Store property name and value in wxPropertyGridEvent, keep track of live event instan...

[wxWidgets.git] / include / wx / buffer.h

diff --git a/include/wx/buffer.h b/include/wx/buffer.h
index 26828843d8df06a3acdd021fa2c2d02b375e61ee..864bb64eb74a74d49476de7e4fa7b3530a2a202a 100644 (file)
--- a/include/wx/buffer.h
+++ b/include/wx/buffer.h
@@ -6,123 +6,423 @@
 // Created:     12.04.99
 // RCS-ID:      $Id$
 // Copyright:   (c) 1998 Vadim Zeitlin <zeitlin@dptmaths.ens-cachan.fr>
 // Created:     12.04.99
 // RCS-ID:      $Id$
 // Copyright:   (c) 1998 Vadim Zeitlin <zeitlin@dptmaths.ens-cachan.fr>

-// Licence:     wxWindows license
+// Licence:     wxWindows licence

 ///////////////////////////////////////////////////////////////////////////////
 
 ///////////////////////////////////////////////////////////////////////////////
 

-// these classes are for private use only for now, they're not documented
-

 #ifndef _WX_BUFFER_H
 #define _WX_BUFFER_H
 
 #ifndef _WX_BUFFER_H
 #define _WX_BUFFER_H
 

-#include "wx/wxchar.h"
+#include "wx/chartype.h"
+#include "wx/wxcrtbase.h"
+
+#ifndef __WXPALMOS5__
+#include <stdlib.h>             // malloc() and free()
+#endif // ! __WXPALMOS5__

 
 

-#include <string.h> // strdup
+class WXDLLIMPEXP_FWD_BASE wxCStrData;

 
 // ----------------------------------------------------------------------------
 // Special classes for (wide) character strings: they use malloc/free instead
 // of new/delete
 // ----------------------------------------------------------------------------
 
 
 // ----------------------------------------------------------------------------
 // Special classes for (wide) character strings: they use malloc/free instead
 // of new/delete
 // ----------------------------------------------------------------------------
 

-class wxCharBuffer
+// helpers used by wxCharTypeBuffer
+namespace wxPrivate
+{
+
+struct UntypedBufferData
+{
+    enum Kind
+    {
+        Owned,
+        NonOwned
+    };
+
+    UntypedBufferData(void *str, size_t len, Kind kind = Owned)
+        : m_str(str), m_length(len), m_ref(1), m_owned(kind == Owned) {}
+
+    ~UntypedBufferData()
+    {
+        if ( m_owned )
+            free(m_str);
+    }
+
+    void *m_str;
+    size_t m_length;
+
+    // "short" to have sizeof(Data)=12 on 32bit archs
+    unsigned short m_ref;
+
+    bool m_owned;
+};
+
+// this has to be defined inside the DLL (and not e.g. as a static variable
+// inside an inline function) as otherwise MSVC gives link errors when the
+// functions are effectively inlined (i.e. in non-debug build)
+//
+// NB: this is defined in string.cpp and not the (non-existent) buffer.cpp
+extern WXDLLIMPEXP_DATA_BASE(UntypedBufferData * const) untypedNullDataPtr;
+
+} // namespace wxPrivate
+
+
+// Reference-counted character buffer for storing string data. The buffer
+// is only valid for as long as the "parent" object that provided the data
+// is valid; see wxCharTypeBuffer<T> for persistent variant.
+template <typename T>
+class wxScopedCharTypeBuffer

 {
 public:
 {
 public:

-    wxCharBuffer(const char *str)
-        : m_str(str ? strdup(str) : NULL)
+    typedef T CharType;
+
+    wxScopedCharTypeBuffer()

     {
     {

-        wxASSERT_MSG( str, wxT("NULL string in wxCharBuffer") );
+        m_data = GetNullData();

     }
 
     }
 

-    wxCharBuffer(size_t len)
-        : m_str((char *)malloc((len + 1)*sizeof(char)))
+    // Creates "non-owned" buffer, i.e. 'str' is not owned by the buffer
+    // and doesn't get freed by dtor. Used e.g. to point to wxString's internal
+    // storage.
+    static
+    const wxScopedCharTypeBuffer CreateNonOwned(const CharType *str,
+                                                size_t len = wxNO_LEN)

     {
     {

-        m_str[len] = '\0';
+        if ( len == wxNO_LEN )
+            len = wxStrlen(str);
+
+        wxScopedCharTypeBuffer buf;
+        if ( str )
+            buf.m_data = new Data(const_cast<CharType*>(str), len, Data::NonOwned);
+        return buf;

     }
 
     }
 

-    // no need to check for NULL, free() does it
-    ~wxCharBuffer() { free(m_str); }
+    // Creates "owned" buffer, i.e. takes over ownership of 'str' and frees it
+    // in dtor (if ref.count reaches 0).
+    static
+    const wxScopedCharTypeBuffer CreateOwned(const CharType *str,
+                                             size_t len = wxNO_LEN )
+    {
+        if ( len == wxNO_LEN )
+            len = wxStrlen(str);
+
+        wxScopedCharTypeBuffer buf;
+        if ( str )
+            buf.m_data = new Data(StrCopy(str, len), len);
+        return buf;
+    }

 
 

-    wxCharBuffer(const wxCharBuffer& src)
-        : m_str(src.m_str)
+    wxScopedCharTypeBuffer(const wxScopedCharTypeBuffer& src)

     {
     {

-        // no reference count yet...
-        ((wxCharBuffer*)&src)->m_str = (char *)NULL;
+        m_data = src.m_data;
+        IncRef();

     }
     }

-    wxCharBuffer& operator=(const wxCharBuffer& src)
+
+    wxScopedCharTypeBuffer& operator=(const wxScopedCharTypeBuffer& src)

     {
     {

-        m_str = src.m_str;
-        // no reference count yet...
-        ((wxCharBuffer*)&src)->m_str = (char *)NULL;
+        if ( &src == this )
+            return *this;
+
+        DecRef();
+        m_data = src.m_data;
+        IncRef();
+

         return *this;
     }
 
         return *this;
     }
 

-    const char *data() const { return m_str; }
-    operator const char *() const { return m_str; }
-    char operator[](size_t n) const { return m_str[n]; }
+    ~wxScopedCharTypeBuffer()
+    {
+        DecRef();
+    }

 
 

-private:
-    char *m_str;
+    // NB: this method is only const for backward compatibility. It used to
+    //     be needed for auto_ptr-like semantics of the copy ctor, but now
+    //     that ref-counting is used, it's not really needed.
+    CharType *release() const
+    {
+        if ( m_data == GetNullData() )
+            return NULL;
+
+        wxASSERT_MSG( m_data->m_owned, wxT("can't release non-owned buffer") );
+        wxASSERT_MSG( m_data->m_ref == 1, wxT("can't release shared buffer") );
+
+        CharType * const p = m_data->Get();
+
+        wxScopedCharTypeBuffer *self = const_cast<wxScopedCharTypeBuffer*>(this);
+        self->m_data->Set(NULL, 0);
+        self->DecRef();
+
+        return p;
+    }
+
+    void reset()
+    {
+        DecRef();
+    }
+
+    CharType *data() { return m_data->Get(); }
+    const CharType *data() const { return  m_data->Get(); }
+    operator const CharType *() const { return data(); }
+    CharType operator[](size_t n) const { return data()[n]; }
+
+    size_t length() const { return m_data->m_length; }
+
+protected:
+    // reference-counted data
+    struct Data : public wxPrivate::UntypedBufferData
+    {
+        Data(CharType *str, size_t len, Kind kind = Owned)
+            : wxPrivate::UntypedBufferData(str, len, kind)
+        {
+        }
+
+        CharType *Get() const { return static_cast<CharType *>(m_str); }
+        void Set(CharType *str, size_t len)
+        {
+            m_str = str;
+            m_length = len;
+        }
+    };
+
+    // placeholder for NULL string, to simplify this code
+    static Data *GetNullData()
+    {
+        return static_cast<Data *>(wxPrivate::untypedNullDataPtr);
+    }
+
+    void IncRef()
+    {
+        if ( m_data == GetNullData() ) // exception, not ref-counted
+            return;
+        m_data->m_ref++;
+    }
+
+    void DecRef()
+    {
+        if ( m_data == GetNullData() ) // exception, not ref-counted
+            return;
+        if ( --m_data->m_ref == 0 )
+            delete m_data;
+        m_data = GetNullData();
+    }
+
+    // sets this object to a be copy of 'other'; if 'src' is non-owned,
+    // a deep copy is made and 'this' will contain new instance of the data
+    void MakeOwnedCopyOf(const wxScopedCharTypeBuffer& src)
+    {
+        this->DecRef();
+
+        if ( src.m_data == this->GetNullData() )
+        {
+            this->m_data = this->GetNullData();
+        }
+        else if ( src.m_data->m_owned )
+        {
+            this->m_data = src.m_data;
+            this->IncRef();
+        }
+        else
+        {
+            // if the scoped buffer had non-owned data, we have to make
+            // a copy here, because src.m_data->m_str is valid only for as long
+            // as 'src' exists
+            this->m_data = new Data
+                               (
+                                   StrCopy(src.data(), src.length()),
+                                   src.length()
+                               );
+        }
+    }
+
+    static CharType *StrCopy(const CharType *src, size_t len)
+    {
+        CharType *dst = (CharType*)malloc(sizeof(CharType) * (len + 1));
+        memcpy(dst, src, sizeof(CharType) * (len + 1));
+        return dst;
+    }
+
+protected:
+    Data *m_data;

 };
 
 };
 

-#if wxUSE_WCHAR_T
+typedef wxScopedCharTypeBuffer<char> wxScopedCharBuffer;
+typedef wxScopedCharTypeBuffer<wchar_t> wxScopedWCharBuffer;

 
 

-class wxWCharBuffer
+
+// this buffer class always stores data in "owned" (persistent) manner
+template <typename T>
+class wxCharTypeBuffer : public wxScopedCharTypeBuffer<T>

 {
 {

+protected:
+    typedef typename wxScopedCharTypeBuffer<T>::Data Data;
+

 public:
 public:

-    wxWCharBuffer(const wchar_t *wcs)
-        : m_wcs((wchar_t *)NULL)
-    {
-        wxASSERT_MSG( wcs, wxT("NULL string in wxWCharBuffer") );
-
-        if (wcs) {
-#if ( defined(__BORLANDC__) && (__BORLANDC__ > 0x530) ) \
-    || ( defined(__MWERKS__) && defined(__WXMSW__) )
-          size_t siz = (std::wcslen(wcs)+1)*sizeof(wchar_t);
-#else
-          size_t siz = (::wcslen(wcs)+1)*sizeof(wchar_t);
-#endif
-          m_wcs = (wchar_t *)malloc(siz);
-          memcpy(m_wcs, wcs, siz);
+    typedef T CharType;
+
+    wxCharTypeBuffer(const CharType *str = NULL, size_t len = wxNO_LEN)
+    {
+        if ( str )
+        {
+            if ( len == wxNO_LEN )
+                len = wxStrlen(str);
+            this->m_data = new Data(StrCopy(str, len), len);

         }
         }

+        else
+        {
+            this->m_data = this->GetNullData();
+        }
+    }
+
+    wxCharTypeBuffer(size_t len)
+    {
+        this->m_data =
+            new Data((CharType *)malloc((len + 1)*sizeof(CharType)), len);
+        this->m_data->Get()[len] = (CharType)0;

     }
     }

-    wxWCharBuffer(size_t len)
-        : m_wcs((wchar_t *)malloc((len + 1)*sizeof(wchar_t)))
+
+    wxCharTypeBuffer(const wxCharTypeBuffer& src)
+        : wxScopedCharTypeBuffer<T>(src) {}
+
+    wxCharTypeBuffer& operator=(const CharType *str)

     {
     {

-        m_wcs[len] = L'\0';
+        this->DecRef();
+
+        if ( str )
+            this->m_data = new Data(wxStrdup(str), wxStrlen(str));
+        return *this;

     }
 
     }
 

-    // no need to check for NULL, free() does it
-    ~wxWCharBuffer() { free(m_wcs); }
+    wxCharTypeBuffer& operator=(const wxCharTypeBuffer& src)
+    {
+        wxScopedCharTypeBuffer<T>::operator=(src);
+        return *this;
+    }

 
 

-    wxWCharBuffer(const wxWCharBuffer& src)
-        : m_wcs(src.m_wcs)
+    wxCharTypeBuffer(const wxScopedCharTypeBuffer<T>& src)

     {
     {

-       // no reference count yet...
-       ((wxWCharBuffer*)&src)->m_wcs = (wchar_t *)NULL;
+        MakeOwnedCopyOf(src);

     }
     }

-    wxWCharBuffer& operator=(const wxWCharBuffer& src)
+
+    wxCharTypeBuffer& operator=(const wxScopedCharTypeBuffer<T>& src)

     {
     {

-        m_wcs = src.m_wcs;
-        // no reference count yet...
-        ((wxWCharBuffer*)&src)->m_wcs = (wchar_t *)NULL;
+        MakeOwnedCopyOf(src);

         return *this;
     }
 
         return *this;
     }
 

-    const wchar_t *data() const { return m_wcs; }
-    operator const wchar_t *() const { return m_wcs; }
-    wchar_t operator[](size_t n) const { return m_wcs[n]; }
+    bool extend(size_t len)
+    {
+        wxASSERT_MSG( this->m_data->m_owned, "cannot extend non-owned buffer" );
+        wxASSERT_MSG( this->m_data->m_ref == 1, "can't extend shared buffer" );

 
 

-private:
-    wchar_t *m_wcs;
+        CharType *str =
+            (CharType *)realloc(this->data(), (len + 1) * sizeof(CharType));
+        if ( !str )
+            return false;
+
+        if ( this->m_data == this->GetNullData() )
+        {
+            this->m_data = new Data(str, len);
+        }
+        else
+        {
+            this->m_data->Set(str, len);
+            this->m_data->m_owned = true;
+        }
+
+        return true;
+    }
+
+    void shrink(size_t len)
+    {
+        wxASSERT_MSG( this->m_data->m_owned, "cannot shrink non-owned buffer" );
+        wxASSERT_MSG( this->m_data->m_ref == 1, "can't shrink shared buffer" );
+
+        wxASSERT( len <= this->length() );
+
+        this->m_data->m_length = len;
+        this->data()[len] = 0;
+    }

 };
 
 };
 

+WXDLLIMPEXP_TEMPLATE_INSTANCE_BASE( wxScopedCharTypeBuffer<char> )
+WXDLLIMPEXP_TEMPLATE_INSTANCE_BASE( wxCharTypeBuffer<char> )
+
+class wxCharBuffer : public wxCharTypeBuffer<char>
+{
+public:
+    typedef wxCharTypeBuffer<char> wxCharTypeBufferBase;
+    typedef wxScopedCharTypeBuffer<char> wxScopedCharTypeBufferBase;
+
+    wxCharBuffer(const wxCharTypeBufferBase& buf)
+        : wxCharTypeBufferBase(buf) {}
+    wxCharBuffer(const wxScopedCharTypeBufferBase& buf)
+        : wxCharTypeBufferBase(buf) {}
+
+    wxCharBuffer(const CharType *str = NULL) : wxCharTypeBufferBase(str) {}
+    wxCharBuffer(size_t len) : wxCharTypeBufferBase(len) {}
+
+    wxCharBuffer(const wxCStrData& cstr);
+};
+
+#if wxUSE_WCHAR_T
+WXDLLIMPEXP_TEMPLATE_INSTANCE_BASE( wxScopedCharTypeBuffer<wchar_t> )
+WXDLLIMPEXP_TEMPLATE_INSTANCE_BASE( wxCharTypeBuffer<wchar_t> )
+
+class wxWCharBuffer : public wxCharTypeBuffer<wchar_t>
+{
+public:
+    typedef wxCharTypeBuffer<wchar_t> wxCharTypeBufferBase;
+    typedef wxScopedCharTypeBuffer<wchar_t> wxScopedCharTypeBufferBase;
+
+    wxWCharBuffer(const wxCharTypeBufferBase& buf)
+        : wxCharTypeBufferBase(buf) {}
+    wxWCharBuffer(const wxScopedCharTypeBufferBase& buf)
+        : wxCharTypeBufferBase(buf) {}
+
+    wxWCharBuffer(const CharType *str = NULL) : wxCharTypeBufferBase(str) {}
+    wxWCharBuffer(size_t len) : wxCharTypeBufferBase(len) {}
+
+    wxWCharBuffer(const wxCStrData& cstr);
+};

 #endif // wxUSE_WCHAR_T
 
 #endif // wxUSE_WCHAR_T
 

+// wxCharTypeBuffer<T> implicitly convertible to T*
+template <typename T>
+class wxWritableCharTypeBuffer : public wxCharTypeBuffer<T>
+{
+public:
+    typedef typename wxScopedCharTypeBuffer<T>::CharType CharType;
+
+    wxWritableCharTypeBuffer(const wxScopedCharTypeBuffer<T>& src)
+        : wxCharTypeBuffer<T>(src) {}
+    // FIXME-UTF8: this won't be needed after converting mb_str()/wc_str() to
+    //             always return a buffer
+    //             + we should derive this class from wxScopedCharTypeBuffer
+    //               then
+    wxWritableCharTypeBuffer(const CharType *str = NULL)
+        : wxCharTypeBuffer<T>(str) {}
+
+    operator CharType*() { return this->data(); }
+};
+
+typedef wxWritableCharTypeBuffer<char> wxWritableCharBuffer;
+typedef wxWritableCharTypeBuffer<wchar_t> wxWritableWCharBuffer;
+
+

 #if wxUSE_UNICODE
 #if wxUSE_UNICODE

+    #define wxWxCharBuffer wxWCharBuffer
+

     #define wxMB2WXbuf wxWCharBuffer
     #define wxWX2MBbuf wxCharBuffer
     #define wxMB2WXbuf wxWCharBuffer
     #define wxWX2MBbuf wxCharBuffer

-    #define wxWC2WXbuf wxChar*
-    #define wxWX2WCbuf wxChar*
+    #if wxUSE_UNICODE_WCHAR
+        #define wxWC2WXbuf wxChar*
+        #define wxWX2WCbuf wxChar*
+    #elif wxUSE_UNICODE_UTF8
+        #define wxWC2WXbuf wxWCharBuffer
+        #define wxWX2WCbuf wxWCharBuffer
+    #endif

 #else // ANSI
 #else // ANSI

+    #define wxWxCharBuffer wxCharBuffer
+

     #define wxMB2WXbuf wxChar*
     #define wxWX2MBbuf wxChar*
     #define wxWC2WXbuf wxCharBuffer
     #define wxMB2WXbuf wxChar*
     #define wxWX2MBbuf wxChar*
     #define wxWC2WXbuf wxCharBuffer


@@ -133,101 +433,151 @@ private:
 // A class for holding growable data buffers (not necessarily strings)
 // ----------------------------------------------------------------------------
 
 // A class for holding growable data buffers (not necessarily strings)
 // ----------------------------------------------------------------------------
 

-class wxMemoryBuffer
+// This class manages the actual data buffer pointer and is ref-counted.
+class wxMemoryBufferData

 {
 public:
 {
 public:

-    enum { BLOCK_SIZE = 1024 };
-    wxMemoryBuffer(size_t size = wxMemoryBuffer::BLOCK_SIZE)
-        : m_data(malloc(size)), m_size(size), m_len(0)
+    // the initial size and also the size added by ResizeIfNeeded()
+    enum { DefBufSize = 1024 };
+
+    friend class wxMemoryBuffer;
+
+    // everyting is private as it can only be used by wxMemoryBuffer
+private:
+    wxMemoryBufferData(size_t size = wxMemoryBufferData::DefBufSize)
+        : m_data(size ? malloc(size) : NULL), m_size(size), m_len(0), m_ref(0)

     {
     }
     {
     }

+    ~wxMemoryBufferData() { free(m_data); }

 
 

-    ~wxMemoryBuffer() { free(m_data); }

 
 

-    // Accessors
-    void*  GetData() const    { return m_data; }
-    size_t GetBufSize() const { return m_size; }
-    size_t GetDataLen() const { return m_len; }
-
-    void   SetBufSize(size_t size) { ResizeIfNeeded(size); }
-    void   SetDataLen(size_t len)
+    void ResizeIfNeeded(size_t newSize)

     {
     {

-        wxASSERT(len <= m_size);
-        m_len = len;
+        if (newSize > m_size)
+        {
+            void *dataOld = m_data;
+            m_data = realloc(m_data, newSize + wxMemoryBufferData::DefBufSize);
+            if ( !m_data )
+            {
+                free(dataOld);
+            }
+
+            m_size = newSize + wxMemoryBufferData::DefBufSize;
+        }

     }
 
     }
 

-    // Ensure the buffer is big enough and return a pointer to it
-    void* GetWriteBuf(size_t sizeNeeded)
+    void IncRef() { m_ref += 1; }
+    void DecRef()

     {
     {

-        ResizeIfNeeded(sizeNeeded);
-        return m_data;
+        m_ref -= 1;
+        if (m_ref == 0)  // are there no more references?
+            delete this;

     }
     }

-    // Update the length after the write
-    void  UngetWriteBuf(size_t sizeUsed) { SetDataLen(sizeUsed); }

 
 

-    // Like the above, but appends to the buffer
-    void* GetAppendBuf(size_t sizeNeeded)
+
+    // the buffer containing the data
+    void  *m_data;
+
+    // the size of the buffer
+    size_t m_size;
+
+    // the amount of data currently in the buffer
+    size_t m_len;
+
+    // the reference count
+    size_t m_ref;
+
+    wxDECLARE_NO_COPY_CLASS(wxMemoryBufferData);
+};
+
+
+class wxMemoryBuffer
+{
+public:
+    // ctor and dtor
+    wxMemoryBuffer(size_t size = wxMemoryBufferData::DefBufSize)

     {
     {

-        ResizeIfNeeded(m_len + sizeNeeded);
-        return (char*)m_data + m_len;
+        m_bufdata = new wxMemoryBufferData(size);
+        m_bufdata->IncRef();

     }
     }

-    void  UngetAppendBuf(size_t sizeUsed) { SetDataLen(m_len + sizeUsed); }

 
 

-    // Other ways to append to the buffer
-    void  AppendByte(char data) {
-        ResizeIfNeeded(m_len + 1);
-        *(((char*)m_data)+m_len) = data;
-        m_len += 1;
+    ~wxMemoryBuffer() { m_bufdata->DecRef(); }
+
+
+    // copy and assignment
+    wxMemoryBuffer(const wxMemoryBuffer& src)
+        : m_bufdata(src.m_bufdata)
+    {
+        m_bufdata->IncRef();

     }
     }

-    void  AppendData(void* data, size_t len)
+
+    wxMemoryBuffer& operator=(const wxMemoryBuffer& src)

     {
     {

-        memcpy(GetAppendBuf(len), data, len);
-        UngetAppendBuf(len);
+        if (&src != this)
+        {
+            m_bufdata->DecRef();
+            m_bufdata = src.m_bufdata;
+            m_bufdata->IncRef();
+        }
+        return *this;

     }
 
     }
 

-    operator const char *() const { return (const char*)m_data; }

 
 

+    // Accessors
+    void  *GetData() const    { return m_bufdata->m_data; }
+    size_t GetBufSize() const { return m_bufdata->m_size; }
+    size_t GetDataLen() const { return m_bufdata->m_len; }

 
 

-    // Copy and assignment
-    wxMemoryBuffer(const wxMemoryBuffer& src)
-        : m_data(src.m_data), m_size(src.m_size), m_len(src.m_len)
+    void   SetBufSize(size_t size) { m_bufdata->ResizeIfNeeded(size); }
+    void   SetDataLen(size_t len)

     {
     {

-        // no reference count yet...
-        ((wxMemoryBuffer*)&src)->m_data = NULL;
-        ((wxMemoryBuffer*)&src)->m_size = 0;
-        ((wxMemoryBuffer*)&src)->m_len  = 0;
+        wxASSERT(len <= m_bufdata->m_size);
+        m_bufdata->m_len = len;

     }
 
     }
 

-    wxMemoryBuffer& operator=(const wxMemoryBuffer& src)
+    // Ensure the buffer is big enough and return a pointer to it
+    void *GetWriteBuf(size_t sizeNeeded)

     {
     {

-        m_data = src.m_data;
-        m_size = src.m_size;
-        m_len  = src.m_len;
+        m_bufdata->ResizeIfNeeded(sizeNeeded);
+        return m_bufdata->m_data;
+    }

 
 

-        // no reference count yet...
-        ((wxMemoryBuffer*)&src)->m_data = NULL;
-        ((wxMemoryBuffer*)&src)->m_size = 0;
-        ((wxMemoryBuffer*)&src)->m_len  = 0;
+    // Update the length after the write
+    void  UngetWriteBuf(size_t sizeUsed) { SetDataLen(sizeUsed); }

 
 

-        return *this;
-   }
+    // Like the above, but appends to the buffer
+    void *GetAppendBuf(size_t sizeNeeded)
+    {
+        m_bufdata->ResizeIfNeeded(m_bufdata->m_len + sizeNeeded);
+        return (char*)m_bufdata->m_data + m_bufdata->m_len;
+    }

 
 

+    // Update the length after the append
+    void  UngetAppendBuf(size_t sizeUsed)
+    {
+        SetDataLen(m_bufdata->m_len + sizeUsed);
+    }

 
 

-protected:
-    void ResizeIfNeeded(size_t newSize)
+    // Other ways to append to the buffer
+    void  AppendByte(char data)

     {
     {

-        if (newSize > m_size)
-        {
-            m_data = realloc(m_data, newSize + wxMemoryBuffer::BLOCK_SIZE);
-            wxASSERT(m_data != NULL);
-            m_size = newSize + wxMemoryBuffer::BLOCK_SIZE;
-        }
+        wxCHECK_RET( m_bufdata->m_data, wxT("invalid wxMemoryBuffer") );
+
+        m_bufdata->ResizeIfNeeded(m_bufdata->m_len + 1);
+        *(((char*)m_bufdata->m_data) + m_bufdata->m_len) = data;
+        m_bufdata->m_len += 1;

     }
 
     }
 

+    void  AppendData(const void *data, size_t len)
+    {
+        memcpy(GetAppendBuf(len), data, len);
+        UngetAppendBuf(len);
+    }
+
+    operator const char *() const { return (const char*)GetData(); }
+

 private:
 private:

-    void*       m_data;
-    size_t      m_size;
-    size_t      m_len;
+    wxMemoryBufferData*  m_bufdata;

 };
 
 // ----------------------------------------------------------------------------
 };
 
 // ----------------------------------------------------------------------------