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 // helpers used by wxCharTypeBuffer
  28 namespace wxPrivate
  29 {
  30
  31 struct UntypedBufferData
  32 {
  33     enum Kind
  34     {
  35         Owned,
  36         NonOwned
  37     };
  38
  39     UntypedBufferData(void *str, size_t len, Kind kind = Owned)
  40         : m_str(str), m_length(len), m_ref(1), m_owned(kind == Owned) {}
  41
  42     ~UntypedBufferData()
  43     {
  44         if ( m_owned )
  45             free(m_str);
  46     }
  47
  48     void *m_str;
  49     size_t m_length;
  50
  51     // "short" to have sizeof(Data)=12 on 32bit archs
  52     unsigned short m_ref;
  53
  54     bool m_owned;
  55 };
  56
  57 // NB: this is defined in string.cpp and not the (non-existent) buffer.cpp
  58 WXDLLIMPEXP_BASE UntypedBufferData * GetUntypedNullData();
  59
  60 } // namespace wxPrivate
  61
  62
  63 // Reference-counted character buffer for storing string data. The buffer
  64 // is only valid for as long as the "parent" object that provided the data
  65 // is valid; see wxCharTypeBuffer<T> for persistent variant.
  66 template <typename T>
  67 class wxScopedCharTypeBuffer
  68 {
  69 public:
  70     typedef T CharType;
  71
  72     wxScopedCharTypeBuffer()
  73     {
  74         m_data = GetNullData();
  75     }
  76
  77     // Creates "non-owned" buffer, i.e. 'str' is not owned by the buffer
  78     // and doesn't get freed by dtor. Used e.g. to point to wxString's internal
  79     // storage.
  80     static
  81     const wxScopedCharTypeBuffer CreateNonOwned(const CharType *str,
  82                                                 size_t len = wxNO_LEN)
  83     {
  84         if ( len == wxNO_LEN )
  85             len = wxStrlen(str);
  86
  87         wxScopedCharTypeBuffer buf;
  88         if ( str )
  89             buf.m_data = new Data(const_cast<CharType*>(str), len, Data::NonOwned);
  90         return buf;
  91     }
  92
  93     // Creates "owned" buffer, i.e. takes over ownership of 'str' and frees it
  94     // in dtor (if ref.count reaches 0).
  95     static
  96     const wxScopedCharTypeBuffer CreateOwned(CharType *str,
  97                                              size_t len = wxNO_LEN )
  98     {
  99         if ( len == wxNO_LEN )
 100             len = wxStrlen(str);
 101
 102         wxScopedCharTypeBuffer buf;
 103         if ( str )
 104             buf.m_data = new Data(str, len);
 105         return buf;
 106     }
 107
 108     wxScopedCharTypeBuffer(const wxScopedCharTypeBuffer& src)
 109     {
 110         m_data = src.m_data;
 111         IncRef();
 112     }
 113
 114     wxScopedCharTypeBuffer& operator=(const wxScopedCharTypeBuffer& src)
 115     {
 116         if ( &src == this )
 117             return *this;
 118
 119         DecRef();
 120         m_data = src.m_data;
 121         IncRef();
 122
 123         return *this;
 124     }
 125
 126     ~wxScopedCharTypeBuffer()
 127     {
 128         DecRef();
 129     }
 130
 131     // NB: this method is only const for backward compatibility. It used to
 132     //     be needed for auto_ptr-like semantics of the copy ctor, but now
 133     //     that ref-counting is used, it's not really needed.
 134     CharType *release() const
 135     {
 136         if ( m_data == GetNullData() )
 137             return NULL;
 138
 139         wxASSERT_MSG( m_data->m_owned, wxT("can't release non-owned buffer") );
 140         wxASSERT_MSG( m_data->m_ref == 1, wxT("can't release shared buffer") );
 141
 142         CharType * const p = m_data->Get();
 143
 144         wxScopedCharTypeBuffer *self = const_cast<wxScopedCharTypeBuffer*>(this);
 145         self->m_data->Set(NULL, 0);
 146         self->DecRef();
 147
 148         return p;
 149     }
 150
 151     void reset()
 152     {
 153         DecRef();
 154     }
 155
 156     CharType *data() { return m_data->Get(); }
 157     const CharType *data() const { return  m_data->Get(); }
 158     operator const CharType *() const { return data(); }
 159     CharType operator[](size_t n) const { return data()[n]; }
 160
 161     size_t length() const { return m_data->m_length; }
 162
 163 protected:
 164     // reference-counted data
 165     struct Data : public wxPrivate::UntypedBufferData
 166     {
 167         Data(CharType *str, size_t len, Kind kind = Owned)
 168             : wxPrivate::UntypedBufferData(str, len, kind)
 169         {
 170         }
 171
 172         CharType *Get() const { return static_cast<CharType *>(m_str); }
 173         void Set(CharType *str, size_t len)
 174         {
 175             m_str = str;
 176             m_length = len;
 177         }
 178     };
 179
 180     // placeholder for NULL string, to simplify this code
 181     static Data *GetNullData()
 182     {
 183         return static_cast<Data *>(wxPrivate::GetUntypedNullData());
 184     }
 185
 186     void IncRef()
 187     {
 188         if ( m_data == GetNullData() ) // exception, not ref-counted
 189             return;
 190         m_data->m_ref++;
 191     }
 192
 193     void DecRef()
 194     {
 195         if ( m_data == GetNullData() ) // exception, not ref-counted
 196             return;
 197         if ( --m_data->m_ref == 0 )
 198             delete m_data;
 199         m_data = GetNullData();
 200     }
 201
 202     // sets this object to a be copy of 'other'; if 'src' is non-owned,
 203     // a deep copy is made and 'this' will contain new instance of the data
 204     void MakeOwnedCopyOf(const wxScopedCharTypeBuffer& src)
 205     {
 206         this->DecRef();
 207
 208         if ( src.m_data == this->GetNullData() )
 209         {
 210             this->m_data = this->GetNullData();
 211         }
 212         else if ( src.m_data->m_owned )
 213         {
 214             this->m_data = src.m_data;
 215             this->IncRef();
 216         }
 217         else
 218         {
 219             // if the scoped buffer had non-owned data, we have to make
 220             // a copy here, because src.m_data->m_str is valid only for as long
 221             // as 'src' exists
 222             this->m_data = new Data
 223                                (
 224                                    StrCopy(src.data(), src.length()),
 225                                    src.length()
 226                                );
 227         }
 228     }
 229
 230     static CharType *StrCopy(const CharType *src, size_t len)
 231     {
 232         CharType *dst = (CharType*)malloc(sizeof(CharType) * (len + 1));
 233         memcpy(dst, src, sizeof(CharType) * (len + 1));
 234         return dst;
 235     }
 236
 237 protected:
 238     Data *m_data;
 239 };
 240
 241 typedef wxScopedCharTypeBuffer<char> wxScopedCharBuffer;
 242 typedef wxScopedCharTypeBuffer<wchar_t> wxScopedWCharBuffer;
 243
 244
 245 // this buffer class always stores data in "owned" (persistent) manner
 246 template <typename T>
 247 class wxCharTypeBuffer : public wxScopedCharTypeBuffer<T>
 248 {
 249 protected:
 250     typedef typename wxScopedCharTypeBuffer<T>::Data Data;
 251
 252 public:
 253     typedef T CharType;
 254
 255     wxCharTypeBuffer(const CharType *str = NULL, size_t len = wxNO_LEN)
 256     {
 257         if ( str )
 258         {
 259             if ( len == wxNO_LEN )
 260                 len = wxStrlen(str);
 261             this->m_data = new Data(this->StrCopy(str, len), len);
 262         }
 263         else
 264         {
 265             this->m_data = this->GetNullData();
 266         }
 267     }
 268
 269     wxCharTypeBuffer(size_t len)
 270     {
 271         this->m_data =
 272             new Data((CharType *)malloc((len + 1)*sizeof(CharType)), len);
 273         this->m_data->Get()[len] = (CharType)0;
 274     }
 275
 276     wxCharTypeBuffer(const wxCharTypeBuffer& src)
 277         : wxScopedCharTypeBuffer<T>(src) {}
 278
 279     wxCharTypeBuffer& operator=(const CharType *str)
 280     {
 281         this->DecRef();
 282
 283         if ( str )
 284             this->m_data = new Data(wxStrdup(str), wxStrlen(str));
 285         return *this;
 286     }
 287
 288     wxCharTypeBuffer& operator=(const wxCharTypeBuffer& src)
 289     {
 290         wxScopedCharTypeBuffer<T>::operator=(src);
 291         return *this;
 292     }
 293
 294     wxCharTypeBuffer(const wxScopedCharTypeBuffer<T>& src)
 295     {
 296         this->MakeOwnedCopyOf(src);
 297     }
 298
 299     wxCharTypeBuffer& operator=(const wxScopedCharTypeBuffer<T>& src)
 300     {
 301         MakeOwnedCopyOf(src);
 302         return *this;
 303     }
 304
 305     bool extend(size_t len)
 306     {
 307         wxASSERT_MSG( this->m_data->m_owned, "cannot extend non-owned buffer" );
 308         wxASSERT_MSG( this->m_data->m_ref == 1, "can't extend shared buffer" );
 309
 310         CharType *str =
 311             (CharType *)realloc(this->data(), (len + 1) * sizeof(CharType));
 312         if ( !str )
 313             return false;
 314
 315         // For consistency with the ctor taking just the length, NUL-terminate
 316         // the buffer.
 317         str[len] = (CharType)0;
 318
 319         if ( this->m_data == this->GetNullData() )
 320         {
 321             this->m_data = new Data(str, len);
 322         }
 323         else
 324         {
 325             this->m_data->Set(str, len);
 326             this->m_data->m_owned = true;
 327         }
 328
 329         return true;
 330     }
 331
 332     void shrink(size_t len)
 333     {
 334         wxASSERT_MSG( this->m_data->m_owned, "cannot shrink non-owned buffer" );
 335         wxASSERT_MSG( this->m_data->m_ref == 1, "can't shrink shared buffer" );
 336
 337         wxASSERT( len <= this->length() );
 338
 339         this->m_data->m_length = len;
 340         this->data()[len] = 0;
 341     }
 342 };
 343
 344 WXDLLIMPEXP_TEMPLATE_INSTANCE_BASE( wxScopedCharTypeBuffer<char> )
 345 WXDLLIMPEXP_TEMPLATE_INSTANCE_BASE( wxCharTypeBuffer<char> )
 346
 347 class wxCharBuffer : public wxCharTypeBuffer<char>
 348 {
 349 public:
 350     typedef wxCharTypeBuffer<char> wxCharTypeBufferBase;
 351     typedef wxScopedCharTypeBuffer<char> wxScopedCharTypeBufferBase;
 352
 353     wxCharBuffer(const wxCharTypeBufferBase& buf)
 354         : wxCharTypeBufferBase(buf) {}
 355     wxCharBuffer(const wxScopedCharTypeBufferBase& buf)
 356         : wxCharTypeBufferBase(buf) {}
 357
 358     wxCharBuffer(const CharType *str = NULL) : wxCharTypeBufferBase(str) {}
 359     wxCharBuffer(size_t len) : wxCharTypeBufferBase(len) {}
 360
 361     wxCharBuffer(const wxCStrData& cstr);
 362 };
 363
 364 WXDLLIMPEXP_TEMPLATE_INSTANCE_BASE( wxScopedCharTypeBuffer<wchar_t> )
 365 WXDLLIMPEXP_TEMPLATE_INSTANCE_BASE( wxCharTypeBuffer<wchar_t> )
 366
 367 class wxWCharBuffer : public wxCharTypeBuffer<wchar_t>
 368 {
 369 public:
 370     typedef wxCharTypeBuffer<wchar_t> wxCharTypeBufferBase;
 371     typedef wxScopedCharTypeBuffer<wchar_t> wxScopedCharTypeBufferBase;
 372
 373     wxWCharBuffer(const wxCharTypeBufferBase& buf)
 374         : wxCharTypeBufferBase(buf) {}
 375     wxWCharBuffer(const wxScopedCharTypeBufferBase& buf)
 376         : wxCharTypeBufferBase(buf) {}
 377
 378     wxWCharBuffer(const CharType *str = NULL) : wxCharTypeBufferBase(str) {}
 379     wxWCharBuffer(size_t len) : wxCharTypeBufferBase(len) {}
 380
 381     wxWCharBuffer(const wxCStrData& cstr);
 382 };
 383
 384 // wxCharTypeBuffer<T> implicitly convertible to T*
 385 template <typename T>
 386 class wxWritableCharTypeBuffer : public wxCharTypeBuffer<T>
 387 {
 388 public:
 389     typedef typename wxScopedCharTypeBuffer<T>::CharType CharType;
 390
 391     wxWritableCharTypeBuffer(const wxScopedCharTypeBuffer<T>& src)
 392         : wxCharTypeBuffer<T>(src) {}
 393     // FIXME-UTF8: this won't be needed after converting mb_str()/wc_str() to
 394     //             always return a buffer
 395     //             + we should derive this class from wxScopedCharTypeBuffer
 396     //               then
 397     wxWritableCharTypeBuffer(const CharType *str = NULL)
 398         : wxCharTypeBuffer<T>(str) {}
 399
 400     operator CharType*() { return this->data(); }
 401 };
 402
 403 typedef wxWritableCharTypeBuffer<char> wxWritableCharBuffer;
 404 typedef wxWritableCharTypeBuffer<wchar_t> wxWritableWCharBuffer;
 405
 406
 407 #if wxUSE_UNICODE
 408     #define wxWxCharBuffer wxWCharBuffer
 409
 410     #define wxMB2WXbuf wxWCharBuffer
 411     #define wxWX2MBbuf wxCharBuffer
 412     #if wxUSE_UNICODE_WCHAR
 413         #define wxWC2WXbuf wxChar*
 414         #define wxWX2WCbuf wxChar*
 415     #elif wxUSE_UNICODE_UTF8
 416         #define wxWC2WXbuf wxWCharBuffer
 417         #define wxWX2WCbuf wxWCharBuffer
 418     #endif
 419 #else // ANSI
 420     #define wxWxCharBuffer wxCharBuffer
 421
 422     #define wxMB2WXbuf wxChar*
 423     #define wxWX2MBbuf wxChar*
 424     #define wxWC2WXbuf wxCharBuffer
 425     #define wxWX2WCbuf wxWCharBuffer
 426 #endif // Unicode/ANSI
 427
 428 // ----------------------------------------------------------------------------
 429 // A class for holding growable data buffers (not necessarily strings)
 430 // ----------------------------------------------------------------------------
 431
 432 // This class manages the actual data buffer pointer and is ref-counted.
 433 class wxMemoryBufferData
 434 {
 435 public:
 436     // the initial size and also the size added by ResizeIfNeeded()
 437     enum { DefBufSize = 1024 };
 438
 439     friend class wxMemoryBuffer;
 440
 441     // everyting is private as it can only be used by wxMemoryBuffer
 442 private:
 443     wxMemoryBufferData(size_t size = wxMemoryBufferData::DefBufSize)
 444         : m_data(size ? malloc(size) : NULL), m_size(size), m_len(0), m_ref(0)
 445     {
 446     }
 447     ~wxMemoryBufferData() { free(m_data); }
 448
 449
 450     void ResizeIfNeeded(size_t newSize)
 451     {
 452         if (newSize > m_size)
 453         {
 454             void *dataOld = m_data;
 455             m_data = realloc(m_data, newSize + wxMemoryBufferData::DefBufSize);
 456             if ( !m_data )
 457             {
 458                 free(dataOld);
 459             }
 460
 461             m_size = newSize + wxMemoryBufferData::DefBufSize;
 462         }
 463     }
 464
 465     void IncRef() { m_ref += 1; }
 466     void DecRef()
 467     {
 468         m_ref -= 1;
 469         if (m_ref == 0)  // are there no more references?
 470             delete this;
 471     }
 472
 473     void *release()
 474     {
 475         if ( m_data == NULL )
 476             return NULL;
 477
 478         wxASSERT_MSG( m_ref == 1, "can't release shared buffer" );
 479
 480         void *p = m_data;
 481         m_data = NULL;
 482         m_len =
 483         m_size = 0;
 484
 485         return p;
 486     }
 487
 488
 489     // the buffer containing the data
 490     void  *m_data;
 491
 492     // the size of the buffer
 493     size_t m_size;
 494
 495     // the amount of data currently in the buffer
 496     size_t m_len;
 497
 498     // the reference count
 499     size_t m_ref;
 500
 501     wxDECLARE_NO_COPY_CLASS(wxMemoryBufferData);
 502 };
 503
 504
 505 class wxMemoryBuffer
 506 {
 507 public:
 508     // ctor and dtor
 509     wxMemoryBuffer(size_t size = wxMemoryBufferData::DefBufSize)
 510     {
 511         m_bufdata = new wxMemoryBufferData(size);
 512         m_bufdata->IncRef();
 513     }
 514
 515     ~wxMemoryBuffer() { m_bufdata->DecRef(); }
 516
 517
 518     // copy and assignment
 519     wxMemoryBuffer(const wxMemoryBuffer& src)
 520         : m_bufdata(src.m_bufdata)
 521     {
 522         m_bufdata->IncRef();
 523     }
 524
 525     wxMemoryBuffer& operator=(const wxMemoryBuffer& src)
 526     {
 527         if (&src != this)
 528         {
 529             m_bufdata->DecRef();
 530             m_bufdata = src.m_bufdata;
 531             m_bufdata->IncRef();
 532         }
 533         return *this;
 534     }
 535
 536
 537     // Accessors
 538     void  *GetData() const    { return m_bufdata->m_data; }
 539     size_t GetBufSize() const { return m_bufdata->m_size; }
 540     size_t GetDataLen() const { return m_bufdata->m_len; }
 541
 542     bool IsEmpty() const { return GetDataLen() == 0; }
 543
 544     void   SetBufSize(size_t size) { m_bufdata->ResizeIfNeeded(size); }
 545     void   SetDataLen(size_t len)
 546     {
 547         wxASSERT(len <= m_bufdata->m_size);
 548         m_bufdata->m_len = len;
 549     }
 550
 551     void Clear() { SetDataLen(0); }
 552
 553     // Ensure the buffer is big enough and return a pointer to it
 554     void *GetWriteBuf(size_t sizeNeeded)
 555     {
 556         m_bufdata->ResizeIfNeeded(sizeNeeded);
 557         return m_bufdata->m_data;
 558     }
 559
 560     // Update the length after the write
 561     void  UngetWriteBuf(size_t sizeUsed) { SetDataLen(sizeUsed); }
 562
 563     // Like the above, but appends to the buffer
 564     void *GetAppendBuf(size_t sizeNeeded)
 565     {
 566         m_bufdata->ResizeIfNeeded(m_bufdata->m_len + sizeNeeded);
 567         return (char*)m_bufdata->m_data + m_bufdata->m_len;
 568     }
 569
 570     // Update the length after the append
 571     void  UngetAppendBuf(size_t sizeUsed)
 572     {
 573         SetDataLen(m_bufdata->m_len + sizeUsed);
 574     }
 575
 576     // Other ways to append to the buffer
 577     void  AppendByte(char data)
 578     {
 579         wxCHECK_RET( m_bufdata->m_data, wxT("invalid wxMemoryBuffer") );
 580
 581         m_bufdata->ResizeIfNeeded(m_bufdata->m_len + 1);
 582         *(((char*)m_bufdata->m_data) + m_bufdata->m_len) = data;
 583         m_bufdata->m_len += 1;
 584     }
 585
 586     void  AppendData(const void *data, size_t len)
 587     {
 588         memcpy(GetAppendBuf(len), data, len);
 589         UngetAppendBuf(len);
 590     }
 591
 592     operator const char *() const { return (const char*)GetData(); }
 593
 594     // gives up ownership of data, returns the pointer; after this call,
 595     // data isn't freed by the buffer and its content is resent to empty
 596     void *release()
 597     {
 598         return m_bufdata->release();
 599     }
 600
 601 private:
 602     wxMemoryBufferData*  m_bufdata;
 603 };
 604
 605 // ----------------------------------------------------------------------------
 606 // template class for any kind of data
 607 // ----------------------------------------------------------------------------
 608
 609 // TODO
 610
 611 #endif // _WX_BUFFER_H