Re: questions - calling matheval() for printf

[Oliver Kiddle <okiddle@xxxxxxxxxxx>]

Peter Stephenson wrote:
> 
> Sorry I didn't reply to this (the bits Bart didn'g) earlier...

Thanks. I've got another question here I'm afraid.

> If we need this, it would be better to hack matheval to give it an option
> to stop and return a pointer to the end, just like strtol().  But I don't
> think we need to adhere to POSIX printf semantics that closely.  I'd be
> more interested in what other shells do.

Ksh handles things in the way that zsh perhaps ideally should:

$ printf '%d\n' 4a
ksh: printf: 4a: arithmetic syntax error
ksh: printf: warning: invalid argument of type d
4
$ printf '%d\n' 123456789012
ksh: printf: warning: 123456789012: overflow exception
2147483647

(though I see no need for two error messages in the first case)

Bash produces an error in each case though it fails to output 4 and max
int respectively as POSIX stipulates. Note that bash doesn't attempt
arithmetic evaluation here.

> > Can a 64-bit integer be something other than long long? It seems I only
> > have ZSH_64_BIT_TYPE to check and it might need a different format
> > specifier for printf(3) if this is something other than long long.
> 
> On Alpha, it will normally be long rather than long long.  However, I
> compiled sizeof(long long) with gcc on the Alpha at Sourceforge, and that

I'll do a bit of testing on Sourceforge then. Thanks.

> Can we make %q do just the same as what ${(q)foo} would do?

Yes. That is what it does at the moment so I'll just ditch the patch.

I have below another experimental feature. This allows the argument to
be specified in the format in much the same way as is possible with
printf(3). e.g:

printf '%2$s %s %1$s\n' World Good Morning

will print `Good Morning World'

Note that glibc's printf(3) would print `Good Good World' for this but
it seems to be the exception.

The question is how should this interact with the printf(1) feature of
reusing the format if more arguments remain. The easy answer would be
to not reuse the format if this feature had been used. As an
experiment, I've made it remove all arguments up to the last one used.
This allows interesting things like:

% printf '%2$s %1$s ' 1 2 3 4 5 6 ;echo
2 1 4 3 6 5

I can see this having some uses but I can also see it being a problem
as this is likely to be used for picking out fields where the arguments
are some command in $(...). A possibly quite good option would be an
option to print to disable format reuse (in which case any suggestion
on the choice of option letter?). Any other ideas on this?

Note that there is no ksh precedent here as ksh seg faults if you give
it these argument specifiers (I've got a lot of bug reporting to do
when I finish this).

If you try the patch, be aware that things may go awry if you try
specifying widths and precisions.

Oliver

Index: Src/builtin.c
===================================================================
RCS file: /cvsroot/zsh/zsh/Src/builtin.c,v
retrieving revision 1.58
diff -u -r1.58 builtin.c
--- Src/builtin.c	2001/10/15 11:34:27	1.58
+++ Src/builtin.c	2001/10/15 16:54:35
@@ -2892,7 +2892,8 @@
 int
 bin_print(char *name, char **args, char *ops, int func)
 {
-    int flen, width, prec, type, argc, n, nnl = 0, ret = 0;
+    int flen, width, prec, type, argc, n, gotwidth;
+    int nnl = 0, ret = 0, maxarg = 0;
     int flags[5], *len;
     char *start, *endptr, *c, *d, *flag, spec[11], *fmt = NULL;
     char **first, *flagch = "0+- #", save, nullstr = '\0';
@@ -3095,6 +3096,11 @@
     /* printf style output */
     *spec='%';
     do {
+    	if (maxarg) {
+	    first += maxarg;
+	    argc -= maxarg;
+    	    maxarg = 0;
+	}
 	for (c = fmt;c-fmt < flen;c++) {
 	    if (*c != '%') {
 		putc(*c, fout);
@@ -3110,7 +3116,7 @@
 	    }
 
 	    type = prec = -1;
-	    width = 0;
+	    width = gotwidth = 0;
 	    d = spec + 1;
 
 	    /* copy only one of each flag as spec has finite size */
@@ -3123,13 +3129,32 @@
 	    	c++;
 	    }
 
-	    if (*c == '*') {
-		if (*args) width = (int)mathevali(*args++);
-		c++;
-	    } else if (idigit(*c)) {
+	    if (idigit(*c)) {
 		width = strtoul(c, &endptr, 0);
 		c = endptr;
+		if (*c == '$') {
+		    DPUTS(width <= 0, "specified zero or negative arg");
+		    if (width > argc) {
+		    	zwarnnam(name, "%d: argument specifier out of range",
+			    0, width);
+			ret = 1;
+		    } else {
+		    	if (width > maxarg) maxarg = width;
+		    	args = first + width - 1;
+		    }
+		    if (idigit(*++c)) {
+		    	width = strtoul(c, &endptr, 0);
+			c = endptr;
+			gotwidth = 1;
+		    } else
+		    	width = 0;
+		} else
+		    gotwidth = 1;
 	    }
+	    if (!gotwidth && *c == '*') {
+		if (*args) width = (int)mathevali(*args++);
+		c++;
+	    }
 	    *d++ = '*';
 
 	    if (*c == '.') {
@@ -3224,7 +3249,7 @@
 		    	*d++ = 'l', *d++ = *c, *d = '\0';
 			zlongval = (*args) ? mathevali(*args++) : 0;
 			if (errflag) {
-			    zlongval = 0;
+			    doubleval = 0;
 			    errflag = 0;
 			}
 			print_val(zlongval)
@@ -3255,8 +3280,11 @@
 		    }
 		}
 	    }
+	    if (maxarg && (args - first > maxarg))
+	    	maxarg = args - first;
 	}
 
+    	if (maxarg) args = first + maxarg;
     /* if there are remaining args, reuse format string */
     } while (*args && args != first);

_____________________________________________________________________
This message has been checked for all known viruses by the 
MessageLabs Virus Scanning Service. For further information visit
http://www.messagelabs.com/stats.asp