--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/StringDataType.h	Sat Jul 14 23:24:22 2018 +0200
@@ -0,0 +1,61 @@
+#pragma once
+
+#include <string>
+#include <sstream>
+#include <iostream>
+#include <vector>
+#include <locale>
+#include <codecvt>
+
+#include "DataType.h"
+#include "RelpipeException.h"
+#include "IntegerDataType.h"
+
+using namespace std;
+
+namespace rp_prototype {
+
+/**
+ * The prototype does not recognize any encoding,
+ * it just works with c++ strings in encoding default to given platform. 
+ * In the real implementation of relational pipes, there will be DataTypes for particular encodings.
+ */
+class StringDataType : public DataType<wstring> {
+private:
+	IntegerDataType integerType;
+	wstring_convert<codecvt_utf8<wchar_t>> convertor; // TODO: support also other encodings.
+public:
+
+	StringDataType() : DataType<wstring>(DATA_TYPE_ID_STRING, DATA_TYPE_CODE_STRING) {
+	}
+
+	wstring readValue(istream &input) override {
+		integer_t length = integerType.readValue(input);
+		// TODO: check maximum length of single field
+		// if (length > 4000) throw RelpipeException("data too long", EXIT_CODE_DATA_ERROR);
+		vector<char> buf(length);
+		input.read(buf.data(), length);
+		if (input.good()) {
+			return convertor.from_bytes(string(buf.data(), length));
+		} else {
+			throw RelpipeException(L"Error while reading string from the stream.", EXIT_CODE_DATA_ERROR);
+		}
+	}
+
+	void writeValue(ostream &output, const wstring &value) override {
+		string s = convertor.to_bytes(value);
+		integerType.writeValue(output, s.length());
+		output << s.c_str();
+	}
+
+	wstring toValue(const wstring &stringValue) override {
+		return stringValue;
+	}
+
+	wstring toString(const wstring &value) override {
+		return value;
+	}
+
+};
+
+}
\ No newline at end of file