From: Mark Thom <markjordanthom@gmail.com>
Date: Sat, 24 Dec 2022 07:31:39 +0000 (-0700)
Subject: use '$enqueue_attr_var' when adding attributes only
X-Git-Tag: v0.9.2~242
X-Git-Url: https://git.sagredo.dev/?a=commitdiff_plain;h=aa7b8e52f37681da803585ea80764f7a28edcc4f;p=scryer-prolog.git

use '$enqueue_attr_var' when adding attributes only
---

diff --git a/src/lib/atts.pl b/src/lib/atts.pl
index a9369426..372a9bdd 100644
--- a/src/lib/atts.pl
+++ b/src/lib/atts.pl
@@ -41,8 +41,7 @@
     (  L \= Attr ->
        nonvar(Ls),
        '$get_from_list'(Ls, V, Attr)
-    ;  L = Attr,
-       '$enqueue_attr_var'(V)
+    ;  L = Attr
     ).
 
 '$put_attr'(V, Attr) :-
@@ -65,8 +64,7 @@
     nonvar(Att),
     (  Att \= Attr ->
        '$del_attr_buried'(Ls0, Ls1, V, Attr)
-    ;  '$enqueue_attr_var'(V),
-       '$del_attr_head'(V),
+    ;  '$del_attr_head'(V),
        '$del_attr'(Ls1, V, Attr)
     ).
 
@@ -84,8 +82,7 @@
     ;  Ls1 = [Att | Ls2] ->
        (  Att \= Attr ->
           '$del_attr_buried'(Ls1, Ls2, V, Attr)
-       ;  '$enqueue_attr_var'(V),
-	      '$del_attr_non_head'(Ls0), %% set tail of Ls0 = tail of Ls1. can be undone by backtracking.
+       ;  '$del_attr_non_head'(Ls0), %% set tail of Ls0 = tail of Ls1. can be undone by backtracking.
 	      '$del_attr_step'(Ls1, V, Attr)
        )
     ).