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Added the search_generate_text_SQL() function that generates

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SQL clauses using documental indexes. Only MySQL for now.
Under 1.8 this isn't used officially (experimental!) but
we need it here right now (won't interfere at all). MDL-8830

Merged from MOODLE_18_STABLE
This commit is contained in:
stronk7 2007-03-09 18:21:06 +00:00
parent cc7565ea84
commit b2964e45d9
1 changed files with 122 additions and 0 deletions
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122
lib/searchlib.php
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@ -302,6 +302,128 @@ class search_parser {
}
}
// Primitive function to generate a SQL string from a parse tree
// using TEXT indexes. If searches aren't suitable to use TEXT
// this function calls the default search_generate_SQL() one.
//
// $parsetree should be a parse tree generated by a
// search_lexer/search_parser combination.
// Other fields are database table names to search.
function search_generate_text_SQL($parsetree, $datafield, $metafield, $mainidfield, $useridfield,
$userfirstnamefield, $userlastnamefield, $timefield, $instancefield) {
global $CFG;
/// First of all, search for reasons to switch to standard SQL generation
/// Only mysql are supported for now
if ($CFG->dbfamily != 'mysql') {
return search_generate_SQL($parsetree, $datafield, $metafield, $mainidfield, $useridfield,
$userfirstnamefield, $userlastnamefield, $timefield, $instancefield);
}
/// Here we'll acumulate non-textual tokens
$non_text_tokens = array();
$ntokens = count($parsetree);
if ($ntokens == 0) {
return "";
}
$SQLString = '';
$text_sql_string = '';
$datasearch_clause = '';
$metasearch_clause = '';
foreach ($parsetree as $token) {
$type = $token->getType();
$value = $token->getValue();
switch($type){
case TOKEN_STRING:
/// If it's a multiword token, quote it
if (strstr($value, ' ')) {
$datasearch_clause .= '"' . $value . '" ';
/// Simple word token, search for it as prefix
} else {
$datasearch_clause .= $value . '* ';
}
break;
case TOKEN_EXACT:
/// token must be exactly as requested
$datasearch_clause .= '+' . $value . ' ';
break;
case TOKEN_NEGATE:
/// token must not exist as prefix
$datasearch_clause .= '-' . $value . '* ';
break;
case TOKEN_META:
/// token in metafield, search for it as prefix
$metasearch_clause .= $value . '* ';
break;
case TOKEN_USER:
case TOKEN_USERID:
case TOKEN_INSTANCE:
case TOKEN_DATETO:
case TOKEN_DATEFROM:
/// delegate to standard search
$non_text_tokens[] = $token;
break;
default:
return '';
}
}
/// Call to standard search for pending tokens
if (!empty($non_text_tokens)) {
$SQLString = search_generate_SQL($non_text_tokens, $datafield, $metafield, $mainidfield, $useridfield,
$userfirstnamefield, $userlastnamefield, $timefield, $instancefield);
}
/// Build the final SQL clause
if (!empty($datasearch_clause)) {
/// Must have $datafield to search within
if (!empty($datafield)) {
$text_sql_string .= 'MATCH (' . $datafield;
/// And optionally $metafield
if (!empty($metafield)) {
$text_sql_string .= ', ' . $metafield;
}
/// Begin with the AGAINST clause
$text_sql_string .= ') AGAINST (' . "'";
/// Add the search terms
$text_sql_string .= trim($datasearch_clause);
/// Close AGAINST clause
$text_sql_string .= "' IN BOOLEAN MODE)";
}
}
/// Now add the metasearch_clause
if (!empty($metasearch_clause)) {
/// Must have $metafield to search within
if (!empty($metafield)) {
/// AND operator if needed
if (!empty($text_sql_string)) {
$text_sql_string .= ' AND ';
}
$text_sql_string .= 'MATCH (' . $metafield;
/// Begin with the AGAINST clause
$text_sql_string .= ') AGAINST (' . "'";
/// Add the search terms
$text_sql_string .= trim($metasearch_clause);
/// Close AGAINST clause
$text_sql_string .= "' IN BOOLEAN MODE)";
}
}
/// Finally add the non-text conditions
if (!empty($SQLString)) {
/// AND operator if needed
if (!empty($text_sql_string)) {
$text_sql_string .= ' AND ';
}
$text_sql_string .= $SQLString;
}
return $text_sql_string;
}
// Primitive function to generate a SQL string from a parse tree.
// Parameters: