more fixes to stream code: allow deriving from wxStreamBuffer and using custom

buffers with wxBufferedInput/OutputStream


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@8777 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/stream.h

@@ -66,17 +66,25 @@ public:
     virtual ~wxStreamBase();
 
     // error testing
-    wxStreamError LastError() const { return m_lasterror; }
     wxStreamError GetLastError() const { return m_lasterror; }
     bool IsOk() const { return LastError() == wxSTREAM_NOERROR; }
     bool operator!() const { return LastError() != wxSTREAM_NOERROR; }
 
-    virtual size_t GetSize() const { return ~((size_t)0); }
+    virtual size_t GetSize() const { return 0; }
+
+    // deprecated, for compatibility only
+    wxStreamError LastError() const { return m_lasterror; }
     size_t StreamSize() const { return GetSize(); }
 
 protected:
+    // VZ: these functions are really pure virtual and shouldn't be declared
+    //     in the base class because it creates ambiguties in stream classes
+    //     deriving from both wxInputStream and wxOutputStream
+#if 0
     virtual size_t OnSysRead(void *buffer, size_t bufsize);
     virtual size_t OnSysWrite(const void *buffer, size_t bufsize);
+#endif
+
     virtual off_t OnSysSeek(off_t seek, wxSeekMode mode);
     virtual off_t OnSysTell() const;
 
@@ -86,7 +94,7 @@ protected:
     wxStreamError m_lasterror;
 };
 
-class WXDLLEXPORT wxInputStream: public wxStreamBase
+class WXDLLEXPORT wxInputStream : /* virtual */ public wxStreamBase
 {
 public:
     wxInputStream();
@@ -120,6 +128,10 @@ public:
     wxInputStream& operator>>( __wxInputManip func) { return func(*this); }
 
 protected:
+    // to be implemented in the derived classes (it should have been pure
+    // virtual)
+    virtual size_t OnSysRead(void *buffer, size_t bufsize);
+
     // Ungetch managers
     char *m_wback;
     size_t m_wbacksize;
@@ -127,9 +139,11 @@ protected:
 
     char *AllocSpaceWBack(size_t needed_size);
     size_t GetWBack(void *buf, size_t bsize);
+
+    friend class wxStreamBuffer;
 };
 
-class WXDLLEXPORT wxOutputStream: public wxStreamBase
+class WXDLLEXPORT wxOutputStream : /* virtual */ public wxStreamBase
 {
 public:
     wxOutputStream();
@@ -151,6 +165,13 @@ public:
     wxOutputStream& operator<<(wxObject& obj);
 #endif
     wxOutputStream& operator<<( __wxOutputManip func) { return func(*this); }
+
+protected:
+    // to be implemented in the derived classes (it should have been pure
+    // virtual)
+    virtual size_t OnSysWrite(const void *buffer, size_t bufsize);
+
+    friend class wxStreamBuffer;
 };
 
 // ---------------------------------------------------------------------------
@@ -166,9 +187,9 @@ public:
     bool Ok() const { return TRUE; }
 
 protected:
-    size_t OnSysWrite(const void *buffer, size_t size);
+    virtual size_t OnSysWrite(const void *buffer, size_t size);
-    off_t OnSysSeek(off_t pos, wxSeekMode mode);
+    virtual off_t OnSysSeek(off_t pos, wxSeekMode mode);
-    off_t OnSysTell() const;
+    virtual off_t OnSysTell() const;
 
     size_t m_currentPos;
 };
@@ -182,12 +203,14 @@ class WXDLLEXPORT wxFilterInputStream: public wxInputStream
 public:
     wxFilterInputStream();
     wxFilterInputStream(wxInputStream& stream);
-    ~wxFilterInputStream();
+    virtual ~wxFilterInputStream();
 
     char Peek() { return m_parent_i_stream->Peek(); }
 
     size_t GetSize() const { return m_parent_i_stream->GetSize(); }
 
+    wxInputStream *GetFilterInputStream() const { return m_parent_i_stream; }
+
 protected:
     wxInputStream *m_parent_i_stream;
 };
@@ -197,16 +220,19 @@ class WXDLLEXPORT wxFilterOutputStream: public wxOutputStream
 public:
     wxFilterOutputStream();
     wxFilterOutputStream(wxOutputStream& stream);
-    ~wxFilterOutputStream();
+    virtual ~wxFilterOutputStream();
 
     size_t GetSize() const { return m_parent_o_stream->GetSize(); }
 
+    wxOutputStream *GetFilterOutputStream() const { return m_parent_o_stream; }
+
 protected:
     wxOutputStream *m_parent_o_stream;
 };
 
 // ---------------------------------------------------------------------------
-// Stream buffer
+// Stream buffer: this class can be derived from and passed to
+// wxBufferedStreams to implement custom buffering
 // ---------------------------------------------------------------------------
 
 class WXDLLEXPORT wxStreamBuffer
@@ -222,19 +248,19 @@ public:
     wxStreamBuffer(wxStreamBase& stream, BufMode mode);
     wxStreamBuffer(BufMode mode);
     wxStreamBuffer(const wxStreamBuffer& buf);
-    ~wxStreamBuffer();
+    virtual ~wxStreamBuffer();
 
     // Filtered IO
-    size_t Read(void *buffer, size_t size);
+    virtual size_t Read(void *buffer, size_t size);
     size_t Read(wxStreamBuffer *buf);
-    size_t Write(const void *buffer, size_t size);
+    virtual size_t Write(const void *buffer, size_t size);
     size_t Write(wxStreamBuffer *buf);
 
-    char Peek();
+    virtual char Peek();
-    char GetChar();
+    virtual char GetChar();
-    void PutChar(char c);
+    virtual void PutChar(char c);
-    off_t Tell() const;
+    virtual off_t Tell() const;
-    off_t Seek(off_t pos, wxSeekMode mode);
+    virtual off_t Seek(off_t pos, wxSeekMode mode);
 
     // Buffer control
     void ResetBuffer();
@@ -267,6 +293,10 @@ public:
     bool IsFixed() const { return m_fixed; }
     bool IsFlushable() const { return m_flushable; }
 
+    // only for input/output buffers respectively, returns NULL otherwise
+    wxInputStream *GetInputStream() const;
+    wxOutputStream *GetOutputStream() const;
+
     // deprecated, for compatibility only
     wxStreamBase *Stream() { return m_stream; }
 
@@ -316,8 +346,10 @@ protected:
 class WXDLLEXPORT wxBufferedInputStream : public wxFilterInputStream
 {
 public:
-    wxBufferedInputStream(wxInputStream& stream);
+    // if a non NULL buffer is given to the stream, it will be deleted by it
-    ~wxBufferedInputStream();
+    wxBufferedInputStream(wxInputStream& stream,
+                          wxStreamBuffer *buffer = NULL);
+    virtual ~wxBufferedInputStream();
 
     char Peek();
     wxInputStream& Read(void *buffer, size_t size);
@@ -326,12 +358,17 @@ public:
     off_t SeekI(off_t pos, wxSeekMode mode = wxFromStart);
     off_t TellI() const;
 
+    // the buffer given to the stream will be deleted by it
+    void SetInputStreamBuffer(wxStreamBuffer *buffer);
+    wxStreamBuffer *GetInputStreamBuffer() const { return m_i_streambuf; }
+
+    // deprecated, for compatibility only
     wxStreamBuffer *InputStreamBuffer() const { return m_i_streambuf; }
 
 protected:
-    size_t OnSysRead(void *buffer, size_t bufsize);
+    virtual size_t OnSysRead(void *buffer, size_t bufsize);
-    off_t OnSysSeek(off_t seek, wxSeekMode mode);
+    virtual off_t OnSysSeek(off_t seek, wxSeekMode mode);
-    off_t OnSysTell() const;
+    virtual off_t OnSysTell() const;
 
     wxStreamBuffer *m_i_streambuf;
 };
@@ -339,8 +376,10 @@ protected:
 class WXDLLEXPORT wxBufferedOutputStream : public wxFilterOutputStream
 {
 public:
-    wxBufferedOutputStream(wxOutputStream& stream);
+    // if a non NULL buffer is given to the stream, it will be deleted by it
-    ~wxBufferedOutputStream();
+    wxBufferedOutputStream(wxOutputStream& stream,
+                           wxStreamBuffer *buffer = NULL);
+    virtual ~wxBufferedOutputStream();
 
     wxOutputStream& Write(const void *buffer, size_t size);
 
@@ -352,18 +391,22 @@ public:
 
     size_t GetSize() const;
 
+    // the buffer given to the stream will be deleted by it
+    void SetOutputStreamBuffer(wxStreamBuffer *buffer);
+    wxStreamBuffer *GetOutputStreamBuffer() const { return m_o_streambuf; }
+
+    // deprecated, for compatibility only
     wxStreamBuffer *OutputStreamBuffer() const { return m_o_streambuf; }
 
 protected:
-    size_t OnSysWrite(const void *buffer, size_t bufsize);
+    virtual size_t OnSysWrite(const void *buffer, size_t bufsize);
-    off_t OnSysSeek(off_t seek, wxSeekMode mode);
+    virtual off_t OnSysSeek(off_t seek, wxSeekMode mode);
-    off_t OnSysTell() const;
+    virtual off_t OnSysTell() const;
 
     wxStreamBuffer *m_o_streambuf;
 };
 
-#endif
+#endif // wxUSE_STREAMS
-  // wxUSE_STREAMS
+
+#endif // _WX_WXSTREAM_H__
 
-#endif
-  // _WX_WXSTREAM_H__

src/common/stream.cpp

@@ -17,6 +17,7 @@
 // ----------------------------------------------------------------------------
 // headers
 // ----------------------------------------------------------------------------
+
 #ifdef __GNUG__
     #pragma implementation "stream.h"
 #endif
@@ -129,6 +130,16 @@ wxStreamBuffer::~wxStreamBuffer()
         delete m_stream;
 }
 
+wxInputStream *wxStreamBuffer::GetInputStream() const
+{
+    return m_mode == write ? NULL : (wxInputStream *)m_stream;
+}
+
+wxOutputStream *wxStreamBuffer::GetOutputStream() const
+{
+    return m_mode == read ? NULL : (wxOutputStream *)m_stream;
+}
+
 void wxStreamBuffer::SetBufferIO(void *buffer_start,
                                  void *buffer_end,
                                  bool takeOwnership)
@@ -185,9 +196,11 @@ void wxStreamBuffer::ResetBuffer()
 // fill the buffer with as much data as possible (only for read buffers)
 bool wxStreamBuffer::FillBuffer()
 {
-    wxCHECK_MSG( m_stream, FALSE, _T("should have a stream in wxStreamBuffer") );
+    wxInputStream *inStream = GetInputStream();
 
-    size_t count = m_stream->OnSysRead(m_buffer_start, m_buffer_size);
+    wxCHECK_MSG( inStream, FALSE, _T("should have a stream in wxStreamBuffer") );
+
+    size_t count = inStream->OnSysRead(m_buffer_start, m_buffer_size);
     if ( !count )
         return FALSE;
 
@@ -206,10 +219,12 @@ bool wxStreamBuffer::FlushBuffer()
     if ( m_buffer_pos == m_buffer_start )
         return FALSE;
 
-    wxCHECK_MSG( m_stream, FALSE, _T("should have a stream in wxStreamBuffer") );
+    wxOutputStream *outStream = GetOutputStream();
+
+    wxCHECK_MSG( outStream, FALSE, _T("should have a stream in wxStreamBuffer") );
 
     size_t current = m_buffer_pos - m_buffer_start;
-    size_t count = m_stream->OnSysWrite(m_buffer_start, current);
+    size_t count = outStream->OnSysWrite(m_buffer_start, current);
     if ( count != current )
         return FALSE;
 
@@ -281,12 +296,14 @@ void wxStreamBuffer::PutToBuffer(const void *buffer, size_t size)
 
 void wxStreamBuffer::PutChar(char c)
 {
-    wxCHECK_RET( m_stream, _T("should have a stream in wxStreamBuffer") );
+    wxOutputStream *outStream = GetOutputStream();
+
+    wxCHECK_RET( outStream, _T("should have a stream in wxStreamBuffer") );
 
     // if we don't have buffer at all, just forward this call to the stream,
     if ( !HasBuffer() )
     {
-        m_stream->OnSysWrite(&c, 1);
+        outStream->OnSysWrite(&c, 1);
     }
     else
     {
@@ -324,12 +341,14 @@ char wxStreamBuffer::Peek()
 
 char wxStreamBuffer::GetChar()
 {
-    wxCHECK_MSG( m_stream, 0, _T("should have a stream in wxStreamBuffer") );
+    wxInputStream *inStream = GetInputStream();
+
+    wxCHECK_MSG( inStream, 0, _T("should have a stream in wxStreamBuffer") );
 
     char c;
     if ( !HasBuffer() )
     {
-        m_stream->OnSysRead(&c, 1);
+        inStream->OnSysRead(&c, 1);
     }
     else
     {
@@ -350,16 +369,16 @@ char wxStreamBuffer::GetChar()
 
 size_t wxStreamBuffer::Read(void *buffer, size_t size)
 {
-    wxCHECK_MSG( m_stream, 0, _T("should have a stream in wxStreamBuffer") );
+    wxInputStream *inStream = GetInputStream();
 
-    wxCHECK_MSG( m_mode != write, 0, _T("can't read from this buffer") );
+    wxCHECK_MSG( inStream, 0, _T("should have a stream in wxStreamBuffer") );
 
     // lasterror is reset before all new IO calls
     m_stream->m_lasterror = wxStream_NOERROR;
 
     if ( !HasBuffer() )
     {
-        m_stream->m_lastcount = m_stream->OnSysRead(buffer, size);
+        m_stream->m_lastcount = inStream->OnSysRead(buffer, size);
     }
     else // we have a buffer, use it
     {
@@ -421,8 +440,9 @@ size_t wxStreamBuffer::Read(wxStreamBuffer *dbuf)
 
 size_t wxStreamBuffer::Write(const void *buffer, size_t size)
 {
-    wxCHECK_MSG( m_stream, 0, _T("should have a stream in wxStreamBuffer") );
+    wxOutputStream *outStream = GetOutputStream();
-    wxCHECK_MSG( m_mode != read, 0, _T("can't write to this buffer") );
+
+    wxCHECK_MSG( outStream, 0, _T("should have a stream in wxStreamBuffer") );
 
     // lasterror is reset before all new IO calls
     m_stream->m_lasterror = wxStream_NOERROR;
@@ -430,7 +450,7 @@ size_t wxStreamBuffer::Write(const void *buffer, size_t size)
     if ( !HasBuffer() && m_fixed )
     {
         // no buffer, just forward the call to the stream
-        m_stream->m_lastcount = m_stream->OnSysWrite(buffer, size);
+        m_stream->m_lastcount = outStream->OnSysWrite(buffer, size);
     }
     else // we [may] have a buffer, use it
     {
@@ -607,26 +627,6 @@ wxStreamBase::~wxStreamBase()
 {
 }
 
-size_t wxStreamBase::OnSysRead(void *WXUNUSED(buffer), size_t WXUNUSED(size))
-{
-    return 0;
-}
-
-size_t wxStreamBase::OnSysWrite(const void *WXUNUSED(buffer), size_t WXUNUSED(bufsize))
-{
-    return 0;
-}
-
-off_t wxStreamBase::OnSysSeek(off_t WXUNUSED(seek), wxSeekMode WXUNUSED(mode))
-{
-    return wxInvalidOffset;
-}
-
-off_t wxStreamBase::OnSysTell() const
-{
-    return wxInvalidOffset;
-}
-
 // ----------------------------------------------------------------------------
 // wxInputStream
 // ----------------------------------------------------------------------------
@@ -643,6 +643,12 @@ wxInputStream::~wxInputStream()
     free(m_wback);
 }
 
+size_t wxInputStream::OnSysRead(void * WXUNUSED(buffer),
+                                size_t WXUNUSED(bufsize))
+{
+    return 0;
+}
+
 bool wxInputStream::Eof() const
 {
     wxInputStream *self = wxConstCast(this, wxInputStream);
@@ -843,6 +849,12 @@ wxOutputStream::~wxOutputStream()
 {
 }
 
+size_t wxOutputStream::OnSysWrite(const void * WXUNUSED(buffer),
+                                  size_t WXUNUSED(bufsize))
+{
+    return 0;
+}
+
 void wxOutputStream::PutC(char c)
 {
     Write(&c, 1);
@@ -945,6 +957,7 @@ off_t wxCountingOutputStream::OnSysTell() const
 
 wxFilterInputStream::wxFilterInputStream()
 {
+    m_parent_i_stream = NULL;
 }
 
 wxFilterInputStream::wxFilterInputStream(wxInputStream& stream)
@@ -962,6 +975,7 @@ wxFilterInputStream::~wxFilterInputStream()
 
 wxFilterOutputStream::wxFilterOutputStream()
 {
+    m_parent_o_stream = NULL;
 }
 
 wxFilterOutputStream::wxFilterOutputStream(wxOutputStream& stream)
@@ -977,13 +991,22 @@ wxFilterOutputStream::~wxFilterOutputStream()
 // wxBufferedInputStream
 // ----------------------------------------------------------------------------
 
-wxBufferedInputStream::wxBufferedInputStream(wxInputStream& s)
+wxBufferedInputStream::wxBufferedInputStream(wxInputStream& s,
+                                             wxStreamBuffer *buffer)
                      : wxFilterInputStream(s)
+{
+    if ( buffer )
+    {
+        // use the buffer provided by the user
+        m_i_streambuf = buffer;
+    }
+    else // create a default buffer
     {
         m_i_streambuf = new wxStreamBuffer(*this, wxStreamBuffer::read);
 
         m_i_streambuf->SetBufferIO(1024);
     }
+}
 
 wxBufferedInputStream::~wxBufferedInputStream()
 {
@@ -1041,16 +1064,33 @@ off_t wxBufferedInputStream::OnSysTell() const
     return m_parent_i_stream->TellI();
 }
 
+void wxBufferedInputStream::SetInputStreamBuffer(wxStreamBuffer *buffer)
+{
+    wxCHECK_RET( buffer, _T("wxBufferedInputStream needs buffer") );
+
+    delete m_i_streambuf;
+    m_i_streambuf = buffer;
+}
+
 // ----------------------------------------------------------------------------
 // wxBufferedOutputStream
 // ----------------------------------------------------------------------------
 
-wxBufferedOutputStream::wxBufferedOutputStream(wxOutputStream& s)
+wxBufferedOutputStream::wxBufferedOutputStream(wxOutputStream& s,
+                                               wxStreamBuffer *buffer)
                       : wxFilterOutputStream(s)
+{
+    if ( buffer )
+    {
+        m_o_streambuf = buffer;
+    }
+    else // create a default one
     {
         m_o_streambuf = new wxStreamBuffer(*this, wxStreamBuffer::write);
+
         m_o_streambuf->SetBufferIO(1024);
     }
+}
 
 wxBufferedOutputStream::~wxBufferedOutputStream()
 {
@@ -1102,6 +1142,14 @@ size_t wxBufferedOutputStream::GetSize() const
    return m_parent_o_stream->GetSize() + m_o_streambuf->GetIntPosition();
 }
 
+void wxBufferedOutputStream::SetOutputStreamBuffer(wxStreamBuffer *buffer)
+{
+    wxCHECK_RET( buffer, _T("wxBufferedOutputStream needs buffer") );
+
+    delete m_o_streambuf;
+    m_o_streambuf = buffer;
+}
+
 // ----------------------------------------------------------------------------
 // Some IOManip function
 // ----------------------------------------------------------------------------