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https://github.com/qdrvm/scale-codec-cpp
Designing a Better World Through Decentralized Technologies
https://github.com/qdrvm/scale-codec-cpp
Last synced: 3 months ago
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Designing a Better World Through Decentralized Technologies
- Host: GitHub
- URL: https://github.com/qdrvm/scale-codec-cpp
- Owner: qdrvm
- Fork: true (Harrm/scale-codec)
- Created: 2021-10-26T08:20:02.000Z (about 3 years ago)
- Default Branch: master
- Last Pushed: 2024-05-29T15:25:27.000Z (5 months ago)
- Last Synced: 2024-06-24T04:55:55.196Z (5 months ago)
- Language: C++
- Homepage:
- Size: 317 KB
- Stars: 4
- Watchers: 1
- Forks: 6
- Open Issues: 7
-
Metadata Files:
- Readme: README.md
Awesome Lists containing this project
- awesome-substrate - C++ - Maintained by Soramitsu. (SCALE Codec)
README
# SCALE codec C++ implementation
fully meets polkadot specification.\
It allows encoding and decoding following data types:
* Built-in integer types specified by size:
* ```uint8_t```, ```int8_t```
* ```uint16_t```, ```int16_t```
* ```uint32_t```, ```int32_t```
* ```uint64_t```, ```int64_t```
* bool values
* pairs of types represented by ```std::pair```
* compact integers represented by CompactInteger type
* optional values represented by ```std::optional```
* as special case of optional values ```std::optional``` is encoded using one byte following specification.
* collections of items represented by ```std::vector```
* variants represented by ```boost::variant```
## ScaleEncoderStream
class ScaleEncoderStream is in charge of encoding data
```c++
ScaleEncoderStream s;
uint32_t ui32 = 123u;
uint8_t ui8 = 234u;
std::string str = "asdasdasd";
auto * raw_str = "zxczxczx";
bool b = true;
CompactInteger ci = 123456789;
boost::variant vint = CompactInteger(12345);
std::optional opt_str = "asdfghjkl";
std::optional opt_bool = false;
std::pair pair{1u, 2u};
std::vector coll_ui32 = {1u, 2u, 3u, 4u};
std::vector coll_str = {"asd", "fgh", "jkl"};
std::vector> coll_coll_i32 = {{1, 2, 3}, {4, 5, 6, 7}};
try {
s << ui32 << ui8 << str << raw_str << b << ci << vint;
s << opt_str << opt_bool << pair << coll_ui32 << coll_str << coll_coll_i32;
} catch (std::runtime_error &e) {
// handle error
// for example make and return outcome::result
return outcome::failure(e.code());
}
```
You can now get encoded data:
```c++
ByteArray data = s.data();
```
## ScaleDecoderStream
class ScaleEncoderStream is in charge of encoding data
```c++
ByteArray bytes = {...};
ScaleEncoderStream s(bytes);
uint32_t ui32 = 0u;
uint8_t ui8 = 0u;
std::string str;
bool b = true;
CompactInteger ci;
boost::variant vint;
std::optional opt_str;
std::optional opt_bool;
std::pair pair{};
std::vector coll_ui32;
std::vector coll_str;
std::vector> coll_coll_i32;
try {
s >> ui32 >> ui8 >> str >> b >> ci >> vint;
s >> opt_str >> opt_bool >> pair >> coll_ui32 >> coll_str >> coll_coll_i32;
} catch (std::system_error &e) {
// handle error
}
```
## Custom types
You may need to encode or decode custom data types, you have to define custom << and >> operators.
Please note, that your custom data types must be default-constructible.
```c++
struct MyType {
int a = 0;
std::string b;
};
ScaleEncoderStream &operator<<(ScaleEncoderStream &s, const MyType &v) {
return s << v.a << v.b;
}
ScaleDecoderStream &operator>>(ScaleDecoderStream &s, MyType &v) {
return s >> v.a >> v.b;
}
```
Now you can use them in collections, optionals and variants
```c++
std::vector v = {{1, "asd"}, {2, "qwe"}};
ScaleEncoderStream s;
try {
s << v;
} catch (...) {
// handle error
}
```
The same for ```ScaleDecoderStream```
```c++
ByteArray data = {...};
std::vector v;
ScaleDecoderStream s{data};
try {
s >> v;
} catch (...) {
// handle error
}
```
## Convenience functions
Convenience functions
```c++
template
outcome::result> encode(T &&t);
template
outcome::result decode(const RangeOfBytes auto& span)
template
outcome::result decode(ScaleDecoderStream &s)
```
are wrappers over ```<<``` and ```>>``` operators described above.
Encoding data using ```encode``` convenience function looks as follows:
```c++
std::vector v = {1u, 2u, 3u, 4u};
auto &&result = encode(v);
if (!res) {
// handle error
}
```
Decoding data using ```decode``` convenience function looks as follows:
```c++
ByteArray bytes = {...};
outcome::result result = decode(bytes);
if (!result) {
// handle error
}
```
or
```c++
ByteArray bytes = {...};
ScaleDecoderStream s(bytes);
outcome::result result = decode(s);
if (!result) {
// handle error
}
```