topical media & game development
[] readme course(s) preface I 1 2 II 3 4 III 5 6 7 IV 8 9 10 V 11 12 afterthought(s) appendix reference(s) example(s) resource(s) _

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professional-php-17-rpn.php / php



  <?php
       
       require_once 'FSM.php';
       
       function BeginBuildNumber(symbol, payload)
       {
           array_push(payload, symbol);
       }
       
      function BuildNumber(symbol, payload)
      {
          n = array_pop(payload);
          n = n . symbol;
          array_push(payload, n);
      }
      
      function EndBuildNumber(symbol, payload)
      {
          n = array_pop(payload);
          array_push(payload, (int)n);
      }
      
      function DoOperator(symbol, payload)
      {
          ar = array_pop(payload);
         al = array_pop(payload);
      
          if (symbol == '+') {
              array_push(payload, al + ar);
          } elseif (symbol == '-') {
              array_push(payload, al - ar);
          } elseif (symbol == '*') {
              array_push(payload, al * ar);
          } elseif (symbol == '/') {
              array_push(payload, al / ar);
          }
     }
      
      function DoEqual(symbol, payload)
      {
          echo array_pop(payload) . "\n";
      }
      
      function Error(symbol, payload)
      {
          echo "This does not compute: symbol\n";
      }
      
      stack = array();
      
      fsm = new FSM('INIT', stack);
     fsm->setDefaultTransition('INIT', 'Error');
      
      fsm->addTransitionAny('INIT', 'INIT');
      fsm->addTransition('=', 'INIT', 'INIT', 'DoEqual');
      fsm->addTransitions(range(0,9), 'INIT', 'BUILDING_NUMBER', 'BeginBuildNumber');
      fsm->addTransitions(range(0,9), 'BUILDING_NUMBER', 'BUILDING_NUMBER', 'BuildNumber');
      fsm->addTransition(' ', 'BUILDING_NUMBER', 'INIT', 'EndBuildNumber');
      fsm->addTransitions(array('+','-','*','/'), 'INIT', 'INIT', 'DoOperator');
      
      echo "Expression:\n";
      stdin = fopen('php://stdin', 'r');
      expression = rtrim(fgets(stdin));
      symbols = preg_split('//', expression, -1, PREG_SPLIT_NO_EMPTY);
      
      fsm->processList(symbols);
[] readme course(s) preface I 1 2 II 3 4 III 5 6 7 IV 8 9 10 V 11 12 afterthought(s) appendix reference(s) example(s) resource(s) _

(C) Æliens 20/2/2008

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