<?php
/**
 * @link http://www.yiiframework.com/
 * @copyright Copyright (c) 2008 Yii Software LLC
 * @license http://www.yiiframework.com/license/
 */

namespace yii\base;

/**
 * Arrayable is the interface that should be implemented by classes who want to support customizable representation of their instances.
 *
 * For example, if a class implements Arrayable, by calling [[toArray()]], an instance of this class
 * can be turned into an array (including all its embedded objects) which can then be further transformed easily
 * into other formats, such as JSON, XML.
 *
 * The methods [[fields()]] and [[extraFields()]] allow the implementing classes to customize how and which of their data
 * should be formatted and put into the result of [[toArray()]].
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @since 2.0
 */
interface Arrayable
{
 /**
 * Returns the list of fields that should be returned by default by [[toArray()]] when no specific fields are specified.
 *
 * A field is a named element in the returned array by [[toArray()]].
 *
 * This method should return an array of field names or field definitions.
 * If the former, the field name will be treated as an object property name whose value will be used
 * as the field value. If the latter, the array key should be the field name while the array value should be
 * the corresponding field definition which can be either an object property name or a PHP callable
 * returning the corresponding field value. The signature of the callable should be:
 *
 * ```php
 * function ($field, $model) {
 * // return field value
 * }
 * ```
 *
 * For example, the following code declares four fields:
 *
 * - `email`: the field name is the same as the property name `email`;
 * - `firstName` and `lastName`: the field names are `firstName` and `lastName`, and their
 * values are obtained from the `first_name` and `last_name` properties;
 * - `fullName`: the field name is `fullName`. Its value is obtained by concatenating `first_name`
 * and `last_name`.
 *
 * ```php
 * return [
 * 'email',
 * 'firstName' => 'first_name',
 * 'lastName' => 'last_name',
 * 'fullName' => function ($model) {
 * return $model->first_name . ' ' . $model->last_name;
 * },
 * ];
 * ```
 *
 * @return array the list of field names or field definitions.
 * @see toArray()
 */
 public function fields();
 /**
 * Returns the list of additional fields that can be returned by [[toArray()]] in addition to those listed in [[fields()]].
 *
 * This method is similar to [[fields()]] except that the list of fields declared
 * by this method are not returned by default by [[toArray()]]. Only when a field in the list
 * is explicitly requested, will it be included in the result of [[toArray()]].
 *
 * @return array the list of expandable field names or field definitions. Please refer
 * to [[fields()]] on the format of the return value.
 * @see toArray()
 * @see fields()
 */
 public function extraFields();
 /**
 * Converts the object into an array.
 *
 * @param array $fields the fields that the output array should contain. Fields not specified
 * in [[fields()]] will be ignored. If this parameter is empty, all fields as specified in [[fields()]] will be returned.
 * @param array $expand the additional fields that the output array should contain.
 * Fields not specified in [[extraFields()]] will be ignored. If this parameter is empty, no extra fields
 * will be returned.
 * @param boolean $recursive whether to recursively return array representation of embedded objects.
 * @return array the array representation of the object
 */
 public function toArray(array $fields = [], array $expand = [], $recursive = true);
}