| 1 |  |  | <?php | 
            
                                                                                                            
                            
            
                                    
            
            
                | 2 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 3 |  |  | /* | 
            
                                                                                                            
                            
            
                                    
            
            
                | 4 |  |  |  * This file is part of the Ivory Google Map package. | 
            
                                                                                                            
                            
            
                                    
            
            
                | 5 |  |  |  * | 
            
                                                                                                            
                            
            
                                    
            
            
                | 6 |  |  |  * (c) Eric GELOEN <[email protected]> | 
            
                                                                                                            
                            
            
                                    
            
            
                | 7 |  |  |  * | 
            
                                                                                                            
                            
            
                                    
            
            
                | 8 |  |  |  * For the full copyright and license information, please read the LICENSE | 
            
                                                                                                            
                            
            
                                    
            
            
                | 9 |  |  |  * file that was distributed with this source code. | 
            
                                                                                                            
                            
            
                                    
            
            
                | 10 |  |  |  */ | 
            
                                                                                                            
                            
            
                                    
            
            
                | 11 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 12 |  |  | namespace Ivory\GoogleMap\Service\Elevation\Request; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 13 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 14 |  |  | use Ivory\GoogleMap\Service\Base\Location\LocationInterface; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 15 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 16 |  |  | /** | 
            
                                                                                                            
                            
            
                                    
            
            
                | 17 |  |  |  * @author GeLo <[email protected]> | 
            
                                                                                                            
                                                                
            
                                    
            
            
                | 18 |  |  |  */ | 
            
                                                                        
                            
            
                                    
            
            
                | 19 |  |  | class PositionalElevationRequest implements ElevationRequestInterface | 
            
                                                                        
                            
            
                                    
            
            
                | 20 |  |  | { | 
            
                                                                        
                            
            
                                    
            
            
                | 21 |  |  |     /** | 
            
                                                                        
                            
            
                                    
            
            
                | 22 |  |  |      * @var LocationInterface[] | 
            
                                                                        
                            
            
                                    
            
            
                | 23 |  |  |      */ | 
            
                                                                        
                            
            
                                    
            
            
                | 24 |  |  |     private $locations = []; | 
            
                                                                        
                            
            
                                    
            
            
                | 25 |  |  |  | 
            
                                                                        
                            
            
                                    
            
            
                | 26 |  |  |     /** | 
            
                                                                        
                            
            
                                    
            
            
                | 27 |  |  |      * @param LocationInterface[] $locations | 
            
                                                                        
                            
            
                                    
            
            
                | 28 |  |  |      */ | 
            
                                                                                                            
                            
            
                                    
            
            
                | 29 |  |  |     public function __construct(array $locations) | 
            
                                                                                                            
                            
            
                                    
            
            
                | 30 |  |  |     { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 31 |  |  |         $this->setLocations($locations); | 
            
                                                                                                            
                                                                
            
                                    
            
            
                | 32 |  |  |     } | 
            
                                                                        
                            
            
                                    
            
            
                | 33 |  |  |  | 
            
                                                                        
                            
            
                                    
            
            
                | 34 |  |  |     /** | 
            
                                                                        
                            
            
                                    
            
            
                | 35 |  |  |      * @return bool | 
            
                                                                        
                            
            
                                    
            
            
                | 36 |  |  |      */ | 
            
                                                                                                            
                            
            
                                    
            
            
                | 37 |  |  |     public function hasLocations() | 
            
                                                                                                            
                            
            
                                    
            
            
                | 38 |  |  |     { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 39 |  |  |         return !empty($this->locations); | 
            
                                                                                                            
                                                                
            
                                    
            
            
                | 40 |  |  |     } | 
            
                                                                        
                            
            
                                    
            
            
                | 41 |  |  |  | 
            
                                                                        
                            
            
                                    
            
            
                | 42 |  |  |     /** | 
            
                                                                        
                            
            
                                    
            
            
                | 43 |  |  |      * @return LocationInterface[] | 
            
                                                                        
                            
            
                                    
            
            
                | 44 |  |  |      */ | 
            
                                                                                                            
                            
            
                                    
            
            
                | 45 |  |  |     public function getLocations() | 
            
                                                                                                            
                            
            
                                    
            
            
                | 46 |  |  |     { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 47 |  |  |         return $this->locations; | 
            
                                                                                                            
                                                                
            
                                    
            
            
                | 48 |  |  |     } | 
            
                                                                        
                            
            
                                    
            
            
                | 49 |  |  |  | 
            
                                                                        
                            
            
                                    
            
            
                | 50 |  |  |     /** | 
            
                                                                        
                            
            
                                    
            
            
                | 51 |  |  |      * @param LocationInterface[] $locations | 
            
                                                                        
                            
            
                                    
            
            
                | 52 |  |  |      */ | 
            
                                                                                                            
                            
            
                                    
            
            
                | 53 |  |  |     public function setLocations(array $locations) | 
            
                                                                                                            
                            
            
                                    
            
            
                | 54 |  |  |     { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 55 |  |  |         $this->locations = []; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 56 |  |  |         $this->addLocations($locations); | 
            
                                                                                                            
                                                                
            
                                    
            
            
                | 57 |  |  |     } | 
            
                                                                        
                            
            
                                    
            
            
                | 58 |  |  |  | 
            
                                                                        
                            
            
                                    
            
            
                | 59 |  |  |     /** | 
            
                                                                        
                            
            
                                    
            
            
                | 60 |  |  |      * @param LocationInterface[] $locations | 
            
                                                                        
                            
            
                                    
            
            
                | 61 |  |  |      */ | 
            
                                                                                                            
                            
            
                                    
            
            
                | 62 |  |  |     public function addLocations(array $locations) | 
            
                                                                                                            
                            
            
                                    
            
            
                | 63 |  |  |     { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 64 |  |  |         foreach ($locations as $location) { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 65 |  |  |             $this->addLocation($location); | 
            
                                                                                                            
                            
            
                                    
            
            
                | 66 |  |  |         } | 
            
                                                                                                            
                                                                
            
                                    
            
            
                | 67 |  |  |     } | 
            
                                                                        
                            
            
                                    
            
            
                | 68 |  |  |  | 
            
                                                                        
                            
            
                                    
            
            
                | 69 |  |  |     /** | 
            
                                                                        
                            
            
                                    
            
            
                | 70 |  |  |      * @param LocationInterface $location | 
            
                                                                        
                            
            
                                    
            
            
                | 71 |  |  |      * | 
            
                                                                        
                            
            
                                    
            
            
                | 72 |  |  |      * @return bool | 
            
                                                                        
                            
            
                                    
            
            
                | 73 |  |  |      */ | 
            
                                                                                                            
                            
            
                                    
            
            
                | 74 |  |  |     public function hasLocation(LocationInterface $location) | 
            
                                                                                                            
                            
            
                                    
            
            
                | 75 |  |  |     { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 76 |  |  |         return in_array($location, $this->locations, true); | 
            
                                                                                                            
                                                                
            
                                    
            
            
                | 77 |  |  |     } | 
            
                                                                        
                            
            
                                    
            
            
                | 78 |  |  |  | 
            
                                                                        
                            
            
                                    
            
            
                | 79 |  |  |     /** | 
            
                                                                        
                            
            
                                    
            
            
                | 80 |  |  |      * @param LocationInterface $location | 
            
                                                                        
                            
            
                                    
            
            
                | 81 |  |  |      */ | 
            
                                                                                                            
                            
            
                                    
            
            
                | 82 |  |  |     public function addLocation(LocationInterface $location) | 
            
                                                                                                            
                            
            
                                    
            
            
                | 83 |  |  |     { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 84 |  |  |         if (!$this->hasLocation($location)) { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 85 |  |  |             $this->locations[] = $location; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 86 |  |  |         } | 
            
                                                                                                            
                                                                
            
                                    
            
            
                | 87 |  |  |     } | 
            
                                                                        
                            
            
                                    
            
            
                | 88 |  |  |  | 
            
                                                                        
                            
            
                                    
            
            
                | 89 |  |  |     /** | 
            
                                                                        
                            
            
                                    
            
            
                | 90 |  |  |      * @param LocationInterface $location | 
            
                                                                        
                            
            
                                    
            
            
                | 91 |  |  |      */ | 
            
                                                                                                            
                            
            
                                    
            
            
                | 92 |  |  |     public function removeLocation(LocationInterface $location) | 
            
                                                                                                            
                            
            
                                    
            
            
                | 93 |  |  |     { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 94 |  |  |         unset($this->locations[array_search($location, $this->locations, true)]); | 
            
                                                                                                            
                            
            
                                    
            
            
                | 95 |  |  |         $this->locations = array_values($this->locations); | 
            
                                                                                                            
                                                                
            
                                    
            
            
                | 96 |  |  |     } | 
            
                                                                        
                            
            
                                    
            
            
                | 97 |  |  |  | 
            
                                                                        
                            
            
                                    
            
            
                | 98 |  |  |     /** | 
            
                                                                        
                            
            
                                    
            
            
                | 99 |  |  |      * {@inheritdoc} | 
            
                                                                        
                            
            
                                    
            
            
                | 100 |  |  |      */ | 
            
                                                                                                            
                            
            
                                    
            
            
                | 101 |  |  |     public function buildQuery() | 
            
                                                                                                            
                            
            
                                    
            
            
                | 102 |  |  |     { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 103 |  |  |         return ['locations' => implode('|', array_map(function (LocationInterface $location) { | 
                            
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                | 104 |  |  |             return $location->buildQuery(); | 
            
                                                                                                            
                            
            
                                    
            
            
                | 105 |  |  |         }, $this->locations))]; | 
            
                                                                                                            
                                                                
            
                                    
            
            
                | 106 |  |  |     } | 
            
                                                        
            
                                    
            
            
                | 107 |  |  | } | 
            
                                                        
            
                                    
            
            
                | 108 |  |  |  | 
            
                        
If you return a value from a function or method, it should be a sub-type of the type that is given by the parent type f.e. an interface, or abstract method. This is more formally defined by the Lizkov substitution principle, and guarantees that classes that depend on the parent type can use any instance of a child type interchangably. This principle also belongs to the SOLID principles for object oriented design.
Let’s take a look at an example:
Our function
my_functionexpects aPostobject, and outputs the author of the post. The base classPostreturns a simple string and outputting a simple string will work just fine. However, the child classBlogPostwhich is a sub-type ofPostinstead decided to return anobject, and is therefore violating the SOLID principles. If aBlogPostwere passed tomy_function, PHP would not complain, but ultimately fail when executing thestrtouppercall in its body.