Like PHP's implode() and explode(), but lets you escape the delimiters for splitting the strings with.

escaped-implode-explode.php

<?php

/**
 * Same as implode, but escape the separator when it exists in the array elements being imploded
 * If the separator is longer than 1 character, only the first character need be escaped (not every character of the delimiter).
 *
 * @param	string	$sep	delimiter to stich the array together with
 * @param	array	$arr	array to combine
 * @param	char	$escape	escape character to escape any found delimiters with
 * @return	imploded string
 * 
 * @author	Sam Pospischil <pospi@spadgos.com>
 */
function escapedimplode($sep, $arr, $escape = '\\') {
	if (!is_array($arr)) {
		return false;
	}
	foreach ($arr as $k => $v) {
		$arr[$k] = str_replace($sep, $escape . $sep, $v);
	}
	return implode($sep, $arr);
}

/**
 * same as explode, but don't treat delimiters preceded by an escaped character as delimiters, and convert them in the output
 * If the separator is longer than 1 character, only the first character need be escaped (not every character of the delimiter).
 *
 * @param	string	$sep	boundary delimiter to split the input string on
 * @param	string	$str	string to explode
 * @param	char	$escape	escape character used to escape delimiters in the string
 * @return	exploded array, with delimiter escape characters removed
 * 
 * @author	Sam Pospischil <pospi@spadgos.com>
 */
function escapedexplode($sep, $str, $escape = '\\') {
	$astr = str_split($str);
	
	$result = array();			// final result array
	$buffer = '';				// buffer for current array item match
	$matchedBuffer = '';		// buffer for storing matched delimiters in case of a mismatch part-way
	$wasEsc = false;			// flag to ignore the current character if the previous one was an escape char
	$sepLen = strlen($sep);		// precomputed length of separator string, for efficiency
	$matchNext = 0;				// character index within separator to attempt to match next
	
	foreach ($astr as $char) {
		if ($matchNext >= $sepLen) {			// full separator has been matched, store and continue
			$result[] = str_replace($escape . $sep, $sep, $buffer);
			$buffer = '';
			$matchedBuffer = '';
			$matchNext = 0;
		}
		
		$nextChar = substr($sep, $matchNext, 1);	// get next character to match
		
		if ($char == $nextChar && !$wasEsc) {	// partial separator match, keep matching
			$matchNext++;
			$matchedBuffer .= $char;
		} else if ($matchNext > 0) {			// matched partially but not completely, add matched chars to buffer
			$buffer .= $matchedBuffer;
			$matchNext = 0;
		} else {
			$buffer .= $char;					// this isnt a separator, add to buffer
		}
		
		if ($char == $escape && $matchNext == 0) {	// detect escape characters and flag that the next character *cannot* match
			$wasEsc = true;
			continue;
		}
		$wasEsc = false;						// otherwise reset the escape character flag
	}
	
	// add any remaining buffered chars as the last element
	if ($buffer || $matchedBuffer) {
		$result[] = str_replace($escape . $sep, $sep, $buffer . $matchedBuffer);
	}
	
	return $result;
}

Maybe I'm not using this the way it is expected but it doesn't seem to work for this scenario:

$array1 = array('one\\', 'two');
$result = $this->escapedimplode(';', $array1);
echo $result . PHP_EOL;
print_r($this->escapedexplode(';', $result));

The expected output is:

one\;two
Array
(
    [0] => one\
    [1] => two
)

And the actual output is:

one\;two
Array
(
    [0] => one;two
)