/**
* Query parsing helper routine.
* Returned structure is based on that used by the Search::QueryParser Perl module.
*/
function _parseQuery($signTokens, $tokens, &$pos, $total)
{
$return = array('+' => array(), '' => array(), '-' => array());
$postBool = $preBool = '';
$notOperator = String::strtolower(Locale::translate('search.operator.not'));
$andOperator = String::strtolower(Locale::translate('search.operator.and'));
$orOperator = String::strtolower(Locale::translate('search.operator.or'));
while ($pos < $total) {
if (!empty($signTokens[$pos])) {
$sign = $signTokens[$pos];
} else {
if (empty($sign)) {
$sign = '+';
}
}
$token = String::strtolower($tokens[$pos++]);
switch ($token) {
case $notOperator:
$sign = '-';
break;
case ')':
return $return;
case '(':
$token = ArticleSearch::_parseQuery($signTokens, $tokens, $pos, $total);
default:
$postBool = '';
if ($pos < $total) {
$peek = String::strtolower($tokens[$pos]);
if ($peek == $orOperator) {
$postBool = 'or';
$pos++;
} else {
if ($peek == $andOperator) {
$postBool = 'and';
$pos++;
}
}
}
$bool = empty($postBool) ? $preBool : $postBool;
$preBool = $postBool;
if ($bool == 'or') {
$sign = '';
}
if (is_array($token)) {
$k = $token;
} else {
$k = ArticleSearchIndex::filterKeywords($token, true);
}
if (!empty($k)) {
$return[$sign][] = $k;
}
$sign = '';
break;
}
}
return $return;
}
/**
* Return an array of search results matching the supplied
* keyword IDs in decreasing order of match quality.
* Keywords are supplied in an array of the following format:
* $keywords[ARTICLE_SEARCH_AUTHOR] = array('John', 'Doe');
* $keywords[ARTICLE_SEARCH_...] = array(...);
* $keywords[null] = array('Matches', 'All', 'Fields');
* @param $journal object The journal to search
* @param $keywords array List of keywords
* @param $error string a reference to a variable that will
* contain an error message if the search service produces
* an error.
* @param $publishedFrom object Search-from date
* @param $publishedTo object Search-to date
* @param $rangeInfo Information on the range of results to return
* @return VirtualArrayIterator An iterator with one entry per retrieved
* article containing the article, published article, issue, journal, etc.
*/
function &retrieveResults(&$journal, &$keywords, &$error, $publishedFrom = null, $publishedTo = null, $rangeInfo = null)
{
// Pagination
if ($rangeInfo && $rangeInfo->isValid()) {
$page = $rangeInfo->getPage();
$itemsPerPage = $rangeInfo->getCount();
} else {
$page = 1;
$itemsPerPage = ARTICLE_SEARCH_DEFAULT_RESULT_LIMIT;
}
// Check whether a search plug-in jumps in to provide ranked search results.
$totalResults = null;
$results =& HookRegistry::call('ArticleSearch::retrieveResults', array(&$journal, &$keywords, $publishedFrom, $publishedTo, $page, $itemsPerPage, &$totalResults, &$error));
// If no search plug-in is activated then fall back to the
// default database search implementation.
if ($results === false) {
// Parse the query.
foreach ($keywords as $searchType => $query) {
$keywords[$searchType] = ArticleSearch::_parseQuery($query);
}
// Fetch all the results from all the keywords into one array
// (mergedResults), where mergedResults[article_id]
// = sum of all the occurences for all keywords associated with
// that article ID.
$mergedResults =& ArticleSearch::_getMergedArray($journal, $keywords, $publishedFrom, $publishedTo);
// Convert mergedResults into an array (frequencyIndicator =>
// $articleId).
// The frequencyIndicator is a synthetically-generated number,
// where higher is better, indicating the quality of the match.
// It is generated here in such a manner that matches with
// identical frequency do not collide.
$results =& ArticleSearch::_getSparseArray($mergedResults);
$totalResults = count($results);
// Use only the results for the specified page.
$offset = $itemsPerPage * ($page - 1);
$length = max($totalResults - $offset, 0);
$length = min($itemsPerPage, $length);
if ($length == 0) {
$results = array();
} else {
$results = array_slice($results, $offset, $length);
}
}
// Take the range of results and retrieve the Article, Journal,
// and associated objects.
$results =& ArticleSearch::formatResults($results);
// Return the appropriate iterator.
import('lib.pkp.classes.core.VirtualArrayIterator');
$returner = new VirtualArrayIterator($results, $totalResults, $page, $itemsPerPage);
return $returner;
}
