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<?php
/**
* Author: Alexander "NeonXP" Kiryukhin
* Date: 14.03.13
* Time: 1:01
*/
namespace NXP;
use NXP\Classes\Func;
use NXP\Classes\Operand;
use NXP\Classes\Token;
use NXP\Classes\TokenParser;
/**
* Class MathExecutor
* @package NXP
*/
class MathExecutor {
private $operators = [ ];
private $functions = [ ];
private $variables = [ ];
/**
* @var \SplStack
*/
private $stack;
/**
* @var \SplQueue
*/
private $queue;
/**
* Base math operators
*/
public function __construct()
{
$this->addOperator(new Operand('+', 1, Operand::LEFT_ASSOCIATED, Operand::BINARY, function ($op1, $op2) { return $op1+$op2; }));
$this->addOperator(new Operand('-', 1, Operand::LEFT_ASSOCIATED, Operand::BINARY, function ($op1, $op2) { return $op1-$op2; }));
$this->addOperator(new Operand('*', 2, Operand::LEFT_ASSOCIATED, Operand::BINARY, function ($op1, $op2) { return $op1*$op2; }));
$this->addOperator(new Operand('/', 2, Operand::LEFT_ASSOCIATED, Operand::BINARY, function ($op1, $op2) { return $op1/$op2; }));
$this->addOperator(new Operand('^', 3, Operand::LEFT_ASSOCIATED, Operand::BINARY, function ($op1, $op2) { return pow($op1,$op2); }));
$this->addFunction(new Func('sin', function ($arg) { return sin($arg); }));
$this->addFunction(new Func('cos', function ($arg) { return cos($arg); }));
$this->addFunction(new Func('tn', function ($arg) { return tan($arg); }));
$this->addFunction(new Func('asin', function ($arg) { return asin($arg); }));
$this->addFunction(new Func('acos', function ($arg) { return acos($arg); }));
$this->addFunction(new Func('atn', function ($arg) { return atan($arg); }));
}
public function addOperator(Operand $operator)
{
$this->operators[$operator->getSymbol()] = $operator;
}
public function addFunction(Func $function)
{
$this->functions[$function->getName()] = $function->getCallback();
}
public function setVar($variable, $value)
{
if (!is_numeric($value)) {
throw new \Exception("Variable value must be a number");
}
$this->variables[$variable] = $value;
}
/**
* 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 $expression
* @return \SplQueue
* @throws \Exception
*/
protected function convertToReversePolishNotation($expression)
{
$this->stack = new \SplStack();
$this->queue = new \SplQueue();
$tokenParser = new TokenParser();
$input = $tokenParser->tokenize($expression);
foreach ($input as $token) {
$this->categorizeToken($token);
}
while (!$this->stack->isEmpty()) {
$token = $this->stack->pop();
if ($token->getType() != Token::OPERATOR) {
throw new \Exception('Opening bracket without closing bracket');
}
$this->queue->push($token);
}
return $this->queue;
}
private function categorizeToken(Token $token)
{
switch ($token->getType()) {
case Token::NUMBER :
$this->queue->push($token);
break;
case Token::STRING:
if (array_key_exists($token->getValue(), $this->variables)) {
$this->queue->push(new Token(Token::NUMBER, $this->variables[$token->getValue()]));
} else {
$this->stack->push($token);
}
break;
case Token::LEFT_BRACKET:
$this->stack->push($token);
break;
case Token::RIGHT_BRACKET:
$previousToken = $this->stack->pop();
while (!$this->stack->isEmpty() && ($previousToken->getType() != Token::LEFT_BRACKET)) {
$this->queue->push($previousToken);
$previousToken = $this->stack->pop();
}
if ((!$this->stack->isEmpty()) && ($this->stack->top()->getType() == Token::STRING)) {
$string = $this->stack->pop()->getValue();
if (!array_key_exists($string, $this->functions)) {
throw new \Exception('Unknown function');
}
$this->queue->push(new Token(Token::FUNC, $string));
}
break;
case Token::OPERATOR:
if (!array_key_exists($token->getValue(), $this->operators)) {
throw new \Exception("Unknown operator '{$token->getValue()}'");
}
$this->proceedOperator($token);
$this->stack->push($token);
break;
default:
throw new \Exception('Unknown token');
}
}
private function proceedOperator($token)
{
if (!array_key_exists($token->getValue(), $this->operators)) {
throw new \Exception('Unknown operator');
}
/** @var Operand $operator */
$operator = $this->operators[$token->getValue()];
while (!$this->stack->isEmpty()) {
$top = $this->stack->top();
if ($top->getType() == Token::OPERATOR) {
$priority = $this->operators[$top->getValue()]->getPriority();
if ( $operator->getAssociation() == Operand::RIGHT_ASSOCIATED) {
if (($priority > $operator->getPriority())) {
$this->queue->push($this->stack->pop());
} else {
return;
}
} else {
if (($priority >= $operator->getPriority())) {
$this->queue->push($this->stack->pop());
} else {
return;
}
}
} elseif ($top->getType() == Token::STRING) {
$this->queue->push($this->stack->pop());
} else {
return;
}
}
}
protected function calculateReversePolishNotation(\SplQueue $expression)
{
$this->stack = new \SplStack();
/** @val Token $token */
foreach ($expression as $token) {
switch ($token->getType()) {
case Token::NUMBER :
$this->stack->push($token);
break;
case Token::OPERATOR:
/** @var Operand $operator */
$operator = $this->operators[$token->getValue()];
if ($operator->getType() == Operand::BINARY) {
$arg2 = $this->stack->pop()->getValue();
$arg1 = $this->stack->pop()->getValue();
} else {
$arg2 = null;
$arg1 = $this->stack->pop()->getValue();
}
$callback = $operator->getCallback();
$this->stack->push(new Token(Token::NUMBER, ($callback($arg1, $arg2))));
break;
case Token::FUNC:
/** @var Func $function */
$callback = $this->functions[$token->getValue()];
$arg = $this->stack->pop()->getValue();
$this->stack->push(new Token(Token::NUMBER, ($callback($arg))));
break;
default:
throw new \Exception('Unknown token');
}
}
$result = $this->stack->pop()->getValue();
if (!$this->stack->isEmpty()) {
throw new \Exception('Incorrect expression');
}
return $result;
}
}
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