A function to extend XLisp's table of function bindings dynamically

lib-src/libnyquist/nyquist/xlisp/xlftab.c

@@ -12,6 +12,7 @@ HISTORY
 
 */
 
+#include <string.h> /* for memcpy */
 #include "switches.h"
 #include "xlisp.h"
 #ifndef NO_PROTOTYPES_IN_XLISP_H
@@ -114,7 +115,7 @@ LVAL xstoprecordio(void);
 #endif
 
 /* the function table */
-FUNDEF funtab[] = {
+FUNDEF init_funtab[] = {
 
     /* read macro functions */
 {	NULL,				S, rmhash		}, /*   0 */
@@ -498,7 +499,32 @@ FUNDEF funtab[] = {
 
 {0,0,0} /* end of table marker */
 
-};			
+};
+
+FUNDEF *funtab = init_funtab;
+static size_t szfuntab = sizeof(init_funtab) / sizeof(*init_funtab);
+
+int xlbindfunctions(FUNDEF *functions, size_t nfunctions)
+{
+   /* This is written very generally, imposing no fixed upper limit on the
+    growth of the table.  But perhaps a lightweight alternative with such a
+    limit could be conditionally compiled.
+    */
+
+   /* malloc, not realloc, to leave old table unchanged in case of failure */
+   FUNDEF *newfuntab = malloc((szfuntab + nfunctions) * sizeof(FUNDEF));
+   if (!newfuntab)
+      return FALSE;
+   memcpy(newfuntab, funtab, (szfuntab - 1) * sizeof(FUNDEF));
+   memcpy(newfuntab + szfuntab - 1, functions, nfunctions * sizeof(FUNDEF));
+   FUNDEF sentinel = { 0, 0, 0 };
+   newfuntab[szfuntab - 1] = sentinel;
+   funtab = newfuntab;
+   szfuntab += nfunctions;
+   return TRUE;
+
+   /* To do: deallocate funtab when XLisp runtime shuts down */
+}
 
 /* xnotimp does not return anything on purpose, so disable
  * "no return value" warning

lib-src/libnyquist/nyquist/xlisp/xlimage.c

@@ -134,7 +134,7 @@ int xlisave(const char *fname)
 /* xlirestore - restore a saved memory image */
 int xlirestore(const char *fname)
 {
-    extern FUNDEF funtab[];
+    extern FUNDEF *funtab;
     char fullname[STRMAX+1];
     unsigned char *cp;
     int n,i,max,type;

lib-src/libnyquist/nyquist/xlisp/xlinit.c

@@ -41,7 +41,7 @@ extern LVAL a_fixnum,a_flonum,a_string,a_stream,a_object;
 extern LVAL a_vector,a_closure,a_char,a_ustream,a_extern;
 extern LVAL s_gcflag,s_gchook;
 extern LVAL s_search_path;
-extern FUNDEF funtab[];
+extern FUNDEF *funtab;
 
 /* forward declarations */
 FORWARD LOCAL void initwks();

lib-src/libnyquist/nyquist/xlisp/xlisp.h

@@ -671,6 +671,11 @@ void xlinit(void);
 void xlsymbols(void);
 
 
+/* xlftab.c */
+/* returns true on success,
+   false if table limits would be exceeded and the table remains unchanged */
+int xlbindfunctions(FUNDEF *functions, size_t nfunctions);
+
 /* xlio.c */
 
 int xlgetc(LVAL fptr);

lib-src/libnyquist/nyquist/xlisp/xlobj.c

@@ -88,7 +88,7 @@ void xladdivar(LVAL cls, const char *var)
 /* xladdmsg - add a message to a class */
 void xladdmsg(LVAL cls, const char *msg, int offset)
 {
-    extern FUNDEF funtab[];
+    extern FUNDEF *funtab;
     LVAL mptr;
 
     /* enter the message selector */

lib-src/libnyquist/nyquist/xlisp/xlprin.c

@@ -21,7 +21,7 @@
 /* external variables */
 extern LVAL s_printcase,k_downcase,k_const,k_nmacro;
 extern LVAL s_ifmt,s_ffmt;
-extern FUNDEF funtab[];
+extern FUNDEF *funtab;
 extern char buf[];
 
 LOCAL void putsymbol(LVAL fptr, char *str, int escflag);

lib-src/libnyquist/nyquist/xlisp/xlread.c

@@ -925,7 +925,7 @@ int xlisnumber(char *str, LVAL *pval)
 /* defmacro - define a read macro */
 void defmacro(int ch, LVAL type, int offset)
 {
-    extern FUNDEF funtab[];
+    extern FUNDEF *funtab;
     LVAL subr;
     subr = cvsubr(funtab[offset].fd_subr,funtab[offset].fd_type,offset);
     setelement(getvalue(s_rtable),ch,cons(type,subr));