From f476ca3777265350305d1f89b04949d6dd0ec8e4 Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Thu, 28 Apr 2022 07:37:44 -0700
Subject: History recall for colon commands and trigger patterns.

---
 pw.1 | 11 +++++++++
 pw.c | 91 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++------
 2 files changed, 94 insertions(+), 8 deletions(-)

diff --git a/pw.1 b/pw.1
index 428a5c1..5c0240e 100644
--- a/pw.1
+++ b/pw.1
@@ -211,6 +211,11 @@ appears, showing the pattern preceded by a question mark.
 The
 .I pattern
 is an extended regular expression (ERE).
+Trigger patterns saved in a history which may be navigated for
+recall using the up and down arrow keys or
+.B Ctrl-P
+and
+.BR Ctrl-N .
 
 .SH COLON COMMANDS
 
@@ -222,6 +227,12 @@ the poll interval period. The longer the poll interval
 .RB ( -i " option),
 the longer the result message persists.
 
+Colon commands are saved in a history which may be navigated for
+recall using the up and down arrow keys or
+.B Ctrl-P
+and
+.BR Ctrl-N .
+
 .IP "\fB:w\fP \fIfilename\fP"
 Write the current contents of the display into the specified file.
 
diff --git a/pw.c b/pw.c
index 7782057..f3c4c34 100644
--- a/pw.c
+++ b/pw.c
@@ -56,6 +56,12 @@ regex_t trigex;
 grep grepstack[maxgrep];
 int ngrep;
 
+char **cmdhist;
+unsigned ncmdhist;
+
+char **pathist;
+unsigned npathist;
+
 static void panic(const char *fmt, ...)
 {
   va_list vl;
@@ -410,7 +416,7 @@ int main(int argc, char **argv)
   };
   int auto_quit = 1;
   int exit_status = EXIT_FAILURE;
-  char cmdbuf[cmdsize], *curcmd = 0;
+  char cmdbuf[cmdsize], *curcmd = 0, *savedcmd = 0;
 
   if (fd < 0)
     panic("unable to obtain input file descriptor");
@@ -486,8 +492,8 @@ int main(int argc, char **argv)
     panic("unable to set stdin nonblocking");
 
   for (unsigned stat = stat_dirty, hpos = 0,
-                kbd_state = kbd_cmd, lasttime = ~0U,
-                work = 1000;
+                kbd_state = kbd_cmd, kbd_prev = kbd_cmd, lasttime = ~0U,
+                work = 1000, histpos = 0;
        kbd_state != kbd_exit ;)
   {
     int force = 0, nfds = 2, pollms = poll_interval;
@@ -647,16 +653,19 @@ int main(int argc, char **argv)
             stat |= stat_dirty;
             break;
           case ESC:
+            kbd_prev = kbd_state;
             kbd_state = kbd_esc;
             break;
           case ':':
             kbd_state = kbd_colon;
+            histpos = 0;
             cmdbuf[0] = ch;
             cmdbuf[1] = 0;
             curcmd = cmdbuf;
             break;
           case '/': case '?':
             kbd_state = kbd_trig;
+            histpos = 0;
             cmdbuf[0] = ch;
             cmdbuf[1] = 0;
             curcmd = cmdbuf;
@@ -664,13 +673,16 @@ int main(int argc, char **argv)
           }
           break;
         case kbd_esc:
-          kbd_state = kbd_cmd;
-          if (ch == '[')
+          if (ch == '[') {
             kbd_state = kbd_bkt;
+            break;
+          }
+          kbd_state = kbd_cmd;
+          curcmd = 0;
           break;
         case kbd_bkt:
-          kbd_state = kbd_cmd;
-          switch (ch) {
+          kbd_state = kbd_prev;
+          if (kbd_prev == kbd_cmd) switch (ch) {
           case 'D':
             ch = 'h';
             goto fakecmd;
@@ -681,6 +693,14 @@ int main(int argc, char **argv)
             ch = '0';
             goto fakecmd;
           }
+          switch (ch) {
+          case 'A':
+            ch = ctrl('p');
+            goto fakecmd;
+          case 'B':
+            ch = ctrl('n');
+            goto fakecmd;
+          }
           break;
         case kbd_trig:
           if (trigpat) {
@@ -692,8 +712,28 @@ int main(int argc, char **argv)
           // fallthrough
         case kbd_colon:
           switch (ch) {
-          case ESC: case CR: case ctrl('c'):
+          case ESC:
+            kbd_prev = kbd_state;
+            kbd_state = kbd_esc;
+            break;
+          case CR: case ctrl('c'):
             if (ch == CR) {
+              if (cmdbuf[1]) {
+                unsigned *pnhist = (kbd_state == kbd_colon
+                                    ? &ncmdhist : &npathist);
+                unsigned nhist = *pnhist;
+                char ***hist = (kbd_state == kbd_colon ?
+                                &cmdhist : &pathist);
+
+                if (nhist == 0 || strcmp(cmdbuf, (*hist)[0]) != 0) {
+                  if ((*hist = realloc(*hist, sizeof **hist * (nhist + 1))) == 0)
+                    panic("out of memory");
+                  memmove(*hist + 1, *hist, sizeof **hist * nhist);
+                  *pnhist = nhist + 1;
+                  (*hist)[0] = dsdup(cmdbuf);
+                }
+              }
+
               if (kbd_state == kbd_colon && cmdbuf[1]) {
                 execute(cmdbuf, &stat);
                 if (cmdbuf[0] != 0) {
@@ -744,6 +784,41 @@ int main(int argc, char **argv)
               cmdbuf[len] = 0;
             }
             break;
+          case ctrl('p'):
+          case ctrl('n'):
+            {
+              unsigned nhist = (kbd_state == kbd_colon ? ncmdhist : npathist);
+              char ***hist = (kbd_state == kbd_colon ? &cmdhist : &pathist);
+
+              if (ch == ctrl('p')) {
+                if (histpos == 0) {
+                  dsdrop(savedcmd);
+                  savedcmd = dsdup(cmdbuf);
+                } else {
+                  dsdrop((*hist)[histpos-1]);
+                  (*hist)[histpos-1] = dsdup(cmdbuf);
+                }
+                if (histpos < nhist) {
+                  char *cmd = (*hist)[histpos++];
+                  strcpy(cmdbuf, cmd);
+                }
+              } else {
+                if (histpos >= 1) {
+                  dsdrop((*hist)[histpos-1]);
+                  (*hist)[histpos-1] = dsdup(cmdbuf);
+                }
+                if (histpos > 1) {
+                  char *cmd = (*hist)[--histpos - 1];
+                  strcpy(cmdbuf, cmd);
+                } else if (histpos == 1) {
+                  --histpos;
+                  strcpy(cmdbuf, savedcmd);
+                  dsdrop(savedcmd);
+                  savedcmd = 0;
+                }
+              }
+            }
+            break;
           default:
             if (isprint(ch))
             {
-- 
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