Add a vi-like colon mode with :w, :a and :! commands.

2 files changed, 192 insertions, 14 deletions

diff --git a/pw.1 b/pw.1
index db849fa..e33e2e4 100644
--- a/pw.1
+++ b/pw.1
@@ -156,6 +156,45 @@ status string disappears. If the status is already
 .B EOF
 then suspend mode cannot be entered.
 
+.IP \fB:\fP
+Enter colon command mode. In colon command mode, the status line clears
+and a colon prompt appears there. An extended command can be entered.
+Pressing
+.I Enter
+in colon mode dispatches the command. Simple editing is available:
+backspace,
+.B Ctrl-W
+word erase and
+.B Ctrl-U
+line erase.  If backspace is used in an empty colon line, colon mode
+terminates without executing a command.
+.B Ctrl-C
+and
+.B Esc
+also terminate colon mode without executing a command. Colon commands
+are documented in the COLON COMMANDS section below.
+
+.SH COLON COMMANDS
+
+First, some general remarks. the current contents of the FIFO buffer may have
+changed relative to what is displayed on the screen. The space between the
+command and the argument may be omitted. The command is replaced with
+a result string, which persists over the poll interval period. The longer
+the poll interval
+.RB ( -i " option),
+the longer the result message persists.
+
+.IP "\fB:w\fP \fIfilename\fP"
+Write the current contents of the FIFO buffer into the specified file.
+
+.IP "\fB:a\fP \fIfilename\fP"
+Append the current contents of the FIFO buffer into the specified file.
+
+.IP "\fB:!\fP \fIfilename\fP"
+Pipe the current contents of the FIFO buffers into the specified command.
+.PP
+Any other command results in a brief error message.
+
 .SH OPTIONS
 
 .IP "\fB-i\fP \fIreal\fP"
@@ -241,6 +280,12 @@ screen.
 There is no support for unwrapping long lines, which would be useful for
 copy and paste.
 
+Ctrl-Z suspend is missing.
+
+During the
+.B :!
+command's execution, the TTY settings are not restored.
+
 .SH AUTHOR
 Kaz Kylheku <kaz@kylheku.com>
 
diff --git a/pw.c b/pw.c
index 8d79183..5ef006d 100644
--- a/pw.c
+++ b/pw.c
@@ -114,29 +114,93 @@ static void drawline(const char *line, int hpos, int columns)
   }
 }
 
-static void drawstatus(unsigned stat)
+static void clear_cur_line()
+{
+  printf("\r\033[J");
+}
+
+static void drawstatus(unsigned stat, char *cmd)
 {
-  if ((stat & (stat_eof | stat_susp))) {
+  if (cmd) {
+    printf(":%s", cmd);
+  } else if ((stat & (stat_eof | stat_susp))) {
     if ((stat & stat_eof))
       printf("EOF ");
     if ((stat & stat_susp))
       printf("SUSPENDED ");
-    fflush(stdout);
+  } else {
+    clear_cur_line();
   }
+  fflush(stdout);
 }
 
 static void redraw(char **circbuf, int nlines, int hpos,
-                   int columns, unsigned stat)
+                   int columns, unsigned stat, char *cmd)
 {
   printf("\r\033[%dA\033[J", nlines);
   for (int i = 0; i < nlines; i++)
     drawline(circbuf[i], hpos, columns);
-  drawstatus(stat);
+  drawstatus(stat, cmd);
 }
 
-static void clear_cur_line()
+static void execute(char *cmd, char **circbuf, int nlines)
 {
-  printf("\r\033[J");
+  char *arg = cmd + 1 + strspn(cmd + 1, " \t");
+
+  clear_cur_line();
+
+  switch (cmd[0]) {
+  case 'w': case 'a':
+    {
+      FILE *f = fopen(arg, cmd[0] == 'w' ? "w" : "a");
+      int ok = 1;
+
+      if (!f) {
+        sprintf(cmd, "unable to open file");
+        break;
+      }
+
+      for (int i = 0; ok && i < nlines; i++)
+        if (fprintf(f, "%s\n", circbuf[i]) < 0) {
+          sprintf(cmd, "write error!");
+          ok = 0;
+          break;
+        }
+
+      fclose(f);
+      if (ok)
+        sprintf(cmd, "saved!");
+    }
+    break;
+  case '!':
+    {
+      FILE *p = popen(arg, "w");
+      int ok = 1;
+
+      if (!p) {
+        sprintf(cmd, "unable to open command");
+        fflush(stdout);
+        break;
+      }
+
+      for (int i = 0; i < nlines && ok; i++)
+        if (fprintf(p, "%s\n", circbuf[i]) < 0) {
+          sprintf(cmd, "write error!");
+          ok = 0;
+          break;
+        }
+
+      pclose(p);
+      if (ok)
+        sprintf(cmd, "piped!");
+    }
+    break;
+  default:
+    sprintf(cmd, "bad command");
+    break;
+  }
+
+  fflush(stdout);
 }
 
 int main(int argc, char **argv)
@@ -153,9 +217,10 @@ int main(int argc, char **argv)
   struct termios tty_saved, tty_new;
   struct winsize ws = { 0 };
   int columns = 80;
-  enum kbd_state { kbd_cmd, kbd_esc, kbd_bkt, kbd_exit };
+  enum kbd_state { kbd_cmd, kbd_esc, kbd_bkt, kbd_exit, kbd_colon, kbd_result };
   int auto_quit = 1;
   int exit_status = EXIT_FAILURE;
+  char cmdbuf[100], *colcmd = 0;
 
   if (fd < 0)
     panic("unable to obtain input file descriptor");
@@ -241,7 +306,7 @@ int main(int argc, char **argv)
       now = (((unsigned) tv.tv_sec)%1000000)*1000 + tv.tv_usec/1000;
       if (lasttime == ~0U || now - lasttime > (unsigned) long_interval) {
         if ((stat & stat_dirty) && nlines == maxlines)
-          redraw(circbuf, nlines, hpos, columns, stat);
+          redraw(circbuf, nlines, hpos, columns, stat, colcmd);
         lasttime = now;
         stat &= ~stat_dirty;
       }
@@ -249,10 +314,15 @@ int main(int argc, char **argv)
 
     if (poll(pe, ((stat & stat_eof)) ? 1 : 2, poll_interval) <= 0) {
       if ((stat & stat_dirty) && nlines == maxlines) {
-        redraw(circbuf, nlines, hpos, columns, stat);
+        redraw(circbuf, nlines, hpos, columns, stat, colcmd);
         stat &= ~stat_dirty;
       }
-      kbd_state = kbd_cmd;
+      if (kbd_state == kbd_esc || kbd_state == kbd_result) {
+        kbd_state = kbd_cmd;
+        colcmd = 0;
+        clear_cur_line();
+        drawstatus(stat, colcmd);
+      }
     } else {
       if ((stat & stat_eof) == 0 && pe[1].revents) {
         if ((line = getln(stdin))) {
@@ -269,14 +339,14 @@ int main(int argc, char **argv)
             circbuf[nlines++] = line;
             clear_cur_line();
             drawline(line, hpos, columns);
-            drawstatus(stat);
+            drawstatus(stat, colcmd);
           }
         } else {
           if (auto_quit)
             kbd_state = kbd_exit;
           else
             stat |= stat_eof;
-          redraw(circbuf, nlines, hpos, columns, stat);
+          redraw(circbuf, nlines, hpos, columns, stat, colcmd);
           stat |= stat_eof;
           stat &= ~stat_dirty;
           if (!ferror(stdin))
@@ -326,6 +396,11 @@ int main(int argc, char **argv)
           case 27:
             kbd_state = kbd_esc;
             break;
+          case ':':
+            kbd_state = kbd_colon;
+            cmdbuf[0] = 0;
+            colcmd = cmdbuf;
+            break;
           }
           break;
         case kbd_esc:
@@ -347,13 +422,71 @@ int main(int argc, char **argv)
             goto fakecmd;
           }
           break;
+        case kbd_colon:
+          switch (ch) {
+          case 27: case 13: case 3:
+            kbd_state = kbd_cmd;
+            stat |= stat_dirty;
+            if (ch == 13 && cmdbuf[0]) {
+              execute(cmdbuf, circbuf, nlines);
+              stat &= ~stat_dirty;
+              kbd_state = kbd_result;
+              break;
+            }
+            colcmd = 0;
+            break;
+          case 8: case 127:
+            {
+              size_t len = strlen(cmdbuf);
+              if (len == 0) {
+                kbd_state = kbd_cmd;
+                colcmd = 0;
+                stat |= stat_dirty;
+              } else {
+                cmdbuf[--len] = 0;
+              }
+            }
+            break;
+          case 21:
+            cmdbuf[0] = 0;
+            break;
+          case 23:
+            {
+              size_t len = strlen(cmdbuf);
+              while (len > 0 && isspace((unsigned char) cmdbuf[len - 1]))
+                len--;
+              while (len > 0 && !isspace((unsigned char) cmdbuf[len - 1]))
+                len--;
+              cmdbuf[len] = 0;
+            }
+            break;
+          default:
+            if (isprint(ch))
+            {
+              size_t len = strlen(cmdbuf);
+              if (len < sizeof cmdbuf - 1 && (int) len < columns - 1) {
+                cmdbuf[len++] = ch;
+                cmdbuf[len] = 0;
+              }
+            }
+            break;
+          }
+          break;
+        case kbd_result:
+          kbd_state = kbd_cmd;
+          stat |= stat_dirty;
+          colcmd = 0;
+          break;
         case kbd_exit:
           break;
         }
 
         if ((stat & stat_dirty)) {
-          redraw(circbuf, nlines, hpos, columns, stat);
+          redraw(circbuf, nlines, hpos, columns, stat, colcmd);
           stat &= ~stat_dirty;
+        } else if (kbd_state == kbd_colon || kbd_state == kbd_result) {
+          clear_cur_line();
+          drawstatus(stat, colcmd);
         }
       }
     }