rewrote wxString::To/FromAscii() to fix a few small problems

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@16626 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/string.h

@@ -446,24 +446,27 @@ public:
 
     // implicit conversion to C string
     operator const wxChar*() const { return m_pchData; }
+
     // explicit conversion to C string (use this with printf()!)
     const wxChar* c_str()   const { return m_pchData; }
-    // identical to c_str()
+    // identical to c_str(), for wxWin 1.6x compatibility
     const wxChar* wx_str()  const { return m_pchData; }
-    // identical to c_str()
+    // identical to c_str(), for MFC compatibility
     const wxChar* GetData() const { return m_pchData; }
 
-    // conversion to plain ascii: this is usefull for
-    // converting numbers or strings which are certain
-    // not to contain special chars (typically system
-    // functions, X atoms, environment variables etc.)
+    // conversion to/from plain (i.e. 7 bit) ASCII: this is useful for
+    // converting numbers or strings which are certain not to contain special
+    // chars (typically system functions, X atoms, environment variables etc.)
+    //
+    // the behaviour of these functions with the strings containing anything
+    // else than 7 bit ASCII characters is undefined, use at your own risk.
 #if wxUSE_UNICODE
-    static wxString FromAscii( char *ascii );
+    static wxString FromAscii(const char *ascii);
     const wxCharBuffer ToAscii() const;
-#else
-    static wxString FromAscii( char *ascii ) { return wxString( ascii ); }
-    const char *ToAscii() const { return m_pchData; }
-#endif
+#else // ANSI
+    static wxString FromAscii(const char *ascii) { return wxString( ascii ); }
+    const char *ToAscii() const { return c_str(); }
+#endif // Unicode/!Unicode
 
     // conversions with (possible) format convertions: have to return a
     // buffer with temporary data
@@ -1147,8 +1150,6 @@ public:
 
 class WXDLLEXPORT wxStringBuffer
 {
-    DECLARE_NO_COPY_CLASS(wxStringBuffer)
-    
 public:
     wxStringBuffer(wxString& str, size_t lenWanted = 1024)
         : m_str(str), m_buf(NULL)
@@ -1161,6 +1162,8 @@ public:
 private:
     wxString& m_str;
     wxChar   *m_buf;
+
+    DECLARE_NO_COPY_CLASS(wxStringBuffer)
 };
 
 // ---------------------------------------------------------------------------

src/common/string.cpp

@@ -759,43 +759,53 @@ wxString operator+(const wxChar *psz, const wxString& str)
 // ===========================================================================
 
 #if wxUSE_UNICODE
-wxString wxString::FromAscii( char *ascii )
+
+wxString wxString::FromAscii(const char *ascii)
 {
     if (!ascii)
        return wxEmptyString;
 
     size_t len = strlen( ascii );
     wxString res;
-    res.AllocBuffer( len );
-    wchar_t *dest = (wchar_t*)(const wchar_t*) res.c_str();
 
-    for (size_t i = 0; i < len+1; i++)
-       dest[i] = (wchar_t) ascii[i];
+    if ( len )
+    {
+        wxStringBuffer buf(res, len);
+
+        wchar_t *dest = buf;
+
+        for ( ;; )
+        {
+           if ( (*dest++ = (wchar_t)(unsigned char)*ascii++) == L'\0' )
+               break;
+        }
+    }
 
     return res;
 }
 
 const wxCharBuffer wxString::ToAscii() const
 {
-    if (IsNull())
-       return wxCharBuffer( (const char*)NULL );
+    // this will allocate enough space for the terminating NUL too
+    wxCharBuffer buffer(length());
 
-    size_t len = Len();
-    wxCharBuffer buffer( len ); // allocates len+1
+    signed char *dest = (signed char *)buffer.data();
 
-    char *dest = (char*)(const char*) buffer;
-    
-    for (size_t i = 0; i < len+1; i++)
+    const wchar_t *pwc = c_str();
+    for ( ;; )
     {
-        if (m_pchData[i] > 127)
-            dest[i] = '_';
-        else
-            dest[i] = (char) m_pchData[i];
+        *dest++ = *pwc > SCHAR_MAX ? '_' : *pwc;
+
+        // the output string can't have embedded NULs anyhow, so we can safely
+        // stop at first of them even if we do have any
+        if ( !*pwc++ )
+            break;
     }
 
     return buffer;
 }
-#endif
+
+#endif // Unicode
 
 // ---------------------------------------------------------------------------
 // simple sub-string extraction