1: <?php
 2: 
 3: namespace BN\Compiler\Postfix;
 4: 
 5: use BN\Collections\Queue;
 6: use BN\Compiler\Token\Token;
 7: use BN\Compiler\Token\TokenType;
 8: use BN\Compiler\Grammar\Operators;
 9: use BN\Compiler\Postfix\Token\ProcessValue;
10: use BN\Compiler\Postfix\Token\ProcessOperator;
11: use BN\Compiler\Postfix\Token\ProcessUnknown;
12: use BN\Compiler\Postfix\Token\ProcessAssign;
13: use BN\Compiler\Postfix\Token\ProcessConstant;
14: 
15: class PostfixEvaluator
16: {
17:     private $accumulator;
18:     private $calculators;
19:     private $tokensQueue;
20:     private $variables;
21: 
22:     public function __construct(CalculatorErrorHandler $errorHandler, Operators $operators, array $constants)
23:     {
24:         $this->variables = new Variables();
25:         $this->accumulator = new StackAccumulator($errorHandler);
26:         $processValue = new ProcessValue($this->accumulator);
27:         $this->calculators = array(
28:             TokenType::NUMBER => $processValue,
29:             TokenType::VARIABLE => $processValue,
30:             TokenType::CONSTANT => new ProcessConstant($this->accumulator, $constants),
31:             TokenType::ASSIGN => new ProcessAssign($this->accumulator, $this->variables),
32:             TokenType::OPERATOR => new ProcessOperator($this->accumulator, $operators, $this->variables),
33:             TokenType::UNKNOWN => new ProcessUnknown($this->accumulator)
34:         );
35:     }
36: 
37:     public function evaluate(Queue $queue, \stdClass $variables)
38:     {
39:         $this->prepareEvaluator($queue, $variables);
40:         while ($this->isTokenInQueue()) {
41:             $this->readNextToken();
42:         }
43:         return $this->evaluateResult();
44:     }
45: 
46:     private function prepareEvaluator($queue, $variables)
47:     {
48:         $this->accumulator->init();
49:         $this->tokensQueue = $queue;
50:         $this->variables->setVariables($variables);
51:     }
52: 
53:     private function isTokenInQueue()
54:     {
55:         return !$this->tokensQueue->isEmpty() && $this->accumulator->continueInCalculation();
56:     }
57: 
58:     private function readNextToken()
59:     {
60:         $token = $this->tokensQueue->pop();
61:         $p = $this->getProcessor($token);
62:         $p->process($token);
63:     }
64: 
65:     private function getProcessor(Token $token)
66:     {
67:         if (array_key_exists($token->type, $this->calculators)) {
68:             return $this->calculators[$token->type];
69:         } else {
70:             return $this->calculators[TokenType::UNKNOWN];
71:         }
72:     }
73: 
74:     private function evaluateResult()
75:     {
76:         return $this->accumulator->getResult();
77:     }
78: }
79: