blank symbol

alib2/src/alphabet/Blank.cpp

+/*
+ * Blank.cpp
+ *
+ *  Created on: Mar 26, 2013
+ *      Author: Jan Travnicek
+ */
+
+#include "Blank.h"
+
+namespace alphabet {
+
+Blank::Blank() : Symbol("") {
+
+}
+
+} /* namespace alphabet */

alib2/src/alphabet/Blank.h

+/*
+ * Blank.h
+ *
+ *  Created on: Mar 26, 2013
+ *      Author: Jan Trávníček
+ */
+
+#ifndef BLANK_H_
+#define BLANK_H_
+
+#include "Symbol.h"
+
+namespace alphabet {
+
+/**
+ * Represents blank symbol in an alphabet.
+ */
+class Blank : public Symbol {
+public:
+	/**
+	 * Creates a blank symbol.
+	 * @param symbol name of the symbol
+	 */
+	Blank();
+
+};
+
+} /* namespace alphabet */
+
+#endif /* BLANK_H_ */

alib2/src/alphabet/Symbol.cpp

@@ -38,8 +38,11 @@ bool Symbol::operator !=(const Symbol& other) const {
 }
 std::ostream& operator<<(std::ostream& out, const Symbol& symbol) {
-
-	out << "(Symbol " << symbol.symbol << ")";
+	if(symbol.symbol.size() == 0) {
+		out << "(Blank)";
+	} else {
+		out << "(Symbol " << symbol.symbol << ")";
+	}
 	return out;
 }