Modern Hierarchical State Machine for C++20

• 🔧 Fluent builder API with lambda-based DSL
• ⚡ Fast runtime performance with zero heap allocation
• 🛡️ Optional guards and actions for transitions
• 🔄 Event-based state transitions
• 🧪 Google Test integration
• 📈 Code coverage with Codecov
• 🌳 Designed for extensibility: nested states, DOT export coming soon
• 🔧 Deployed as Shared Library and as Single Header-Only library

#include <iostream>
#include "CXXStateTree/StateTree.hpp"
using namespace CXXStateTree;
int main() {
    auto machine = StateTree::Builder()
        .initial("Idle")
        .state("Idle", [](State& s) {
            s.on("Start", "Running", nullptr, []() {
                std::cout << "Idle -> Running" << std::endl;
            });
        })
        .state("Running", [](State& s) {
            s.on("Stop", "Idle", nullptr, []() {
                std::cout << "Running -> Idle" << std::endl;
            });
        })
        .build();
    machine.send("Start");
    machine.send("Stop");
}

cmake -S . -B build 
cmake --build build

After these command the Shared Library can be found in build directory

Please Note: in future release cmake will have the ability to install the library automatically, for now it is necessary to do it manually

cmake -S . -B build -DENABLE_SINGLE_HEADER=ON
cmake --build build

After these command the Single Header-Only Library can be found in single_include directory with the name CXXStateTree.hpp

Please Note: in future release cmake will have the ability to install the library automatically, for now it is necessary to do it manually

cmake -S . -B build -DENABLE_TEST=ON -DENABLE_COVERAGE=ON
cmake --build build
cd build && ctest

• C++20 compiler (GCC >= 10, Clang >= 11, MSVC >= 2019)
• GoogleTest (auto-downloaded via CMake)

CXXStateTree/
├── include/CXXStateTree/     # Public header-only API
├── examples/                 # Usage examples
├── tests/                    # Google Test suite
├── CMakeLists.txt            # Project build
└── .github/workflows/ci.yml  # GitHub Actions CI

MPL2.0 License — see LICENSE for details.

• Nested (hierarchical) state support
• DOT/Graphviz state diagram export
• Transitions with context/parameters

Issues, feature suggestions, and PRs are welcome!