<?php
class parent {
    function traverseTable($table) {
        foreach($table->getElementsByTagName('tr') {
            $rowCnt++;
            $this->uniqueSearch($rowCnt);
        }
    }
}

class child1 extends parent {
    function search($input) {
        //parse input, get $table
        $this->traverseTable($table);
    }

    function uniqueSearch($rowCnt) {
         echo 'child1';
        //Do different things
    }
}

class child2 extends parent {
    function search($input) {
        //parse input, get $table
        $this->traverseTable($table);
    }

    function uniqueSearch($rowCnt) {
         echo 'child2';
        //Do different things
    }
}
?>

Fatal error: Cannot use 'parent' as class name as it is reserved on line 2