Let the input module see only Keyword, not KeywordExt.

src/input.cc

@@ -26,6 +26,11 @@ Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111, USA.  */
 #include "options.h"
 #include "input.h"
 
+Input::Input (Keyword_Factory *keyword_factory)
+  : _factory (keyword_factory)
+{
+}
+
 /* Gathers the input stream into a buffer until one of two things occur:
 
    1. We read a '%' followed by a '%'
@@ -177,11 +182,11 @@ Input::set_output_types ()
     }
 }
 
-/* Extracts a key from an input line and creates a new KeywordExt_List for
+/* Extracts a key from an input line and creates a new Keyword_List for
    it. */
 
-static KeywordExt_List *
-parse_line (const char *line, const char *delimiters)
+Keyword_List *
+Input::parse_line (const char *line, const char *delimiters)
 {
   if (*line == '"')
     {
@@ -299,7 +304,7 @@ parse_line (const char *line, const char *delimiters)
             }
           lp++;
         }
-      return new KeywordExt_List (new KeywordExt (key, kp - key, option[TYPE] ? lp : ""));
+      return new Keyword_List (_factory->create_keyword (key, kp - key, option[TYPE] ? lp : ""));
     }
   else
     {
@@ -312,7 +317,7 @@ parse_line (const char *line, const char *delimiters)
       else
         /* Skip the first delimiter. */
         rest = &line[len + 1];
-      return new KeywordExt_List (new KeywordExt (line, len, option[TYPE] ? rest : ""));
+      return new Keyword_List (_factory->create_keyword (line, len, option[TYPE] ? rest : ""));
     }
 }
 
@@ -336,7 +341,7 @@ Input::read_keys ()
 
   _head = parse_line (ptr, delimiter);
 
-  for (KeywordExt_List *temp = _head;
+  for (Keyword_List *temp = _head;
        (ptr = Read_Line::read_next_line ()) && strcmp (ptr, "%%");
        temp = temp->rest())
     temp->rest() = parse_line (ptr, delimiter);

src/input.h

@@ -31,6 +31,7 @@ Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111, USA.  */
 class Input : private Read_Line
 {
 public:
+                        Input (Keyword_Factory *keyword_factory);
   void                  read_keys ();
 private:
 #ifndef strcspn
@@ -46,7 +47,10 @@ public:
   const char *          _struct_tag;                           /* Shorthand for user-defined struct tag type. */
   const char *          _include_src;                          /* C source code to be included verbatim. */
   bool                  _additional_code;                      /* True if any additional C code is included. */
-  KeywordExt_List *     _head;                            /* Points to the head of the linked list. */
+  Keyword_Factory *     _factory;                              /* Creates the keywords. */
+  Keyword_List *        _head;                            /* Points to the head of the linked list. */
+private:
+  Keyword_List *        parse_line (const char *line, const char *delimiters);
 };
 
 #endif

src/key-list.cc

@@ -48,6 +48,18 @@ Key_List::~Key_List ()
     }
 }
 
+class KeywordExt_Factory : public Keyword_Factory
+{
+virtual Keyword *       create_keyword (const char *allchars, int allchars_length,
+                                        const char *rest);
+};
+
+Keyword *
+KeywordExt_Factory::create_keyword (const char *allchars, int allchars_length, const char *rest)
+{
+  return new KeywordExt (allchars, allchars_length, rest);
+}
+
 /* Reads in all keys from standard input and creates a linked list pointed
    to by _head.  This list is then quickly checked for "links", i.e.,
    unhashable elements possessing identical key sets and lengths. */
@@ -55,14 +67,15 @@ Key_List::~Key_List ()
 void
 Key_List::read_keys ()
 {
-  Input inputter;
+  KeywordExt_Factory factory;
+  Input inputter (&factory);
   inputter.read_keys ();
   _array_type      = inputter._array_type;
   _return_type     = inputter._return_type;
   _struct_tag      = inputter._struct_tag;
   _include_src     = inputter._include_src;
   _additional_code = inputter._additional_code;
-  _head            = inputter._head;
+  _head            = static_cast<KeywordExt_List*>(inputter._head);
 
   KeywordExt_List *temp;
   KeywordExt_List *trail = NULL;

src/keyword-list.cc

@@ -23,7 +23,13 @@ Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111, USA.  */
 #include "keyword-list.h"
 
 /* Constructor.  */
-KeywordExt_List::KeywordExt_List (KeywordExt *car)
+Keyword_List::Keyword_List (Keyword *car)
   : _cdr (NULL), _car (car)
 {
 }
+
+/* Unused constructor.  */
+KeywordExt_List::KeywordExt_List (KeywordExt *car)
+  : Keyword_List (car)
+{
+}

src/keyword-list.h

@@ -27,19 +27,33 @@ Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111, USA.  */
 #include "keyword.h"
 
 /* List node of a linear list of Keyword.  */
-class KeywordExt_List {
+class Keyword_List
+{
 public:
   /* Constructor.  */
+                        Keyword_List (Keyword *car);
+
+  /* Access to first element of list.  */
+  Keyword *             first () { return _car; }
+  /* Access to next element of list.  */
+  Keyword_List *&       rest () { return _cdr; }
+
+protected:
+  Keyword_List *        _cdr;
+  Keyword * const       _car;
+};
+
+/* List node of a linear list of KeywordExt.  */
+class KeywordExt_List : public Keyword_List
+{
+public:
+  /* Unused constructor.  */
                         KeywordExt_List (KeywordExt *car);
 
   /* Access to first element of list.  */
-  KeywordExt *          first () { return _car; }
+  KeywordExt *          first () { return static_cast<KeywordExt*>(_car); }
   /* Access to next element of list.  */
-  KeywordExt_List *&    rest () { return _cdr; }
-
-private:
-  KeywordExt_List *     _cdr;
-  KeywordExt * const    _car;
+  KeywordExt_List *&    rest () { return static_cast<KeywordExt_List*>(_cdr); }
 };
 
 #endif