Extract dates, times and date ranges from text in PHP

Question

I'm building a local events calendar which takes RSS feeds and website scrapes and extracts event dates from them.

I've previously asked how to extract dates from text in PHP here, and received a good answer at the time from MarcDefiant:

function parse_date_tokens($tokens) {
  # only try to extract a date if we have 2 or more tokens
  if(!is_array($tokens) || count($tokens) < 2) return false;
  return strtotime(implode(" ", $tokens));
}

function extract_dates($text) {
  static $patterns = Array(
    '/^[0-9]+(st|nd|rd|th|)?$/i', # day
    '/^(Jan(uary)?|Feb(ruary)?|Mar(ch)?|etc)$/i', # month
    '/^20[0-9]{2}$/', # year
    '/^of$/' #words
  );
  # defines which of the above patterns aren't actually part of a date
  static $drop_patterns = Array(
    false,
    false,
    false,
    true
  );
  $tokens = Array();
  $result = Array();
  $text = str_word_count($text, 1, '0123456789'); # get all words in text

  # iterate words and search for matching patterns
  foreach($text as $word) {
    $found = false;
    foreach($patterns as $key => $pattern) {
      if(preg_match($pattern, $word)) {
        if(!$drop_patterns[$key]) {
          $tokens[] = $word;
        }
        $found = true;
        break;
      }
    }

    if(!$found) {
      $result[] = parse_date_tokens($tokens);
      $tokens = Array();
    }
  }
  $result[] = parse_date_tokens($tokens);

  return array_filter($result);
}

# test
$texts = Array(
  "The focus of the seminar, on Saturday 2nd February 2013 will be [...]",
  "Valentines Special @ The Radisson, Feb 14th",
  "On Friday the 15th of February, a special Hollywood themed [...]",
  "Symposium on Childhood Play on Friday, February 8th",
  "Hosting a craft workshop March 9th - 11th in the old [...]"
);

$dates = extract_dates(implode(" ", $texts));
echo "Dates: 
";
foreach($dates as $date) {
  echo "  " . date('d.m.Y H:i:s', $date) . "
";
}

However, the solution has some downsides - for one thing, it can't match date ranges.

I'm now looking for a more complex solution that can extract dates, times and date ranges from sample text.

Whats the best approach for this? It seems like I'm leaning back toward a series of regex statements run one after the other to catch these cases. I can't see a better way of catching date ranges in particular, but I know there must be a better way of doing this. Are there any libraries out there just for date parsing in PHP?

Date / Date Range samples, as requested

$dates = [
    " Saturday 28th December",
    "2013/2014",
    "Friday 10th of January",
    "Thursday 19th December",
    " on Sunday the 15th December at 1 p.m",
    "On Saturday December 14th ",
    "On Saturday December 21st at 7.30pm",
    "Saturday, March 21st, 9.30 a.m.",
    "Jan-April 2014",
    "January 21st - Jan 24th 2014",
    "Dec 30th - Jan 3rd, 2014",
    "February 14th-16th, 2014",
    "Mon 14 - Wed 16 April, 12 - 2pm",
    "Sun 13 April, 8pm",
    "Mon 21 - Wed 23 April",
    "Friday 25 April, 10 – 3pm",            
    "The focus of the seminar, on Saturday 2nd February 2013 will be [...]",
    "Valentines Special @ The Radisson, Feb 14th",
    "On Friday the 15th of February, a special Hollywood themed [...]",
    "Symposium on Childhood Play on Friday, February 8th",
    "Hosting a craft workshop March 9th - 11th in the old [...]"
];

The function I'm currently using (not the above) is about 90% accurate. It can catch date ranges, but has difficulty if a time is also specified. It uses a list of regex expressions and is very convoluted.

UPDATE: Jan 6th, 2014

I'm working on code that does this, working on my original method of a series of regex statements run one after the other. I think I'm close to a working solution that can pretty much extract almost any date/time range / format from a piece of text. When I'm done I'll post it here as an answer.

Extract dates, times and date ranges from text in PHP

1 Answers