# assert.pl
# [email protected] (Tom Christiansen)
#
# Usage:
#
# &assert('@x > @y');
# &assert('$var > 10', $var, $othervar, @various_info);
#
# That is, if the first expression evals false, we blow up. The
# rest of the args, if any, are nice to know because they will
# be printed out by &panic, which is just the stack-backtrace
# routine shamelessly borrowed from the perl debugger.

sub assert {
&panic("ASSERTION BOTCHED: $_[$[]",$@) unless eval $_[$[];
}

sub panic {
package DB;

select(STDERR);

print "\npanic: @_\n";

exit 1 if $] <= 4.003; # caller broken

# stack traceback gratefully borrowed from perl debugger

local $_;
my $i;
my ($p,$f,$l,$s,$h,$a,@a,@frames);
for ($i = 0; ($p,$f,$l,$s,$h,$w) = caller($i); $i++) {
@a = @args;
for (@a) {
if (/^StB\000/ && length($_) == length($_main{'_main'})) {
$_ = sprintf("%s",$_);
}
else {
s/'/\\'/g;
s/([^\0]*)/'$1'/ unless /^-?[\d.]+$/;
s/([\200-\377])/sprintf("M-%c",ord($1)&0177)/eg;
s/([\0-\37\177])/sprintf("^%c",ord($1)^64)/eg;
}
}
$w = $w ? '@ = ' : '$ = ';
$a = $h ? '(' . join(', ', @a) . ')' : '';
push(@frames, "$w&$s$a from file $f line $l\n");
}
for ($i=0; $i <= $#frames; $i++) {
print $frames[$i];
}
exit 1;
}

1;