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Diffstat (limited to 'NXP/MathExecutor.php')
| -rw-r--r-- | NXP/MathExecutor.php | 197 |
1 files changed, 197 insertions, 0 deletions
diff --git a/NXP/MathExecutor.php b/NXP/MathExecutor.php new file mode 100644 index 0000000..d7eaf82 --- /dev/null +++ b/NXP/MathExecutor.php @@ -0,0 +1,197 @@ +<?php +/** + * Author: Alexander "NeonXP" Kiryukhin + * Date: 14.03.13 + * Time: 1:01 + */ +namespace NXP; + +/** + * Class MathExecutor + * @package NXP + */ +class MathExecutor { + const LEFT_ASSOCIATED = 'LEFT_ASSOCIATED'; + const RIGHT_ASSOCIATED = 'RIGHT_ASSOCIATED'; + const NOT_ASSOCIATED = 'NOT_ASSOCIATED'; + + const UNARY = 'UNARY'; + const BINARY = 'BINARY'; + + private $operators = [ ]; + + /** + * Base math operators + */ + public function __construct() + { + $this->addOperator('+', 1, function ($op1, $op2) { return $op1 + $op2; }); + $this->addOperator('-', 1, function ($op1, $op2) { return $op1 - $op2; }); + $this->addOperator('*', 2, function ($op1, $op2) { return $op1 * $op2; }); + $this->addOperator('/', 2, function ($op1, $op2) { return $op1 / $op2; }); + $this->addOperator('^', 3, function ($op1, $op2) { return pow($op1, $op2); }); + } + + /** + * Add custom operator + * @param string $name + * @param int $priority + * @param callable $callback + * @param string $association + * @param string $type + */ + public function addOperator($name, $priority, callable $callback, $association = self::LEFT_ASSOCIATED, $type = self::BINARY) + { + $this->operators[$name] = [ + 'priority' => $priority, + 'association' => $association, + 'type' => $type, + 'callback' => $callback + ]; + } + + /** + * Execute expression + * @param $expression + * @return int|float + */ + public function execute($expression) + { + $reversePolishNotation = $this->convertToReversePolishNotation($expression); + $result = $this->calculateReversePolishNotation($reversePolishNotation); + + return $result; + } + + /** + * Convert expression from normal expression form to RPN + * @param $expression + * @return array + * @throws \Exception + */ + protected function convertToReversePolishNotation($expression) + { + $stack = new \SplStack(); + $queue = []; + $currentNumber = ''; + + for ($i = 0; $i < strlen($expression); $i++) + { + $char = substr($expression, $i, 1); + if (is_numeric($char) || (($char == '.') && (strpos($currentNumber, '.')===false))) { + $currentNumber .= $char; + } elseif ($currentNumber!='') { + $queue = $this->insertNumberToQueue($currentNumber, $queue); + $currentNumber = ''; + } + if (array_key_exists($char, $this->operators)) { + while ($this->o1HasLowerPriority($char, $stack)) { + $queue[] = $stack->pop(); + } + $stack->push($char); + } + if ($char == '(') { + $stack->push($char); + } + if ($char == ')') { + if ($currentNumber!='') { + $queue = $this->insertNumberToQueue($currentNumber, $queue); + $currentNumber = ''; + } + while (($stackChar = $stack->pop()) != '(') { + $queue[] = $stackChar; + } + /** + * @TODO parse functions here + */ + } + } + + if ($currentNumber!='') { + $queue = $this->insertNumberToQueue($currentNumber, $queue); + } + + while (!$stack->isEmpty()) { + $queue[] = ($char = $stack->pop()); + if (!array_key_exists($char, $this->operators)) { + throw new \Exception('Opening bracket has no closing bracket'); + } + } + + return $queue; + } + + /** + * Calculate value of expression + * @param array $expression + * @return int|float + * @throws \Exception + */ + protected function calculateReversePolishNotation(array $expression) + { + $stack = new \SplStack(); + foreach ($expression as $element) { + if (is_numeric($element)) { + $stack->push($element); + } elseif (array_key_exists($element, $this->operators)) { + $operator = $this->operators[$element]; + switch ($operator['type']) { + case self::BINARY: + $op2 = $stack->pop(); + $op1 = $stack->pop(); + $operatorResult = $operator['callback']($op1, $op2); + break; + case self::UNARY: + $op = $stack->pop(); + $operatorResult = $operator['callback']($op); + break; + default: + throw new \Exception('Incorrect type'); + } + $stack->push($operatorResult); + } + } + $result = $stack->pop(); + if (!$stack->isEmpty()) { + throw new \Exception('Incorrect expression'); + } + + return $result; + } + + /** + * @param $char + * @param $stack + * @return bool + */ + private function o1HasLowerPriority($char, \SplStack $stack) { + if (($stack->isEmpty()) || ($stack->top() == '(')) { + return false; + } + $stackTopAssociation = $this->operators[$stack->top()]['association']; + $stackTopPriority = $this->operators[$stack->top()]['priority']; + $charPriority = $this->operators[$char]['priority']; + + + return + (($stackTopAssociation != self::LEFT_ASSOCIATED) && ($stackTopPriority > $charPriority)) || + (($stackTopAssociation == self::LEFT_ASSOCIATED) && ($stackTopPriority >= $charPriority)); + } + + /** + * @param string $currentNumber + * @param array $queue + * @return array + */ + private function insertNumberToQueue($currentNumber, $queue) + { + if ($currentNumber[0]=='.') { + $currentNumber = '0'.$currentNumber; + } + $currentNumber = trim($currentNumber, '.'); + $queue[] = $currentNumber; + + return $queue; + } + +}
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