xml_parse_into_struct
Parse XML data into an array structure
&reftitle.description;
intxml_parse_into_struct
resourceparser
stringdata
arrayvalues
arrayindex
This function parses an XML string into 2 parallel array structures, one
(index) containing pointers to the location of the
appropriate values in the values array. These last
two parameters must be passed by reference.
&reftitle.parameters;
parser
A reference to the XML parser.
data
A string containing the XML data.
values
An array containing the values of the XML data
index
An array containing pointers to the location of the appropriate values in the $values.
&reftitle.returnvalues;
xml_parse_into_struct returns 0 for failure and 1 for
success. This is not the same as &false; and &true;, be careful with
operators such as ===.
&reftitle.examples;
Below is an example that illustrates the internal structure of
the arrays being generated by the function. We use a simple
note tag embedded inside a
para tag, and then we parse this and print out
the structures generated:
<function>xml_parse_into_struct</function> example
simple note";
$p = xml_parser_create();
xml_parse_into_struct($p, $simple, $vals, $index);
xml_parser_free($p);
echo "Index array\n";
print_r($index);
echo "\nVals array\n";
print_r($vals);
?>
]]>
When we run that code, the output will be:
Array
(
[0] => 0
[1] => 2
)
[NOTE] => Array
(
[0] => 1
)
)
Vals array
Array
(
[0] => Array
(
[tag] => PARA
[type] => open
[level] => 1
)
[1] => Array
(
[tag] => NOTE
[type] => complete
[level] => 2
[value] => simple note
)
[2] => Array
(
[tag] => PARA
[type] => close
[level] => 1
)
)
]]>
Event-driven parsing (based on the expat library) can get
complicated when you have an XML document that is complex.
This function does not produce a DOM style object, but it
generates structures amenable of being transversed in a tree
fashion. Thus, we can create objects representing the data
in the XML file easily. Let's consider the following XML file
representing a small database of aminoacids information:
moldb.xml - small database of molecular information
Alanine
ala
A
hydrophobic
Lysine
lys
K
charged
]]>
And some code to parse the document and generate the appropriate
objects:
parsemoldb.php - parses moldb.xml into an array of
molecular objects
$v)
$this->$k = $aa[$k];
}
}
function readDatabase($filename)
{
// read the XML database of aminoacids
$data = implode("", file($filename));
$parser = xml_parser_create();
xml_parser_set_option($parser, XML_OPTION_CASE_FOLDING, 0);
xml_parser_set_option($parser, XML_OPTION_SKIP_WHITE, 1);
xml_parse_into_struct($parser, $data, $values, $tags);
xml_parser_free($parser);
// loop through the structures
foreach ($tags as $key=>$val) {
if ($key == "molecule") {
$molranges = $val;
// each contiguous pair of array entries are the
// lower and upper range for each molecule definition
for ($i=0; $i < count($molranges); $i+=2) {
$offset = $molranges[$i] + 1;
$len = $molranges[$i + 1] - $offset;
$tdb[] = parseMol(array_slice($values, $offset, $len));
}
} else {
continue;
}
}
return $tdb;
}
function parseMol($mvalues)
{
for ($i=0; $i < count($mvalues); $i++) {
$mol[$mvalues[$i]["tag"]] = $mvalues[$i]["value"];
}
return new AminoAcid($mol);
}
$db = readDatabase("moldb.xml");
echo "** Database of AminoAcid objects:\n";
print_r($db);
?>
]]>
After executing parsemoldb.php, the variable
$db contains an array of
AminoAcid objects, and the output of the
script confirms that:
aminoacid Object
(
[name] => Alanine
[symbol] => ala
[code] => A
[type] => hydrophobic
)
[1] => aminoacid Object
(
[name] => Lysine
[symbol] => lys
[code] => K
[type] => charged
)
)
]]>