diff -r 543f1613c2da -r e8de089f95dd src/types/IntegerDataTypeReader.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/types/IntegerDataTypeReader.h	Sat Aug 25 18:16:53 2018 +0200
@@ -0,0 +1,108 @@
+#pragma once
+
+#include <string>
+#include <iostream>
+#include <cassert>
+#include <limits>
+
+#include <relpipe/protocol/constants.h>
+
+#include "../../include/relpipe/reader/RelpipeReaderException.h"
+#include "../../include/relpipe/reader/typedefs.h"
+#include "../DataTypeReader.h"
+
+namespace relpipe {
+namespace reader {
+namespace types {
+
+using namespace relpipe::protocol;
+using namespace relpipe::reader;
+
+/**
+ * The prototype does not have various integer and other numeric data types,
+ * it just works with one type of integer.
+ * But this integer has variable length -- smaller values occupy only one byte, bigger ones, more bytes 1,2,4,8 + first byte (contains length signalization).
+ * In the real implementation of relational pipes, there will be DataTypes for particular numeric types.
+ * 
+ * TODO: support also big endian architectures.
+ * TODO: throw exception if a value was stored in bigger type than needed (while reading – there should be only one supported way how to encode a single value)
+ * 
+ * Example of encoded values:
+ * -------------------------------------------------------------------------------------------------
+ * $ for n in 0 1 10 250 251 252 65535 65536 4294967295 4294967296 18446744073709551615; do printf '%20s = ' $n; dist/Debug/GNU-Linux/rp-prototype write integer $n | hd | head -n 1; done
+ *                    0 = 00000000  00                                                |.|
+ *                    1 = 00000000  01                                                |.|
+ *                   10 = 00000000  0a                                                |.|
+ *                  250 = 00000000  fa                                                |.|
+ *                  251 = 00000000  fb fb                                             |..|
+ *                  252 = 00000000  fb fc                                             |..|
+ *                65535 = 00000000  fc ff ff                                          |...|
+ *                65536 = 00000000  fd 00 00 01 00                                    |.....|
+ *           4294967295 = 00000000  fd ff ff ff ff                                    |.....|
+ *           4294967296 = 00000000  fe 00 00 00 00 01 00 00  00                       |.........|
+ * 18446744073709551615 = 00000000  fe ff ff ff ff ff ff ff  ff                       |.........|
+ * -------------------------------------------------------------------------------------------------
+ * 
+ * Example of decoded values:
+ * -------------------------------------------------------------------------------------------------
+ * $ for n in 0 1 10 250 251 252 65535 65536 4294967295 4294967296 18446744073709551615; do dist/Debug/GNU-Linux/rp-prototype write integer $n | dist/Debug/GNU-Linux/rp-prototype read integer; done;
+ * 0
+ * 1
+ * 10
+ * 250
+ * 251
+ * 252
+ * 65535
+ * 65536
+ * 4294967295
+ * 4294967296
+ * 18446744073709551615
+ * -------------------------------------------------------------------------------------------------
+ * 
+ * Note: similar format as original idea: https://en.wikipedia.org/wiki/X.690#Length_octets
+ * 
+ */
+class IntegerDataTypeReader : public DataTypeReader<integer_t> {
+private:
+	static const uint8_t INTEGER_TYPE_UINT8 = 251;
+	static const uint8_t INTEGER_TYPE_UINT16 = 252;
+	static const uint8_t INTEGER_TYPE_UINT32 = 253;
+	static const uint8_t INTEGER_TYPE_UINT64 = 254;
+	static const uint8_t INTEGER_TYPE_RESERVED = 255;
+
+	template<typename T> integer_t read(std::istream &input) {
+		T value = 0;
+		input.read(reinterpret_cast<char *> (&value), sizeof (value));
+		return value;
+	}
+
+public:
+
+	IntegerDataTypeReader() : DataTypeReader<integer_t>(TypeId::INTEGER, DATA_TYPE_CODE_INTEGER) {
+	}
+
+	integer_t readValue(std::istream &input) override {
+		uint8_t first;
+		input.read(reinterpret_cast<char *> (&first), sizeof (first));
+		if (input.good()) {
+
+			if (first < INTEGER_TYPE_UINT8) return first;
+			else if (first == INTEGER_TYPE_UINT8) return read<uint8_t>(input);
+			else if (first == INTEGER_TYPE_UINT16) return read<uint16_t>(input);
+			else if (first == INTEGER_TYPE_UINT32) return read<uint32_t>(input);
+			else if (first == INTEGER_TYPE_UINT64) return read<uint64_t>(input);
+			else throw RelpipeReaderException(L"Error while parsing integer type: unsupported type");
+		} else {
+			throw RelpipeReaderException(L"Error while reading integer from the stream.");
+		}
+	}
+
+	string_t toString(const integer_t &value) override {
+		return std::to_wstring(value);
+	}
+
+};
+
+}
+}
+}
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