$_=<<END_OF_FILTER;
(AND
  (OR
    (AND
      (COND AUTHOR=John)
      (COND PROFIT=90%)
    )
    (AND
      (COND AUTHOR=Matt)
      (COND PROFIT=80%)
    )
  )
  (COND PUBLISHER=OReilly)
)
END_OF_FILTER

%hash = (
	AUTHOR=> 'John',
	PROFIT=> '90%',
	PUBLISHER=> 'OReilly',
	BOOK=> 'OPERATING SYSTEMS'
);

sub AND
{
	print "and debug: [@_]";
	for(@_)
		{ return 0 if ! $_ }
	return 1
}
	
sub OR
{
	print "or debug: [@_]";
	for(@_)
		{ return 1 if $_ }
	return 0
}
	
sub COND
{
	my ($key, $value)=@_;
	$ret = 0 | ($hash{$key} eq $value);
	print "cond debug: @_ -> $ret";
	return $ret
}

# add comas between ) and ( braces
s/\)(\s*)\(/),$1(/g;

# convert COND a little - I hope you do not have O'reilly name... :)
s/\(COND (\w+)=([^)]+)\)/(COND '$1','$2')/g;

# we have proper parens already, move it only
s/\((AND|OR|COND)\b/$1(/g;

# see how it looks now
print $_;

# and voila!
print "ok" if eval;

##</code><code>##

s/\w+=\S+/(COND $&)/g