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                <?php  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                declare(strict_types=1);  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                namespace Ray\Aop;  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                final class Bind implements BindInterface  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                { | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                    /**  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                     * @var array<string, array<MethodInterceptor>>  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                     */  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                    private $bindings = [];  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                    /**  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                     * @var MethodMatch  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                     */  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                    private $methodMatch;  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                    /**  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                     * @throws \Doctrine\Common\Annotations\AnnotationException  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                     */  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                    public function __construct()  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                    { | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                        $this->methodMatch = new MethodMatch($this);  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                    }  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                    public function __sleep()  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                    { | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                        return ['bindings'];  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                    }  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                    /**  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                     * {@inheritdoc} | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                     */  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                    public function bind(string $class, array $pointcuts) : BindInterface  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                    { | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                        $pointcuts = $this->getAnnotationPointcuts($pointcuts);  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                        $class = new \ReflectionClass($class);  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                        $methods = $class->getMethods(ReflectionMethod::IS_PUBLIC);  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                        foreach ($methods as $method) { | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                            ($this->methodMatch)($class, $method, $pointcuts);  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                        }  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                        return $this;  | 
            
                            
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                    }  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                    /**  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                     * {@inheritdoc} | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                     */  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                    public function bindInterceptors(string $method, array $interceptors) : BindInterface  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                    { | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                        $this->bindings[$method] = ! array_key_exists($method, $this->bindings) ? $interceptors : array_merge(  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                            $this->bindings[$method],  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                            $interceptors  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                        );  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                        return $this;  | 
            
                            
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                    }  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                    /**  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                     * {@inheritdoc} | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                     */  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                    public function getBindings() : array  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                    { | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                        return $this->bindings;  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                    }  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                    /**  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                     * {@inheritdoc} | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                     */  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                    public function toString($salt) : string  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                    { | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                        unset($salt);  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                        return strtr(rtrim(base64_encode(pack('H*', sprintf('%u', crc32(serialize($this->bindings))))), '='), '+/', '-_'); | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                    }  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                    /**  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                     * @param Pointcut[] $pointcuts  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                     *  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                     * @return Pointcut[]  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                     */  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                    public function getAnnotationPointcuts(array &$pointcuts) : array  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                    { | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                        $keyPointcuts = [];  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                        foreach ($pointcuts as $key => $pointcut) { | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                            if ($pointcut->methodMatcher instanceof AnnotatedMatcher) { | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                                $key = $pointcut->methodMatcher->annotation;  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                            }  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                            $keyPointcuts[$key] = $pointcut;  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                        }  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                        return $keyPointcuts;  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                    }  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                }  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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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.