"function readInt($file)\n"

"{\n"

"  $b1 = ord(fgetc($file)); $b2 = ord(fgetc($file));\n"

"  $b3 = ord(fgetc($file)); $b4 = ord(fgetc($file));\n"

"  return ($b1<<24)|($b2<<16)|($b3<<8)|$b4;\n"

"}\n"

"\n"

"function readString($file)\n"

"{\n"

"  $result=\"\";\n"

"  while (ord($c=fgetc($file))) $result.=$c;\n"

"  return $result;\n"

"}\n"

"\n"

"function readHeader($file)\n"

"{\n"

"  $header =fgetc($file); $header.=fgetc($file);\n"

"  $header.=fgetc($file); $header.=fgetc($file);\n"

"  return $header;\n"

"}\n"

"\n"

"function computeIndex($word)\n"

"{\n"

"  // Simple hashing that allows for substring search\n"

"  if (strlen($word)<2) return -1;\n"

"  // high char of the index\n"

"  $hi = ord($word{0});\n"

"  if ($hi==0) return -1;\n"

"  // low char of the index\n"

"  $lo = ord($word{1});\n"

"  if ($lo==0) return -1;\n"

"  // return index\n"

"  return $hi*256+$lo;\n"

"}\n"

"\n"

"function search($file,$word,&$statsList)\n"

"{\n"

"  $index = computeIndex($word);\n"

"  if ($index!=-1) // found a valid index\n"

"  {\n"

"    fseek($file,$index*4+4); // 4 bytes per entry, skip header\n"

"    $index = readInt($file);\n"

"    if ($index) // found words matching the hash key\n"

"    {\n"

"      $start=sizeof($statsList);\n"

"      $count=$start;\n"

"      fseek($file,$index);\n"

"      $w = readString($file);\n"

"      while ($w)\n"

"      {\n"

"        $statIdx = readInt($file);\n"

"        if ($word==substr($w,0,strlen($word)))\n"

"        { // found word that matches (as substring)\n"

"          $statsList[$count++]=array(\n"

"              \"word\"=>$word,\n"

"              \"match\"=>$w,\n"

"              \"index\"=>$statIdx,\n"

"              \"full\"=>strlen($w)==strlen($word),\n"

"              \"docs\"=>array()\n"

"              );\n"

"        }\n"

"        $w = readString($file);\n"

"      }\n"

"      $totalHi=0;\n"

"      $totalFreqHi=0;\n"

"      $totalFreqLo=0;\n"

"      for ($count=$start;$count<sizeof($statsList);$count++)\n"

"      {\n"

"        $statInfo = &$statsList[$count];\n"

"        $multiplier = 1;\n"

"        // whole word matches have a double weight\n"

"        if ($statInfo[\"full\"]) $multiplier=2;\n"

"        fseek($file,$statInfo[\"index\"]); \n"

"        $numDocs = readInt($file);\n"

"        $docInfo = array();\n"

"        // read docs info + occurrence frequency of the word\n"

"        for ($i=0;$i<$numDocs;$i++)\n"

"        {\n"

"          $idx=readInt($file); \n"

"          $freq=readInt($file); \n"

"          $docInfo[$i]=array(\"idx\"  => $idx,\n"

"                             \"freq\" => $freq>>1,\n"

"                             \"rank\" => 0.0,\n"

"                             \"hi\"   => $freq&1\n"

"                            );\n"

"          if ($freq&1) // word occurs in high priority doc\n"

"          {\n"

"            $totalHi++;\n"

"            $totalFreqHi+=$freq*$multiplier;\n"

"          }\n"

"          else // word occurs in low priority doc\n"

"          {\n"

"            $totalFreqLo+=$freq*$multiplier;\n"

"          }\n"

"        }\n"

"        // read name and url info for the doc\n"

"        for ($i=0;$i<$numDocs;$i++)\n"

"        {\n"

"          fseek($file,$docInfo[$i][\"idx\"]);\n"

"          $docInfo[$i][\"name\"]=readString($file);\n"

"          $docInfo[$i][\"url\"]=readString($file);\n"

"        }\n"

"        $statInfo[\"docs\"]=$docInfo;\n"

"      }\n"

"      $totalFreq=($totalHi+1)*$totalFreqLo + $totalFreqHi;\n"

"      for ($count=$start;$count<sizeof($statsList);$count++)\n"

"      {\n"

"        $statInfo = &$statsList[$count];\n"

"        $multiplier = 1;\n"

"        // whole word matches have a double weight\n"

"        if ($statInfo[\"full\"]) $multiplier=2;\n"

"        for ($i=0;$i<sizeof($statInfo[\"docs\"]);$i++)\n"

"        {\n"

"          $docInfo = &$statInfo[\"docs\"];\n"

"          // compute frequency rank of the word in each doc\n"

"          $freq=$docInfo[$i][\"freq\"];\n"

"          if ($docInfo[$i][\"hi\"])\n"

"          {\n"

"            $statInfo[\"docs\"][$i][\"rank\"]=\n"

"              (float)($freq*$multiplier+$totalFreqLo)/$totalFreq;\n"

"          }\n"

"          else\n"

"          {\n"

"            $statInfo[\"docs\"][$i][\"rank\"]=\n"

"              (float)($freq*$multiplier)/$totalFreq;\n"

"          }\n"

"        }\n"

"      }\n"

"    }\n"

"  }\n"

"  return $statsList;\n"

"}\n"

"\n"

"function combine_results($results,&$docs)\n"

"{\n"

"  foreach ($results as $wordInfo)\n"

"  {\n"

"    $docsList = &$wordInfo[\"docs\"];\n"

"    foreach ($docsList as $di)\n"

"    {\n"

"      $key=$di[\"url\"];\n"

"      $rank=$di[\"rank\"];\n"

"      if (in_array($key, array_keys($docs)))\n"

"      {\n"

"        $docs[$key][\"rank\"]+=$rank;\n"

"      }\n"

"      else\n"

"      {\n"

"        $docs[$key] = array(\"url\"=>$key,\n"

"            \"name\"=>$di[\"name\"],\n"

"            \"rank\"=>$rank\n"

"            );\n"

"      }\n"

"      $docs[$key][\"words\"][] = array(\n"

"               \"word\"=>$wordInfo[\"word\"],\n"

"               \"match\"=>$wordInfo[\"match\"],\n"

"               \"freq\"=>$di[\"freq\"]\n"

"               );\n"

"    }\n"

"  }\n"

"  return $docs;\n"

"}\n"

"\n"

"function filter_results($docs,&$requiredWords,&$forbiddenWords)\n"

"{\n"

"  $filteredDocs=array();\n"

"  while (list ($key, $val) = each ($docs)) \n"

"  {\n"

"    $words = &$docs[$key][\"words\"];\n"

"    $copy=1; // copy entry by default\n"

"    if (sizeof($requiredWords)>0)\n"

"    {\n"

"      foreach ($requiredWords as $reqWord)\n"

"      {\n"

"        $found=0;\n"

"        foreach ($words as $wordInfo)\n"

"        { \n"

"          $found = $wordInfo[\"word\"]==$reqWord;\n"

"          if ($found) break;\n"

"        }\n"

"        if (!$found) \n"

"        {\n"

"          $copy=0; // document contains none of the required words\n"

"          break;\n"

"        }\n"

"      }\n"

"    }\n"

"    if (sizeof($forbiddenWords)>0)\n"

"    {\n"

"      foreach ($words as $wordInfo)\n"

"      {\n"

"        if (in_array($wordInfo[\"word\"],$forbiddenWords))\n"

"        {\n"

"          $copy=0; // document contains a forbidden word\n"

"          break;\n"

"        }\n"

"      }\n"

"    }\n"

"    if ($copy) $filteredDocs[$key]=$docs[$key];\n"

"  }\n"

"  return $filteredDocs;\n"

"}\n"

"\n"

"function compare_rank($a,$b)\n"

"{\n"

"  if ($a[\"rank\"] == $b[\"rank\"]) \n"

"  {\n"

"    return 0;\n"

"  }\n"

"  return ($a[\"rank\"]>$b[\"rank\"]) ? -1 : 1; \n"

"}\n"

"\n"

"function sort_results($docs,&$sorted)\n"

"{\n"

"  $sorted = $docs;\n"

"  usort($sorted,\"compare_rank\");\n"

"  return $sorted;\n"

"}\n"

"\n"

"function report_results(&$docs)\n"

"{\n"

"  echo \"<table cellspacing=\\\"2\\\">\\n\";\n"

"  echo \"  <tr>\\n\";\n"

"  echo \"    <td colspan=\\\"2\\\"><h2>\".search_results().\"</h2></td>\\n\";\n"

"  echo \"  </tr>\\n\";\n"

"  $numDocs = sizeof($docs);\n"

"  if ($numDocs==0)\n"

"  {\n"

"    echo \"  <tr>\\n\";\n"

"    echo \"    <td colspan=\\\"2\\\">\".matches_text(0).\"</td>\\n\";\n"

"    echo \"  </tr>\\n\";\n"

"  }\n"

"  else\n"

"  {\n"

"    echo \"  <tr>\\n\";\n"

"    echo \"    <td colspan=\\\"2\\\">\".matches_text($numDocs);\n"

"    echo \"\\n\";\n"

"    echo \"    </td>\\n\";\n"

"    echo \"  </tr>\\n\";\n"

"    $num=1;\n"

"    foreach ($docs as $doc)\n"

"    {\n"

"      echo \"  <tr>\\n\";\n"

"      echo \"    <td align=\\\"right\\\">$num.</td>\";\n"

"      echo     \"<td><a class=\\\"el\\\" href=\\\"\".$doc[\"url\"].\"\\\">\".$doc[\"name\"].\"</a></td>\\n\";\n"

"      echo \"  <tr>\\n\";\n"

"      echo \"    <td></td><td class=\\\"tiny\\\">\".report_matches().\" \";\n"

"      foreach ($doc[\"words\"] as $wordInfo)\n"

"      {\n"

"        $word = $wordInfo[\"word\"];\n"

"        $matchRight = substr($wordInfo[\"match\"],strlen($word));\n"

"        echo \"<b>$word</b>$matchRight(\".$wordInfo[\"freq\"].\") \";\n"

"      }\n"

"      echo \"    </td>\\n\";\n"

"      echo \"  </tr>\\n\";\n"

"      $num++;\n"

"    }\n"

"  }\n"

"  echo \"</table>\\n\";\n"

"}\n"

"\n"

"function main()\n"

"{\n"

"  if(strcmp('4.1.0', phpversion()) > 0) \n"

"  {\n"

"    die(\"Error: PHP version 4.1.0 or above required!\");\n"

"  }\n"

"  if (!($file=fopen(\"search/search.idx\",\"rb\"))) \n"

"  {\n"

"    die(\"Error: Search index file could NOT be opened!\");\n"

"  }\n"

"  if (readHeader($file)!=\"DOXS\")\n"

"  {\n"

"    die(\"Error: Header of index file is invalid!\");\n"

"  }\n"

"  $query=\"\";\n"

"  if (array_key_exists(\"query\", $_GET))\n"

"  {\n"

"    $query=$_GET[\"query\"];\n"

"  }\n"

"  end_form(preg_replace(\"/[^a-zA-Z0-9\\-\\_\\.]/i\", \" \", $query ));\n"

"  echo \"&nbsp;\\n<div class=\\\"searchresults\\\">\\n\";\n"

"  $results = array();\n"

"  $requiredWords = array();\n"

"  $forbiddenWords = array();\n"

"  $foundWords = array();\n"

"  $word=strtok($query,\" \");\n"

"  while ($word) // for each word in the search query\n"

"  {\n"

"    if (($word{0}=='+')) { $word=substr($word,1); $requiredWords[]=$word; }\n"

"    if (($word{0}=='-')) { $word=substr($word,1); $forbiddenWords[]=$word; }\n"

"    if (!in_array($word,$foundWords))\n"

"    {\n"

"      $foundWords[]=$word;\n"

"      search($file,strtolower($word),$results);\n"

"    }\n"

"    $word=strtok(\" \");\n"

"  }\n"

"  $docs = array();\n"

"  combine_results($results,$docs);\n"

"  // filter out documents with forbidden word or that do not contain\n"

"  // required words\n"

"  $filteredDocs = filter_results($docs,$requiredWords,$forbiddenWords);\n"

"  // sort the results based on rank\n"

"  $sorted = array();\n"

"  sort_results($filteredDocs,$sorted);\n"

"  // report results to the user\n"

"  report_results($sorted);\n"

"  echo \"</div>\\n\";\n"

"  fclose($file);\n"

"}\n"

"\n"

"main();\n"

"\n"