64 lines
1.9 KiB
PHP
64 lines
1.9 KiB
PHP
<?php
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/** Ïîëó÷àåì íà âõîä ñòðîêó, à íà âûõîä ðåçóëüòàò ìàòåìàòè÷åñêîé îïåðàöèè â ñòðîêå. */
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class CalculateFromString
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{
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const PATTERN = '/(?:\-?\d+(?:\.?\d+)?[\+\-\*\/])+\-?\d+(?:\.?\d+)?/';
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const PARENTHESIS_DEPTH = 10;
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public function calculate($input){
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if(strpos($input, '+') != null || strpos($input, '-') != null || strpos($input, '/') != null || strpos($input, '*') != null){
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// Remove white spaces and invalid math chars
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$input = str_replace(',', '.', $input);
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$input = str_replace(' ', '', $input);
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$input = preg_replace('[^0-9\.\+\-\*\/\(\)]', '', $input);
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// Calculate each of the parenthesis from the top
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$i = 0;
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while(strpos($input, '(') || strpos($input, ')')){
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$input = preg_replace_callback('/\(([^\(\)]+)\)/', 'self::callback', $input);
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$i++;
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if($i > self::PARENTHESIS_DEPTH){
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break;
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}
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}
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// Calculate the result
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if(preg_match(self::PATTERN, $input, $match)){
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return $this->compute($match[0]);
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}
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// To handle the special case of expressions surrounded by global parenthesis like "(1+1)"
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if(is_numeric($input)){
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return $input;
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}
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return 0;
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}
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return $input;
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}
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private function compute($input){
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$compute = create_function('', 'return '.$input.';');
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return 0 + $compute();
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}
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private function callback($input){
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if(is_numeric($input[1])){
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return $input[1];
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}
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elseif(preg_match(self::PATTERN, $input[1], $match)){
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return $this->compute($match[0]);
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}
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return 0;
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}
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}
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$Cal = new CalculateFromString();
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$xyz='(100 * 25000) + (250 * 25000) + ((500/100) * 25000)';
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$result = $Cal->calculate($xyz);
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echo $result;
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