libENI¶
Official C++ implementation of libENI, which is part of the Lity project.
Contents¶
Getting Started¶
Download the Prebuilt libENI¶
See libENI releases for the latest release.
- libeni-dev: for ENI operation developers
- libeni: for general ENI users.
Releases¶
| Version | libeni-dev | libeni |
|---|---|---|
| v1.3.3 | Ubuntu 16.04, CentOS 7 | Ubuntu 16.04, CentOS 7 |
| v1.2.x | Ubuntu 16.04, CentOS 7 | Ubuntu 16.04, CentOS 7 |
| v1.2.0 | Ubuntu 16.04, CentOS 7 | Ubuntu 16.04, CentOS 7 |
Prerequisites¶
| libeni-dev | libeni |
|---|---|
|
|
See Prerequisites for platform specific prerequisites guide.
Install¶
tar zxvf libeni.tgz --strip-components 1 -C ${LIBENI_PATH}
Test Manually¶
See Testing Prebuilt ENI Operations for how to test the prebuilt shared libraries of ENI operations.
Build From Source¶
Prerequisites¶
- Boost >= 1.58
- CMake >= 3.1
- OpenSSL >= 1.0.2
- SkyPat >= 3.1.1 (see SkyPat releases)
Download Source Code¶
git clone https://github.com/CyberMiles/libeni.git ${LIBENI_PATH}
Build with CMake¶
cd ${LIBENI_PATH}
mkdir build
cd build
cmake ..
make
Run Tests¶
In your build directory, run ctest.
The result looks like the below.
Test project ${LIBENI_PATH}/build
Start 1: crypto_unittests
1/7 Test #1: crypto_unittests ................. Passed 0.02 sec
Start 2: t0000-smoke
2/7 Test #2: t0000-smoke ...................... Passed 0.01 sec
Start 3: t0001-testlib
3/7 Test #3: t0001-testlib .................... Passed 0.03 sec
Start 4: t0002-examples-eni-reverse
4/7 Test #4: t0002-examples-eni-reverse ....... Passed 0.02 sec
Start 5: t0003-examples-eni-caesar
5/7 Test #5: t0003-examples-eni-caesar ........ Passed 0.02 sec
Start 6: t0004-tools-eni-crypto
6/7 Test #6: t0004-tools-eni-crypto ........... Passed 0.07 sec
Start 7: unittests
7/7 Test #7: unittests ........................ Passed 0.01 sec
100% tests passed, 0 tests failed out of 7
Label Time Summary:
auto = 0.15 sec*proc (5 tests)
regression = 0.15 sec*proc (5 tests)
unittest = 0.03 sec*proc (2 tests)
Total Test time (real) = 0.19 sec
See Testing/Temporary/LastTest.log for the detailed output of all tests.
Developer Guide¶
In this tutorial, we will guide you through how to create new ENI operations with libENI in C++.
Prerequisites¶
In order to build your ENI operations, you need to install libeni-dev first.
See Getting Started for more information.
Implement an ENI Operation¶
Here, we use examples/eni/reverse as an example. In this example, we will create an ENI operation called reverse that takes a string, and returns the reversed string.
The below code piece shows how developers use this ENI operation when writing a contract in Solidity.
string memory reversed;
reversed = eni("reverse", "The string to be reversed.");
Subclass EniBase¶
In order to implement an ENI operation, you need to #include <eni.h>,
create a subclass of eni::EniBase, and implement the following functions.
- A constructor that takes a string as its parameter.
Remember to pass the string to the constructor of the superclass,
eni::EniBase, which will convert the raw string into ajson::Arraycontaining the arguments for your ENI operation. - A destructor.
- Three pure virtual functions, which should be implement privately.
parseto parse the arguments.gasto calculate gas consumption from the arguments.runto execute your ENI operation with the arguments.
#include <eni.h>
class Reverse : public eni::EniBase {
public:
Reverse(const std::string& pArgStr)
: eni::EniBase(pArgStr) { ... }
~Reverse() { ... }
private:
bool parse(const json::Array& pArgs) override { ... }
eni::Gas gas() const override { ... }
bool run(json::Array& pRetVal) override { ... }
};
The parse function takes a json::Array containing the arguments given
to your ENI operation. To ensure the other two functions gas and run
process the arguments in the same way, please validate, preprocess, and store
the arguments into member variables in the parse function.
The parse function should return true when all arguments are good, and
return false otherwise. (i.e. when the given arguments are not correct,
e.g., lacking arguments, or wrong type).
In this example, the json::Array constructed by eni::EniBase contains
only the argument string for ENI operation reverse.
["The string to be reversed."]
Here we just take the first argument and convert it to a string.
class Reverse : public eni::EniBase {
...
private:
bool parse(const json::Array& pArgs) override {
m_Str = pArgs[0].toString();
return true;
}
std::string m_Str;
};
Check the documentation to see more detail
about how arguments are converted into a json::Array.
Before your ENI operation is run, you need to estimate how much gas it will cost.
Override the pure virtual function gas, and return your estimated gas cost.
In this example, we use the string length as its gas consumption.
class Reverse : public eni::EniBase {
...
private:
eni::Gas gas() const override {
return m_Str.length();
}
};
Return 0 when error occurs (e.g., gas is incalculable).
Override the pure virtual function run, and push the result of your ENI
operation back into the json::Array.
class Reverse : public eni::EniBase {
...
private:
bool run(json::Array& pRetVal) override {
std::string ret(m_Str.rbegin(), m_Str.rend());
pRetVal.emplace_back(ret);
return true;
}
};
Return true only when your ENI operation is successfully executed.
Export the ENI Operation with C Interface¶
Your ENI operation will be called via its C interface, so be sure to export
the C interface with ENI_C_INTERFACE(OP, CLASS), where OP is your ENI
operation name (i.e., reverse in this example), and CLASS is the name of
implemented class (i.e., Reverse in this example).
ENI_C_INTERFACE(reverse, Reverse)
Test Your ENI Operations¶
Test From EniBase Interface¶
Your ENI operations will only be accessed from the two public member functions
of eni::EniBase.
Gas getGas()should return the gas cost of your ENI operation.char* start()should run your ENI operation and return the results in JSON format.
You may test your subclass through these two public functions.
eni::EniBase* functor = new Reverse("[\"Hello World\"]");
ASSERT_NE(functor, nullptr);
EXPECT_EQ(functor->getGas(), 12);
char* ret = functor->start();
EXPECT_EQ(::strcmp(ret, "[\"!dlroW olleH\"]"), 0);
free(ret);
delete functor;
Documentation¶
Types¶
ENI Types¶
These types are provided to be coherent with primitive types of Lity (Solidity).
ENI Integers¶
All integer types in ENI is implemented using boost::multiprecision::number. Some of them are aliases for types predefined in boost::multiprecision::cpp_int.
| Integer Type | Size (bits) | Signed | Note |
|---|---|---|---|
eni::s256 |
256 | ✔ | Alias for boost::multiprecision::int256_t. |
eni::Int |
256 | ✔ | Alias for eni::s256. |
eni::u256 |
256 | ✘ | Alias for boost::multiprecision::uint256_t. |
eni::u160 |
160 | ✘ | Size of an Ethereum address. |
eni::u128 |
128 | ✘ | Alias for boost::multiprecision::uint128_t. |
eni::u64 |
64 | ✘ | |
eni::UInt |
256 | ✘ | Alias for eni::u256. |
See the documentation for boost::multiprecision::number for supported operations.
This section does not exist yet. (´-ι_-`)
ENI Boolean¶
eni::Bool is an alias for C++ bool.
ENI Address¶
eni::Address is an alias for eni::u160 (20 bytes, size of an Ethereum address).
Convert ENI Types to C++ String¶
eni::to_string uses boost::lexical_cast internally to
convert ENI types to std::string.
All ENI integers, eni::Bool, eni::Address are supported.
std::string to_string(eni::TypeName);
eni::Int int32max(2147483647);
std::string s = eni::to_string(int32max); // "2147483647"
eni::Bool bTrue(true);
std::string t = eni::to_string(bTrue); // "true"
JSON Types¶
This section does not exist yet. (´-ι_-`)
Contributing to libENI¶
See Getting Started for how to build libENI.
Overview of libENI Code¶
The following image illustrates the libENI code hierarchy and the use of namespaces.
Directory Structure¶
| Path | Description |
| docs/ | Documentations. |
| examples/ | Examples of how to use libENI. |
| include/ | Header files for libENI. |
| lib/ | Implementations for libENI. |
| test/ | All tests for libENI and its examples. |
| tools/ | Tools and modules for libENI. |
Report an Issue¶
Please provide the following information as much as possible.
- The version (commit-ish) your using.
- Your platform, environment setup, etc.
- Steps to reproduce the issue.
- Your expected result of the issue.
- Current result of the issue.
Create a Pull Request¶
- Fork from the master branch.
- Avoid to create merge commits when you update from master by using
git rebaseorgit pull --rebase(instead ofgit merge). - Add test cases for your pull request if you’re proposing new features or major bug fixes.
- Build and test locally before submit your pull request. See Getting Started for how to test libENI.
Please try to follow the existing coding style of libENI (although it is neither well-styled nor documented at this moment), which is basically based on LLVM coding standards.