Don't print or read the hash table size parameter

It's not a meaningful part of the external representation.
This allows for faster printing and reading, smaller
external representation, and less memory consumption.

* src/print.c (print_object): Omit size.
* src/lread.c (hash_table_from_plist): Take size from the data.

2 files changed, 11 insertions, 13 deletions

diff --git a/src/lread.c b/src/lread.c
index e95dafcf222..18894801376 100644
--- a/src/lread.c
+++ b/src/lread.c
@@ -3426,7 +3426,6 @@ hash_table_from_plist (Lisp_Object plist)
       }                                                 \
   } while (0)
 
-  ADDPARAM (size);
   ADDPARAM (test);
   ADDPARAM (weakness);
   ADDPARAM (rehash_size);
@@ -3434,23 +3433,25 @@ hash_table_from_plist (Lisp_Object plist)
   ADDPARAM (purecopy);
 
   Lisp_Object data = plist_get (plist, Qdata);
+  if (!(NILP (data) || CONSP (data)))
+    error ("Hash table data is not a list");
+  ptrdiff_t data_len = list_length (data);
+  if (data_len & 1)
+    error ("Hash table data length is odd");
+  *par++ = QCsize;
+  *par++ = make_fixnum (data_len / 2);
 
   /* Now use params to make a new hash table and fill it.  */
   Lisp_Object ht = Fmake_hash_table (par - params, params);
 
-  Lisp_Object last = data;
-  FOR_EACH_TAIL_SAFE (data)
+  while (!NILP (data))
     {
       Lisp_Object key = XCAR (data);
       data = XCDR (data);
-      if (!CONSP (data))
-        break;
       Lisp_Object val = XCAR (data);
-      last = XCDR (data);
       Fputhash (key, val, ht);
+      data = XCDR (data);
     }
-  if (!NILP (last))
-    error ("Hash table data is not a list of even length");
 
   return ht;
 }
diff --git a/src/print.c b/src/print.c
index d011962d85b..c1c91b2383a 100644
--- a/src/print.c
+++ b/src/print.c
@@ -2574,11 +2574,8 @@ print_object (Lisp_Object obj, Lisp_Object printcharfun, bool escapeflag)
           {
             struct Lisp_Hash_Table *h = XHASH_TABLE (obj);
             /* Implement a readable output, e.g.:
-               #s(hash-table size 2 test equal data (k1 v1 k2 v2)) */
-            /* Always print the size.  */
-            int len = sprintf (buf, "#s(hash-table size %"pD"d",
-                               HASH_TABLE_SIZE (h));
-            strout (buf, len, len, printcharfun);
+               #s(hash-table test equal data (k1 v1 k2 v2)) */
+            print_c_string ("#s(hash-table", printcharfun);
 
             if (!BASE_EQ (h->test.name, Qeql))
               {