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 #ifndef __WXPALMOS5__
  19 #include <stdlib.h>             // malloc() and free()
  20 #endif // ! __WXPALMOS5__
  21
  22 class WXDLLIMPEXP_FWD_BASE wxCStrData;
  23
  24 // ----------------------------------------------------------------------------
  25 // Special classes for (wide) character strings: they use malloc/free instead
  26 // of new/delete
  27 // ----------------------------------------------------------------------------
  28
  29 // helpers used by wxCharTypeBuffer
  30 namespace wxPrivate
  31 {
  32
  33 struct UntypedBufferData
  34 {
  35     enum Kind
  36     {
  37         Owned,
  38         NonOwned
  39     };
  40
  41     UntypedBufferData(void *str, Kind kind = Owned)
  42         : m_str(str), m_ref(1), m_owned(kind == Owned) {}
  43
  44     ~UntypedBufferData()
  45     {
  46         if ( m_owned )
  47             free(m_str);
  48     }
  49
  50     void *m_str;
  51
  52     // "short" to have sizeof(Data)=8 on 32bit archs
  53     unsigned short m_ref;
  54
  55     bool m_owned;
  56 };
  57
  58 // this has to be defined inside the DLL (and not e.g. as a static variable
  59 // inside an inline function) as otherwise MSVC gives link errors when the
  60 // functions are effectively inlined (i.e. in non-debug build)
  61 //
  62 // NB: this is defined in string.cpp and not the (non-existent) buffer.cpp
  63 extern WXDLLIMPEXP_DATA_BASE(UntypedBufferData * const) untypedNullDataPtr;
  64
  65 } // namespace wxPrivate
  66
  67 template <typename T>
  68 class wxCharTypeBuffer
  69 {
  70 public:
  71     typedef T CharType;
  72
  73     wxCharTypeBuffer(const CharType *str = NULL)
  74     {
  75         if ( str )
  76             m_data = new Data(wxStrdup(str));
  77         else
  78             m_data = GetNullData();
  79     }
  80
  81     wxCharTypeBuffer(size_t len)
  82     {
  83         m_data = new Data((CharType *)malloc((len + 1)*sizeof(CharType)));
  84         m_data->Get()[len] = (CharType)0;
  85     }
  86
  87     static const wxCharTypeBuffer CreateNonOwned(const CharType *str)
  88     {
  89         wxCharTypeBuffer buf;
  90         if ( str )
  91             buf.m_data = new Data(const_cast<CharType*>(str), Data::NonOwned);
  92         return buf;
  93     }
  94
  95     ~wxCharTypeBuffer()
  96     {
  97         DecRef();
  98     }
  99
 100     // NB: this method is only const for backward compatibility. It used to
 101     //     be needed for auto_ptr-like semantics of the copy ctor, but now
 102     //     that ref-counting is used, it's not really needed.
 103     CharType *release() const
 104     {
 105         if ( m_data == GetNullData() )
 106             return NULL;
 107
 108         wxASSERT_MSG( m_data->m_owned, _T("can't release non-owned buffer") );
 109         wxASSERT_MSG( m_data->m_ref == 1, _T("can't release shared buffer") );
 110
 111         CharType * const p = m_data->Get();
 112
 113         wxCharTypeBuffer *self = const_cast<wxCharTypeBuffer*>(this);
 114         self->m_data->Set(NULL);
 115         self->DecRef();
 116
 117         return p;
 118     }
 119
 120     void reset()
 121     {
 122         DecRef();
 123     }
 124
 125     wxCharTypeBuffer(const wxCharTypeBuffer& src)
 126     {
 127         m_data = src.m_data;
 128         IncRef();
 129     }
 130
 131     wxCharTypeBuffer& operator=(const CharType *str)
 132     {
 133         DecRef();
 134
 135         if ( str )
 136             m_data = new Data(wxStrdup(str));
 137         return *this;
 138     }
 139
 140     wxCharTypeBuffer& operator=(const wxCharTypeBuffer& src)
 141     {
 142         if ( &src == this )
 143             return *this;
 144
 145         DecRef();
 146         m_data = src.m_data;
 147         IncRef();
 148
 149         return *this;
 150     }
 151
 152     bool extend(size_t len)
 153     {
 154         wxASSERT_MSG( m_data->m_owned, _T("cannot extend non-owned buffer") );
 155         wxASSERT_MSG( m_data->m_ref == 1, _T("can't extend shared buffer") );
 156
 157         CharType *str =
 158             (CharType *)realloc(data(), (len + 1) * sizeof(CharType));
 159         if ( !str )
 160             return false;
 161
 162         if ( m_data == GetNullData() )
 163         {
 164             m_data = new Data(str);
 165         }
 166         else
 167         {
 168             m_data->Set(str);
 169             m_data->m_owned = true;
 170         }
 171
 172         return true;
 173     }
 174
 175     CharType *data() { return m_data->Get(); }
 176     const CharType *data() const { return  m_data->Get(); }
 177     operator const CharType *() const { return data(); }
 178     CharType operator[](size_t n) const { return data()[n]; }
 179
 180 private:
 181     // reference-counted data
 182     struct Data : wxPrivate::UntypedBufferData
 183     {
 184         Data(CharType *str, Kind kind = Owned)
 185             : UntypedBufferData(str, kind)
 186         {
 187         }
 188
 189         CharType *Get() const { return static_cast<CharType *>(m_str); }
 190         void Set(CharType *str) { m_str = str; }
 191     };
 192
 193     // placeholder for NULL string, to simplify this code
 194     static Data *GetNullData()
 195     {
 196         return static_cast<Data *>(wxPrivate::untypedNullDataPtr);
 197     }
 198
 199     void IncRef()
 200     {
 201         if ( m_data == GetNullData() ) // exception, not ref-counted
 202             return;
 203         m_data->m_ref++;
 204     }
 205
 206     void DecRef()
 207     {
 208         if ( m_data == GetNullData() ) // exception, not ref-counted
 209             return;
 210         if ( --m_data->m_ref == 0 )
 211             delete m_data;
 212         m_data = GetNullData();
 213     }
 214
 215 private:
 216     Data *m_data;
 217 };
 218
 219 WXDLLIMPEXP_TEMPLATE_INSTANCE_BASE( wxCharTypeBuffer<char> )
 220
 221 class wxCharBuffer : public wxCharTypeBuffer<char>
 222 {
 223 public:
 224     typedef wxCharTypeBuffer<char> wxCharTypeBufferBase;
 225
 226     wxCharBuffer(const wxCharTypeBufferBase& buf)
 227         : wxCharTypeBufferBase(buf) {}
 228
 229     wxCharBuffer(const CharType *str = NULL) : wxCharTypeBufferBase(str) {}
 230     wxCharBuffer(size_t len) : wxCharTypeBufferBase(len) {}
 231
 232     wxCharBuffer(const wxCStrData& cstr);
 233 };
 234
 235 #if wxUSE_WCHAR_T
 236 WXDLLIMPEXP_TEMPLATE_INSTANCE_BASE( wxCharTypeBuffer<wchar_t> )
 237
 238 class wxWCharBuffer : public wxCharTypeBuffer<wchar_t>
 239 {
 240 public:
 241     typedef wxCharTypeBuffer<wchar_t> wxCharTypeBufferBase;
 242
 243     wxWCharBuffer(const wxCharTypeBufferBase& buf)
 244         : wxCharTypeBufferBase(buf) {}
 245
 246     wxWCharBuffer(const CharType *str = NULL) : wxCharTypeBufferBase(str) {}
 247     wxWCharBuffer(size_t len) : wxCharTypeBufferBase(len) {}
 248
 249     wxWCharBuffer(const wxCStrData& cstr);
 250 };
 251 #endif // wxUSE_WCHAR_T
 252
 253 // wxCharTypeBuffer<T> implicitly convertible to T*
 254 template <typename T>
 255 class wxWritableCharTypeBuffer : public wxCharTypeBuffer<T>
 256 {
 257 public:
 258     typedef typename wxCharTypeBuffer<T>::CharType CharType;
 259
 260     wxWritableCharTypeBuffer(const wxCharTypeBuffer<T>& src)
 261         : wxCharTypeBuffer<T>(src) {}
 262     // FIXME-UTF8: this won't be needed after converting mb_str()/wc_str() to
 263     //             always return a buffer
 264     wxWritableCharTypeBuffer(const CharType *str = NULL)
 265         : wxCharTypeBuffer<T>(str) {}
 266
 267     operator CharType*() { return this->data(); }
 268 };
 269
 270 typedef wxWritableCharTypeBuffer<char> wxWritableCharBuffer;
 271 typedef wxWritableCharTypeBuffer<wchar_t> wxWritableWCharBuffer;
 272
 273
 274 #if wxUSE_UNICODE
 275     #define wxWxCharBuffer wxWCharBuffer
 276
 277     #define wxMB2WXbuf wxWCharBuffer
 278     #define wxWX2MBbuf wxCharBuffer
 279     #if wxUSE_UNICODE_WCHAR
 280         #define wxWC2WXbuf wxChar*
 281         #define wxWX2WCbuf wxChar*
 282     #elif wxUSE_UNICODE_UTF8
 283         #define wxWC2WXbuf wxWCharBuffer
 284         #define wxWX2WCbuf wxWCharBuffer
 285     #endif
 286 #else // ANSI
 287     #define wxWxCharBuffer wxCharBuffer
 288
 289     #define wxMB2WXbuf wxChar*
 290     #define wxWX2MBbuf wxChar*
 291     #define wxWC2WXbuf wxCharBuffer
 292     #define wxWX2WCbuf wxWCharBuffer
 293 #endif // Unicode/ANSI
 294
 295 // type of the value returned by wxString::utf8_str()
 296 #if wxUSE_UNICODE_UTF8
 297     #define wxUTF8Buf char *
 298 #else
 299     #define wxUTF8Buf wxCharBuffer
 300 #endif
 301
 302 // ----------------------------------------------------------------------------
 303 // A class for holding growable data buffers (not necessarily strings)
 304 // ----------------------------------------------------------------------------
 305
 306 // This class manages the actual data buffer pointer and is ref-counted.
 307 class wxMemoryBufferData
 308 {
 309 public:
 310     // the initial size and also the size added by ResizeIfNeeded()
 311     enum { DefBufSize = 1024 };
 312
 313     friend class wxMemoryBuffer;
 314
 315     // everyting is private as it can only be used by wxMemoryBuffer
 316 private:
 317     wxMemoryBufferData(size_t size = wxMemoryBufferData::DefBufSize)
 318         : m_data(size ? malloc(size) : NULL), m_size(size), m_len(0), m_ref(0)
 319     {
 320     }
 321     ~wxMemoryBufferData() { free(m_data); }
 322
 323
 324     void ResizeIfNeeded(size_t newSize)
 325     {
 326         if (newSize > m_size)
 327         {
 328             void *dataOld = m_data;
 329             m_data = realloc(m_data, newSize + wxMemoryBufferData::DefBufSize);
 330             if ( !m_data )
 331             {
 332                 free(dataOld);
 333             }
 334
 335             m_size = newSize + wxMemoryBufferData::DefBufSize;
 336         }
 337     }
 338
 339     void IncRef() { m_ref += 1; }
 340     void DecRef()
 341     {
 342         m_ref -= 1;
 343         if (m_ref == 0)  // are there no more references?
 344             delete this;
 345     }
 346
 347
 348     // the buffer containing the data
 349     void  *m_data;
 350
 351     // the size of the buffer
 352     size_t m_size;
 353
 354     // the amount of data currently in the buffer
 355     size_t m_len;
 356
 357     // the reference count
 358     size_t m_ref;
 359
 360     DECLARE_NO_COPY_CLASS(wxMemoryBufferData)
 361 };
 362
 363
 364 class wxMemoryBuffer
 365 {
 366 public:
 367     // ctor and dtor
 368     wxMemoryBuffer(size_t size = wxMemoryBufferData::DefBufSize)
 369     {
 370         m_bufdata = new wxMemoryBufferData(size);
 371         m_bufdata->IncRef();
 372     }
 373
 374     ~wxMemoryBuffer() { m_bufdata->DecRef(); }
 375
 376
 377     // copy and assignment
 378     wxMemoryBuffer(const wxMemoryBuffer& src)
 379         : m_bufdata(src.m_bufdata)
 380     {
 381         m_bufdata->IncRef();
 382     }
 383
 384     wxMemoryBuffer& operator=(const wxMemoryBuffer& src)
 385     {
 386         if (&src != this)
 387         {
 388             m_bufdata->DecRef();
 389             m_bufdata = src.m_bufdata;
 390             m_bufdata->IncRef();
 391         }
 392         return *this;
 393     }
 394
 395
 396     // Accessors
 397     void  *GetData() const    { return m_bufdata->m_data; }
 398     size_t GetBufSize() const { return m_bufdata->m_size; }
 399     size_t GetDataLen() const { return m_bufdata->m_len; }
 400
 401     void   SetBufSize(size_t size) { m_bufdata->ResizeIfNeeded(size); }
 402     void   SetDataLen(size_t len)
 403     {
 404         wxASSERT(len <= m_bufdata->m_size);
 405         m_bufdata->m_len = len;
 406     }
 407
 408     // Ensure the buffer is big enough and return a pointer to it
 409     void *GetWriteBuf(size_t sizeNeeded)
 410     {
 411         m_bufdata->ResizeIfNeeded(sizeNeeded);
 412         return m_bufdata->m_data;
 413     }
 414
 415     // Update the length after the write
 416     void  UngetWriteBuf(size_t sizeUsed) { SetDataLen(sizeUsed); }
 417
 418     // Like the above, but appends to the buffer
 419     void *GetAppendBuf(size_t sizeNeeded)
 420     {
 421         m_bufdata->ResizeIfNeeded(m_bufdata->m_len + sizeNeeded);
 422         return (char*)m_bufdata->m_data + m_bufdata->m_len;
 423     }
 424
 425     // Update the length after the append
 426     void  UngetAppendBuf(size_t sizeUsed)
 427     {
 428         SetDataLen(m_bufdata->m_len + sizeUsed);
 429     }
 430
 431     // Other ways to append to the buffer
 432     void  AppendByte(char data)
 433     {
 434         wxCHECK_RET( m_bufdata->m_data, _T("invalid wxMemoryBuffer") );
 435
 436         m_bufdata->ResizeIfNeeded(m_bufdata->m_len + 1);
 437         *(((char*)m_bufdata->m_data) + m_bufdata->m_len) = data;
 438         m_bufdata->m_len += 1;
 439     }
 440
 441     void  AppendData(const void *data, size_t len)
 442     {
 443         memcpy(GetAppendBuf(len), data, len);
 444         UngetAppendBuf(len);
 445     }
 446
 447     operator const char *() const { return (const char*)GetData(); }
 448
 449 private:
 450     wxMemoryBufferData*  m_bufdata;
 451 };
 452
 453 // ----------------------------------------------------------------------------
 454 // template class for any kind of data
 455 // ----------------------------------------------------------------------------
 456
 457 // TODO
 458
 459 #endif // _WX_BUFFER_H