Custom comparison

By implementing CHItA\PHPDiff\Comparison\ComparisonInterface, you may add a custom data comparison implementation to the algorithm. This could be useful if you would like to compare the trimmed versions of the units for example.

Warning

Comparison algorithm never alters the content of the passed elements. Any manipulation of the input data in the comparison algorithm will not be present in the output.

However, please be aware that when you use this option, the returned units from two-way diffs will contain the units from the modified version (second parameter of the Differ::diff() method). Please also note, that when using custom comparisons with three-way diffs, the units in the output could be from either of the modified documents.

Example

An example comparison algorithm that trims whitespaces from the end of the units before comparing them.

use CHItA\PHPDiff\Comparison\ComparisonInterface;

class TrimCompare implements ComparisonInterface
{
    public function compare($value1, $value2)
    {
            return rtrim($value1) === rtrim($value2);
    }
}

use CHItA\PHPDiff\DifferBase;
use CHItA\PHPDiff\Differ;

$differ = new Differ();
$differ->setComparisonAlgorithm(new TrimCompare());
$diff = $differ->diff(
    array('a', 'b', 'b', 'c'),
    array(' a', 'b  ', 'b   ', 'c')
);

// $diff will contain an array with the following structure:
//
// array(
//     array(
//          array(
//              'type'  => DifferBase::REMOVED,
//              array('a')
//          ),
//          array(
//              'type'  => DifferBase::ADDED,
//              array(' a')
//          )
//     ),
//     array(
//          'type'  => DifferBase::UNCHANGED,
//          array('b  ', 'b   ', 'c')
//     )
// )