1 #pragma once

     2 

     3 #include <string>

     4 #include <iostream>

     5 #include <cassert>

     6 #include <limits>

     7 

     8 #include "../include/typedefs.h"

     9 #include "../include/DataTypeReader.h"

    10 #include "../include/DataTypeReader.h"

    11 #include "format.h"

    12 

    13 namespace relpipe {

    14 namespace reader {

    15 

    16 /**

    17  * The prototype does not have various integer and other numeric data types,

    18  * it just works with one type of integer.

    19  * 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).

    20  * In the real implementation of relational pipes, there will be DataTypes for particular numeric types.

    21  * 

    22  * TODO: support also big endian architectures.

    23  * 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)

    24  * 

    25  * Example of encoded values:

    26  * -------------------------------------------------------------------------------------------------

    27  * $ 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

    28  *                    0 = 00000000  00                                                |.|

    29  *                    1 = 00000000  01                                                |.|

    30  *                   10 = 00000000  0a                                                |.|

    31  *                  250 = 00000000  fa                                                |.|

    32  *                  251 = 00000000  fb fb                                             |..|

    33  *                  252 = 00000000  fb fc                                             |..|

    34  *                65535 = 00000000  fc ff ff                                          |...|

    35  *                65536 = 00000000  fd 00 00 01 00                                    |.....|

    36  *           4294967295 = 00000000  fd ff ff ff ff                                    |.....|

    37  *           4294967296 = 00000000  fe 00 00 00 00 01 00 00  00                       |.........|

    38  * 18446744073709551615 = 00000000  fe ff ff ff ff ff ff ff  ff                       |.........|

    39  * -------------------------------------------------------------------------------------------------

    40  * 

    41  * Example of decoded values:

    42  * -------------------------------------------------------------------------------------------------

    43  * $ 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;

    44  * 0

    45  * 1

    46  * 10

    47  * 250

    48  * 251

    49  * 252

    50  * 65535

    51  * 65536

    52  * 4294967295

    53  * 4294967296

    54  * 18446744073709551615

    55  * -------------------------------------------------------------------------------------------------

    56  * 

    57  * Note: similar format as original idea: https://en.wikipedia.org/wiki/X.690#Length_octets

    58  * 

    59  */

    60 class IntegerDataTypeReader : public DataTypeReader<integer_t> {

    61 private:

    62 	static const uint8_t INTEGER_TYPE_UINT8 = 251;

    63 	static const uint8_t INTEGER_TYPE_UINT16 = 252;

    64 	static const uint8_t INTEGER_TYPE_UINT32 = 253;

    65 	static const uint8_t INTEGER_TYPE_UINT64 = 254;

    66 	static const uint8_t INTEGER_TYPE_RESERVED = 255;

    67 

    68 	template<typename T> integer_t read(std::istream &input) {

    69 		T value = 0;

    70 		input.read(reinterpret_cast<char *> (&value), sizeof (value));

    71 		return value;

    72 	}

    73 

    74 public:

    75 

    76 	IntegerDataTypeReader() : DataTypeReader<integer_t>(DATA_TYPE_ID_INTEGER, DATA_TYPE_CODE_INTEGER) {

    77 	}

    78 

    79 	integer_t readValue(std::istream &input) override {

    80 		uint8_t first;

    81 		input.read(reinterpret_cast<char *> (&first), sizeof (first));

    82 		if (input.good()) {

    83 

    84 			if (first < INTEGER_TYPE_UINT8) return first;

    85 			else if (first == INTEGER_TYPE_UINT8) return read<uint8_t>(input);

    86 			else if (first == INTEGER_TYPE_UINT16) return read<uint16_t>(input);

    87 			else if (first == INTEGER_TYPE_UINT32) return read<uint32_t>(input);

    88 			else if (first == INTEGER_TYPE_UINT64) return read<uint64_t>(input);

    89 			else throw RelpipeReaderException(L"Error while parsing integer type: unsupported type");

    90 		} else {

    91 			throw RelpipeReaderException(L"Error while reading integer from the stream.");

    92 		}

    93 	}

    94 

    95 	string_t toString(const integer_t &value) override {

    96 		return std::to_wstring(value);

    97 	}

    98 

    99 };

   100 

   101 }

   102 }