ETL/ETL/_smach.h

   1 /*! ========================================================================
   2 ** Extended Template and Library
   3 ** State Machine Abstraction Class Implementation
   4 ** $Id$
   5 **
   6 ** Copyright (c) 2002 Robert B. Quattlebaum Jr.
   7 ** Copyright (c) 2008 Chris Moore
   8 **
   9 ** This package is free software; you can redistribute it and/or
  10 ** modify it under the terms of the GNU General Public License as
  11 ** published by the Free Software Foundation; either version 2 of
  12 ** the License, or (at your option) any later version.
  13 **
  14 ** This package is distributed in the hope that it will be useful,
  15 ** but WITHOUT ANY WARRANTY; without even the implied warranty of
  16 ** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17 ** General Public License for more details.
  18 **
  19 ** === N O T E S ===========================================================
  20 **
  21 ** ========================================================================= */
  22
  23 /* === S T A R T =========================================================== */
  24
  25 #ifndef __ETL__SMACH_H_
  26 #define __ETL__SMACH_H_
  27
  28 /* === H E A D E R S ======================================================= */
  29
  30 #include <vector>
  31 #include <algorithm>
  32 #include <stdexcept>
  33 #include "_mutex_null.h"
  34 #include "_misc.h"
  35
  36 /* === M A C R O S ========================================================= */
  37
  38 #define SMACH_STATE_STACK_SIZE          (32)
  39
  40 #ifdef _MSC_VER
  41 #pragma warning (disable:4786)
  42 #pragma warning (disable:4290) // MSVC6 doesn't like function declarations with exception specs
  43 #endif
  44
  45 //#define ETL_MUTEX_LOCK()              _mutex::lock lock(mutex)
  46 #define ETL_MUTEX_LOCK()
  47
  48 /* === T Y P E D E F S ===================================================== */
  49
  50 /* === C L A S S E S & S T R U C T S ======================================= */
  51
  52 _ETL_BEGIN_NAMESPACE
  53
  54 /*! ========================================================================
  55 ** \class       smach
  56 ** \brief       Templatized State Machine
  57 **
  58 ** A more detailed description needs to be written.
  59 */
  60 template <typename CON, typename K=int, typename M=mutex_null>
  61 class smach
  62 {
  63 public:
  64
  65         typedef K event_key;
  66         typedef M _mutex;
  67         typedef CON context_type;
  68
  69
  70         struct egress_exception { };
  71         struct pop_exception { };
  72
  73
  74         //! Result type for event processing
  75         enum event_result
  76         {
  77                 // These values are returned by the event
  78                 // handlers cast to state pointers.
  79                 RESULT_ERROR,           //!< General error or malfunction
  80                 RESULT_OK,                      //!< Event has been processed
  81                 RESULT_ACCEPT,          //!< The event has been explicitly accepted.
  82                 RESULT_REJECT,          //!< The event has been explicitly rejected.
  83
  84                 RESULT_END                      //!< Not a valid result
  85         };
  86
  87         //template<typename T> class state;
  88
  89         //! Event base class
  90         struct event
  91         {
  92                 event_key key;
  93
  94                 event() { }
  95                 event(const event_key& key):key(key) { }
  96
  97                 operator event_key()const { return key; }
  98         };
  99
 100         //! Event definition class
 101         template<typename T>
 102         class event_def_internal
 103         {
 104                 // List our friends
 105                 friend class smach;
 106                 //friend class state<T>;
 107
 108         public:
 109                 typedef T state_context_type;
 110
 111                 //! Event function type
 112                 typedef event_result (T::*funcptr)(const event&);
 113
 114         //private:
 115
 116                 event_key id;           //<! Event ID
 117                 funcptr handler;        //<! Pointer event handler
 118
 119         public:
 120
 121                 //! Less-than operator for sorting. Based on event_key value.
 122                 bool operator<(const event_def_internal &rhs)const
 123                         { return id<rhs.id; }
 124
 125                 //! Equal-to operator. Based on event_key value.
 126                 bool operator==(const event_def_internal &rhs)const
 127                         { return id==rhs.id; }
 128
 129                 //! Less-than operator for finding.
 130                 bool operator<(const event_key &rhs)const
 131                         { return id<rhs; }
 132
 133                 //! Equal-to operator. Based on event_key value.
 134                 bool operator==(const event_key &rhs)const
 135                         { return id==rhs; }
 136
 137                 //! Trivial Constructor
 138                 event_def_internal() { }
 139
 140                 //! Constructor for creating an event_def_internal from the given key and function reference.
 141                 event_def_internal(event_key a, funcptr b):id(a),handler(b) { }
 142
 143                 //! Copy constructor
 144                 event_def_internal(const event_def_internal &x):id(x.id),handler(x.handler) { }
 145
 146         };
 147
 148         class state_base
 149         {
 150                 // Our parent is our friend
 151                 friend class smach;
 152         public:
 153                 virtual ~state_base() { }
 154
 155                 virtual void* enter_state(context_type* machine_context)const=0;
 156
 157                 virtual bool leave_state(void* state_context)const=0;
 158
 159                 virtual event_result process_event(void* state_context,const event& id)const=0;
 160
 161                 virtual const char *get_name() const=0;
 162         };
 163
 164         //! State class
 165         template<typename T>
 166         class state : public state_base
 167         {
 168                 // Our parent is our friend
 169                 friend class smach;
 170
 171         public:
 172                 typedef event_def_internal<T> event_def;
 173                 typedef T state_context_type;
 174
 175
 176         private:
 177
 178                 std::vector<event_def> event_list;
 179
 180                 smach *nested;          //! Nested machine
 181                 event_key low,high;     //! Lowest and Highest event values
 182                 const char *name;       //! Name of the state
 183                 typename event_def::funcptr default_handler;    //! Default handler for unknown key
 184
 185         public:
 186
 187                 //! Constructor
 188                 state(const char *n, smach* nest=0):
 189                         nested(nest),name(n),default_handler(NULL)
 190                 { }
 191
 192                 virtual ~state() { }
 193
 194                 //! Setup a nested state machine
 195                 /*! A more detailed explanation needs to be written */
 196                 void set_nested_machine(smach *sm) { nested=sm; }
 197
 198                 //! Sets the default handler
 199                 void set_default_handler(const typename event_def::funcptr &x) { default_handler=x; }
 200
 201                 //! Returns given the name of the state
 202                 virtual const char *get_name() const { return name; }
 203
 204                 state_context_type& get_context(smach& machine)
 205                 {
 206                         state_context_type *context(dynamic_cast<state_context_type*>(machine.state_context));
 207                         if(context)
 208                                 return context;
 209
 210                 }
 211
 212                 //! Adds an event_def onto the list and then make sure it is sorted correctly.
 213                 void
 214                 insert(const event_def &x)
 215                 {
 216                         // If this is our first event_def,
 217                         // setup the high and low values.
 218                         if(!event_list.size())
 219                                 low=high=x.id;
 220
 221                         // Sort the event_def onto the list
 222                         event_list.push_back(x);
 223                         sort(event_list.begin(),event_list.end());
 224
 225                         // Update the low and high markers
 226                         if(x.id<low)
 227                                 low=x.id;
 228                         if(high<x.id)
 229                                 high=x.id;
 230                 }
 231
 232                 typename std::vector<event_def>::iterator find(const event_key &x) { return binary_find(event_list.begin(),event_list.end(),x); }
 233                 typename std::vector<event_def>::const_iterator find(const event_key &x)const { return binary_find(event_list.begin(),event_list.end(),x); }
 234
 235         protected:
 236
 237                 virtual void* enter_state(context_type* machine_context)const
 238                 {
 239                         return new state_context_type(machine_context);
 240                 }
 241
 242                 virtual bool leave_state(void* x)const
 243                 {
 244                         state_context_type* state_context(reinterpret_cast<state_context_type*>(x));
 245                         delete state_context;
 246                         return true;
 247                 }
 248
 249                 virtual event_result
 250                 process_event(void* x,const event& id)const
 251                 {
 252                         state_context_type* state_context(reinterpret_cast<state_context_type*>(x));
 253
 254                         // Check for nested machine in state
 255                         if(nested)
 256                         {
 257                                 const event_result ret(nested->process_event(id));
 258                                 if(ret!=RESULT_OK)
 259                                         return ret;
 260                         }
 261
 262                         // Quick test to make sure that the
 263                         // given event is in the state
 264                         if(id.key<low || high<id.key)
 265                                 return RESULT_OK;
 266
 267                         // Look for the event
 268                         typename std::vector<event_def>::const_iterator iter(find(id.key));
 269
 270                         // If search results were negative, fail.
 271                         if(iter->id!=id.key)
 272                                 return RESULT_OK;
 273
 274                         // Execute event function
 275                         event_result ret((state_context->*(iter->handler))(id));
 276
 277                         if(ret==RESULT_OK && default_handler)
 278                                 ret=(state_context->*(default_handler))(id);
 279
 280                         return ret;
 281                 }
 282         };
 283
 284 private:
 285
 286         // Machine data
 287         const state_base* curr_state;   //!< Current state of the machine
 288         smach* child;                              //!< Child machine
 289
 290 public: // this really should be private
 291         void* state_context;            //!< State Context
 292 private:
 293
 294         context_type* machine_context;          //!< Machine Context
 295
 296         const state_base* default_state;
 297         void*   default_context;
 298
 299 #ifdef ETL_MUTEX_LOCK
 300         _mutex mutex;
 301 #endif
 302
 303         //! State stack data
 304         const state_base*       state_stack[SMACH_STATE_STACK_SIZE];
 305         void*                           state_context_stack[SMACH_STATE_STACK_SIZE];
 306         int                             states_on_stack;
 307
 308 public:
 309
 310         //! Gets the name of the currently active state
 311         const char *
 312         get_state_name()const
 313         {
 314 #ifdef ETL_MUTEX_LOCK
 315                 ETL_MUTEX_LOCK();
 316 #endif
 317                 if(curr_state)
 318                         return curr_state->get_name();
 319                 if(default_state)
 320                         return default_state->get_name();
 321                 return 0;
 322         }
 323
 324         //! Determines if a given event result is an error
 325         /*! This function allows us to quickly see
 326                 if an event_result contained an error */
 327         static bool
 328         event_error(const event_result &rhs)
 329                 { return rhs<=RESULT_ERROR; }
 330
 331         bool
 332         set_default_state(const state_base *nextstate)
 333         {
 334 #ifdef ETL_MUTEX_LOCK
 335                 ETL_MUTEX_LOCK();
 336 #endif
 337                 // Keep track of the current state unless
 338                 // the state switch fails
 339                 const state_base *prev_state=default_state;
 340
 341                 // If we are already in a state, leave it and
 342                 // collapse the state stack
 343                 if(default_state)
 344                         default_state->leave_state(default_context);
 345
 346                 // Set this as our current state
 347                 default_state=nextstate;
 348                 default_context=0;
 349
 350                 // Attempt to enter the state
 351                 if(default_state)
 352                 {
 353                         default_context=default_state->enter_state(machine_context);
 354                         if(default_context)
 355                                 return true;
 356                 }
 357                 else
 358                         return true;
 359
 360                 // We failed, so attempt to return to previous state
 361                 default_state=prev_state;
 362
 363                 // If we had a previous state, enter it
 364                 if(default_state)
 365                         default_context=default_state->enter_state(machine_context);
 366
 367                 // At this point we are not in the
 368                 // requested state, so return failure
 369                 return false;
 370         }
 371
 372         //! Leaves the current state
 373         /*! Effectively makes the state_depth() function return zero. */
 374         bool
 375         egress()
 376         {
 377 #ifdef ETL_MUTEX_LOCK
 378                 ETL_MUTEX_LOCK();
 379 #endif
 380
 381                 // Pop all states off the state stack
 382                 while(states_on_stack) pop_state();
 383
 384                 // If we are not in a state, then I guess
 385                 // we were successful.
 386                 if(!curr_state)
 387                         return true;
 388
 389                 // Grab the return value from the exit function
 390                 bool ret=true;
 391
 392                 const state_base* old_state=curr_state;
 393                 void *old_context=state_context;
 394
 395                 // Clear out the current state and its state_context
 396                 curr_state=0;state_context=0;
 397
 398                 // Leave the state
 399                 return old_state->leave_state(old_context);
 400
 401                 return ret;
 402         }
 403
 404         //! State entry function
 405         /*! Attempts to enter the given state,
 406                 popping off all states on the stack
 407                 in the process. */
 408         bool
 409         enter(const state_base *nextstate)
 410         {
 411 #ifdef ETL_MUTEX_LOCK
 412                 ETL_MUTEX_LOCK();
 413 #endif
 414
 415                 // Keep track of the current state unless
 416                 // the state switch fails
 417                 const state_base *prev_state=curr_state;
 418
 419                 // If we are already in a state, leave it and
 420                 // collapse the state stack
 421                 if(curr_state)
 422                         egress();
 423
 424                 // Set this as our current state
 425                 curr_state=nextstate;
 426                 state_context=0;
 427
 428                 // Attempt to enter the state
 429                 state_context=curr_state->enter_state(machine_context);
 430                 if(state_context)
 431                         return true;
 432
 433                 // We failed, so attempt to return to previous state
 434                 curr_state=prev_state;
 435
 436                 // If we had a previous state, enter it
 437                 if(curr_state)
 438                         state_context=curr_state->enter_state(machine_context);
 439
 440                 // At this point we are not in the
 441                 // requested state, so return failure
 442                 return false;
 443         }
 444
 445         //! Pushes state onto state stack
 446         /*! This allows you to enter a state without
 447                 leaving your current state.
 448                 \param   nextstate Pointer to the state to enter
 449                 \sa      pop_state()
 450         */
 451         bool
 452         push_state(const state_base *nextstate)
 453         {
 454 #ifdef ETL_MUTEX_LOCK
 455                 ETL_MUTEX_LOCK();
 456 #endif
 457
 458                 // If there are not enough slots, then throw something.
 459                 if(states_on_stack==SMACH_STATE_STACK_SIZE)
 460                         throw(std::overflow_error("smach<>::push_state(): state stack overflow!"));
 461
 462                 // If there is no current state, nor anything on stack,
 463                 // just go ahead and enter the given state.
 464                 if(!curr_state && !states_on_stack)
 465                         return enter(nextstate);
 466
 467                 // Push the current state onto the stack
 468                 state_stack[states_on_stack]=curr_state;
 469                 state_context_stack[states_on_stack++]=state_context;
 470
 471                 // Make the next state the current state
 472                 curr_state=nextstate;
 473
 474                 // Try to enter the next state
 475                 state_context=curr_state->enter_state(machine_context);
 476                 if(state_context)
 477                         return true;
 478
 479                 // Unable to push state, return to old one
 480                 curr_state=state_stack[--states_on_stack];
 481                 state_context=state_context_stack[states_on_stack];
 482                 return false;
 483         }
 484
 485         //! Pops state off of state stack
 486         /*! Decreases state depth */
 487         void
 488         pop_state()
 489         {
 490 #ifdef ETL_MUTEX_LOCK
 491                 ETL_MUTEX_LOCK();
 492 #endif
 493
 494                 // If we aren't in a state, then there is nothing
 495                 // to do.
 496                 if(!curr_state)
 497                         throw(std::underflow_error("smach<>::pop_state(): stack is empty!"));
 498
 499                 if(states_on_stack)
 500                 {
 501                         const state_base* old_state=curr_state;
 502                         void *old_context=state_context;
 503
 504                         // Pop previous state off of stack
 505                         --states_on_stack;
 506                         curr_state=state_stack[states_on_stack];
 507                         state_context=state_context_stack[states_on_stack];
 508
 509                         old_state->leave_state(old_context);
 510                 }
 511                 else // If there are no states on stack, just egress
 512                         egress();
 513         }
 514
 515         //! State Machine Constructor
 516         /*! A more detailed description needs to be written */
 517         smach(context_type* machine_context=0):
 518                 curr_state(0),
 519                 child(0),
 520                 state_context(0),
 521                 machine_context(machine_context),
 522                 default_state(0),
 523                 default_context(0),
 524                 states_on_stack(0)
 525         { }
 526
 527         //! The destructor
 528         ~smach()
 529         {
 530                 egress();
 531
 532                 if(default_state)
 533                         default_state->leave_state(default_context);
 534         }
 535
 536         //! Sets up a child state machine
 537         /*! A child state machine runs in parallel with
 538                 its parent, and gets event priority. This
 539                 mechanism is useful in cases where an inherited
 540                 object has its own state machine. */
 541         void set_child(smach *x)
 542         {
 543 #ifdef ETL_MUTEX_LOCK
 544                 ETL_MUTEX_LOCK();
 545 #endif
 546                 child=x;
 547         }
 548
 549         //! Returns the number states currently active
 550         int
 551         state_depth()
 552                 { return curr_state?states_on_stack+1:0; }
 553
 554         event_result
 555         process_event(const event_key& id) { return process_event(event(id)); }
 556
 557         //! Process an event
 558         event_result
 559         process_event(const event& id)
 560         {
 561 #ifdef ETL_MUTEX_LOCK
 562                 ETL_MUTEX_LOCK();
 563 #endif
 564
 565                 event_result ret(RESULT_OK);
 566
 567                 // Check for child machine
 568                 if(child)
 569                 {
 570                         ret=child->process_event(id);
 571                         if(ret!=RESULT_OK)
 572                                 return ret;
 573                 }
 574
 575                 try
 576                 {
 577                         if(curr_state)
 578                                 ret=curr_state->process_event(state_context,id);
 579
 580                         if(ret==RESULT_OK)
 581                                 return default_state->process_event(default_context,id);
 582
 583                         return ret;
 584                 }
 585                 catch(egress_exception) { return egress()?RESULT_ACCEPT:RESULT_ERROR; }
 586                 catch(pop_exception) { pop_state(); return RESULT_ACCEPT; }
 587                 catch(const state_base* state) { return enter(state)?RESULT_ACCEPT:RESULT_ERROR; }
 588         }
 589
 590 }; // END of template class smach
 591
 592 _ETL_END_NAMESPACE
 593
 594 /* === E X T E R N S ======================================================= */
 595
 596 /* === E N D =============================================================== */
 597
 598 #endif