New feature: grep mode with pattern stack.

2 files changed, 131 insertions, 24 deletions

diff --git a/pw.1 b/pw.1
index 6effc43..755d220 100644
--- a/pw.1
+++ b/pw.1
@@ -230,6 +230,40 @@ Append the current contents of the display into the specified file.
 
 .IP "\fB:!\fP \fIfilename\fP"
 Pipe the current contents of of the display into the specified command.
+
+.IP "\fB:g\fP \fIpattern\fP, \fB:v\fP \fIpattern\fP"
+Push a
+.I grep
+pattern onto the grep stack. The
+.B :g
+command pushes a plain pattern; the
+.B :v
+command pushes a logically inverted pattern. The grep stack holds up to 64
+patterns.  If the pattern is successfully pushed onto the stack, it
+restricts which lines are admitted into the FIFO and available for display.
+The plain pattern admits only the lines which match
+.IR pattern ;
+the inverted pattern admits only lines which do
+.I not
+match
+.IR pattern .
+The status line shows
+.B GREP
+.BI ( depth )
+to indicate that grep mode and the depth of the stack. Lines which are
+already in the FIFO are not affected.
+
+.IP \fB:r\fP[\fB!\fP]
+Remove and forget the most recent grep pattern
+.RB ( :g or :v )
+from the grep stack. If the stack depth decrements from 1, the grep mode
+is disabled and the
+.B GREP
+status line disappears. If the optional
+.B !
+modifier is included in the command, then it pops the entire stack,
+forgetting all the patterns and disabling grep mode.
+
 .PP
 Any other command results in a brief error message.
 
diff --git a/pw.c b/pw.c
index fdd5846..34e5feb 100644
--- a/pw.c
+++ b/pw.c
@@ -21,9 +21,19 @@ enum status_flags {
   stat_susp = 4,    // display refresh suspended
   stat_htmode = 8,  // head trigger mode
   stat_ttmode = 16, // tail trigger mode
-  stat_trgrd = 32   // triggered flag
+  stat_trgrd = 32,  // triggered flag
+  stat_grep = 64    // grep mode
 };
 
+typedef struct grep {
+  char *pat;
+  regex_t rx;
+  int inv;
+} grep;
+
+#define cmdsize 100
+#define maxgrep 64
+
 typedef struct dstr {
   int refs;
   size_t len;
@@ -37,6 +47,9 @@ int snaplines;
 char *trigpat;
 regex_t trigex;
 
+grep grepstack[maxgrep];
+int ngrep;
+
 static void panic(const char *fmt, ...)
 {
   va_list vl;
@@ -201,10 +214,14 @@ static void drawstatus(unsigned stat, char *cmd)
 {
   if (cmd) {
     printf("%s", cmd);
-  } else if ((stat & (stat_eof | stat_susp | stat_htmode | stat_ttmode))) {
+  } else if ((stat & (stat_eof | stat_susp | stat_htmode | stat_ttmode |
+                      stat_grep)))
+  {
     if ((stat & stat_eof))
       printf("EOF ");
-    else if ((stat & stat_htmode))
+    if ((stat & stat_grep))
+      printf("GREP (%d) ", ngrep);
+    if ((stat & stat_htmode))
       printf("TRIG (/%s) ", trigpat);
     else if ((stat & stat_ttmode))
       printf("TRIG (?%s) ", trigpat);
@@ -241,7 +258,7 @@ static void redraw(char **circbuf, int nlines, int hpos,
   drawstatus(stat, cmd);
 }
 
-static void execute(char *cmd)
+static void execute(char *cmd, unsigned *pstat)
 {
   char *arg = cmd + 2 + strspn(cmd + 2, " \t");
 
@@ -300,6 +317,47 @@ static void execute(char *cmd)
         sprintf(cmd, "piped!");
     }
     break;
+  case 'g':
+  case 'v':
+    {
+      int err;
+      grep *gr = &grepstack[ngrep];
+
+      if (arg[0] == 0) {
+        sprintf(cmd, "pattern required!");
+        break;
+      }
+
+      if (ngrep >= maxgrep) {
+        sprintf(cmd, "too many greps");
+        break;
+      }
+
+      if ((err = regcomp(&gr->rx, arg, REG_EXTENDED | REG_NOSUB)) != 0) {
+        regerror(err, &gr->rx, cmd, cmdsize);
+        break;
+      }
+
+      gr->pat = dsdup(arg);
+
+      if (cmd[1] == 'v')
+        gr->inv = 1;
+
+      if (ngrep++ == 0)
+        *pstat |= stat_grep;
+    }
+    break;
+  case 'r':
+    while (ngrep > 0) {
+      grep *gr = &grepstack[--ngrep];
+      regfree(&gr->rx);
+      dsdrop(gr->pat);
+      if (cmd[2] != '!')
+        break;
+    }
+    if (ngrep == 0)
+      *pstat &= ~stat_grep;
+    break;
   default:
     sprintf(cmd, "bad command");
     break;
@@ -328,7 +386,7 @@ int main(int argc, char **argv)
   };
   int auto_quit = 1;
   int exit_status = EXIT_FAILURE;
-  char cmdbuf[100], *curcmd = 0;
+  char cmdbuf[cmdsize], *curcmd = 0;
 
   if (fd < 0)
     panic("unable to obtain input file descriptor");
@@ -435,27 +493,42 @@ int main(int argc, char **argv)
       } else {
         nfds = 1;
         line = addch(line, 0);
-        if ((stat & stat_htmode))
-          if (regexec(&trigex, line, 0, NULL, 0) == 0)
-            stat |= stat_trgrd;
-        if (nlines == maxlines) {
-          dsdrop(circbuf[0]);
-          memmove(circbuf, circbuf + 1, (nlines - 1) * sizeof *circbuf);
-          circbuf[nlines - 1] = line;
-          stat |= stat_dirty;
-          if ((stat & stat_ttmode))
-            if (regexec(&trigex, circbuf[0], 0, NULL, 0) == 0)
+        if ((stat & stat_grep)) {
+          int i;
+          for (i = 0; i < ngrep; i++) {
+            grep *gr = &grepstack[i];
+            int match = regexec(&gr->rx, line, 0, NULL, 0) == 0;
+            if (match == gr->inv)
+              break;
+          }
+          if (i < ngrep) {
+            dsdrop(line);
+            line = 0;
+          }
+        }
+        if (line) {
+          if ((stat & stat_htmode))
+            if (regexec(&trigex, line, 0, NULL, 0) == 0)
               stat |= stat_trgrd;
-        } else {
-          circbuf[nlines++] = line;
-          if ((stat & stat_susp) == 0) {
-            snapshot[snaplines++] = dsref(line);
-            clrline();
-            drawline(line, hpos, columns);
-            drawstatus(stat, curcmd);
+          if (nlines == maxlines) {
+            dsdrop(circbuf[0]);
+            memmove(circbuf, circbuf + 1, (nlines - 1) * sizeof *circbuf);
+            circbuf[nlines - 1] = line;
+            stat |= stat_dirty;
+            if ((stat & stat_ttmode))
+              if (regexec(&trigex, circbuf[0], 0, NULL, 0) == 0)
+                stat |= stat_trgrd;
+          } else {
+            circbuf[nlines++] = line;
+            if ((stat & stat_susp) == 0) {
+              snapshot[snaplines++] = dsref(line);
+              clrline();
+              drawline(line, hpos, columns);
+              drawstatus(stat, curcmd);
+            }
           }
+          line = 0;
         }
-        line = 0;
       }
     } else {
       nfds = 1;
@@ -606,7 +679,7 @@ int main(int argc, char **argv)
             stat |= stat_dirty;
             if (ch == 13) {
               if (kbd_state == kbd_colon && cmdbuf[1]) {
-                execute(cmdbuf);
+                execute(cmdbuf, &stat);
                 if (cmdbuf[0] != 0) {
                   kbd_state = kbd_result;
                   break;