Which HTML Parser (preferably PHP) supports getting the offset of the current node in the input string?

Question

I'm looking for an HTML or XML parser that lets one access the offset/position of the current element in the input string or file.

For example if walking through this string:

<div>
    <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit</p>
    <p>sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.</p>
</div>

I'm looking for a way to get the starting position (including whitespace) of each <p> tag, here: 7 and 72.

It'd be great if a PHP parser supported that natively (I've looked at DOM, XMLReader, and other libraries mentionned in this SO question but haven't found a way to do it), but otherwise any language/framework would be fine.

Note: Related to this question, but less localized.

Answer 1

Maybe you could use Generic XML parser class (also on github).
According to the author's description:

• Parses arbitrary XML input and builds an array with the structure of all tag and data elements.
• It can validate and extract data from a whole XML document with just a single call. It supports validationg common tag value data types and can perform custom validations using a subclass.
• Optionally, keeps track of the positions of each element to allow the determination of the exact location of elements that may be contextually in error.
• Supports parsed file cache to minimize the overhead of parsing the same file repeatdly.
• Optimized parsing of simplified XML (SML) formats ignoring the tag attributes.
• Validate and extract data from a whole XML document with single function call

I've tested it with this code:

<?php

require('xml_parser.php');

$file_name = 'test.xml';
$error = XMLParseFile($parser, $file_name, 1, $file_name.'.cache');

foreach ($parser->structure as $key => $val) {
    if (is_array($val) && isset($val['Tag']) && !strcasecmp($val['Tag'], 'p')) {
        print_r($parser->positions[$key]);
    }
}

?>

The test.xml file contains your sample HTML snippet.
By running the script from the command line I get this output:

Array
(
    [Line] => 2
    [Column] => 7
    [Byte] => 12
)
Array
(
    [Line] => 3
    [Column] => 7
    [Byte] => 80
)

So, the Byte field is probably what you're looking for.
For a better understanding of how it works, have also a look at its source code.

Answer 2

If you do not mind coding in Java (after Java code there is a solution in PHP), you can use indexOf method in String class, getting the offset if this token.

Here is an example:

class Index {
    public static void main ( String [] args )
    {   
        String token = "<p>";
        String input = "<p> hola </p> <p> adios </a>";
        int beginIdx = -1; 
        while ( (beginIdx = input.indexOf( token, beginIdx + 1 )) != -1 ) {                                                                                                                                         
            System.out.println( "Token at: " + beginIdx );
        }   
    }   
}

And the output is:

Token at: 0
Token at: 14

In PHP there is a similar function:

int strrpos ( string $haystack , string $needle [, int $offset = 0 ] )

You can have a quick look to the "man" page about it (it has some examples): http://php.net/manual/es/function.strrpos.php