(message_log_check_duplicate): New function.

(message_dolog): Delete previous line if the new one is a duplicate.  Include
a counter if appropriate.
Don't bother truncating the buffer until after adding newline.

1 files changed, 83 insertions, 8 deletions

diff --git a/src/xdisp.c b/src/xdisp.c
index a4ff8d25fc6..faf2271387c 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -148,6 +148,7 @@ int debug_end_pos;
 /* Nonzero means display mode line highlighted */
 int mode_line_inverse_video;
 
+static int message_log_check_duplicate ();
 static void echo_area_display ();
 void mark_window_display_accurate ();
 static void redisplay_windows ();
@@ -254,15 +255,52 @@ message_dolog (m, len, nlflag)
       if (len)
         insert_1 (m, len, 1, 0);
       if (nlflag)
-        insert_1 ("\n", 1, 1, 0);
-      if (NATNUMP (Vmessage_log_max))
         {
-          int pos = scan_buffer ('\n', PT, 0,
-                                 -XFASTINT (Vmessage_log_max) - 1, 0, 1);
-          oldpoint -= min (pos, oldpoint) - BEG;
-          oldbegv -= min (pos, oldbegv) - BEG;
-          oldzv -= min (pos, oldzv) - BEG;
-          del_range_1 (BEG, pos, 0);
+          int this_bol, prev_bol, dup;
+          insert_1 ("\n", 1, 1, 0);
+
+          this_bol = scan_buffer ('\n', Z, 0, -2, 0, 0);
+          if (this_bol > BEG)
+            {
+              prev_bol = scan_buffer ('\n', this_bol, 0, -2, 0, 0);
+              dup = message_log_check_duplicate (prev_bol, this_bol);
+              if (dup)
+                {
+                  if (oldpoint > prev_bol)
+                    oldpoint -= min (this_bol, oldpoint) - prev_bol;
+                  if (oldbegv > prev_bol)
+                    oldbegv -= min (this_bol, oldbegv) - prev_bol;
+                  if (oldzv > prev_bol)
+                    oldzv -= min (this_bol, oldzv) - prev_bol;
+                  del_range_1 (prev_bol, this_bol, 0);
+                  if (dup > 1)
+                    {
+                      char dupstr[40];
+                      int duplen;
+
+                      /* If you change this format, don't forget to also
+                         change message_log_check_duplicate.  */
+                      sprintf (dupstr, " [%d times]", dup);
+                      duplen = strlen (dupstr);
+                      TEMP_SET_PT (Z-1);
+                      if (oldpoint == Z)
+                        oldpoint += duplen;
+                      if (oldzv == Z)
+                        oldzv += duplen;
+                      insert_1 (dupstr, duplen, 1, 0);
+                    }
+                }
+            }
+
+          if (NATNUMP (Vmessage_log_max))
+            {
+              int pos = scan_buffer ('\n', Z, 0,
+                                     -XFASTINT (Vmessage_log_max) - 1, 0, 0);
+              oldpoint -= min (pos, oldpoint) - BEG;
+              oldbegv -= min (pos, oldbegv) - BEG;
+              oldzv -= min (pos, oldzv) - BEG;
+              del_range_1 (BEG, pos, 0);
+            }
         }
       BEGV = oldbegv;
       ZV = oldzv;
@@ -273,6 +311,43 @@ message_dolog (m, len, nlflag)
 }
 
 
+/* We are at the end of the buffer after just having inserted a newline.
+   (Note: We depend on the fact we won't be crossing the gap.)
+   Check to see if the most recent message looks a lot like the previous one.
+   Return 0 if different, 1 if the new one should just replace it, or a
+   value N > 1 if we should also append " [N times]".  */
+static int
+message_log_check_duplicate (prev_bol, this_bol)
+     int prev_bol, this_bol;
+{
+  int i;
+  int len = Z - 1 - this_bol;
+  int seen_dots = 0;
+  char *p1 = BUF_CHAR_ADDRESS (current_buffer, prev_bol);
+  char *p2 = BUF_CHAR_ADDRESS (current_buffer, this_bol);
+
+  for (i = 0; i < len; i++)
+    {
+      if (i >= 3 && p1[i-3] == '.' && p1[i-2] == '.' && p1[i-1] == '.'
+          && p1[i] != '\n')
+        seen_dots = 1;
+      if (p1[i] != p2[i])
+        return seen_dots;
+    }
+  p1 += len;
+  if (*p1 == '\n')
+    return 2;
+  if (*p1++ == ' ' && *p1++ == '[')
+    {
+      int n = 0;
+      while (*p1 >= '0' && *p1 <= '9')
+        n = n * 10 + *p1++ - '0';
+      if (strncmp (p1, " times]\n", 8) == 0)
+        return n+1;
+    }
+  return 0;
+}
+
 /* Display an echo area message M with a specified length of LEN chars.
    The string may include null characters.  If m is 0, clear out any
    existing message, and let the minibuffer text show through.