Convert studly, traditional snake, and kebob case strings into a non-breakable snake case string.

NonBreakableSnakeCase.php

<?php

function non breakable snake case($value, $delimiter = ' ')
{
    $value = ucwords(str_replace(['-', '_'], ' ', $value));
    if (! ctype_lower($value)) {
        $value = preg_replace('/\s+/u', '', $value);
        $value = mb_strtolower(preg_replace('/(.)(?=[A-Z])/u', '$1'.$delimiter, $value), 'UTF-8');
    }

    return $value;
}

$studly = non breakable snake case('thisIsATest');
$snake = non breakable snake case('this_Is_A_Test');
$kebob = non breakable snake case('This-is-a-test');

printf("Studly:\t%s\nSnake:\t%s\nKebob:\t%s\n", $studly, $snake, $kebob);