#!/usr/bin/perl

# Run the command into PS
# Run gv with the -watch option
# go into a loop watching the file and rerun command whenever the file
# has changed.

use POSIX ":sys_wait_h";

$usage = "usage: $0 comand -args -args filename\n";

die $usage unless -f $ARGV[$#ARGV];
$file = $ARGV[$#ARGV];
$cmd = "@ARGV > PS";
$gv = "gv -spartan -antialias PS";

system $cmd;
$pid = fork;
if ($pid == 0) {
	exec $gv;
	die $gv;
}
$stat{$file} = (stat($file))[9];
open(F, $file);
while (<F>) {
	next unless /^\.so\s+(.*)\s*$/;
	$stat{$1} = (stat($1))[9];
}
close(F);
while (1) {
	select(undef, undef, undef, .2);
	$kid = waitpid($pid,&WNOHANG);
	exit 0 if (kill(0, $pid) != 1);
	$doit = 0;
	foreach $f (keys %stat) {
		if ($stat{$f} != (stat($f))[9]) {
			$stat{$f} = (stat($f))[9];
			$doit = 1;
		}
	}
	if ($doit) {
		system $cmd;
		kill(1, $pid);
	}
}