parsing a delimited, encapsulated string

[sneakyimp]

ok...i've used fgetscv() before. It has some kind of built in logic to determine when a comma is inside a field versus when it's used as a delimiter and works quite well.

i would like to put together some kind of preg_match expression that can take a delimited, encapsulated list of values and return all the elements. can some preg pro help me develop this expression?

[Drakla]

Can you give an example of what kind of thing you'd be searching, with possible snag scenarios. And will there always be a fixed number of fields?

[sneakyimp]

$delim = '|';
$encapsulator = '"';
$string = 'field1|field2|"field 3 has | in it"|field 4|"field 5 is |"very tricky|"|, no?"|field6';

//that field 5 might be pretty tough.  you might also try field 7 which is nearly impossible

$string .= '|"field 7 probably "|" cannot be solved"|field8';


// * i don't know how many fields...it could change
// * snag scenarios should be pretty obvious in fields 3, 5, and 7

for what it's worth, i found this is my current approach:

$string = 'field1|field2|"field 3 has | in it"|field 4';

function csv_parse($str,$f_delim = ',',$r_delim = "\n",$qual = '"')
{
   $output = array();
   $row = array();
   $word = '';

   $len = strlen($str);
   $inside = false;

   $skipchars = array($qual,'\\');

   for ($i = 0; $i < $len; ++$i) {
       $c = $str[$i];
       if (!$inside && $c == $f_delim) {
           $row[] = $word;
           $word = '';
       } elseif (!$inside && $c == $r_delim) {
           $row[] = $word;
           $word = '';
           $output[] = $row;
           $row = array();
       } else if ($inside && in_array($c,$skipchars) && ($i+1 < $len && $str[$i+1] == $qual)) {
           $word .= $qual;
           ++$i;
       } else if ($c == $qual) {
           $inside = !$inside;
       } else {
           $word .= $c;
       }
   }

   $row[] = $word;
   $output[] = $row;

   return $output;
}

$result = csv_parse($string, '|', '\n', '"');
$result2 = $result[0];
echo sizeof($result2) . ' elements<br>';
foreach($result2 as $key=>$value) {
  echo $key .'='. $value . '<br>';
}