Tighten the command syntax.

Commands are now separated from their argument by exactly
one space, which may only be omitted for an argument which
does not begin with a letter.

Thus :gfoo no longer pushes a regular expression foo onto
the grep stack, but is the unrecognized command gfoo.
The command :g  foo specifies the regular expression " foo".

2 files changed, 40 insertions, 14 deletions

diff --git a/pw.1 b/pw.1
index 6729e47..b818c0e 100644
--- a/pw.1
+++ b/pw.1
@@ -578,13 +578,27 @@ direction.
 
 .SH COLON COMMANDS
 
-First, some general remarks. Display refresh doesn't pause during the editing
-of a colon command. If that is required, the suspend command must be used.
-The space between the command and the argument may be omitted. After a command
-is executed, a result message appears in its place.  This message persists over
-the poll interval period. The longer the poll interval
-.RB ( -i " option),
-the longer the result message persists.
+First, some general remarks.
+
+The capture of snaphots, driving display refresh, doesn't pause during the
+editing of a colon command. If that is desired, the suspend command must
+be used first.
+
+The name of a colon command consists of lower-case letters. Currently, no
+command has a name more than one letter long. The command may be followed
+by an argument, which is separated from the command by exactly one space.
+If the argument does not begin with a lower-case letter, then the space
+may be omitted. If the command is followed by no characters at all, or
+exactly one space, then its argument is effectively the empty string;
+by convention, this is understood as there being no argument.
+
+When a command is executed, a message appears in its place, diagnosing
+an error situation or confirming a successful result. When such a message
+appears, it persists until a command is issued. If the command is Enter,
+it has only the effect of dismissing the message and restoring the usual
+status line, and not the usual effect of resuming
+.I pw
+out of suspended capture mode.
 
 Colon commands are saved in a history which may be navigated for
 recall using the up and down arrow keys or
@@ -592,6 +606,8 @@ recall using the up and down arrow keys or
 and
 .BR Ctrl-N .
 
+The commands are:
+
 .IP "\fB:w\fP \fIfilename\fP"
 Write the currently displayed lines into the specified file.
 
@@ -636,8 +652,9 @@ 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.
+modifier is added to the command, then it pops the entire stack,
+forgetting all the patterns and disabling grep mode. The modifier
+is not an argument and may not be separated from the command.
 
 .IP "\fB:i\fP \fIreal\fP"
 Set the poll interval to the number of seconds specified by
diff --git a/pw.c b/pw.c
index aaaeea0..1a1e5ea 100644
--- a/pw.c
+++ b/pw.c
@@ -801,9 +801,15 @@ static execode execute(pwstate *pw, char *cmd, char *resbuf,
                        size_t size, int count)
 {
   execode res = exec_failed;
-  char *arg = cmd + 2 + strspn(cmd + 2, " \t");
+  char cmdbuf[16];
+  int cmdlen = 0;
+  int ntok = sscanf(cmd + 1, "%15[a-z]%n", cmdbuf, &cmdlen);
+  char *arg = cmd + 1 + cmdlen;
 
-  if (cmd[0] == ':') switch (cmd[1]) {
+  if (*arg == ' ')
+    arg++;
+
+  if (cmd[0] == ':' && ntok == 1 && cmdlen == 1) switch (cmd[1]) {
   case 'w': case 'a':
     if (arg[0] == 0) {
       snprintf(resbuf, size, "file name required!");
@@ -989,7 +995,7 @@ static execode execute(pwstate *pw, char *cmd, char *resbuf,
           rflg = gr->flags;
           fputs(((gr->flags & REG_EXTENDED)) ? ":E\n" : ":B\n", f);
         }
-        fputs(gr->inv ? ":v" : ":g", f);
+        fputs(gr->inv ? ":v " : ":g ", f);
         fputs(gr->pat, f);
         putc('\n', f);
       }
@@ -1027,9 +1033,9 @@ static execode execute(pwstate *pw, char *cmd, char *resbuf,
     res = exec_ok;
     break;
   default:
-    snprintf(resbuf, size, "bad command");
+    goto badcmd;
     break;
-  } else {
+  } else if (cmd[0] == '?' || cmd[0] == '/') {
     int trig = count > 0 ? count - 1 : count;
 
     if (trig < pw->maxlines && trig < maxtrig)
@@ -1082,6 +1088,9 @@ static execode execute(pwstate *pw, char *cmd, char *resbuf,
         }
       }
     }
+  } else {
+badcmd:
+    snprintf(resbuf, size, "unrecognized command");
   }
 
   return res;