Add logging

Author: michalsustr

README.md

@@ -22,6 +22,7 @@ Additionally:
   This is done by using the "type state" pattern. Each state/input/output struct is wrapped by an internal enum that is automatically generated by the macro.
 - Each transition can have an optional **guard** (a predicate function).
 - The input or output can be missing (e.g. for a Moore machine). This is internally implemented by a special `Nothing` symbol.
+- No dynamic memory allocations and minimal stack memory usage.
 
 ## [Examples](https://github.com/michalsustr/rust-automata/tree/main/examples)
 
@@ -113,8 +114,8 @@ Major:
 
 Minor (soon):
 - [x] Guards as bool expressions
-- [ ] Performance improvements
-- [ ] Logging transitions -- tracing?
+- [x] Performance improvements
+- [x] Logging transitions
 - [ ] Configurable `should_panic` for invalid transitions  
 - [ ] Better error messages
   - sig checks for guards

examples/Cargo.toml

@@ -5,3 +5,4 @@ edition = "2021"
 
 [dependencies]
 rust-automata = { path = "../rust-automata", version = "0.0.3", features = ["mermaid", "dsl"] }
+env_logger = "0.11"

examples/src/vikings.rs

@@ -125,6 +125,7 @@ impl Torch {
 #[test]
 fn vikings_successfully_cross() {
     use events::*;
+    env_logger::init();
 
     let clock = ManualClock::new();
 

rust-automata-macros/src/lib.rs

@@ -590,6 +590,10 @@ pub fn state_machine(attr: TokenStream, item: TokenStream) -> TokenStream {
                         (_, _) => None,
                     }
                 }
+
+                fn name() -> &'static str {
+                    stringify!(#machine_ident)
+                }
             }
         }
     };

rust-automata/Cargo.toml

@@ -22,6 +22,8 @@ aquamarine = { version = "0.6", optional = true }
 rust-automata-macros = { path = "../rust-automata-macros", version = "0.0.3" }
 chrono = "0.4"
 serde = { version = "1", features = ["derive"] }
+log = "0.4"
+env_logger = "0.11"
 
 [dev-dependencies]                            
 trybuild = "1.0"

rust-automata/src/lib.rs

@@ -17,6 +17,7 @@ pub mod timestamp;
 use core::fmt::Display;
 use std::hash::Hash;
 use std::marker::PhantomData;
+use log;
 
 #[doc(hidden)]
 pub use takeable::Takeable;
@@ -112,6 +113,8 @@ pub trait StateMachineImpl {
         state: &Self::State,
         input: EnumId<Self::Input>,
     ) -> Option<EnumId<Self::Output>>;
+    /// The name of the state machine.
+    fn name() -> &'static str;
 }
 
 /// Encapsulates the state and other SM data and expose transition functions.
@@ -171,8 +174,15 @@ where
             let from_str = T::State::get_variant(&from_id);
             let input_str = T::Input::get_variant(&input_id);
             panic!("Invalid transition from {from_str} using input {input_str}");
+        } else {
+            log::debug!("{}: ({}, {}) -> ({}, {})", 
+                T::name(),
+                T::State::get_variant(&from_id), 
+                T::Input::get_variant(&input_id),
+                T::State::get_variant(&self.state.as_ref().enum_id()),
+                T::Output::get_variant(&output.enum_id()),
+            );
         }
-
         O::from(output)
     }