PHP Simplest XML tokenizer for string processing?

Question

I need to do some text processing tasks with short XML fragments. The section "details" shows an example... My solution is to use a tokenizer based on regular expresions, but it is not elegant and not uses any build-in function. The candidate build-in functions (that others indicates to me) are strtok and SimpleXML.

So, my question have two parts:

1. My assumptions are correct? There are no other "candidates", only strtok and SimpleXML? Is correct to think DomDocument as an "elephant" (with big CPU overhead) for a simple text processing task?

2. How to use SimpleXML to do the same (illustred) task? PS: I not need all algorithm or implementation, only some clues.

---

Details

PHP offers a tokenizer, strtok, very simple, and I not see how to use it with XML string. The option, SimpleXML, is perhaps heavy for tasks like ''text processing'' (see this example and the below), and is more than a tokenizer.

What exactly I whant to say with "tokenizer" and "text processing"? See example below. I used a "regex parser", but I would like an algorithm based on some built-in function like SimpleXML, if it is simpler and faster.

 $xmlFrag = '
   <p align="center">&nbsp; Hello world!</p> 
   <p class="test"><i>&nbsp; Beautiful</i> day today.</p>';

 // TOKENIZING TAGS AND ENTITIES:
 $reg=array();
 $xmlFrag = preg_replace_callback(
    '/<!\-\-.+?\-\->|<.+?>|&[a-z0-9]+;/is', 
    function ($m) {
        global $reg; $reg[]=$m[0]; $n=count($reg)-1;
        return "##$n#";
    },
    $xmlFrag
 );
 echo $xmlFrag;     // results:
 //  ##0###1# Hello world!##2#  ##3###4###5# Beautiful##6# day today.##7#

 // PROCESS THE TEXT: any, in one step. Example: lower, upper, change orthography, etc.
 $xmlFrag = strtoupper($xmlFrag);
 echo $xmlFrag;
 //  ##0###1# HELLO WORLD!##2#  ##3###4###5# BEAUTIFUL##6# DAY TODAY.##7#

 // EXPAND TOKENS:
 $xmlFrag = preg_replace_callback(
    '/##([0-9]+)#/is', 
    function ($m) { global $reg; return $reg[$m[1]]; },
    $xmlFrag
 );
 echo $xmlFrag;
 //  <p align="center">  HELLO WORLD!</p> 
 //  <p class="test"><i>  BEAUTIFUL</i> DAY TODAY.</p>

---

Using SimpleXML

How to implement a SimpleXML algorithm to resolve the illustrated problem (code above)? PROBLEMS:

• Load a XML with named entities (as   in the example).
• Traverse XML to get only text nodes. With $sx->xpath('//text()'); I can not edit the nodes.

Using DomDocument

It is out of context, because my XML fragments are short and DomDocument imposes a big CPU overhead (? is this a preconception?) for the simple text processing.

Answer 1

Sorry, I find (!), and have a misconception about DomDocument (it is not an "elephant"):

1. DomDocument have comparable performance (times) with SimpleXML.

2. There are a simple algorithm to solve my problem!

    $dom = new DOMDocument;
    $dom->loadXML($xmlFrag);  
    $xpath = new DOMXpath($dom);
    $elements = $xpath->query("//text()");
    foreach ($elements as $element) // loop for text processing:
        $element->nodeValue = strtoupper($element->nodeValue);
    print $dom->saveXML();
   

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Performance (execution times for a 10000 loop):

• DOMDocument (implementation above): 0.481 seconds;
• regex tokenizer (implemention of the question): 0.571 seconds;
• SimpleXML (no implementation, only simulating iniciatizations and process): 0.481 seconds.
  @IMSoP shows that "traverse and edit" is more complex with SimpleXML than DOM.