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  1. <?php
  2.  
  3. class Lexer {
  4. 	protected static $_terminals = array(
  5.         '~^(\[)~'				=> "T_OPEN",
  6.         '~^(\])~'				=> "T_CLOSE",
  7.         '~^(".+?(?<!\\\\)")~'	=> "T_ITEM",
  8.         '~^(,)(?!,)~'			=> "T_SEPARATOR",
  9.         '~^(\d+)~'				=> "T_NUMBER",
  10.         '~^(,)(?=,)~'			=> "T_EMPTY"
  11.     );
  12.  
  13.     public static function run($line) {
  14.     	$tokens = array();
  15.     	$offset = 0;
  16.     	while($offset < strlen($line)) {
  17.     		$result = static::_match($line, $offset);
  18.     		if($result === false) {
  19.     			throw new Exception("Unable to parse line " . ($line+1) . ".");
  20.     		}
  21.     		$tokens[] = $result;
  22.     		$offset += strlen($result['match']);
  23.     	}
  24.     	return static::_generate($tokens);
  25.     }
  26.  
  27.     protected static function _match($line, $offset) {
  28.     	$string = substr($line, $offset);
  29.  
  30.     	foreach(static::$_terminals as $pattern => $name) {
  31.     		if(preg_match($pattern, $string, $matches)) {
  32.     			return array(
  33.     				'match' => $matches[1],
  34.     				'token' => $name
  35.     			);
  36.     		}
  37.     	}
  38.     	return false;
  39.     }
  40.  
  41. 	// a recursive function to actually build the structure
  42. 	protected static function _generate($arr=array(), $idx=0) {
  43. 	    $output = array();
  44. 	    $current = 0;
  45. 	    for($i=$idx;$i<count($arr);$i++) {
  46. 	    	$type = $arr[$i]["token"];
  47. 	    	$element = $arr[$i]["match"];
  48. 	    	switch ($type) {
  49. 	    		case 'T_OPEN':
  50. 	    			list($out, $index) = static::_generate($arr, $i+1);
  51. 	        		$output[] = $out;
  52. 	        		$i = $index;
  53. 	        		break;
  54. 	        	case 'T_CLOSE':
  55. 	        		return array($output, $i);
  56. 	        		break;
  57. 	        	case 'T_ITEM':
  58. 	        	case 'T_NUMBER':
  59. 	        		$output[] = $element;
  60. 	        		break;
  61. 	        	case 'T_EMPTY':
  62. 	        		$output[] = "";
  63. 	        		break;
  64. 	    	}
  65. 	    }
  66. 	    return $output;
  67. 	}    
  68. }
  69.  
  70. $input  = '[[["Hello, \"how\" are you?","Good!",,,123]],,"ok"]';
  71. $items = Lexer::run($input);
  72. print_r($items);
  73.  
  74. ?>
Success #stdin #stdout 0.01s 82944KB
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Standard input is empty
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Array
(
    [0] => Array
        (
            [0] => Array
                (
                    [0] => Array
                        (
                            [0] => "Hello, \"how\" are you?"
                            [1] => "Good!"
                            [2] => 
                            [3] => 
                            [4] => 123
                        )

                )

            [1] => 
            [2] => "ok"
        )

)
https://ideone.com/tiskwt
language:
PHP (php 7.3.5)
created:
9 years ago
visibility:
public

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