PHP - get defined constants for a given namespace - php

Question

I have a set of classes for data storage. It currently have a working connector for Google Drive, Dropbox, Box, FTP and local connection. I have designed this to construct a file manager where a client can manage multiple data storage sources.
Here comes my question. Currently, my implementation of the addConnection() method is the following:
// addConnection - adds a storage connection to the storage manager
public function addConnection($service, $credentials) {
if (!empty($service) && !empty($credentials)) {
if (in_array($service, [Connectors\Box, Connectors\Dropbox, Connectors\FTP, Connectors\GoogleDrive, Connectors\Local], true)) {
// rest goes here...
}
}
}
I have my constants in a separate namespace like this:
namespace Services\Storage\Connectors {
const Box = "Box";
const Dropbox = "Dropbox";
const FTP = "FTP";
const GoogleDrive = "GoogleDrive";
const Local = "Local";
}
Is there a way for me to get all defined constant for a given namespace? That way, I could construct a function to get all defined constants and write something more elegant like in_array($service, getConstants($this->getNamespace()), true).
Can you give me a hint?

Answer 1

You can get all user defined constants with get_defined_constants and then check the namespace using strpos:
$constants = get_defined_constants(TRUE)['user'];
foreach ($constants as $name => $value)
{
if (0 === strpos($name, 'services\storage\connectors'))
{
$services_storage_connectors[] = $name;
}
}
echo '<pre>' . print_r($services_storage_connectors, TRUE) . '</pre>';
/*
Array
(
[0] => services\storage\connectors\Box
[1] => services\storage\connectors\Dropbox
[2] => services\storage\connectors\FTP
[3] => services\storage\connectors\GoogleDrive
[4] => services\storage\connectors\Local
)
*/
Note that $name is lowercase, even if the namespace is defined with uppercase letters.
Edit: In case you'd like it in fewer lines
$constants = array_filter(array_keys(get_defined_constants(TRUE)['user']), function ($name)
{
return 0 === strpos($name, 'services\storage\connectors');
}
);