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Parse phrases from string

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  1. <?php
  2. /**
  3.  * Parses a String of Tags
  4.  *
  5.  * Tags are space delimited. Either single or double quotes mark a phrase.
  6.  * Odd quotes will cause everything on their right to reflect as one single
  7.  * tag or phrase. All white-space within a phrase is converted to single
  8.  * space characters. Quotes burried within tags are ignored! Duplicate tags
  9.  * are ignored, even duplicate phrases that are equivalent.
  10.  *
  11.  * Returns an array of tags.
  12.  */
  13. function ParseTagString($sTagString)
  14. {
  15. 	$arTags = array();		// Array of Output
  16. 	$cPhraseQuote = null;	// Record of the quote that opened the current phrase
  17. 	$sPhrase = null;		// Temp storage for the current phrase we are building
  18.  
  19. 	// Define some constants
  20. 	static $sTokens = " 
  21. \t";	// Space, Return, Newline, Tab
  22. 	static $sQuotes = "'\"";		// Single and Double Quotes
  23.  
  24. 	// Start the State Machine
  25. 	do
  26. 	{
  27. 		// Get the next token, which may be the first
  28. 		$sToken = isset($sToken)? strtok($sTokens) : strtok($sTagString, $sTokens);
  29.  
  30. 		// Are there more tokens?
  31. 		if ($sToken === false)
  32. 		{
  33. 			// Ensure that the last phrase is marked as ended
  34. 			$cPhraseQuote = null;
  35. 		}
  36. 		else
  37. 		{		
  38. 			// Are we within a phrase or not?
  39. 			if ($cPhraseQuote !== null)
  40. 			{
  41. 				// Will the current token end the phrase?
  42. 				if (substr($sToken, -1, 1) === $cPhraseQuote)
  43. 				{
  44. 					// Trim the last character and add to the current phrase, with a single leading space if necessary
  45. 					if (strlen($sToken) > 1) $sPhrase .= ((strlen($sPhrase) > 0)? ' ' : null) . substr($sToken, 0, -1);
  46. 					$cPhraseQuote = null;
  47. 				}
  48. 				else
  49. 				{
  50. 					// If not, add the token to the phrase, with a single leading space if necessary
  51. 					$sPhrase .= ((strlen($sPhrase) > 0)? ' ' : null) . $sToken;
  52. 				}
  53. 			}
  54. 			else
  55. 			{
  56. 				// Will the current token start a phrase?
  57. 				if (strpos($sQuotes, $sToken[0]) !== false)
  58. 				{
  59. 					// Will the current token end the phrase?
  60. 					if ((strlen($sToken) > 1) && ($sToken[0] === substr($sToken, -1, 1)))
  61. 					{
  62. 						// The current token begins AND ends the phrase, trim the quotes
  63. 						$sPhrase = substr($sToken, 1, -1);
  64. 					}
  65. 					else
  66. 					{
  67. 						// Remove the leading quote
  68. 						$sPhrase = substr($sToken, 1);
  69. 						$cPhraseQuote = $sToken[0];
  70. 					}
  71. 				}
  72. 				else
  73. 					$sPhrase = $sToken;
  74. 			}
  75. 		}
  76.  
  77. 		// If, at this point, we are not within a phrase, the prepared phrase is complete and can be added to the array
  78. 		if (($cPhraseQuote === null) && ($sPhrase != null))
  79. 		{
  80. 			$sPhrase = strtolower($sPhrase);
  81. 			if (!in_array($sPhrase, $arTags)) $arTags[] = $sPhrase;
  82. 			$sPhrase = null;
  83. 		}
  84. 	}
  85. 	while ($sToken !== false);	// Stop when we receive FALSE from strtok()
  86. 	return $arTags;
  87. }
  88.  

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