2 files changed, 44 insertions, 10 deletions

diff --git a/pw.1 b/pw.1
index f4f05fc..95be260 100644
--- a/pw.1
+++ b/pw.1
@@ -191,7 +191,7 @@ and
 also terminate colon mode without executing a command. Colon commands
 are documented in the COLON COMMANDS section below.
 
-.IP "[\fIpos\fP]\fB/\fP\fIpattern\fP, [\fIpos\fP]\fB?\fP\fIpattern\fP"
+.IP "[\fIpos\fP]\fB/[!]\fP\fIpattern\fP, [\fIpos\fP]\fB?[!]\fP\fIpattern\fP"
 Set a trigger if a non-empty
 .I pattern
 is specified, or else cancel a trigger if an empty pattern is specified.
@@ -285,6 +285,24 @@ expression (ERE) or (BRE) depending on the current setting.
 This is true even if it is recalled from a history entry which had been created
 under a different mode.
 
+If the
+.I pattern
+is preceded by the character
+.B !
+then it is logically inverted. The trigger will activate on lines which do
+.I not
+match the pattern. To write an uninverted pattern which begins with
+.BR ! ,
+precede the
+.B !
+with a backslash. This is not a regex character escape sequence, but part
+of the trigger command syntax. It must not be used anywhere in a pattern,
+other than immediately after the
+.B /
+or
+.B ?
+command character.
+
 In trigger mode, the status string
 .B TRIG/
 or
diff --git a/pw.c b/pw.c
index 2f19e25..69898e1 100644
--- a/pw.c
+++ b/pw.c
@@ -314,7 +314,7 @@ static void drawstatus(unsigned hist, int columns, unsigned stat, char *cmd)
             ptr += snprintf(ptr, end - ptr, ", ");
           if (i > 0)
             ptr += snprintf(ptr, end - ptr, "[%d]", i + 1);
-          ptr += snprintf(ptr, end - ptr, "%s", gr->pat);
+          ptr += snprintf(ptr, end - ptr, "%s%s", gr->inv ? "!" : "", gr->pat);
           first = 0;
         }
       }
@@ -758,9 +758,12 @@ int main(int argc, char **argv)
               int trig = 1;
               for (int i = 0; i < lim; i++) {
                 grep *gr = triglist[i];
-                if (gr && regexec(&gr->rx, circbuf[i], 0, NULL, 0) != 0) {
-                  trig = 0;
-                  break;
+                if (gr) {
+                  int match = regexec(&gr->rx, circbuf[i], 0, NULL, 0) == 0;
+                  if (match == gr->inv) {
+                    trig = 0;
+                    break;
+                  }
                 }
               }
               if (trig)
@@ -769,9 +772,12 @@ int main(int argc, char **argv)
               int trig = 1;
               for (int j = nlines - 1, i = 0; j >= 0 && i < maxtrig; j--, i++) {
                 grep *gr = triglist[i];
-                if (gr && regexec(&gr->rx, circbuf[j], 0, NULL, 0) != 0) {
-                  trig = 0;
-                  break;
+                if (gr) {
+                  int match = regexec(&gr->rx, circbuf[j], 0, NULL, 0) == 0;
+                  if (match == gr->inv) {
+                    trig = 0;
+                    break;
+                  }
                 }
               }
               if (trig)
@@ -1083,9 +1089,19 @@ int main(int argc, char **argv)
                 }
               } else if (kbd_state == kbd_trig && (int) trig < maxlines && trig < maxtrig) {
                 int err;
-                char *pat = dsdup(cmdbuf + 1);
+                char *rx = cmdbuf + 1;
+                int inv = 0;
                 regex_t regex;
 
+                if (strncmp(rx, "\\!", 2) == 0) {
+                  rx++;
+                } else if (rx[0] == '!') {
+                  rx++;
+                  inv = 1;
+                }
+
+                char *pat = dsdup(rx);
+
                 if (*pat && (err = regcomp(&regex, pat, regex_flags | REG_NOSUB))) {
                   regerror(err, &regex, cmdbuf, sizeof cmdbuf);
                   if (columns < (int) sizeof cmdbuf - 1)
@@ -1121,7 +1137,7 @@ int main(int argc, char **argv)
                     regfree(&regex);
                     regcomp(&gr->rx, pat, regex_flags | REG_NOSUB);
                     gr->pat = dsdup(pat);
-                    gr->inv = 0;
+                    gr->inv = inv;
                     triglist[trig] = gr;
                   }
                 }