include/wx/buffer.h

   1 ///////////////////////////////////////////////////////////////////////////////
   2 // Name:        wx/buffer.h
   3 // Purpose:     auto buffer classes: buffers which automatically free memory
   4 // Author:      Vadim Zeitlin
   5 // Modified by:
   6 // Created:     12.04.99
   7 // RCS-ID:      $Id$
   8 // Copyright:   (c) 1998 Vadim Zeitlin <zeitlin@dptmaths.ens-cachan.fr>
   9 // Licence:     wxWindows licence
  10 ///////////////////////////////////////////////////////////////////////////////
  11
  12 #ifndef _WX_BUFFER_H
  13 #define _WX_BUFFER_H
  14
  15 #include "wx/chartype.h"
  16 #include "wx/wxcrtbase.h"
  17
  18 #include <stdlib.h>             // malloc() and free()
  19
  20 class WXDLLIMPEXP_FWD_BASE wxCStrData;
  21
  22 // ----------------------------------------------------------------------------
  23 // Special classes for (wide) character strings: they use malloc/free instead
  24 // of new/delete
  25 // ----------------------------------------------------------------------------
  26
  27 template <typename T>
  28 class wxCharTypeBuffer
  29 {
  30 public:
  31     typedef T CharType;
  32
  33     wxCharTypeBuffer(const CharType *str = NULL)
  34         : m_str(str ? wxStrdup(str) : NULL),
  35           m_owned(true)
  36     {
  37     }
  38
  39     wxCharTypeBuffer(size_t len)
  40         : m_str((CharType *)malloc((len + 1)*sizeof(CharType))),
  41           m_owned(true)
  42     {
  43         m_str[len] = (CharType)0;
  44     }
  45
  46     static const wxCharTypeBuffer CreateNonOwned(const CharType *str)
  47     {
  48         wxCharTypeBuffer buf;
  49         buf.m_str = wx_const_cast(CharType*, str);
  50         buf.m_owned = false;
  51         return buf;
  52     }
  53
  54     /* no need to check for NULL, free() does it */
  55     ~wxCharTypeBuffer()
  56     {
  57         if ( m_owned)
  58             free(m_str);
  59     }
  60
  61     /*
  62         WARNING:
  63
  64         the copy ctor and assignment operators change the passed in object
  65         even although it is declared as "const", so:
  66
  67         a) it shouldn't be really const
  68         b) you shouldn't use it afterwards (or know that it was reset)
  69
  70         This is very ugly but is unfortunately needed to make the normal use
  71         of wxCharTypeBuffer buffer objects possible and is very similar to what
  72         std::auto_ptr<> does (as if it were an excuse...)
  73     */
  74
  75     /*
  76        because of the remark above, release() is declared const even if it
  77        isn't really const
  78      */
  79     CharType *release() const
  80     {
  81         wxASSERT_MSG( m_owned, _T("can't release non-owned buffer") );
  82         return DoRelease();
  83     }
  84
  85     void reset()
  86     {
  87         if ( m_owned )
  88             free(m_str);
  89         m_str = NULL;
  90     }
  91
  92     wxCharTypeBuffer(const wxCharTypeBuffer& src)
  93     {
  94         CopyFrom(src);
  95     }
  96
  97     wxCharTypeBuffer& operator=(const CharType *str)
  98     {
  99         if ( m_owned )
 100             free(m_str);
 101         m_str = str ? wxStrdup(str) : NULL;
 102         m_owned = true;
 103         return *this;
 104     }
 105
 106     wxCharTypeBuffer& operator=(const wxCharTypeBuffer& src)
 107     {
 108         if ( m_owned )
 109             free(m_str);
 110         CopyFrom(src);
 111         return *this;
 112     }
 113
 114     bool extend(size_t len)
 115     {
 116         wxASSERT_MSG( m_owned, _T("cannot extend non-owned buffer") );
 117
 118         CharType *
 119             str = (CharType *)realloc(m_str, (len + 1)*sizeof(CharType));
 120         if ( !str )
 121             return false;
 122
 123         m_str = str;
 124
 125         return true;
 126     }
 127
 128     CharType *data() { return m_str; }
 129     const CharType *data() const { return m_str; }
 130     operator const CharType *() const { return m_str; }
 131     CharType operator[](size_t n) const { return m_str[n]; }
 132
 133
 134 private:
 135     CharType *DoRelease() const
 136     {
 137         CharType *p = m_str;
 138         ((wxCharTypeBuffer *)this)->m_str = NULL;
 139         return p;
 140     }
 141
 142     void CopyFrom(const wxCharTypeBuffer& src)
 143     {
 144         m_owned = src.m_owned;
 145         m_str = src.DoRelease();
 146     }
 147
 148 private:
 149     CharType *m_str;
 150     bool m_owned;
 151 };
 152
 153 class wxCharBuffer : public wxCharTypeBuffer<char>
 154 {
 155 public:
 156     typedef wxCharTypeBuffer<char> wxCharTypeBufferBase;
 157
 158     wxCharBuffer(const wxCharTypeBufferBase& buf)
 159         : wxCharTypeBufferBase(buf) {}
 160
 161     wxCharBuffer(const CharType *str = NULL) : wxCharTypeBufferBase(str) {}
 162     wxCharBuffer(size_t len) : wxCharTypeBufferBase(len) {}
 163
 164     wxCharBuffer(const wxCStrData& cstr);
 165 };
 166
 167 #if wxUSE_WCHAR_T
 168 class wxWCharBuffer : public wxCharTypeBuffer<wchar_t>
 169 {
 170 public:
 171     typedef wxCharTypeBuffer<wchar_t> wxCharTypeBufferBase;
 172
 173     wxWCharBuffer(const wxCharTypeBufferBase& buf)
 174         : wxCharTypeBufferBase(buf) {}
 175
 176     wxWCharBuffer(const CharType *str = NULL) : wxCharTypeBufferBase(str) {}
 177     wxWCharBuffer(size_t len) : wxCharTypeBufferBase(len) {}
 178
 179     wxWCharBuffer(const wxCStrData& cstr);
 180 };
 181 #endif // wxUSE_WCHAR_T
 182
 183 // wxCharTypeBuffer<T> implicitly convertible to T*
 184 template <typename T>
 185 class wxWritableCharTypeBuffer : public wxCharTypeBuffer<T>
 186 {
 187 public:
 188     typedef typename wxCharTypeBuffer<T>::CharType CharType;
 189
 190     wxWritableCharTypeBuffer(const wxCharTypeBuffer<T>& src)
 191         : wxCharTypeBuffer<T>(src) {}
 192     // FIXME-UTF8: this won't be needed after converting mb_str()/wc_str() to
 193     //             always return a buffer
 194     wxWritableCharTypeBuffer(const CharType *str = NULL)
 195         : wxCharTypeBuffer<T>(str) {}
 196
 197     operator CharType*() { return this->data(); }
 198 };
 199
 200 typedef wxWritableCharTypeBuffer<char> wxWritableCharBuffer;
 201 typedef wxWritableCharTypeBuffer<wchar_t> wxWritableWCharBuffer;
 202
 203
 204 #if wxUSE_UNICODE
 205     #define wxWxCharBuffer wxWCharBuffer
 206
 207     #define wxMB2WXbuf wxWCharBuffer
 208     #define wxWX2MBbuf wxCharBuffer
 209     #if wxUSE_UNICODE_WCHAR
 210         #define wxWC2WXbuf wxChar*
 211         #define wxWX2WCbuf wxChar*
 212     #elif wxUSE_UNICODE_UTF8
 213         #define wxWC2WXbuf wxWCharBuffer
 214         #define wxWX2WCbuf wxWCharBuffer
 215     #endif
 216 #else // ANSI
 217     #define wxWxCharBuffer wxCharBuffer
 218
 219     #define wxMB2WXbuf wxChar*
 220     #define wxWX2MBbuf wxChar*
 221     #define wxWC2WXbuf wxCharBuffer
 222     #define wxWX2WCbuf wxWCharBuffer
 223 #endif // Unicode/ANSI
 224
 225 // ----------------------------------------------------------------------------
 226 // A class for holding growable data buffers (not necessarily strings)
 227 // ----------------------------------------------------------------------------
 228
 229 // This class manages the actual data buffer pointer and is ref-counted.
 230 class wxMemoryBufferData
 231 {
 232 public:
 233     // the initial size and also the size added by ResizeIfNeeded()
 234     enum { DefBufSize = 1024 };
 235
 236     friend class wxMemoryBuffer;
 237
 238     // everyting is private as it can only be used by wxMemoryBuffer
 239 private:
 240     wxMemoryBufferData(size_t size = wxMemoryBufferData::DefBufSize)
 241         : m_data(size ? malloc(size) : NULL), m_size(size), m_len(0), m_ref(0)
 242     {
 243     }
 244     ~wxMemoryBufferData() { free(m_data); }
 245
 246
 247     void ResizeIfNeeded(size_t newSize)
 248     {
 249         if (newSize > m_size)
 250         {
 251             void *dataOld = m_data;
 252             m_data = realloc(m_data, newSize + wxMemoryBufferData::DefBufSize);
 253             if ( !m_data )
 254             {
 255                 free(dataOld);
 256             }
 257
 258             m_size = newSize + wxMemoryBufferData::DefBufSize;
 259         }
 260     }
 261
 262     void IncRef() { m_ref += 1; }
 263     void DecRef()
 264     {
 265         m_ref -= 1;
 266         if (m_ref == 0)  // are there no more references?
 267             delete this;
 268     }
 269
 270
 271     // the buffer containing the data
 272     void  *m_data;
 273
 274     // the size of the buffer
 275     size_t m_size;
 276
 277     // the amount of data currently in the buffer
 278     size_t m_len;
 279
 280     // the reference count
 281     size_t m_ref;
 282
 283     DECLARE_NO_COPY_CLASS(wxMemoryBufferData)
 284 };
 285
 286
 287 class wxMemoryBuffer
 288 {
 289 public:
 290     // ctor and dtor
 291     wxMemoryBuffer(size_t size = wxMemoryBufferData::DefBufSize)
 292     {
 293         m_bufdata = new wxMemoryBufferData(size);
 294         m_bufdata->IncRef();
 295     }
 296
 297     ~wxMemoryBuffer() { m_bufdata->DecRef(); }
 298
 299
 300     // copy and assignment
 301     wxMemoryBuffer(const wxMemoryBuffer& src)
 302         : m_bufdata(src.m_bufdata)
 303     {
 304         m_bufdata->IncRef();
 305     }
 306
 307     wxMemoryBuffer& operator=(const wxMemoryBuffer& src)
 308     {
 309         m_bufdata->DecRef();
 310         m_bufdata = src.m_bufdata;
 311         m_bufdata->IncRef();
 312         return *this;
 313     }
 314
 315
 316     // Accessors
 317     void  *GetData() const    { return m_bufdata->m_data; }
 318     size_t GetBufSize() const { return m_bufdata->m_size; }
 319     size_t GetDataLen() const { return m_bufdata->m_len; }
 320
 321     void   SetBufSize(size_t size) { m_bufdata->ResizeIfNeeded(size); }
 322     void   SetDataLen(size_t len)
 323     {
 324         wxASSERT(len <= m_bufdata->m_size);
 325         m_bufdata->m_len = len;
 326     }
 327
 328     // Ensure the buffer is big enough and return a pointer to it
 329     void *GetWriteBuf(size_t sizeNeeded)
 330     {
 331         m_bufdata->ResizeIfNeeded(sizeNeeded);
 332         return m_bufdata->m_data;
 333     }
 334
 335     // Update the length after the write
 336     void  UngetWriteBuf(size_t sizeUsed) { SetDataLen(sizeUsed); }
 337
 338     // Like the above, but appends to the buffer
 339     void *GetAppendBuf(size_t sizeNeeded)
 340     {
 341         m_bufdata->ResizeIfNeeded(m_bufdata->m_len + sizeNeeded);
 342         return (char*)m_bufdata->m_data + m_bufdata->m_len;
 343     }
 344
 345     // Update the length after the append
 346     void  UngetAppendBuf(size_t sizeUsed)
 347     {
 348         SetDataLen(m_bufdata->m_len + sizeUsed);
 349     }
 350
 351     // Other ways to append to the buffer
 352     void  AppendByte(char data)
 353     {
 354         wxCHECK_RET( m_bufdata->m_data, _T("invalid wxMemoryBuffer") );
 355
 356         m_bufdata->ResizeIfNeeded(m_bufdata->m_len + 1);
 357         *(((char*)m_bufdata->m_data) + m_bufdata->m_len) = data;
 358         m_bufdata->m_len += 1;
 359     }
 360
 361     void  AppendData(const void *data, size_t len)
 362     {
 363         memcpy(GetAppendBuf(len), data, len);
 364         UngetAppendBuf(len);
 365     }
 366
 367     operator const char *() const { return (const char*)GetData(); }
 368
 369 private:
 370     wxMemoryBufferData*  m_bufdata;
 371 };
 372
 373 // ----------------------------------------------------------------------------
 374 // template class for any kind of data
 375 // ----------------------------------------------------------------------------
 376
 377 // TODO
 378
 379 #endif // _WX_BUFFER_H