<?
function searchString($string,$fieldName,$insensitive = true, $allKeywords = false) {
/*
 * This function analyses a search string. It splits it into its constituent words
 * and remembers whether these were separated by "+" signs or blanks
 * It then builds part of an SQL query where $fieldName is compared to the
 * words found, with corresponding AND or OR keywords
 *
 *	$string			search string. Assumed not to be empty
 *	$fieldName		name of the field to be searched
 *	$insensitive	if set to true, the search is case insensitive
 *					(can be omitted, defaults to true)
 *	$allKeywords	if set to true forces all tokens of the search string to be mandatory,
 *					i.e. all parts of the search are linked by AND keywords and not OR
 *					(can be omitted, defaults to false)
 *
 * Francois Suter, December 2002
 */

	$string = trim($string); // remove extra spaces

// Perform a number of initialisations

	$length = strlen($string);
	$position = 0;
	$lastPosition = 0;
	$keywordCount = 0;
/*
 * $keyword is a two-dimensional array for storing the search keywords
 * and whether they are mandatory or optional. The keyword is stored in the first slot,
 * the flag in the second slot (= 0 if optional, = 1 if mandatory)
 *
 */
	$keywords[0][$keywordCount] = ""; // we don't know yet what the first keyword is (maybe the whole string)
	$keywords[1][$keywordCount] = 1; // the first keyword is necessarily mandatory

/*
 * In this loop, the search string is parsed and cut into words each a "+" symbol or a blank space is found
 * A "+" symbol is interpreted as a logical AND. To reflect this the flag mandatoryToggle is set to 1.
 * A blank space is interpreted as a logical OR. The flag mandatoryToggle is set to 0.
 *
 */
	do {
		$thePlus = strpos($string,"+",$position);
		$theSpace = strpos($string," ",$position);
		$mandatoryToggle = 0;

/*
 * If at least one "+" symbol or a blank space has been detected, check which one comes firts,
 * record position and set mandatoryToggle accordingly
 *
 */

		if ($thePlus > 0 || $theSpace > 0) {
			if ($thePlus > 0 && ($theSpace == 0 || $thePlus < $theSpace)) {
				$wordLength = $thePlus - $position;
				$mandatoryToggle = 1;
				$lastPosition = $thePlus + 1;
			}
			elseif ($theSpace > 0 && ($thePlus == 0 || $theSpace < $thePlus)) {
				$wordLength = $theSpace - $position;
				$lastPosition = $theSpace + 1;
			}

// Get the word, increase word count

			$keywords[0][$keywordCount] = substr($string,$position,$wordLength);
			$keywordCount++;
			$keywords[1][$keywordCount] = $mandatoryToggle; // the state applies to the next word
			$position = $lastPosition; // increase position inside the string
		}
		else {
			$position = $length; // nothing has been found. Set position to last character to break the loop
		}
	} while ($position < $length);

// Get last (or only) word in list

	$keywords[0][$keywordCount] = substr($string,$lastPosition,$length - $lastPosition + 1);

/*
 * Build the part of the SQL statement corresponding to the comparison of the
 * field name to the keywords, with the list of words and the appropriate logical operators
 */

	$sqlString = "";
	if ($insensitive) {
		$operator = "ILIKE";
	}
	else {
		$operator = "LIKE";
	}
	for ($i = 0; $i <= $keywordCount; $i++) {
		$sqlString .= "\"$fieldName\" $operator '%{$keywords[0][$i]}%'";

/*
 * Logical operators are set only if there is more than one word.
 * The toggle to consider is the one from the next word
 * (or always AND is $allKeywords is true)
 */

		if ($i < $keywordCount) {
			if ($allKeywords) {
				$sqlString .= " AND ";
			}
			else {
				if ($keywords[1][$i+1] == 1) {
					$sqlString .= " AND ";
				}
				else {
					$sqlString .= " OR ";
				}
			}
		}
	}
	return $sqlString;
}
?>