added non const accessors to wx(W)CharBuffer; minor changes to wxMemoryBuffer; made copy ctor and assignment operator argument non const

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_2_4_BRANCH@17492 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/buffer.h

@@ -40,20 +40,22 @@ public:
     // no need to check for NULL, free() does it
     ~wxCharBuffer() { free(m_str); }
 
-    wxCharBuffer(const wxCharBuffer& src)
+    wxCharBuffer(/* non const! */ wxCharBuffer& src)
         : m_str(src.m_str)
     {
         // no reference count yet...
-        ((wxCharBuffer*)&src)->m_str = (char *)NULL;
+        src.m_str = (char *)NULL;
     }
-    wxCharBuffer& operator=(const wxCharBuffer& src)
+    wxCharBuffer& operator=(/* non const! */ wxCharBuffer& src)
     {
         m_str = src.m_str;
+
         // no reference count yet...
-        ((wxCharBuffer*)&src)->m_str = (char *)NULL;
+        src.m_str = (char *)NULL;
         return *this;
     }
 
+    char *data() { return m_str; }
     const char *data() const { return m_str; }
     operator const char *() const { return m_str; }
     char operator[](size_t n) const { return m_str[n]; }
@@ -85,20 +87,21 @@ public:
     // no need to check for NULL, free() does it
     ~wxWCharBuffer() { free(m_wcs); }
 
-    wxWCharBuffer(const wxWCharBuffer& src)
+    wxWCharBuffer(/* non const! */ wxWCharBuffer& src)
         : m_wcs(src.m_wcs)
     {
        // no reference count yet...
-       ((wxWCharBuffer*)&src)->m_wcs = (wchar_t *)NULL;
+       src.m_wcs = (wchar_t *)NULL;
     }
-    wxWCharBuffer& operator=(const wxWCharBuffer& src)
+    wxWCharBuffer& operator=(/* non const! */ wxWCharBuffer& src)
     {
         m_wcs = src.m_wcs;
         // no reference count yet...
-        ((wxWCharBuffer*)&src)->m_wcs = (wchar_t *)NULL;
+        src.m_wcs = (wchar_t *)NULL;
         return *this;
     }
 
+    wchar_t *data() { return m_wcs; }
     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]; }
@@ -128,16 +131,22 @@ private:
 class wxMemoryBuffer
 {
 public:
-    enum { BLOCK_SIZE = 1024 };
+    // the initial size and also the size added by ResizeIfNeeded()
+    enum
+    {
+        BLOCK_SIZE = 1024
+    };
+
+    // ctor and dtor
     wxMemoryBuffer(size_t size = wxMemoryBuffer::BLOCK_SIZE)
-        : m_data(malloc(size)), m_size(size), m_len(0)
+        : m_data(size ? malloc(size) : NULL), m_size(size), m_len(0)
     {
     }
 
     ~wxMemoryBuffer() { free(m_data); }
 
     // Accessors
-    void*  GetData() const    { return m_data; }
+    void  *GetData() const    { return m_data; }
     size_t GetBufSize() const { return m_size; }
     size_t GetDataLen() const { return m_len; }
 
@@ -149,7 +158,7 @@ public:
     }
 
     // Ensure the buffer is big enough and return a pointer to it
-    void* GetWriteBuf(size_t sizeNeeded)
+    void *GetWriteBuf(size_t sizeNeeded)
     {
         ResizeIfNeeded(sizeNeeded);
         return m_data;
@@ -158,7 +167,7 @@ public:
     void  UngetWriteBuf(size_t sizeUsed) { SetDataLen(sizeUsed); }
 
     // Like the above, but appends to the buffer
-    void* GetAppendBuf(size_t sizeNeeded)
+    void *GetAppendBuf(size_t sizeNeeded)
     {
         ResizeIfNeeded(m_len + sizeNeeded);
         return (char*)m_data + m_len;
@@ -166,7 +175,10 @@ public:
     void  UngetAppendBuf(size_t sizeUsed) { SetDataLen(m_len + sizeUsed); }
 
     // Other ways to append to the buffer
-    void  AppendByte(char data) {
+    void  AppendByte(char data)
+    {
+        wxCHECK_RET( m_data, _T("invalid wxMemoryBuffer") );
+
         ResizeIfNeeded(m_len + 1);
         *(((char*)m_data)+m_len) = data;
         m_len += 1;
@@ -181,25 +193,25 @@ public:
 
 
     // Copy and assignment
-    wxMemoryBuffer(const wxMemoryBuffer& src)
+    wxMemoryBuffer(/* non const! */ wxMemoryBuffer& src)
         : m_data(src.m_data), m_size(src.m_size), m_len(src.m_len)
     {
         // no reference count yet...
-        ((wxMemoryBuffer*)&src)->m_data = NULL;
+        src.m_data = NULL;
-        ((wxMemoryBuffer*)&src)->m_size = 0;
+        src.m_size = 0;
-        ((wxMemoryBuffer*)&src)->m_len  = 0;
+        src.m_len  = 0;
     }
 
-    wxMemoryBuffer& operator=(const wxMemoryBuffer& src)
+    wxMemoryBuffer& operator=(/* not const! */ wxMemoryBuffer& src)
     {
         m_data = src.m_data;
         m_size = src.m_size;
         m_len  = src.m_len;
 
         // no reference count yet...
-        ((wxMemoryBuffer*)&src)->m_data = NULL;
+        src.m_data = NULL;
-        ((wxMemoryBuffer*)&src)->m_size = 0;
+        src.m_size = 0;
-        ((wxMemoryBuffer*)&src)->m_len  = 0;
+        src.m_len  = 0;
 
         return *this;
    }
@@ -210,15 +222,25 @@ protected:
     {
         if (newSize > m_size)
         {
+            void *dataOld = m_data;
             m_data = realloc(m_data, newSize + wxMemoryBuffer::BLOCK_SIZE);
-            wxASSERT(m_data != NULL);
+            if ( !m_data )
+            {
+                free(dataOld);
+            }
+
             m_size = newSize + wxMemoryBuffer::BLOCK_SIZE;
         }
     }
 
 private:
-    void*       m_data;
+    // 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;
 };