--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/IntegerDataTypeReader.h Sun Jul 15 00:15:09 2018 +0200
@@ -0,0 +1,102 @@
+#pragma once
+
+#include <string>
+#include <iostream>
+#include <cassert>
+#include <limits>
+
+#include "../include/typedefs.h"
+#include "../include/DataTypeReader.h"
+#include "../include/DataTypeReader.h"
+#include "format.h"
+
+namespace relpipe {
+namespace 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>(DATA_TYPE_ID_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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