src/ServiceContainer.php
public function getServiceIdFromAlias($alias, $default = null)
    {
        if (isset($this->aliases[$alias])) {
            return $this->aliases[$alias];
        }

        return $default;
    }
public function getServiceIdFromAlias($alias, $default = null)
    {
        if (isset($this->aliases[$alias])) {
            return $this->aliases[$alias];
        }

        return $default;
    }
public function getServiceIdFromAlias ( $ alias , $ default = null ) { if ( isset ( $ this -> aliases [ $ alias ] ) ) { return $ this -> aliases [ $ alias ] ; } return $ default ; }
Retrive service identifier for alias or default value, if alias is not
define.

@param string $alias Alias identifier.
@param mixed $default Default value, if alias not registred.
@return string|mixed Service identifier or default value.
Retrive service identifier for alias or default value if alias is not define .