protected function SearchQuery::parseSearchExpression

Parses the search query into SQL conditions.

We build two queries that match the dataset bodies.

File

modules/search/search.extender.inc, line 186

Search query extender and helper functions.

Class

SearchQuery

Do a query on the full-text search index for a word or words.

Code

protected function parseSearchExpression() {
  // Matchs words optionally prefixed by a dash. A word in this case is
  // something between two spaces, optionally quoted.
  preg_match_all('/ (-?)("[^"]+"|[^" ]+)/i', ' ' . $this->searchExpression, $keywords, PREG_SET_ORDER);

  if (count($keywords) == 0) {
    return;
  }

  // Classify tokens.
  $or = FALSE;
  $warning = '';
  $limit_combinations = config_get('search.settings', 'search_and_or_limit');
  // The first search expression does not count as AND.
  $and_count = -1;
  $or_count = 0;
  foreach ($keywords as $match) {
    if ($or_count && $and_count + $or_count >= $limit_combinations) {
      // Ignore all further search expressions to prevent Denial-of-Service
      // attacks using a high number of AND/OR combinations.
      $this->expressionsIgnored = TRUE;
      break;
    }
    $phrase = FALSE;
    // Strip off phrase quotes.
    if ($match[2][0] == '"') {
      $match[2] = substr($match[2], 1, -1);
      $phrase = TRUE;
      $this->simple = FALSE;
    }
    // Simplify keyword according to indexing rules and external
    // preprocessors. Use same process as during search indexing, so it
    // will match search index.
    $words = search_simplify($match[2]);
    // Re-explode in case simplification added more words, except when
    // matching a phrase.
    $words = $phrase ? array($words) : preg_split('/ /', $words, -1, PREG_SPLIT_NO_EMPTY);
    // Negative matches.
    if ($match[1] == '-') {
      $this->keys['negative'] = array_merge($this->keys['negative'], $words);
    }
    // OR operator: instead of a single keyword, we store an array of all
    // OR'd keywords.
    elseif ($match[2] == 'OR' && count($this->keys['positive'])) {
      $last = array_pop($this->keys['positive']);
      // Starting a new OR?
      if (!is_array($last)) {
        $last = array($last);
      }
      $this->keys['positive'][] = $last;
      $or = TRUE;
      $or_count++;
      continue;
    }
    // AND operator: implied, so just ignore it.
    elseif ($match[2] == 'AND' || $match[2] == 'and') {
      $warning = $match[2];
      continue;
    }

    // Plain keyword.
    else {
      if ($match[2] == 'or') {
        $warning = $match[2];
      }
      if ($or) {
        // Add to last element (which is an array).
        $this->keys['positive'][count($this->keys['positive']) - 1] = array_merge($this->keys['positive'][count($this->keys['positive']) - 1], $words);
      }
      else {
        $this->keys['positive'] = array_merge($this->keys['positive'], $words);
        $and_count++;
      }
    }
    $or = FALSE;
  }

  // Convert keywords into SQL statements.
  $this->conditions = db_and();
  $simple_and = FALSE;
  $simple_or = FALSE;
  // Positive matches.
  foreach ($this->keys['positive'] as $key) {
    // Group of ORed terms.
    if (is_array($key) && count($key)) {
      $simple_or = TRUE;
      $any = FALSE;
      $queryor = db_or();
      foreach ($key as $or) {
        list($num_new_scores) = $this->parseWord($or);
        $any |= $num_new_scores;
        $queryor->condition('d.data', "% $or %", 'LIKE');
      }
      if (count($queryor)) {
        $this->conditions->condition($queryor);
        // A group of OR keywords only needs to match once.
        $this->matches += ($any > 0);
      }
    }
    // Single ANDed term.
    else {
      $simple_and = TRUE;
      list($num_new_scores, $num_valid_words) = $this->parseWord($key);
      $this->conditions->condition('d.data', "% $key %", 'LIKE');
      if (!$num_valid_words) {
        $this->simple = FALSE;
      }
      // Each AND keyword needs to match at least once.
      $this->matches += $num_new_scores;
    }
  }
  if ($simple_and && $simple_or) {
    $this->simple = FALSE;
  }
  // Negative matches.
  foreach ($this->keys['negative'] as $key) {
    $this->conditions->condition('d.data', "% $key %", 'NOT LIKE');
    $this->simple = FALSE;
  }

  if ($warning == 'or') {
    backdrop_set_message(t('Search for either of the two terms with uppercase <strong>OR</strong>. For example, <strong>cats OR dogs</strong>.'));
  }
}