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

126 ” XMLReader Extension
cate to subsequent if branch cases that the iterator points to a node that is within
the desired table.
The next if branch is entered when table row elements within the table are
encountered. A combination of checking the node name and the previously set
$inTable flag facilitates this. When the branch is entered, a new element in the
$tableData array is initialized to an empty array. This array will later store data from
cells in that row. The key associated with the row in $tableData is stored in the $row
variable.
Finally, the last if branch executes when table cell elements are encountered. Like
the row branch, this branch checks the node name and the $inTable flag. If the check
passes, it then stores the current node’s value in the array associated with the current
table row.
H e r e’s where the XMLREADER::END_ELEMENT node type comes into play. Once the end
of the table is reached, no further data should be read into the array. So, if the ending
element has the name ’table’ and the $inTable flag currently indicates that the
iterator points to a node within the desired table, the flag is then set to false. Since
no other tables should theoretically have the same id attribute, no if branches will
execute in subsequent while loop iterations.
If this table was the only one of interest in the document, it would be prudent
to replace the $inTable = false; statement with a break 2; statement. This would
terminate the while loop used to read nodes from the document as soon as the end
of the table was encountered, preventing any further unnecessary read operations.
i
readString() A v a i l a b i l i t y
As its entry in the PHP manual notes, the readString() method used in the above example
is only present when the XMLReader extension is compiled against certain versions
of the underlying libxml library.
If this method is unavailable in your environment, an alternative in the example would
be to have opening and closing table cell checks that toggle their ow n flag ($inCell for
example) and switch cases for the TEXT and CDATA node types that check this flag
and, when it is set to true, add the contents of the value property from the XMLReader
instance to the $tableData array.