afsm is a finite state machine C++11 library designed for usage in multithreaded asynchronous environment.

Theafsm library was inspired by::boost::msm library and implemented so that the migration from::boost::msm was a bunch of search and replace operations. The main motivation was to create a thread-safe FSM library and to achieve decent compile times for large and complex state machines not sacrificing performance. A state machine defined withafms library compiles several times faster than same library defined with::boost::msm and has similar (or better) performance. You can find some benchmark resultshere.

• Statechart features
  • Hierarchical states
  • Entry and exit actions
  • Internal transitions
  • Transition actions
  • Transition guards (conditions)
  • State history
  • Event deferring
  • Orthogonal regions
• Statechart extensions
  • Optionalevent priority
  • Optionalcommon base for states and easy definition of dispatching common interface calls to current state
  • Pushdown automaton
• Compile-time checks
• Thread safety
• Exception safety
• No vtables (unless common base feature is used)
• Header only
• Relatively fast compile time
• No external dependencies except STL

• State machine persistense

Here is a UML diagram of a trivial state machine and source code that it is mapped to.

#include<afsm/fsm.hpp>// Eventsstructstart {};structstop {};// State machine definitionstructminimal_def : ::afsm::def::state_machine<minimal_def> {//@{/** @name States*/structinitial      : state<initial> {};structrunning      : state<running> {};structterminated   : terminal_state<terminated> {};//@}using initial_state = initial;using transitions   = transition_table</*  State       Event       Next*/        tr< initial,    start,      running     >,        tr< running,    stop,       terminated  >    >;};// State machine objectusing minimal = ::afsm::state_machine<minimal_def>;voiduse(){    mimimal fsm;    fsm.process_event(start{});    fsm.process_event(stop{});}

You can find a tutorial covering most of basic featureshere.

TODO doxygen generated documentation.

The library is header only and doesn't requre build or installation. Just add theafsm/include andlib/meta/include directories under the root of this repository to your include paths.

You can add the library to your project as a subtree, e.g.lib/afsm, and in your rootCMakeLists.txt file just do the following:

add_subdirectory(lib/afsm)include_directories(${AFSM_INCLUDE_DIRS})

TODO write docs on gitrc subtree commands and link to the repository

git clone git@github.com:zmij/afsm.gitmkdir afsm/buildcd afsm/buildcmake ..sudo make install

find_package(AFSM REQUIRED)# Will set AFSM_INCLUDE_DIRS variable

The project is mostly developed as a part of other projects (pg_async, PostgreSQL asynchronous driver,wire, an RPC library for C++) which are in turn developed as a part of a bigger commercial project.

The Artistic License 2.0