php之XML转数组函数的详解

如下所示：
代码如下:
<?
/**
* xml2array() will convert the given XML text to an array in the XML structure.
* Link: http://www.bin-co.com/php/scripts/xml2array/
* Arguments : $contents - The XML text
*                 $get_attributes - 1 or 0. If this is 1 the function will get the attributes as well as the tag values - this results in a different array structure in the return value.
*                 $priority - Can be 'tag' or 'attribute'. This will change the way the resulting array sturcture. For 'tag', the tags are given more importance.
* Return: The parsed XML in an array form. Use print_r() to see the resulting array structure.
* Examples: $array =   xml2array(file_get_contents('feed.xml'));
*               $array =   xml2array(file_get_contents('feed.xml', 1, 'attribute'));
*/
function xml2array($contents, $get_attributes=1, $priority = 'tag') {
     if(!$contents) return array();
     if(!function_exists('xml_parser_create')) {
        //print "'xml_parser_create()' function not found!";
        return array();
     }
    //Get the XML parser of PHP - PHP must have this module for the parser to work
    $parser = xml_parser_create('');
    xml_parser_set_option($parser, XML_OPTION_TARGET_ENCODING, "UTF-8"); # http://minutillo.com/steve/weblog/2004/6/17/php-xml-and-character-encodings-a-tale-of-sadness-rage-and-data-loss
    xml_parser_set_option($parser, XML_OPTION_CASE_FOLDING, 0);
    xml_parser_set_option($parser, XML_OPTION_SKIP_WHITE, 1);
    xml_parse_into_struct($parser, trim($contents), $xml_values);
    xml_parser_free($parser);
     if(!$xml_values) return;//Hmm...
     //Initializations
    $xml_array = array();
    $parents = array();
    $opened_tags = array();
    $arr = array();
    $current = &$xml_array; //Refference
     //Go through the tags.
    $repeated_tag_index = array();//Multiple tags with same name will be turned into an array
    foreach($xml_values as $data) {
         unset($attributes,$value);//Remove existing values, or there will be trouble
         //This command will extract these variables into the foreach scope
         // tag(string), type(string), level(int), attributes(array).
        extract($data);//We could use the array by itself, but this cooler.
        $result = array();
        $attributes_data = array();

         if(isset($value)) {
             if($priority == 'tag') $result = $value;
             else $result['value'] = $value; //Put the value in a assoc array if we are in the 'Attribute' mode
        }
        //Set the attributes too.
        if(isset($attributes) and $get_attributes) {
             foreach($attributes as $attr => $val) {
                 if($priority == 'tag') $attributes_data[$attr] = $val;
                 else $result['attr'][$attr] = $val; //Set all the attributes in a array called 'attr'
            }
         }
        //See tag status and do the needed.
        if($type == "open") {//The starting of the tag '<tag>'
            $parent[$level-1] = &$current;
             if(!is_array($current) or (!in_array($tag, array_keys($current)))) { //Insert New tag
                $current[$tag] = $result;
                 if($attributes_data) $current[$tag. '_attr'] = $attributes_data;
                $repeated_tag_index[$tag.'_'.$level] = 1;
                $current = &$current[$tag];
             } else { //There was another element with the same tag name
                if(isset($current[$tag][0])) {//If there is a 0th element it is already an array
                    $current[$tag][$repeated_tag_index[$tag.'_'.$level]] = $result;
                    $repeated_tag_index[$tag.'_'.$level]++;
                 } else {//This section will make the value an array if multiple tags with the same name appear together
                    $current[$tag] = array($current[$tag],$result);//This will combine the existing item and the new item together to make an array
                    $repeated_tag_index[$tag.'_'.$level] = 2;

                     if(isset($current[$tag.'_attr'])) { //The attribute of the last(0th) tag must be moved as well
                        $current[$tag]['0_attr'] = $current[$tag.'_attr'];
                         unset($current[$tag.'_attr']);
                     }
                 }
                $last_item_index = $repeated_tag_index[$tag.'_'.$level]-1;
                $current = &$current[$tag][$last_item_index];
             }
         } elseif($type == "complete") { //Tags that ends in 1 line '<tag />'
             //See if the key is already taken.
            if(!isset($current[$tag])) { //New Key
                $current[$tag] = $result;
                $repeated_tag_index[$tag.'_'.$level] = 1;
                 if($priority == 'tag' and $attributes_data) $current[$tag. '_attr'] = $attributes_data;
             } else { //If taken, put all things inside a list(array)
                if(isset($current[$tag][0]) and is_array($current[$tag])) {//If it is already an array...
                     // ...push the new element into that array.
                    $current[$tag][$repeated_tag_index[$tag.'_'.$level]] = $result;

                     if($priority == 'tag' and $get_attributes and $attributes_data) {
                        $current[$tag][$repeated_tag_index[$tag.'_'.$level] . '_attr'] = $attributes_data;
                     }
                    $repeated_tag_index[$tag.'_'.$level]++;
                 } else { //If it is not an array...
                    $current[$tag] = array($current[$tag],$result); //...Make it an array using using the existing value and the new value
                    $repeated_tag_index[$tag.'_'.$level] = 1;
                     if($priority == 'tag' and $get_attributes) {
                         if(isset($current[$tag.'_attr'])) { //The attribute of the last(0th) tag must be moved as well

                            $current[$tag]['0_attr'] = $current[$tag.'_attr'];
                             unset($current[$tag.'_attr']);
                         }

                         if($attributes_data) {
                            $current[$tag][$repeated_tag_index[$tag.'_'.$level] . '_attr'] = $attributes_data;
                         }
                     }
                    $repeated_tag_index[$tag.'_'.$level]++; //0 and 1 index is already taken
                }
             }
         } elseif($type == 'close') { //End of tag '</tag>'
            $current = &$parent[$level-1];
         }
     }

     return($xml_array);
}
?>

函数描述及例子:
代码如下:
$arr = xml2array(file_get_contents("tools.xml"),1,'attribute');