Override some methods in wxF(F)ileStream to resolve ambiguities.

Override virtual methods IsSeekable(), GetLength() and OnSysSeek/Tell() to
forward to wxF(F)InputStream base class as otherwise it's impossible to use
them at all because of ambiguity between the versions inherited from this
class and wxF(F)OutputStream (even though the two versions should do the same
thing as they operate on the same file descriptor/handle).

Also improve documentation of these classes: provide a brief description,
correct the base classes.

Closes #11577.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@62995 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/wfstream.h

@@ -118,6 +118,31 @@ public:
     wxFileStream(const wxString& fileName);
     virtual bool IsOk() const;
 
+    // override (some) virtual functions inherited from both classes to resolve
+    // ambiguities (this wouldn't be necessary if wxStreamBase were a virtual
+    // base class but it isn't)
+
+    virtual bool IsSeekable() const
+    {
+        return wxFileInputStream::IsSeekable();
+    }
+
+    virtual wxFileOffset GetLength() const
+    {
+        return wxFileInputStream::GetLength();
+    }
+
+protected:
+    virtual wxFileOffset OnSysSeek(wxFileOffset pos, wxSeekMode mode)
+    {
+        return wxFileInputStream::OnSysSeek(pos, mode);
+    }
+
+    virtual wxFileOffset OnSysTell() const
+    {
+        return wxFileInputStream::OnSysTell();
+    }
+
 private:
     wxDECLARE_NO_COPY_CLASS(wxFileStream);
 };
@@ -193,8 +218,33 @@ class WXDLLIMPEXP_BASE wxFFileStream : public wxFFileInputStream,
 {
 public:
     wxFFileStream(const wxString& fileName, const wxString& mode = "w+b");
+
+    // override some virtual functions to resolve ambiguities, just as in
+    // wxFileStream
+
     virtual bool IsOk() const;
 
+    virtual bool IsSeekable() const
+    {
+        return wxFFileInputStream::IsSeekable();
+    }
+
+    virtual wxFileOffset GetLength() const
+    {
+        return wxFFileInputStream::GetLength();
+    }
+
+protected:
+    virtual wxFileOffset OnSysSeek(wxFileOffset pos, wxSeekMode mode)
+    {
+        return wxFFileInputStream::OnSysSeek(pos, mode);
+    }
+
+    virtual wxFileOffset OnSysTell() const
+    {
+        return wxFFileInputStream::OnSysTell();
+    }
+
 private:
     wxDECLARE_NO_COPY_CLASS(wxFFileStream);
 };

interface/wx/wfstream.h

@@ -122,7 +122,7 @@ class wxFileOutputStream : public wxOutputStream
 public:
     /**
         Creates a new file with @a ofileName name and initializes the stream in write-only mode.
-        
+
         @warning
         You should use wxStreamBase::IsOk() to verify if the constructor succeeded.
     */
@@ -171,7 +171,7 @@ class wxFileInputStream : public wxInputStream
 public:
     /**
         Opens the specified file using its @a ifileName name in read-only mode.
-        
+
         @warning
         You should use wxStreamBase::IsOk() to verify if the constructor succeeded.
     */
@@ -253,24 +253,34 @@ public:
 /**
     @class wxFFileStream
 
-    @todo describe this class.
+    This stream allows to both read from and write to a file using buffered
+    STDIO functions.
 
     @library{wxbase}
     @category{streams}
 
-    @see wxStreamBuffer
+    @see wxFFileInputStream, wxFFileOutputStream, wxFileStream
 */
-class wxFFileStream : public wxFFileOutputStream
+class wxFFileStream : public wxFFileInputStream,
+                      public wxFFileOutputStream
 {
 public:
     /**
         Initializes a new file stream in the given @a mode using the specified
         @a iofileName name.
-        
+
         @warning
         You should use wxStreamBase::IsOk() to verify if the constructor succeeded.
     */
     wxFFileStream(const wxString& iofileName, const wxString& mode = "w+b");
+
+    /**
+        Returns @true if the stream is initialized and ready.
+
+        This method returns @true if the stream can be both read from and
+        written to.
+    */
+    bool IsOk() const;
 };
 
 
@@ -278,23 +288,34 @@ public:
 /**
     @class wxFileStream
 
-    @todo describe this class.
+    This class represents data that can be both read from and written to a file.
+    There are actually two such groups of classes: this one is based on wxFile
+    whereas wxFFileStream is based in the wxFFile class.
 
     @library{wxbase}
     @category{streams}
 
-    @see wxStreamBuffer
+    @see wxFileInputStream, wxFileOutputStream, wxFFileStream
 */
-class wxFileStream : public wxFileOutputStream
+class wxFileStream : public wxFileOutputStream,
+                     public wxFileInputStream
 {
 public:
     /**
         Initializes a new file stream in read-write mode using the specified
         @a iofileName name.
-        
+
         @warning
-        You should use wxStreamBase::IsOk() to verify if the constructor succeeded.
+        You should use IsOk() to verify if the constructor succeeded.
     */
     wxFileStream(const wxString& iofileName);
+
+    /**
+        Returns @true if the stream is initialized and ready.
+
+        This method returns @true if the stream can be both read from and
+        written to.
+    */
+    bool IsOk() const;
 };