsBufferHandle_h___)
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