BREAKING CHANGE: State hooks onEnter, onExit now calls only if nextState differs from currentState

Author: polesskiy-dev

src/active_object/active_object.h

@@ -16,7 +16,7 @@
  * ### Example:
  * @code
  * // Active Object inheritance
- * typedef enum { NO_STATE, STATE_1 = 1, STATES_MAX } TEST_STATE; // state names
+ * typedef enum { INVALID_STATE = -1, NO_STATE, STATE_1 = 1, STATES_MAX } TEST_STATE; // state names
  * typedef enum { NO_SIG, EVENT_SIG_1 = 1, EVENTS_MAX } TEST_EVENT_SIG; // event signals names
  * TEvent events[QUEUE_MAX_SIZE]; // events list for the queue
  * 
@@ -66,17 +66,17 @@ typedef bool (*TStateHook)(TActiveObject *const activeObject, void *const ctx);
 
 /** @brief Struct representing a single state of an active object. */
 typedef struct {
-    int32_t name;
-    TStateHook onEnter;
-    TStateHook onTraverse;
-    TStateHook onExit;
+    int name; /**< State name. */
+    TStateHook onEnter; /**< State onEnter hook. If the next state is the same as the current state, this hook won't be called. */
+    TStateHook onTraverse; /**< State onTraverse hook. If next state is the same as current state, this hook will be called. */
+    TStateHook onExit; /**< State onExit hook. If the next state is the same as the current state, this hook won't be called. */
 } TState;
 
 /** @brief Struct representing an active object. */
 struct TActiveObject {
-    uint8_t id;
-    const TState *state;
-    TEventQueue queue;
+    uint8_t id; /**< Object ID. */
+    const TState *state; /**< Pointer to the current state. */
+    TEventQueue queue; /**< Event queue. */
 };
 
 /** @brief Initialize an active object.

src/event_queue/event_queue.h

@@ -23,7 +23,6 @@
 #include <stdbool.h>
 #include <stddef.h>
 
-
 /**
  * @brief Event structure containing a signal and payload
  */

src/fsm/fsm.c

@@ -13,31 +13,32 @@ inline bool FSM_IsValidState(const TState *const state) {
 };
 
 const TState *FSM_ProcessEventToNextState(
-    TActiveObject *const activeObject,
-    TEvent event,
-    uint32_t statesMax,
-    uint32_t eventsMax,
-    const TState statesList[statesMax],
-    const TEventHandler transitionTable[statesMax][eventsMax]) {
+        TActiveObject *const activeObject,
+        TEvent event,
+        uint32_t statesMax,
+        uint32_t eventsMax,
+        const TState statesList[statesMax],
+        const TEventHandler transitionTable[statesMax][eventsMax]) {
 
-    /* Validate input args */    
+    /* Validate input args */
 
     // Validate Active object
-    if (NULL == activeObject 
-        || NULL == statesList 
-        || NULL == transitionTable) return &invalidState; // Handle null pointers as needed
+    if (NULL == activeObject
+        || NULL == statesList
+        || NULL == transitionTable)
+        return &invalidState; // Handle null pointers as needed
 
     const TState *const currState = activeObject->state;
-    
+
     // Validate current state
     if (currState->name < 0 || currState->name >= statesMax) return &invalidState;
-    
+
     // Validate current event
     if (event.sig < 0 || event.sig >= eventsMax) return &invalidState;
 
     // Lookup transition table to find the handler for the current state and event
     const TEventHandler eventHandler = transitionTable[currState->name][event.sig];
-    
+
     // Call the handler to get the next state and make side effects
     if (eventHandler) {
         const TState *nextState = eventHandler(activeObject, event);
@@ -46,49 +47,48 @@ const TState *FSM_ProcessEventToNextState(
     }
 
     // Return empty state if no transition exists
-    return &emptyState; 
+    return &emptyState;
 };
 
-bool FSM_TraverseNextState(
-    TActiveObject *const activeObject,
-    const TState *const nextState) {
+// Execute a state hook and return its status.
+bool _executeHook(TStateHook hook, TActiveObject *activeObject) {
+    if (hook) {
+        return hook(activeObject, NULL);
+    }
+    return true; // No hook to execute, so consider it successful
+}
 
-    // Null args checks        
-    if (NULL == activeObject 
-        || NULL == nextState) {
+bool FSM_TraverseNextState(
+        TActiveObject *const activeObject,
+        const TState *const nextState) {
+    // Null args checks
+    if (!activeObject || !nextState) {
         return false;
-    };
+    }
 
     // Validate next state
     if (!FSM_IsValidState(nextState)) {
         return false;
-    };
-
-    // Call onExit of current state, if any
-    if (NULL != activeObject->state->onExit) {
-        bool isSuccessfulHook = activeObject->state->onExit(activeObject, NULL);
-        if (!isSuccessfulHook) {
-            return false; // Hook failed
-        }
     }
 
-    // Update the state
-    activeObject->state = (TState *)nextState;
-
-    // Call onEnter of next state, if any
-    if (activeObject->state->onEnter) {
-        bool isSuccessfulHook = activeObject->state->onEnter(activeObject, NULL);
-        if (!isSuccessfulHook) {
-            return false; // Hook failed
-        }
+    const TState *currState = &(*activeObject->state);
+
+    // If the next state is the same as the current state
+    if (FSM_IsEqualStates(currState, nextState)) {
+        return _executeHook(currState->onTraverse, activeObject);
+    }
+
+    // If the next state is different, execute hooks for transitioning
+    if (!_executeHook(currState->onExit, activeObject)) {
+        return false;
     }
 
-    // Finally, call onTraverse of next state, if any
-    if (activeObject->state->onTraverse) {
-        bool isSuccessfulHook = activeObject->state->onTraverse(activeObject, NULL);
-        if (!isSuccessfulHook) {
-            return false; // Hook failed
-        }
+    // Update the state
+    activeObject->state = (TState *) nextState;
+
+    if (!_executeHook(activeObject->state->onEnter, activeObject) ||
+        !_executeHook(activeObject->state->onTraverse, activeObject)) {
+        return false;
     }
 
     return true;

src/fsm/fsm.h

@@ -33,12 +33,12 @@ typedef const TState* (*TEventHandler)(TActiveObject *const activeObject, TEvent
  * @returns -1 (INVALID_STATE) in case of invalid input args
  */
 const TState *FSM_ProcessEventToNextState(
-    TActiveObject *const activeObject,
-    TEvent event,
-    uint32_t statesMax,
-    uint32_t eventsMax,
-    const TState statesList[statesMax],
-    const TEventHandler transitionTable[statesMax][eventsMax]);
+    TActiveObject *const activeObject, /**< The active object. */
+    TEvent event, /**< The incoming event. */
+    uint32_t statesMax, /**< The maximum number of states. */
+    uint32_t eventsMax, /**< The maximum number of events. */
+    const TState statesList[statesMax], /**< The list of states. */
+    const TEventHandler transitionTable[statesMax][eventsMax]); /**< The transition table for state-event. */
 
 /**
  * @brief Transitions the active object to the next state 
@@ -48,8 +48,6 @@ const TState *FSM_ProcessEventToNextState(
  *
  * @param[in,out] activeObject The active object.
  * @param[in] nextState The next state to transition to.
- * @param[in] statesMax The maximum number of states.
- * @param[in] statesList The list of states.
  *
  * @return True if the transition is successful, false otherwise.
  */
@@ -63,12 +61,28 @@ bool FSM_IsEqualStates(const TState *const stateA, const TState *const stateB);
 /** @brief Checks if a state is valid (i.e., not an empty or invalid state). */
 bool FSM_IsValidState(const TState *const state);
 
-#define DECLARE_GUARD(CONDITION_FUNCTION, ON_TRUE_FUNCTION) \
-    const TState* GUARD_##CONDITION_FUNCTION##_##ON_TRUE_FUNCTION(TActiveObject *const activeObject, TEvent event) { \
-        if (CONDITION_FUNCTION(activeObject, event)) return ON_TRUE_FUNCTION(activeObject, event); \
+/**
+ * @brief Guard function declaration macro
+ * @note should be invoked before using appropriate GUARD macro in transition table
+ * @details Creates a guard function for a given condition function and two event handler functions.
+ * For true condition result the first event handler function will be called, for false - the second one.
+ *
+ * ### Example
+ * @code
+ * TODO make an example
+ * @endcode
+ */
+#define DECLARE_GUARD(CONDITION_FUNCTION, ON_TRUE_FUNCTION, ON_FALSE_FUNCTION) \
+    const TState* GUARD_##CONDITION_FUNCTION##_##ON_TRUE_FUNCTION##_##ON_FALSE_FUNCTION(TActiveObject *const activeObject, TEvent event) { \
+        if (CONDITION_FUNCTION(activeObject, event)) return ON_TRUE_FUNCTION(activeObject, event);  \
+        return ON_FALSE_FUNCTION(activeObject, event);  \
         return (const TState*)NULL;   \
     };
 
-#define GUARD(CONDITION_FUNCTION, ON_TRUE_FUNCTION) (GUARD_##CONDITION_FUNCTION##_##ON_TRUE_FUNCTION)    
+/**
+ * @brief Guard function macro
+ * @note DECLARE_GUARD should be invoked before using appropriate GUARD macro in transition table
+ */
+#define GUARD(CONDITION_FUNCTION, ON_TRUE_FUNCTION, ON_FALSE_FUNCTION) GUARD_##CONDITION_FUNCTION##_##ON_TRUE_FUNCTION##_##ON_FALSE_FUNCTION
 
 #endif //FSM_H

test/fsm/fsm.test.c

@@ -8,8 +8,8 @@
 typedef enum { NO_STATE, EMPTY_HOOKS_ST, SUCCESS_HOOKS_ST, FAILURE_HOOKS_ST, STATES_MAX } STATES_NAMES; // state names
 typedef enum { NO_SIG, GO_EMPTY_HOOKS_ST, GO_SUCCESS_HOOKS_ST, GO_FAILURE_HOOKS_ST, EVENTS_MAX } EVENT_SIGS; // events signals names
 
-bool _successHook(void *const activeObject, void *const ctx) { return true; };
-bool _failureHook(void *const activeObject, void *const ctx) { return false; };
+bool _successHook(TActiveObject *const AO, void *const ctx) { return true; };
+bool _failureHook(TActiveObject *const AO, void *const ctx) { return false; };
 
 const TState statesList[STATES_MAX] = { 
     [NO_STATE]          = {.name = NO_STATE},
@@ -24,12 +24,12 @@ const TState* _goToFailureHooksState(TActiveObject *const activeObject, TEvent e
 
 bool _onTrue(TActiveObject *const activeObject, TEvent event) { return true; };
 
-DECLARE_GUARD(_onTrue, _goToFailureHooksState);
+DECLARE_GUARD(_onTrue, _goToFailureHooksState, _goToSuccessHooksState);
 
 const TEventHandler transitionTable[STATES_MAX][EVENTS_MAX] = {
     [NO_STATE]          = { [GO_EMPTY_HOOKS_ST] = _goToEmmptyHooksState },
     [EMPTY_HOOKS_ST]    = { [GO_SUCCESS_HOOKS_ST] = _goToSuccessHooksState },
-    [SUCCESS_HOOKS_ST]  = { [GO_FAILURE_HOOKS_ST] = GUARD(_onTrue, _goToFailureHooksState) },
+    [SUCCESS_HOOKS_ST]  = { [GO_FAILURE_HOOKS_ST] = GUARD(_onTrue, _goToFailureHooksState, _goToSuccessHooksState) },
     [FAILURE_HOOKS_ST]  = { [GO_SUCCESS_HOOKS_ST] = _goToSuccessHooksState },
 };