function parse_access_log_line($format, $line) {

  // Get list of consistent patterns
  $patterns = array();
  while($res = preg_match('/(([^%]*)%[^ ]*([a-z]))([^%]*)/i', $format, $matches)) {
    $patterns[$matches[3]] = '('.preg_quote($matches[2]).'(.+?))'.preg_quote($matches[4]);
    // Shift format string
    $format = str_replace($matches[1], '', $format);
  }

  // Add beginning of the string to the first pattern and end to the last
  $keys = array_keys($patterns);
  $patterns[$keys[0]] = '^'.$patterns[$keys[0]];
  $patterns[end($keys)] .= '$';

  $result = array();

  // Consistently apply patterns to the log line shifting it to the right
  foreach ($patterns as $node => $pattern) {
    preg_match('/'.$pattern.'/', $line, $matches);
    $line = str_replace($matches[1], '', $line);
    $result[$node] = $matches[2];
  }

  return $result;
}

I written this code to parse apache log in common log formats.  It may have problems with irresponsible formatting like non-concluded into quotes request line. I welcome any modifications to my snippet because it was written if short time and this is my first snippet I publish here. Thanks.

Apache log line parser

format, apache, log

PHP