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author
Dominik Liebler
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added FluentInterface
2 parents 1f37ca3 + b025906 commit 80d73c4

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7 files changed

+510
-4
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7 files changed

+510
-4
lines changed

‎ChainOfResponsibilities/ChainOfResponsibilities.php

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<?php
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namespace DesignPatterns;
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/**
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* chain of responsibilities pattern
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*
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* Purpose:
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* to build a chain of objects to handle a call. if one object cannot handle a call, it delegates the call to the next
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* in the chain and so forth
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*
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* Examples:
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* - Caching: first object is an instance of e.g. a Memcached Interface, if that "misses" it delegates the call to the
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* Database Interface
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*
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*/
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interface KeyValueStorage
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{
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public function get($key);
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}
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class SlowStorage implements KeyValueStorage
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{
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protected $_data = array();
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public function __construct($data = array())
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{
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$this->_data = $data;
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}
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/**
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* this class has no next handler, so it MUST be able to handle all requests
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*
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* @param $key
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* @return mixed
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*/
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public function get($key)
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{
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return $this->_data[$key];
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}
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}
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class FastStorage implements KeyValueStorage
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{
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/**
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* @var array
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*/
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protected $_data;
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/**
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* the next handler in the chain
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*
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* @var \DesignPatterns\KeyValueStorage
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*/
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protected $_nextHandler;
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public function __construct(array $data, KeyValueStorage $nextHandler)
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{
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$this->_data = $data;
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$this->_nextHandler = $nextHandler;
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}
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/**
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* when this storage gets a "miss", search in next handler
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*
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* @param $key
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* @return mixed
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*/
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public function get($key)
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{
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if (true /* miss */) {
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// delegate the call to the next handler in the chain
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return $this->_nextHandler->get($key);
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}
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}
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}
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// BUILD THE STORAGES AND CHAIN
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$slowStorage = new SlowStorage(array('foo' => 'bar'));
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$fastStorage = new FastStorage(array('bar' => 'baz'), $slowStorage);
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$fastStorage->get('foo'); // will be handled by SlowStorage
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$fastStorage->get('bar'); // will be handled by FastStorage
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/**
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* In this example we could also add a abstract class and extend it to build Fast- and SlowStorage. That class would
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* then manage the chain and when the cache hits a "miss", it would check if there is a next handler
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*/

‎Composite/Composite.php

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* composite pattern
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*
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* Purpose:
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* to treat a group of objects the same way as a single instance of the object, it establishes 1-to-n relationships
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* between objects
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* to treat a group of objects the same way as a single instance of the object
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*
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* Example:
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* - a form class instance handles all its form elements like a single instance of the form, when render() is called, it
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* subsequently runs trough all its child elements and calls render() on them
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* - a class to process files would process it by running process on all row objects in the file
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* subsequently runs trough all its child elements and calls render() on them
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* - Zend_Config: a tree of configuration options, each one is a Zend_Config object
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*
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*/
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class Form

‎Decorator/Decorator.php

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<?php
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namespace DesignPatterns;
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/**
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* Decorator pattern
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*
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* Purpose:
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* to dynamically add new functionality to class instances
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*
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* Examples:
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* - Zend Framework: decorators for Zend_Form_Element instances
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* - Web Service Layer: Decorators JSON and XML for a REST service (in this case, only one of these should be allowed of
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* course)
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*
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*/
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class Webservice
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{
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protected $_data;
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/**
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* an array to holds all added decorators, often there would be defaults set in this
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* array, e.g. the service could be defaulted to use JSON and only for special APIs
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* use XML
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*
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* @var array
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*/
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protected $_decorators = array();
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public function __construct($data)
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{
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$this->_data = $data;
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}
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/**
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*
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*
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* @param WebserviceDecorator $decorator
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* @return void
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*/
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public function addDecorator(WebserviceDecorator $decorator)
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{
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$this->_decorators[] = $decorator;
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}
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/**
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* @return string
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*/
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public function renderData()
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{
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$response = '';
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foreach ($this->_decorators as $decorator) {
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$response = $decorator->renderData($this->_data);
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}
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return $response;
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}
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}
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interface WebserviceDecorator
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{
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public function renderData($data);
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}
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class JsonDecorator implements WebserviceDecorator
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{
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public function renderData($data)
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{
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return json_encode($data);
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}
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}
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class XmlDecorator implements WebserviceDecorator
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{
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public function renderData($data)
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{
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// do some fany conversion to xml from array ...
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return simplexml_load_string($data);
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}
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}
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$service = new Webservice(array('foo' => 'bar'));
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$service->addDecorator(new JsonDecorator());
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echo $service->renderData();

‎FluentInterface/FluentInterface.php

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<?php
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namespace DesignPatterns;
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/**
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* fluent interface pattern
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*
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* Purpose:
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* to write code that is easy readable just like "real" sentences
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*
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* Examples:
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* - Doctrine2's QueryBuilder works something like that example class below
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* - PHPUnit uses fluent interfaces to build mock objects
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*
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*/
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class SQL
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{
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protected $_fields = array();
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protected $_from = array();
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protected $_where = array();
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/**
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*
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* @param array $fields
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* @return SQL
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*/
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public function select(array $fields = array())
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{
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$this->_fields = $fields;
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return $this;
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}
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/**
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*
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* @param string $table
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* @param string $alias
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* @return SQL
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*/
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public function from($table, $alias)
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{
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$this->_from[] = $table . ' AS ' . $alias;
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return $this;
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}
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/**
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* @param string $condition
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* @return SQL
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*/
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public function where($condition)
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{
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$this->_where[] = $condition;
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return $this;
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}
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}
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$instance = new SQL();
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$instance->select(array('foo', 'bar'))
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->from('foobar', 'f')
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->where('f.bar = ?');

‎Iterator/Iterator.php

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<?php
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namespace DesignPatterns;
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/**
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* iterator pattern
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*
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* Purpose:
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* to make an object iterable
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*
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* Examples:
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* - to process a file line by line by just running over all lines (which have an object representation) for a file
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* (which of course is an object, too)
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*
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* Note:
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* Standard PHP Library (SPL) defines an interface Iterator which is best suited for this!
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* Often you would want to implement the Countable interface too, to allow count($object) on your iterable object
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*
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* THIS EXAMPLE ALSO APPLIES THE COMPOSITE PATTERN
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*
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*/
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class File
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{
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protected $_rowset;
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protected $_pathName;
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public function __construct($pathName)
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{
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$this->_rowset = new Rowset($this);
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}
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public function process()
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{
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$this->_rowset->process();
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}
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}
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class Rowset implements Iterator
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{
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protected $_currentRow;
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protected $_file;
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public function __construct($file)
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{
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$this->_file = $file;
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}
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/**
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* composite pattern: run through all rows and process them
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*
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* @return void
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*/
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public function process()
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{
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// this actually calls rewind(), { next(), valid(), key() and current() :}
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foreach ($this as $line => $row) {
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$row->process();
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}
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}
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public function rewind()
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{
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// seek to first line from $this->_file
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}
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public function next()
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{
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// read the next line from $this->_file
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if (!$eof) {
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$data = ''; // get the line
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$this->_currentRow = new Row($data);
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} else {
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$this->_currentRow = null;
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}
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}
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public function current()
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{
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return $this->_currentRow;
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}
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public function valid()
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{
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return null !== $this->_currentRow;
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}
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public function key()
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{
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// you would want to increment this in next() or whatsoever
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return $this->_lineNumber;
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}
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}
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class Row
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{
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protected $_data;
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public function __construct($data)
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{
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$this->_data = $data;
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}
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public function process()
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{
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// do some fancy things here ...
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}
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}

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