indexer.php

<?php
/**
 * Common DokuWiki functions
 *
 * @license    GPL 2 (http://www.gnu.org/licenses/gpl.html)
 * @author     Andreas Gohr <andi@splitbrain.org>
 */

  if(!defined('DOKU_INC')) define('DOKU_INC',realpath(dirname(__FILE__).'/../').'/');
  require_once(DOKU_CONF.'dokuwiki.php');
  require_once(DOKU_INC.'inc/io.php');
  require_once(DOKU_INC.'inc/utf8.php');
  require_once(DOKU_INC.'inc/parserutils.php');

/**
 * Split a page into words
 *
 * Returns an array of of word counts, false if an error occured
 *
 * @author Andreas Gohr <andi@splitbrain.org>
 * @author Christopher Smith <chris@jalakai.co.uk>
 */
function idx_getPageWords($page){
    global $conf;
    $word_idx = file($conf['cachedir'].'/word.idx');
    $swfile   = DOKU_INC.'inc/lang/'.$conf['lang'].'/stopwords.txt';
    if(@file_exists($swfile)){
        $stopwords = file($swfile);
    }else{
        $stopwords = array();
    }

    $body   = rawWiki($page);
    $body   = strtr($body, "\r\n\t", '   ');
    $tokens = explode(' ', $body);
    $tokens = array_count_values($tokens);   // count the frequency of each token
    
    $words = array();
    foreach ($tokens as $word => $count) {

        // simple filter to restrict use of utf8_stripspecials 
        if (preg_match('/[^0-9A-Za-z]/u', $word)) {
            $arr = explode(' ', utf8_stripspecials($word,' ','._\-:'));
            $arr = array_count_values($arr);
            
            foreach ($arr as $w => $c) {
                if (!is_numeric($w) && strlen($w) < 3) continue;
    		    $w = utf8_strtolower($w);
                $words[$w] = $c + (isset($words[$w]) ? $words[$w] : 0);
            }
        } else {
            if (!is_numeric($w) && strlen($w) < 3) continue;
	        $word = strtolower($word);
            $words[$word] = $count + (isset($words[$word]) ? $words[$word] : 0);
        }
    }
 
    // arrive here with $words = array(word => frequency)
 
    $index = array(); //resulting index
    foreach ($words as $word => $freq) {
	if (is_int(array_search("$word\n",$stopwords))) continue;
        $wid = array_search("$word\n",$word_idx);
        if(!is_int($wid)){
            $word_idx[] = "$word\n";
            $wid = count($word_idx)-1;
        }
        $index[$wid] = $freq;
    }
 
    // save back word index
    $fh = fopen($conf['cachedir'].'/word.idx','w');
    if(!$fh){
        trigger_error("Failed to write word.idx", E_USER_ERROR);
        return false;
    }
    fwrite($fh,join('',$word_idx));
    fclose($fh);
 
    return $index;
}

/**
 * Adds/updates the search for the given page
 *
 * This is the core function of the indexer which does most
 * of the work. This function needs to be called with proper
 * locking!
 *
 * @author Andreas Gohr <andi@splitbrain.org>
 */
function idx_addPage($page){
    global $conf;

    // load known documents
    $page_idx = file($conf['cachedir'].'/page.idx');

    // get page id (this is the linenumber in page.idx)
    $pid = array_search("$page\n",$page_idx);
    if(!is_int($pid)){
        $page_idx[] = "$page\n";
        $pid = count($page_idx)-1;
        // page was new - write back
        $fh = fopen($conf['cachedir'].'/page.idx','w');
        if(!$fh) return false;
        fwrite($fh,join('',$page_idx));
        fclose($fh);
    }

    // get word usage in page
    $words = idx_getPageWords($page);
    if($words === false) return false;
    if(!count($words)) return true;

    // Open index and temp file
    $idx = fopen($conf['cachedir'].'/index.idx','r');
    $tmp = fopen($conf['cachedir'].'/index.tmp','w');
    if(!$idx || !$tmp){
       trigger_error("Failed to open index files", E_USER_ERROR);
       return false;
    } 

    // copy from index to temp file, modifying were needed
    $lno = 0;
    $line = '';
    while (!feof($idx)) {
        // read full line
        $line .= fgets($idx, 4096);
        if(substr($line,-1) != "\n") continue;

        // write a new Line to temp file
        idx_writeIndexLine($tmp,$line,$pid,$words[$lno]);

        $line = ''; // reset line buffer
        $lno++;     // increase linecounter
    }
    fclose($idx);

    // add missing lines (usually index and word should contain
    // the same number of lines, however if the page contained
    // new words the word file has some more lines which need to
    // be added here
    $word_idx = file($conf['cachedir'].'/word.idx');
    $wcnt = count($word_idx);
    for($lno; $lno<$wcnt; $lno++){
        idx_writeIndexLine($tmp,'',$pid,$words[$lno]);
    }

    // close the temp file and move it over to be the new one
    fclose($tmp);
    return rename($conf['cachedir'].'/index.tmp',
                  $conf['cachedir'].'/index.idx');
}

/**
 * Write a new index line to the filehandle
 *
 * This function writes an line for the index file to the
 * given filehandle. It removes the given document from
 * the given line and readds it when $count is >0.
 *
 * @author Andreas Gohr <andi@splitbrain.org>
 */
function idx_writeIndexLine($fh,$line,$pid,$count){
    $line = trim($line);

    if($line != ''){
        $parts = explode(':',$line);
        // remove doc from given line
        foreach($parts as $part){
            if($part == '') continue;
            list($doc,$cnt) = explode('*',$part);
            if($doc != $pid){
                fwrite($fh,"$doc*$cnt:");
            }
        }
    }

    // add doc
    if ($count){
        fwrite($fh,"$pid*$count");
    }

    // add newline
    fwrite($fh,"\n");
}

/**
 * Lookup words in index
 *
 * Takes an array of word and will return a list of matching
 * documents for each one.
 *
 * @author Andreas Gohr <andi@splitbrain.org>
 */
function idx_lookup($words){
    global $conf;

    $result = array();

    // load known words and documents
    $page_idx = file($conf['cachedir'].'/page.idx');
    $word_idx = file($conf['cachedir'].'/word.idx');

    // get word IDs
    $wids = array();
    foreach($words as $word){
        $wid = array_search("$word\n",$word_idx);
        if(is_int($wid)){
            $wids[] = $wid;
            $result[$word] = $wid;
        }else{
            $result[$word] = array();
        }
    }
    sort($wids);
    $wids = array_unique($wids);

    // Open index
    $idx = fopen($conf['cachedir'].'/index.idx','r');
    if(!$idx){
       msg("Failed to open index files",-1);
       return false;
    } 

    // Walk the index til the lines are found
    $docs = array();                          // hold docs found
    $lno  = 0;
    $line = '';
    $srch = array_shift($wids);               // which word do we look for?
    while (!feof($idx)) {
        // read full line
        $line .= fgets($idx, 4096);
        if(substr($line,-1) != "\n") continue;
        if($lno > $srch)             break;   // shouldn't happen
 

        // do we want this line?
        if($lno == $srch){
            // add docs to list
            $docs[$srch] = idx_parseIndexLine($page_idx,$line);

            $srch = array_shift($wids);        // next word to look up
            if($srch == null) break;           // no more words
        }

        $line = ''; // reset line buffer
        $lno++;     // increase linecounter
    }
    fclose($idx);

    // merge found pages into result array
    foreach(array_keys($result) as $word){
        if(is_int($result[$word])){
            $result[$word] = $docs[$result[$word]];
        }
    }

    return $result;
}

/**
 * Returns a list of documents and counts from a index line
 *
 * It omits docs with a count of 0 and pages that no longer
 * exist.
 *
 * @param  array  $page_idx The list of known pages
 * @param  string $line     A line from the main index
 * @author Andreas Gohr <andi@splitbrain.org>
 */
function idx_parseIndexLine(&$page_idx,$line){
    $result = array();

    $line = trim($line);
    if($line == '') return $result;

    $parts = explode(':',$line);
    foreach($parts as $part){
        if($part == '') continue;
        list($doc,$cnt) = explode('*',$part);
        if(!$cnt) continue;
        $doc = trim($page_idx[$doc]);
        if(!$doc) continue;
        // make sure the document still exists
        if(!@file_exists(wikiFN($doc))) continue;

        $result[$doc] = $cnt;
    }
    return $result;
}

/**
 * Tokenizes a string into an array of search words
 *
 * Uses the same algorithm as idx_getPageWords()
 *
 * @todo make combined function to use alone or in getPageWords
 */
function idx_tokenizer($string,&$stopwords){
    $words = array();

    if(preg_match('/[^0-9A-Za-z]/u', $string)){
        $arr = explode(' ', utf8_stripspecials($string,' ','._\-:'));
        foreach ($arr as $w) {
            if (!is_numeric($w) && strlen($w) < 3) continue;
            $w = utf8_strtolower($w);
            if(is_int(array_search("$w\n",$stopwords))) continue;
            $words[] = $w;
        }
    }else{
        $w = $string;
        if (!is_numeric($w) && strlen($w) < 3) return $words;
        $w = strtolower($w);
        if(is_int(array_search("$w\n",$stopwords))) return $words;
        $words[] = $w;
    }

    return $words;
}

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