34 |
34 |
35 using namespace relpipe::protocol; |
35 using namespace relpipe::protocol; |
36 using namespace relpipe::writer; |
36 using namespace relpipe::writer; |
37 |
37 |
38 /** |
38 /** |
39 * The prototype does not have various integer and other numeric data types, |
39 * Unsigned variable-length integer. |
40 * it just works with one type of integer. |
40 * ULEB128 |
41 * 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). |
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42 * In the real implementation of relational pipes, there will be DataTypes for particular numeric types. |
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43 * |
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44 * TODO: support also big endian architectures. |
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45 * 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) |
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46 * |
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47 * Example of encoded values: |
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48 * ------------------------------------------------------------------------------------------------- |
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49 * $ 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 |
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50 * 0 = 00000000 00 |.| |
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51 * 1 = 00000000 01 |.| |
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52 * 10 = 00000000 0a |.| |
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53 * 250 = 00000000 fa |.| |
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54 * 251 = 00000000 fb fb |..| |
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55 * 252 = 00000000 fb fc |..| |
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56 * 65535 = 00000000 fc ff ff |...| |
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57 * 65536 = 00000000 fd 00 00 01 00 |.....| |
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58 * 4294967295 = 00000000 fd ff ff ff ff |.....| |
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59 * 4294967296 = 00000000 fe 00 00 00 00 01 00 00 00 |.........| |
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60 * 18446744073709551615 = 00000000 fe ff ff ff ff ff ff ff ff |.........| |
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61 * ------------------------------------------------------------------------------------------------- |
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62 * |
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63 * Example of decoded values: |
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64 * ------------------------------------------------------------------------------------------------- |
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65 * $ 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; |
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66 * 0 |
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67 * 1 |
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68 * 10 |
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69 * 250 |
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70 * 251 |
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71 * 252 |
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72 * 65535 |
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73 * 65536 |
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74 * 4294967295 |
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75 * 4294967296 |
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76 * 18446744073709551615 |
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77 * ------------------------------------------------------------------------------------------------- |
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78 * |
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79 * Note: similar format as original idea: https://en.wikipedia.org/wiki/X.690#Length_octets |
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80 * |
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81 */ |
41 */ |
82 class IntegerDataTypeWriter : public DataTypeWriter<integer_t> { |
42 class IntegerDataTypeWriter : public DataTypeWriter<integer_t> { |
83 private: |
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84 static const uint8_t INTEGER_TYPE_UINT8 = 251; |
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85 static const uint8_t INTEGER_TYPE_UINT16 = 252; |
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86 static const uint8_t INTEGER_TYPE_UINT32 = 253; |
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87 static const uint8_t INTEGER_TYPE_UINT64 = 254; |
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88 static const uint8_t INTEGER_TYPE_RESERVED = 255; |
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89 |
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90 template<typename T> void write(std::ostream &output, const integer_t &value) { |
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91 assert(sizeof (T) <= sizeof (value)); |
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92 output.write(reinterpret_cast<const char *> (&value), sizeof (T)); |
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93 } |
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94 |
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95 template<typename T> void write(std::ostream &output, const uint8_t type, const integer_t &value) { |
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96 write<uint8_t>(output, type); |
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97 write<T>(output, value); |
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98 } |
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99 |
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100 template<typename T> bool fits(const integer_t &value) { |
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101 return value <= numeric_limits<T>::max(); |
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102 } |
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103 |
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104 public: |
43 public: |
105 |
44 |
106 IntegerDataTypeWriter() : DataTypeWriter<integer_t>(TypeId::INTEGER, DATA_TYPE_CODE_INTEGER) { |
45 IntegerDataTypeWriter() : DataTypeWriter<integer_t>(TypeId::INTEGER, DATA_TYPE_CODE_INTEGER) { |
107 } |
46 } |
108 |
47 |
109 void writeValue(std::ostream &output, const integer_t &value) override { |
48 void writeValue(std::ostream &output, const integer_t &value) override { |
110 // output << value; // by zapsalo číslo jako ASII text |
49 integer_t v = value; |
111 |
50 do { |
112 if (value < INTEGER_TYPE_UINT8) write<uint8_t>(output, value); |
51 octet_t octet = v & 0x7F; |
113 else if (fits<uint8_t>(value)) write<uint8_t>(output, INTEGER_TYPE_UINT8, value); |
52 v >>= 7; |
114 else if (fits<uint16_t>(value)) write<uint16_t>(output, INTEGER_TYPE_UINT16, value); |
53 if (v) octet |= 0x80; // more bytes follow |
115 else if (fits<uint32_t>(value)) write<uint32_t>(output, INTEGER_TYPE_UINT32, value); |
54 output << char(octet); |
116 else if (fits<uint64_t>(value)) write<uint64_t>(output, INTEGER_TYPE_UINT64, value); |
55 } while (v); |
117 else throw RelpipeWriterException(L"Error while writing integer type: value too long"); |
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118 } |
56 } |
119 |
57 |
120 integer_t toValue(const string_t &stringValue) override { |
58 integer_t toValue(const string_t &stringValue) override { |
121 // throws „terminate called after throwing an instance of 'std::invalid_argument'“ SIGABRT, core dumped on invalid number |
59 // throws „terminate called after throwing an instance of 'std::invalid_argument'“ SIGABRT, core dumped on invalid number |
122 return stoul(stringValue); |
60 return stoul(stringValue); |