XML_PullParser

XML_PullParser Coding Strategies 2: the 'which' parameter &version; Turner Myron Contents Several functions take a $which parameter. In this section we'll look at two of these which often work in tandem: array XML_PullParser_getAttributes (mixed $name, [mixed $which = 1], [array $el = ""]) string XML_PullParser_getText ([mixed $el = ""], [integer $which = 0], [boolean $xcl = false]) As we said in the section on instantiation, the $child_tags and the $tags arrays in conjunction with XML_PullParser_getToken and XML_PullParser_getElement act as selectors. The $which parameter refines the selection. Where a token contains more than one element of the same name, $which specifies which of them is the subject of the query. The elements are stored in the token arrays in document order, beginning at a $which value of 1. Note: The $which value is a selector and shouldn't be confused with array indexes, which start at zero. In the DNS Example that we've been working with, there are three server elements:

<server ip="192.168.10.1">example_1.com</server> <server ip="192.168.10.2">example_2.com</server> <server ip="192.168.10.3">example_3.com</server>

The following code will get both the names and the ip addresses of the three servers:

Listing 9 1. $tags = array("entry"); 2. $child_tags = array("server","ipaddress", "domain"); 3. $parser = new XML_PullParser("DNS.xml",$tags,$child_tags); 4. while($token = $parser->XML_PullParser_getToken()) 5. { 6. $parser->XML_PullParser_getElement('server'); 7. $which=1; 8. while($server = $parser->XML_PullParser_getText('server',$which)) { 9. $ip = $parser->XML_PullParser_getAttributes('server',$which); 10. echo "Name: $server\n"; 11. echo "\tIP: " . $parser->XML_PullParser_getAttrVal('ip', $ip) . "\n"; 12. $which++; 13. } 14. } /* Result Name: example_1.com IP: 192.168.10.1 Name: example_2.com IP: 192.168.10.2 Name: example_3.com IP: 192.168.10.3 */

Listing 9 assumes that we are going to be interested more than just the servers. So we declare the "entry" element in the $tags array and the other elements of interest in the $child_tags array. Line 4 gets the "entry" token and then XML_PullParser_getElement (line 6) isolates the token's server elements for processing. Beginning with line 8, the while loop first gets each server's name and then its ipaddress, which is stored as an attribute of server. The server name is returned as a string and the attribute as an array, which is passed in to the helper function XML_PullParser_getAttributes, which then returns the attribute value as a string. The $which value is updated with each turn of the loop (line 12).

Note XML_PullParser_getText is a complex function; its return value depends on what is passed in as parameters, including the $xcl parameter, which has not been discussed here. See the class documentation and the TextAccesors section of this manual.

Introduction to Coding Strategies Strategies 3: XML_PullParser_getSequence