[slang-users] patch: push and pop args using lists rather than an array of structs

[Doug Burke]

I've included below a patch I think is useful - it adds two new 
intrinsics
that mirror __push_args/__pop_args but using a list rather than an array
of structures. If there's interest I'll submit a patch with tests and 
docs
as well. Any comments on how to improve it are most welcome (including
better routine names :-), since I'm sure the list processing is not the
most efficient (e.g. would it be better to add the items to the end of 
the
list and then reverse it in the push_args routine?).

The patch is against S-Lang v2.0.6.

Doug

--- sllist.c.orig	2006-04-27 17:10:20.000000000 -0400
+++ sllist.c	2006-04-27 18:03:43.000000000 -0400
@@ -760,6 +760,79 @@
     return -1;
  }

+void _pSLlist_pop_args (int *np)
+{
+  SLang_List_Type *list;
+  SLindex_Type i, n;
+
+  n = *np;
+
+  if (n < 0)
+    {
+      SLang_set_error (SL_INVALID_PARM);
+      return;
+    }
+
+  if (NULL == (list = allocate_list ()))
+    {
+      SLdo_pop_n (n);
+      return;
+    }
+
+  i = n;
+  while (i > 0)
+    {
+      SLang_Object_Type obj;
+
+      i--;
+
+      if (-1 == SLang_pop (&obj))
+        {
+	  delete_list (list);
+	  return;
+	}
+
+      /*
+       * Keep on adding to the start of the list.
+       * Probably not very efficient.
+       */
+      if (-1 == insert_element (list, &obj, 0))
+        {
+	  /* SLang_free_object (obj); */
+	  delete_list (list);
+	  return;
+	}
+     }
+
+  (void) push_list (list);
+  return;
+
+}
+
+static void _pSLlist_push_args (SLang_List_Type *list)
+{
+  Chunk_Type *c;
+  int counter = 1;
+
+  if (NULL == list)
+    return;
+
+  c = list->first;
+  while (NULL != c)
+    {
+      SLang_Object_Type *obj = c->elements;
+      SLang_Object_Type *obj_max = obj + c->num_elements;
+
+      while (obj < obj_max)
+        {
+	  (void) _pSLpush_slang_obj (obj);
+	  obj++;
+	}
+
+      c = c->next;
+    }
+}
+
  #define L SLANG_LIST_TYPE
  #define I SLANG_INT_TYPE
  static SLang_Intrin_Fun_Type Intrin_Table [] =
@@ -770,6 +843,8 @@
     MAKE_INTRINSIC_0("list_append", list_append_elem, SLANG_VOID_TYPE),
     MAKE_INTRINSIC_0("list_new", list_new, SLANG_VOID_TYPE),
     MAKE_INTRINSIC_0("list_pop", list_pop, SLANG_VOID_TYPE),
+   MAKE_INTRINSIC_1("__pop_args_as_list", _pSLlist_pop_args, 
SLANG_VOID_TYPE, I),
+   MAKE_INTRINSIC_1("__push_args_from_list", _pSLlist_push_args, 
SLANG_VOID_TYPE, L),
     SLANG_END_INTRIN_FUN_TABLE
  };
  #undef L