Added option to have empty paths

[gabrielbull]

For example, this code:

$klein->with('/users/', function () use ($klein) {
    $klein->respond('GET', '', function () {
        echo 'Hello World';
    });
});

Responds to the given the path /users/, as it should, but throws an error:

Notice: Uninitialized string offset: 0 in /klein/klein/src/Klein/RouteFactory.php on line 84

This PR fixes that bug and allows for paths to be empty.
Please note that providing null as an argument for the path creates a catch-all route so this is not an option.

[Rican7]

Couldn't you achieve this same thing with just:

$klein->with('/users', function () use ($klein) {
    $klein->respond('GET', '/?', function () {
        echo 'Hello World';
    });
});

[gabrielbull]

Yes

[Rican7]

Hmm, I can see a case for an empty string, but its implicit nature is strange to me.
It would need to be documented well.

[gabrielbull]

Could it be replaced by a . like some other path system use to reference the current path (E.G. href attribute in HTML).

Example:

$klein->with('/users/', function () use ($klein) {
    $klein->respond('GET', '.', function () {
        echo 'Hello World';
    });
});

Should match the path /users/,that could be a feature.

But, I beleive my current pull request should be considered a bug fix since all it does is prevent an undesirable notice. Maybe we could remove the unit test as it may not be a documented behaviour, but it should not throw notices anyhow.

[Rican7]

Very true. Not checking for the offset first is bad, so this PR fixes that. An empty string is weird, but I guess its technically legal.

If you could just split up the line into a multi-line if block so it doesn't go beyond 120 characters, then the Travis style tests would pass. Maybe like this?:

if ($this->namespace
    && (isset($path[0]) && $path[0] === '@')
    || (isset($path[0]) && $path[0] === '!' && isset($path[1]) && $path[1] === '@')) {

[gabrielbull]

Is that the intended condition? Because before it was this:

$this->namespace && $path[0] === '@' || ($path[0] === '!' && $path[1] === '@')

which match $this->namespace && $path[0] === '@' OR $path[0] === '!' && $path[1] === '@'

With the one you provided, it would be $this->namespace AND ($path[0] === '@' OR $path[0] === '!' && $path[1] === '@')

[Rican7]

The intended condition check was admittedly poorly written before.
That if block is actually not how it would be evaluated, as not wrapping it still gives this result:

[gabrielbull]

Alright, so, using your condition, this PR should be good to go. I'll open an issue to discuss the addition of the . string in paths.

[Rican7]

I hate to be a pain, but this would be a bit more readable to me if it wasn't negated in front:

$test_path = is_string($test_path) ? $test_path : '/test';

[gabrielbull]

Alright, done

[Rican7]

Awesome! Tests passed!
Thank you so much for the PR, @gabrielbull. :)