mfsm

This header-only library is inspired by boost MSM and copies how it defines its transition tables. Only a subset of Boost.MSM features are implemented.

Overview of differences

• requires a c++23 compiler
• many compile-time checks using concepts
• removes 5 arguments limitation on state-machine constructor
• removes transition table limitations due to boost MPL vector/map size
• states don't require any decoration
• accepts non-copyable events
• auto-detects if deferred events are used

Dependencies

• c++23 compiler such as clang++ or g++
• boost (required for unit-tests)
• python (required for conan build)

Build and install

user@mach:~$ git clone https://github.com/SBAM/mfsm.git
user@mach:~$ cd mfsm
user@mach:~$ ./test.sh
user@mach:~$ conan upload -r <my_remote> mfsm/1.3

Interface overview

struct sm
{
  using transition_table_t = mfsm::transition_table<
    //        Start   Event Next        Action       Guard
    //       +-------+-----+-----------+------------+--------+
    mfsm::row<state1, evt2, state2,     action,      mfsm::none>,
    mfsm::row<state1, evt1, mfsm::none, mfsm::defer, mfsm::none>,
    mfsm::row<state2, evt1, state1,     action,      mfsm::none>,
    mfsm::row<state2, evt2, mfsm::none, mfsm::defer, mfsm::none>,
    mfsm::row<state2, evt3, state1,     action,      guard>,
    mfsm::row<state2, evt3, state2,     action,      not_guard>>;

  using initial_state = state1;

  template <typename EVT>
  void no_transition(EVT&&, std::size_t);
};

auto actual_sm = mfsm::state_machine<sm>{};

actual_sm.process_event(evt3{true});

Refer to unit-tests for more examples.

Additional notes

• minimizes state-machine size, declares deferred queue only if needed
• low runtime complexity, candidate rows (match event) are deduced at compile time