Php/docs/function.xml-parse-into-struct
xml_parse_into_struct
(PHP 4, PHP 5, PHP 7)
xml_parse_into_struct — Parse XML data into an array structure
Description
xml_parse_into_struct
( XMLParser $parser
, string $data
, array &$values
[, array &$index = NULL
] ) : int
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.
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 $values.
Return Values
xml_parse_into_struct() returns 0 for failure and 1 for
success. This is not the same as FALSE and TRUE, be careful with
operators such as ===.
Changelog
| Version | Description |
|---|---|
| 8.0.0 | parser expects an XMLParser
instance now; previously, a resource was expected. |
Examples
Below is an example that illustrates the internal structure of
the arrays being generated by the function. We use a simple
note tag embedded inside a
para tag, and then we parse this and print out
the structures generated:
Example #1 xml_parse_into_struct() example
<?php$simple = "<para><note>simple note</note></para>";$p = xml_parser_create();xml_parse_into_struct($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:
Index array
Array
(
[PARA] => 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:
Example #2 moldb.xml - small database of molecular information
<?xml version="1.0"?>
<moldb>
<molecule>
<name>Alanine</name>
<symbol>ala</symbol>
<code>A</code>
<type>hydrophobic</type>
</molecule>
<molecule>
<name>Lysine</name>
<symbol>lys</symbol>
<code>K</code>
<type>charged</type>
</molecule>
</moldb>
And some code to parse the document and generate the appropriate objects:
Example #3 parsemoldb.php - parses moldb.xml into an array of molecular objects
<?phpclass AminoAcid { var $name; // aa name var $symbol; // three letter symbol var $code; // one letter code var $type; // hydrophobic, charged or neutral function __construct ($aa) { foreach ($aa as $k=>$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:
** Database of AminoAcid objects:
Array
(
[0] => aminoacid Object
(
[name] => Alanine
[symbol] => ala
[code] => A
[type] => hydrophobic
)
[1] => aminoacid Object
(
[name] => Lysine
[symbol] => lys
[code] => K
[type] => charged
)
)
