search_index

search_index($type, $sid, $langcode, $text)

function search_index($type, $sid, $langcode, $text) {
  $minimum_word_size = \Drupal::config('search.settings')->get('index.minimum_word_size');

  // Multipliers for scores of words inside certain HTML tags. The weights are
  // stored in config so that modules can overwrite the default weights.
  // Note: 'a' must be included for link ranking to work.
  $tags = \Drupal::config('search.settings')->get('index.tag_weights');

  // Strip off all ignored tags to speed up processing, but insert space before
  // and after them to keep word boundaries.
  $text = str_replace(array('<', '>'), array(' <', '> '), $text);
  $text = strip_tags($text, '<' . implode('><', array_keys($tags)) . '>');

  // Split HTML tags from plain text.
  $split = preg_split('/\s*<([^>]+?)>\s*/', $text, -1, PREG_SPLIT_DELIM_CAPTURE);
  // Note: PHP ensures the array consists of alternating delimiters and literals
  // and begins and ends with a literal (inserting $null as required).

  $tag = FALSE; // Odd/even counter. Tag or no tag.
  $score = 1; // Starting score per word
  $accum = ' '; // Accumulator for cleaned up data
  $tagstack = array(); // Stack with open tags
  $tagwords = 0; // Counter for consecutive words
  $focus = 1; // Focus state

  $scored_words = array(); // Accumulator for words for index

  foreach ($split as $value) {
    if ($tag) {
      // Increase or decrease score per word based on tag
      list($tagname) = explode(' ', $value, 2);
      $tagname = Unicode::strtolower($tagname);
      // Closing or opening tag?
      if ($tagname[0] == '/') {
        $tagname = substr($tagname, 1);
        // If we encounter unexpected tags, reset score to avoid incorrect boosting.
        if (!count($tagstack) || $tagstack[0] != $tagname) {
          $tagstack = array();
          $score = 1;
        }
        else {
          // Remove from tag stack and decrement score
          $score = max(1, $score - $tags[array_shift($tagstack)]);
        }
      }
      else {
        if (isset($tagstack[0]) && $tagstack[0] == $tagname) {
          // None of the tags we look for make sense when nested identically.
          // If they are, it's probably broken HTML.
          $tagstack = array();
          $score = 1;
        }
        else {
          // Add to open tag stack and increment score
          array_unshift($tagstack, $tagname);
          $score += $tags[$tagname];
        }
      }
      // A tag change occurred, reset counter.
      $tagwords = 0;
    }
    else {
      // Note: use of PREG_SPLIT_DELIM_CAPTURE above will introduce empty values
      if ($value != '') {
        $words = search_index_split($value, $langcode);
        foreach ($words as $word) {
          // Add word to accumulator
          $accum .= $word . ' ';
          // Check wordlength
          if (is_numeric($word) || Unicode::strlen($word) >= $minimum_word_size) {
            if (!isset($scored_words[$word])) {
              $scored_words[$word] = 0;
            }
            $scored_words[$word] += $score * $focus;
            // Focus is a decaying value in terms of the amount of unique words up to this point.
            // From 100 words and more, it decays, to e.g. 0.5 at 500 words and 0.3 at 1000 words.
            $focus = min(1, .01 + 3.5 / (2 + count($scored_words) * .015));
          }
          $tagwords++;
          // Too many words inside a single tag probably mean a tag was accidentally left open.
          if (count($tagstack) && $tagwords >= 15) {
            $tagstack = array();
            $score = 1;
          }
        }
      }
    }
    $tag = !$tag;
  }

  // Remove the item $sid from the search index, and invalidate the relevant
  // cache tags.
  search_index_clear($type, $sid, $langcode);

  // Insert cleaned up data into dataset
  db_insert('search_dataset')
    ->fields(array(
      'sid' => $sid,
      'langcode' => $langcode,
      'type' => $type,
      'data' => $accum,
      'reindex' => 0,
    ))
    ->execute();

  // Insert results into search index
  foreach ($scored_words as $word => $score) {
    // If a word already exists in the database, its score gets increased
    // appropriately. If not, we create a new record with the appropriate
    // starting score.
    db_merge('search_index')
      ->keys(array(
        'word' => $word,
        'sid' => $sid,
        'langcode' => $langcode,
        'type' => $type,
      ))
      ->fields(array('score' => $score))
      ->expression('score', 'score + :score', array(':score' => $score))
      ->execute();
    search_dirty($word);
  }
}