Header-only heriarchical FSM framework in C 11, with fully statically-defined structure (no dynamic allocations), built with variadic templates.

• Visual Studio: 2015, 2017, 2019, 2022
• GCC: 8, 9, 10, 11, 12, 13
• GCC (ARM): 9
• Clang: 6, 7, 8, 9, 10, 11, 12, 13, 14, 15
• AppleClang: 14

• Minimal Example
• Extended Tutorial

• HFSM2 UPlugin: Unreal Engine plugin for HFSM2 library
• FFSM2: High-Performance Flat Finite State Machine
• FFSM2 UPlugin: Unreal Engine plugin for FFSM2 library
• HFSM Mono: Monospaced bitmap Unicode fonts for HFSM2 and FFSM2 libraries

• Wiki

• Permissive MIT License
• Written in widely-supported modern(ish) C 11
• Header-only
• Convenient, minimal boilerplate
• Fully static, no dynamic allocations
• Uses inline-friendly compile-time polymorphism, no virtual methods are used
• Type-safe transitions: FSM.changeTo<TargetState>() with optional payloads
• Flexible configuration using HFSM2_ENABLE_* macros
• Scalable, supports robust state re-use via state injections
• Hierarchical, with a selection of composite (sub-machine) and orthogonal regions
• Gamedev-friendly, supports explicit State::update()
• Also supports traditional event-based workflow with State::react()
• Inspect anything: previous and current transitions, state activation status, and more!
• Game AI-friendly with dynamic planning support
• Utility theory support (max score and ranked weighted random)
• Serializable, with activity and transition history support
• Debug-assisted, includes automatic structure and activity visualization API with #define HFSM_ENABLE_STRUCTURE_REPORT
• Built-in logging support

• doctest unit testing framework
• XoShiRo pseuto-random number generators

• Twitter: @andrew_gresyk
• Discord: HFSM.dev
• Gitter: andrew-gresyk/HFSM2

• alexandrosk0
• Casey Sanchez
• DJuego
• Kevin Greene
• Kjeld Mathias Petersen
• Lau Bakman
• Mehdi Houshmand
• mrcmry
• Phil Nash
• Romain Cheminade
• Schoppenglas
• Tristan Brindle
• C ::London meetup
• programming community at Splash Damage