function search_excerpt

Returns snippets from a piece of text, with certain keywords highlighted. Used for formatting search results.

Parameters

$keys: A string containing a search query.

$text: The text to extract fragments from.

Return value

A string containing HTML for the excerpt.

Related topics

File

modules/search/search.module, line 1127

Code

function search_excerpt($keys, $text) {
    // We highlight around non-indexable or CJK characters.
    $boundary = '(?:(?<=[' . PREG_CLASS_UNICODE_WORD_BOUNDARY . PREG_CLASS_CJK . '])|(?=[' . PREG_CLASS_UNICODE_WORD_BOUNDARY . PREG_CLASS_CJK . ']))';
    // Extract positive keywords and phrases
    preg_match_all('/ ("([^"]+)"|(?!OR)([^" ]+))/', ' ' . $keys, $matches);
    $keys = array_merge($matches[2], $matches[3]);
    // Prepare text by stripping HTML tags and decoding HTML entities.
    $text = strip_tags(str_replace(array(
        '<',
        '>',
    ), array(
        ' <',
        '> ',
    ), $text));
    $text = decode_entities($text);
    // Slash-escape quotes in the search keyword string.
    array_walk($keys, '_search_excerpt_replace');
    $workkeys = $keys;
    // Extract fragments around keywords.
    // First we collect ranges of text around each keyword, starting/ending
    // at spaces, trying to get to 256 characters.
    // If the sum of all fragments is too short, we look for second occurrences.
    $ranges = array();
    $included = array();
    $foundkeys = array();
    $length = 0;
    while ($length < 256 && count($workkeys)) {
        foreach ($workkeys as $k => $key) {
            if (strlen($key) == 0) {
                unset($workkeys[$k]);
                unset($keys[$k]);
                continue;
            }
            if ($length >= 256) {
                break;
            }
            // Remember occurrence of key so we can skip over it if more occurrences
            // are desired.
            if (!isset($included[$key])) {
                $included[$key] = 0;
            }
            // Locate a keyword (position $p, always >0 because $text starts with a
            // space). First try bare keyword, but if that doesn't work, try to find a
            // derived form from search_simplify().
            $p = 0;
            if (preg_match('/' . $boundary . $key . $boundary . '/iu', $text, $match, PREG_OFFSET_CAPTURE, $included[$key])) {
                $p = $match[0][1];
            }
            else {
                $info = search_simplify_excerpt_match($key, $text, $included[$key], $boundary);
                if (isset($info['where'])) {
                    $p = $info['where'];
                    if ($info['keyword']) {
                        $foundkeys[] = $info['keyword'];
                    }
                }
            }
            // Now locate a space in front (position $q) and behind it (position $s),
            // leaving about 60 characters extra before and after for context.
            // Note that a space was added to the front and end of $text above.
            if ($p) {
                if (($q = strpos(' ' . $text, ' ', max(0, $p - 61))) !== FALSE) {
                    $end = substr($text . ' ', $p, 80);
                    if (($s = strrpos($end, ' ')) !== FALSE) {
                        // Account for the added spaces.
                        $q = max($q - 1, 0);
                        $s = min($s, strlen($end) - 1);
                        $ranges[$q] = $p + $s;
                        $length += $p + $s - $q;
                        $included[$key] = $p + 1;
                    }
                    else {
                        unset($workkeys[$k]);
                    }
                }
                else {
                    unset($workkeys[$k]);
                }
            }
            else {
                unset($workkeys[$k]);
            }
        }
    }
    if (count($ranges) == 0) {
        // We didn't find any keyword matches, so just return the first part of the
        // text. We also need to re-encode any HTML special characters that we
        // entity-decoded above.
        return check_plain(truncate_utf8($text, 256, TRUE, TRUE));
    }
    // Sort the text ranges by starting position.
    ksort($ranges);
    // Now we collapse overlapping text ranges into one. The sorting makes it O(n).
    $newranges = array();
    foreach ($ranges as $from2 => $to2) {
        if (!isset($from1)) {
            $from1 = $from2;
            $to1 = $to2;
            continue;
        }
        if ($from2 <= $to1) {
            $to1 = max($to1, $to2);
        }
        else {
            $newranges[$from1] = $to1;
            $from1 = $from2;
            $to1 = $to2;
        }
    }
    $newranges[$from1] = $to1;
    // Fetch text
    $out = array();
    foreach ($newranges as $from => $to) {
        $out[] = substr($text, $from, $to - $from);
    }
    // Let translators have the ... separator text as one chunk.
    $dots = explode('!excerpt', t('... !excerpt ... !excerpt ...'));
    $text = (isset($newranges[0]) ? '' : $dots[0]) . implode($dots[1], $out) . $dots[2];
    $text = check_plain($text);
    // Slash-escape quotes in keys found in a derived form and merge with original keys.
    array_walk($foundkeys, '_search_excerpt_replace');
    $keys = array_merge($keys, $foundkeys);
    // Highlight keywords. Must be done at once to prevent conflicts ('strong' and '<strong>').
    $text = preg_replace('/' . $boundary . '(' . implode('|', $keys) . ')' . $boundary . '/iu', '<strong>\\0</strong>', $text);
    return $text;
}