add a pprint function pointer to HTTEntry

src/internal.h

@@ -428,6 +428,7 @@ typedef struct HTTEntry_ {
   const char* name;
   HTokenType value;
   void (*unamb_sub)(const HParsedToken *tok, struct result_buf *buf);
+  void (*pprint)(FILE* stream, const HParsedToken* tok, int indent, int delta);
 } HTTEntry;
 
 const HTTEntry* h_get_token_type_entry(HTokenType token_type);

src/pprint.c

@@ -69,9 +69,11 @@ void h_pprint(FILE* stream, const HParsedToken* tok, int indent, int delta) {
     break;
   default:
     if(tok->token_type >= TT_USER) {
-      const char *name = h_get_token_type_name(tok->token_type);
+      const HTTEntry *e = h_get_token_type_entry(tok->token_type);
       int num = tok->token_type-TT_USER;
-      fprintf(stream, "%*sUSER:%s %d\n", indent, "", name, num);
+      fprintf(stream, "%*sUSER:%s %d\n", indent, "", e->name, num);
+      if (e->pprint)
+        e->pprint(stream, tok, indent + delta, delta);
     } else {
       assert_message(0, "Should not reach here.");
     }

src/registry.c

@@ -60,6 +60,7 @@ HTokenType h_allocate_token_new(
   new_entry->name = name;
   new_entry->value = 0;
   new_entry->unamb_sub = unamb_sub;
+  new_entry->pprint = NULL;
   HTTEntry* probe = *(HTTEntry**)tsearch(new_entry, &tt_registry, compare_entries);
   if (probe->value != 0) {
     // Token type already exists...