#! perl -sw
use strict;

my @stack;
while( <DATA> ) {
	print;
	s[NOT\s+][-]g;
	1 while s[(?<!\+)(\b\w+\b)\s+AND\s+][+$1 AND ]g
	  or    s[\s+AND\s+(?<!\+)(\b\w+\b)][ AND +$1]g;
	s[\sAND\s][ ]g;
	s[\s+OR\s+][ ]g;
	print $_, $/;
}

__DATA__
word1 AND word2
word1 OR word2
word1 AND NOT word2
(word1 AND NOT word2) OR word3
word1 AND word2 AND word3
(word1 AND word2 OR word3) AND NOT (word4 OR word5)
(word1 AND (word2 OR (word3 AND word4 AND NOT word5)) AND word6) OR word7