php|architect's Guide to Web Scraping with PHP - Wind Business ...

XMLReader Extension ” 125
Element nodes can have attributes. When the iterator points to an element
node, the hasAttributes property indicates the presence of attributes and the
getAttribute() method can be used to obtain an attribute value in the form of a
string.
The example below uses both of these together to parse data from an HTML table.
localName == ’table’
&& $doc->getAttribute(’id’) == ’thetable’) {
$inTable = true;
} elseif ($doc->localName == ’tr’ && $inTable) {
$row = count($tableData);
$tableData[$row] = array();
} elseif ($doc->localName == ’td’ && $inTable) {
$tableData[$row][] = $doc->readString();
}
break;
case XMLREADER::END_ELEMENT:
if ($doc->localName == ’table’ && $inTable) {
$inTable = false;
}
break;
}
}
?>
This showcases the main difference between pull parsers and tree parsers: the former
have no concept of hierarchical context, only of the node to which the iterator
is currently pointing. As such, you must create your o w n indicators of context where
they are needed.
In this example, the node type is checked as nodes are read and any node that isn’t
either an opening or closing element is ignored. If an opening element is encountered,
its name ($doc->localName) is evaluated to confirm that it’s a table and its id
attribute value ($doc->getAttribute(’id’)) is also examined to confirm that it has a
value of ’thetable’ If so, . a flag variable $inTable is set to true. This is used to indi-