From octave-sources-request at bevo dot che dot wisc dot edu  Wed Apr 28 03:25:36 1999
Subject: octave readline, no double entries in history anymore
From: Thomas Walter <walter at pctc dot chemie dot uni-erlangen dot de>
To: octave-sources at bevo dot che dot wisc dot edu
Date: Wed, 28 Apr 1999 10:25:38 +0200


Hi,
I solved the tast to avoid double entries in the octave coammand
history.  Some small additions in 'liboctave/cmd-hist.cc' and it works.
After applying the patch below you can re-enter the previous command
in octave and it is not added to the command history.

Hints are welcome

Bye
Thomas

===================== patch start ===================
Index: octave-2_0_14.1/liboctave/ChangeLog
--- octave-2_0_14.1/liboctave/ChangeLog Mon, 19 Apr 1999 10:14:55 +0200 twalter (octave/p/4_ChangeLog 1.5 640)
+++ octave-2_0_14-loc.2/liboctave/ChangeLog Tue, 27 Apr 1999 12:28:25 +0200 twalter (octave/p/4_ChangeLog 1.7 640)
 at @ -1,3 +1,9 @@
+1999-04-27  Thomas Walter  <twalter at pc2-69 dot chemie dot uni-erlangen dot de>
+
+	* cmd-hist.cc (add): First simple version to avoid double history entries.
+	(compare_history_entries): New function.
+	(add): Use the new function to compare history two entries.
+
 Wed Apr 14 12:55:42 1999  John W. Eaton  <jwe at bevo dot che dot wisc dot edu>
 
 	* Version 2.0.14 released.
Index: octave-2_0_14.1/liboctave/cmd-hist.cc
--- octave-2_0_14.1/liboctave/cmd-hist.cc Tue, 26 Jan 1999 13:07:01 +0100 twalter (octave/q/26_cmd-hist.c 1.1 640)
+++ octave-2_0_14-loc.2/liboctave/cmd-hist.cc Tue, 27 Apr 1999 12:28:25 +0200 twalter (octave/q/26_cmd-hist.c 1.3 640)
 at @ -114,17 +114,57 @@ command_history::ignoring_entries (void)
   return ignoring_additions;
 }
 
+static bool
+compare_history_entries (const char* previous, const char* current)
+{
+  // Compare two strings from a command history
+  // Return 'false' if they are different
+  // Return 'true' if they are equal
+
+  if (previous[0] != current[0])
+    {
+      return (false);
+    }
+
+  if (((long *)previous)[0] != ((long *)current)[0])
+    {
+      return (false);
+    }
+
+  if (strlen (previous) != strlen (current))
+    {
+      return (false);
+    }
+
+  if (strcmp (previous, current) == 0)
+    {
+      return (true);
+    }
+
+  // In the case something fails be conservative and say they are different.
+  // And make the compiler happy to see always a return value.
+  return (false);
+}
+
 void
 command_history::add (const string& s)
 {
   if (! ignoring_entries ())
     {
+      HIST_ENTRY *p_h_entry;
+
       if (s.empty ()
 	  || (s.length () == 1 && (s[0] == '\r' || s[0] == '\n')))
 	return;
 
-      ::add_history (s.c_str ());
-      lines_this_session++;
+      using_history ();		// Must be called always at this point or 'p_h_entry' has the wrong value.
+      p_h_entry = previous_history ();
+      // cout << p_h_entry->line << endl; // Simple debugging
+      if ((p_h_entry == 0) || (compare_history_entries (p_h_entry->line, s.c_str ()) == false))
+	{
+	  ::add_history (s.c_str ());
+	  lines_this_session++;
+	}
     }
 }
 
===================== patch end ===================


-- 
Platzangst:
Der dauerhafte Zustand eines Luftballons.

----------------------------------------------
Dipl. Phys. Thomas Walter
Inst. f. Physiklische Chemie II
Egerlandstr. 3				Tel.: ++9131-85 27326 / 27330
91058 Erlangen, Germany			email: walter at pctc dot chemie dot uni-erlangen dot de