[Emacs-diffs] refs/scratch/raeburn/startup 98a2a33 3/5: Short-circuit substitutions for some simple types.

[Ken Raeburn]

reference: refs/scratch/raeburn/startup
commit 98a2a3369f5e2848cf9feffaa275cb2d9b418ff2
Author: Ken Raeburn <address@hidden>
Commit: Ken Raeburn <address@hidden>

    Short-circuit substitutions for some simple types.
    
    Values that don't contain other values cannot be circular, so checking
    for circular objects is a waste of cycles.
    
    * src/lread.c (substitute_object_recurse): If the subtree being
    examined is a symbol, number, or property-less string, just return
    it.
---
 src/lread.c |    7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/lread.c b/src/lread.c
index a06a78f..dec0df0 100644
--- a/src/lread.c
+++ b/src/lread.c
@@ -3355,6 +3355,13 @@ substitute_object_recurse (Lisp_Object object, 
Lisp_Object placeholder, Lisp_Obj
   if (EQ (placeholder, subtree))
     return object;
 
+  /* For common object types that can't contain other objects, don't
+     bother looking them up; we're done.  */
+  if (SYMBOLP (subtree)
+      || (STRINGP (subtree) && !string_intervals (subtree))
+      || NUMBERP (subtree))
+    return subtree;
+
   /* If we've been to this node before, don't explore it again.  */
   if (!EQ (Qnil, Fmemq (subtree, seen_list)))
     return subtree;