Allow specifying the replacement character in wxString::ToAscii()

Don't hardcode "_" as the replacement character but accept the one specified
by the user.

Closes https://github.com/wxWidgets/wxWidgets/pull/116

docs/changes.txt

@@ -75,6 +75,7 @@ All:
 - Add wxART_FULL_SCREEN standard bitmap (Igor Korot).
 - Fix wxStringTokenizer copy ctor and assignment operator.
 - Added wxASSERT_MSG_AT() and wxFAIL_MSG_AT() macros.
+- Accept replacement character in wxString::ToAscii() (Stefano D. Mtangoo).
 
 Unix:
 

include/wx/string.h

@@ -1556,13 +1556,13 @@ public:
     static wxString FromAscii(const char *ascii, size_t len);
     static wxString FromAscii(const char *ascii);
     static wxString FromAscii(char ascii);
-    const wxScopedCharBuffer ToAscii() const;
+    const wxScopedCharBuffer ToAscii(char replaceWith = '_') const;
 #else // ANSI
     static wxString FromAscii(const char *ascii) { return wxString( ascii ); }
     static wxString FromAscii(const char *ascii, size_t len)
         { return wxString( ascii, len ); }
     static wxString FromAscii(char ascii) { return wxString( ascii ); }
-    const char *ToAscii() const { return c_str(); }
+    const char *ToAscii(char WXUNUSED(replaceWith) = '_') const { return c_str(); }
 #endif // Unicode/!Unicode
 
     // also provide unsigned char overloads as signed/unsigned doesn't matter

interface/wx/string.h

@@ -739,17 +739,21 @@ public:
         a wxCharBuffer (Unicode builds only) or a C string (ANSI builds).
 
         Note that this conversion is only lossless if the string contains only
-        ASCII characters as all the non-ASCII ones are replaced with the @c '_'
-        (underscore) character.
+        ASCII characters as all the non-ASCII ones are replaced with the (same)
+        provided replacement character.
 
         Use mb_str() or utf8_str() to convert to other encodings.
+
+        @param replaceWith
+            The character used to replace any non-ASCII characters, default to
+            underscore (@c "_"). This parameter is new since wxWidgets 3.1.0.
     */
-    const char* ToAscii() const;
+    const char* ToAscii(char replaceWith = '_') const;
 
     /**
         @overload
     */
-    const wxCharBuffer ToAscii() const;
+    const wxCharBuffer ToAscii(char replaceWith = '_') const;
 
     /**
         Return the string as an std::string in current locale encoding.

src/common/string.cpp

@@ -1205,7 +1205,7 @@ wxString wxString::FromAscii(char ascii)
     return wxString(wxUniChar((wchar_t)c));
 }
 
-const wxScopedCharBuffer wxString::ToAscii() const
+const wxScopedCharBuffer wxString::ToAscii(char replaceWith) const
 {
     // this will allocate enough space for the terminating NUL too
     wxCharBuffer buffer(length());
@@ -1215,7 +1215,7 @@ const wxScopedCharBuffer wxString::ToAscii() const
     {
         wxUniChar c(*i);
         // FIXME-UTF8: unify substituted char ('_') with wxUniChar ('?')
-        *dest++ = c.IsAscii() ? (char)c : '_';
+        *dest++ = c.IsAscii() ? (char)c : replaceWith;
 
         // the output string can't have embedded NULs anyhow, so we can safely
         // stop at first of them even if we do have any