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<?php
// Some smart guy removed XMLReader's global constants from PHP 5.1
// and replaced them with class constants. Breaking source compatibility
// is SUPER awesome, and I love languages which do this constantly!
$xmlReaderConstants = array(
"NONE",
"ELEMENT",
"ATTRIBUTE",
"TEXT",
"CDATA",
"ENTITY_REF",
"ENTITY",
"PI",
"COMMENT",
"DOC",
"DOC_TYPE",
"DOC_FRAGMENT",
"NOTATION",
"WHITESPACE",
"SIGNIFICANT_WHITESPACE",
"END_ELEMENT",
"END_ENTITY",
"XML_DECLARATION",
"LOADDTD",
"DEFAULTATTRS",
"VALIDATE",
"SUBST_ENTITIES" );
foreach( $xmlReaderConstants as $name ) {
$fullName = "XMLREADER_$name";
$newName = "XMLReader::$name";
if( !defined( $fullName ) ) {
if( defined( $newName ) ) {
define( $fullName, constant( $newName ) );
} else {
// broken or missing the extension...
}
}
}
/**
* Readahead helper for making large MediaWiki data dumps;
* reads in a previous XML dump to sequentially prefetch text
* records already normalized and decompressed.
*
* This can save load on the external database servers, hopefully.
*
* Assumes that dumps will be recorded in the canonical order:
* - ascending by page_id
* - ascending by rev_id within each page
* - text contents are immutable and should not change once
* recorded, so the previous dump is a reliable source
*
* Requires PHP 5 and the XMLReader PECL extension.
* @ingroup Maintenance
*/
class BaseDump {
var $reader = null;
var $atEnd = false;
var $atPageEnd = false;
var $lastPage = 0;
var $lastRev = 0;
function BaseDump( $infile ) {
$this->reader = new XMLReader();
$this->reader->open( $infile );
}
/**
* Attempts to fetch the text of a particular page revision
* from the dump stream. May return null if the page is
* unavailable.
*
* @param int $page ID number of page to read
* @param int $rev ID number of revision to read
* @return string or null
*/
function prefetch( $page, $rev ) {
$page = intval( $page );
$rev = intval( $rev );
while( $this->lastPage < $page && !$this->atEnd ) {
$this->debug( "BaseDump::prefetch at page $this->lastPage, looking for $page" );
$this->nextPage();
}
if( $this->lastPage > $page || $this->atEnd ) {
$this->debug( "BaseDump::prefetch already past page $page looking for rev $rev [$this->lastPage, $this->lastRev]" );
return null;
}
while( $this->lastRev < $rev && !$this->atEnd && !$this->atPageEnd ) {
$this->debug( "BaseDump::prefetch at page $this->lastPage, rev $this->lastRev, looking for $page, $rev" );
$this->nextRev();
}
if( $this->lastRev == $rev && !$this->atEnd ) {
$this->debug( "BaseDump::prefetch hit on $page, $rev [$this->lastPage, $this->lastRev]" );
return $this->nextText();
} else {
$this->debug( "BaseDump::prefetch already past rev $rev on page $page [$this->lastPage, $this->lastRev]" );
return null;
}
}
function debug( $str ) {
wfDebug( $str . "\n" );
//global $dumper;
//$dumper->progress( $str );
}
/**
* @access private
*/
function nextPage() {
if( $this->skipTo( 'page', 'mediawiki' ) ) {
if( $this->skipTo( 'id' ) ) {
$this->lastPage = intval( $this->nodeContents() );
$this->lastRev = 0;
$this->atPageEnd = false;
}
} else {
$this->atEnd = true;
}
}
/**
* @access private
*/
function nextRev() {
if( $this->skipTo( 'revision' ) ) {
if( $this->skipTo( 'id' ) ) {
$this->lastRev = intval( $this->nodeContents() );
}
} else {
$this->atPageEnd = true;
}
}
/**
* @access private
*/
function nextText() {
$this->skipTo( 'text' );
return strval( $this->nodeContents() );
}
/**
* @access private
*/
function skipTo( $name, $parent='page' ) {
if( $this->atEnd ) {
return false;
}
while( $this->reader->read() ) {
if( $this->reader->nodeType == XMLREADER_ELEMENT &&
$this->reader->name == $name ) {
return true;
}
if( $this->reader->nodeType == XMLREADER_END_ELEMENT &&
$this->reader->name == $parent ) {
$this->debug( "BaseDump::skipTo found </$parent> searching for <$name>" );
return false;
}
}
return $this->close();
}
/**
* Shouldn't something like this be built-in to XMLReader?
* Fetches text contents of the current element, assuming
* no sub-elements or such scary things.
* @return string
* @access private
*/
function nodeContents() {
if( $this->atEnd ) {
return null;
}
if( $this->reader->isEmptyElement ) {
return "";
}
$buffer = "";
while( $this->reader->read() ) {
switch( $this->reader->nodeType ) {
case XMLREADER_TEXT:
// case XMLREADER_WHITESPACE:
case XMLREADER_SIGNIFICANT_WHITESPACE:
$buffer .= $this->reader->value;
break;
case XMLREADER_END_ELEMENT:
return $buffer;
}
}
return $this->close();
}
/**
* @access private
*/
function close() {
$this->reader->close();
$this->atEnd = true;
return null;
}
}
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