diff options
Diffstat (limited to 'src/search.php')
| -rw-r--r-- | src/search.php | 303 |
1 files changed, 303 insertions, 0 deletions
diff --git a/src/search.php b/src/search.php new file mode 100644 index 0000000..3900f6b --- /dev/null +++ b/src/search.php @@ -0,0 +1,303 @@ +function readInt($file) +{ + $b1 = ord(fgetc($file)); $b2 = ord(fgetc($file)); + $b3 = ord(fgetc($file)); $b4 = ord(fgetc($file)); + return ($b1<<24)|($b2<<16)|($b3<<8)|$b4; +} + +function readString($file) +{ + $result=""; + while (ord($c=fgetc($file))) $result.=$c; + return $result; +} + +function readHeader($file) +{ + $header =fgetc($file); $header.=fgetc($file); + $header.=fgetc($file); $header.=fgetc($file); + return $header; +} + +function computeIndex($word) +{ + if (strlen($word)<2) return -1; + // high char of the index + $hi = ord($word{0}); + if ($hi==0) return -1; + // low char of the index + $lo = ord($word{1}); + if ($lo==0) return -1; + // return index + return $hi*256+$lo; +} + +function search($file,$word,&$statsList) +{ + $index = computeIndex($word); + if ($index!=-1) // found a valid index + { + fseek($file,$index*4+4); // 4 bytes per entry, skip header + $index = readInt($file); + if ($index) // found words matching first two characters + { + $start=sizeof($statsList); + $count=$start; + fseek($file,$index); + $w = readString($file); + while ($w) + { + $statIdx = readInt($file); + if ($word==substr($w,0,strlen($word))) + { // found word that matches (as substring) + $statsList[$count++]=array( + "word"=>$word, + "match"=>$w, + "index"=>$statIdx, + "full"=>strlen($w)==strlen($word), + "docs"=>array() + ); + } + $w = readString($file); + } + $totalFreq=0; + for ($count=$start;$count<sizeof($statsList);$count++) + { + $statInfo = &$statsList[$count]; + fseek($file,$statInfo["index"]); + $numDocs = readInt($file); + $docInfo = array(); + // read docs info + occurrence frequency of the word + for ($i=0;$i<$numDocs;$i++) + { + $idx=readInt($file); + $freq=readInt($file); + $docInfo[$i]=array("idx"=>$idx,"freq"=>$freq,"rank"=>0.0); + $totalFreq+=$freq; + if ($statInfo["full"]) $totalfreq+=$freq; + } + // read name an url info for the doc + for ($i=0;$i<$numDocs;$i++) + { + fseek($file,$docInfo[$i]["idx"]); + $docInfo[$i]["name"]=readString($file); + $docInfo[$i]["url"]=readString($file); + } + $statInfo["docs"]=$docInfo; + } + for ($count=$start;$count<sizeof($statsList);$count++) + { + $statInfo = &$statsList[$count]; + for ($i=0;$i<sizeof($statInfo["docs"]);$i++) + { + $docInfo = &$statInfo["docs"]; + // compute frequency rank of the word in each doc + $statInfo["docs"][$i]["rank"]= + (float)$docInfo[$i]["freq"]/$totalFreq; + } + } + } + } + return $statsList; +} + +function combine_results($results,&$docs) +{ + foreach ($results as $wordInfo) + { + $docsList = &$wordInfo["docs"]; + foreach ($docsList as $di) + { + $key=$di["url"]; + $rank=$di["rank"]; + if (in_array($key, array_keys($docs))) + { + $docs[$key]["rank"]+=$rank; + $docs[$key]["rank"]*=2; // multiple matches increases rank + } + else + { + $docs[$key] = array("url"=>$key, + "name"=>$di["name"], + "rank"=>$rank + ); + } + $docs[$key]["words"][] = array( + "word"=>$wordInfo["word"], + "match"=>$wordInfo["match"], + "freq"=>$di["freq"] + ); + } + } + return $docs; +} + +function normalize_ranking(&$docs) +{ + $maxRank = 0.0000001; + // compute maximal rank + foreach ($docs as $doc) + { + if ($doc["rank"]>$maxRank) + { + $maxRank=$doc["rank"]; + } + } + reset($docs); + // normalize rankings + while (list ($key, $val) = each ($docs)) + { + $docs[$key]["rank"]*=100/$maxRank; + } +} + +function filter_results($docs,&$requiredWords,&$forbiddenWords) +{ + $filteredDocs=array(); + while (list ($key, $val) = each ($docs)) + { + $words = &$docs[$key]["words"]; + $copy=1; // copy entry by default + if (sizeof($requiredWords)>0) + { + foreach ($requiredWords as $reqWord) + { + $found=0; + foreach ($words as $wordInfo) + { + $found = $wordInfo["word"]==$reqWord; + if ($found) break; + } + if (!$found) + { + $copy=0; // document contains none of the required words + break; + } + } + } + if (sizeof($forbiddenWords)>0) + { + foreach ($words as $wordInfo) + { + if (in_array($wordInfo["word"],$forbiddenWords)) + { + $copy=0; // document contains a forbidden word + break; + } + } + } + if ($copy) $filteredDocs[$key]=$docs[$key]; + } + return $filteredDocs; +} + +function compare_rank($a,$b) +{ + return ($a["rank"]>$b["rank"]) ? -1 : 1; +} + +function sort_results($docs,&$sorted) +{ + $sorted = $docs; + usort($sorted,"compare_rank"); + return $sorted; +} + +function report_results(&$docs) +{ + echo "<table cellspacing=\"2\">\n"; + echo " <tr>\n"; + echo " <td colspan=\"2\"><h2>".search_results()."</h2></td>\n"; + echo " </tr>\n"; + $numDocs = sizeof($docs); + if ($numDocs==0) + { + echo " <tr>\n"; + echo " <td colspan=\"2\">".matches_text(0)."</td>\n"; + echo " </tr>\n"; + } + else + { + echo " <tr>\n"; + echo " <td colspan=\"2\">".matches_text($numDocs); + echo "\n"; + echo " </td>\n"; + echo " </tr>\n"; + $num=1; + foreach ($docs as $doc) + { + echo " <tr>\n"; + echo " <td align=\"right\">$num.</td>"; + echo "<td><a class=\"el\" href=\"".$doc["url"]."\">".$doc["name"]."</a></td>\n"; + echo " <tr>\n"; + echo " <td></td><td class=\"tiny\">".report_matches()." "; + foreach ($doc["words"] as $wordInfo) + { + $word = $wordInfo["word"]; + $matchRight = substr($wordInfo["match"],strlen($word)); + echo "<b>$word</b>$matchRight(".$wordInfo["freq"].") "; + } + echo " </td>\n"; + echo " </tr>\n"; + $num++; + } + } + echo "</table>\n"; +} + +function main() +{ + if(strcmp('4.1.0', phpversion()) > 0) + { + die("Error: PHP version 4.1.0 or above required!"); + } + if (!($file=fopen("search.idx","rb"))) + { + die("Error: Search index file could NOT be opened!"); + } + if (readHeader($file)!="DOXS") + { + die("Error: Header of index file is invalid!"); + } + $query=""; + if (array_key_exists("query", $_GET)) + { + $query=$_GET["query"]; + } + echo "<input class=\"search\" type=\"text\" name=\"query\" value=\"$query\" size=\"20\" accesskey=\"s\"/>\n"; + echo "</span>\n"; + echo "</form>\n"; + echo "</div>\n"; + $results = array(); + $requiredWords = array(); + $forbiddenWords = array(); + $foundWords = array(); + $word=strtolower(strtok($query," ")); + while ($word) // for each word in the search query + { + if (($word{0}=='+')) { $word=substr($word,1); $requiredWords[]=$word; } + if (($word{0}=='-')) { $word=substr($word,1); $forbiddenWords[]=$word; } + if (!in_array($word,$foundWords)) + { + $foundWords[]=$word; + search($file,$word,$results); + } + $word=strtolower(strtok(" ")); + } + $docs = array(); + combine_results($results,$docs); + // filter out documents with forbidden word or that do not contain + // required words + $filteredDocs = filter_results($docs,$requiredWords,$forbiddenWords); + // normalize rankings so they are in the range [0-100] + normalize_ranking($filteredDocs); + // sort the results based on rank + $sorted = array(); + sort_results($filteredDocs,$sorted); + // report results to the user + report_results($sorted); + fclose($file); +} + +main(); + |