algo: make ReversedBMH use size_t instead of ints

ints unnecessarily reduce range of values for indexes

alib2algo/src/stringology/exact/ReversedBoyerMooreHorspool.h

@@ -31,18 +31,29 @@ ext::set < unsigned > ReversedBoyerMooreHorspool::match ( const string::LinearSt
 	ext::set < unsigned > occ;
 	ext::map < SymbolType, size_t > bcs = string::properties::ReversedBadCharacterShiftTable::bcs ( pattern ); // NOTE: the subjects alphabet must be a subset or equal to the pattern
-	int haystack_offset = string.getContent ( ).size ( ) - pattern.getContent ( ).size ( );
-	while ( haystack_offset >= 0 ) {
-		size_t i = 0;
-		while ( i < pattern.getContent ( ).size ( ) && string.getContent ( )[haystack_offset + i] == pattern.getContent ( )[i] )
-			i++;
+	if ( string.getContent ( ).size ( ) < pattern.getContent ( ).size ( ) )
+		return occ;
+	 // index to the subject
+	size_t i = string.getContent ( ).size ( ) - pattern.getContent ( ).size ( );
+	 // main loop of the algorithm over all possible indexes where the pattern can start
+	while ( true ) {
+		size_t j = 0;
+
+		while ( j < pattern.getContent ( ).size ( ) && string.getContent ( ) [ i + j ] == pattern.getContent ( ) [ j ] )
+			j++;
 		 // Yay, there is match!!!
-		if ( i == pattern.getContent ( ).size ( ) ) occ.insert ( haystack_offset );
-		haystack_offset -= bcs[string.getContent ( )[haystack_offset]];
+		if ( j == pattern.getContent ( ).size ( ) ) occ.insert ( i );
+
+		 // shift heristics
+		size_t shift = bcs [ string.getContent ( ) [ i ] ];
+
+		if ( shift > i )
+			break;
+		i -= shift;
 		// common::Streams::out << haystack_offset << std::endl;
 	}