silverstripe-framework/view/TemplateIteratorProvider.php

<?php
/**
 * Interface that is implemented by any classes that want to expose a method that can be called in any
 * scope in a template that returns values dependant on the state of the iterator of the current scope.
 *
 * SSViewer_BasicIteratorSupport is an example of this. See also @TemplateGlobalProvider
 *
 * @package framework
 * @subpackage core
 */
interface TemplateIteratorProvider {

	/**
	 * Called by SSViewer to get a list of iterator variables to expose to the template, the instance method to call
	 * on an instance of this class to get the value for those variables, and the class to use for casting the returned
	 * value for use in a template
	 *
	 * If the method to call is not included for a particular template variable, a method named the same as the
	 * template variable will be called
	 *
	 * If the casting class is not specified for a particular template variable, ViewableData::$default_cast is used
	 *
	 * The first letter of the template variable is case-insensitive. However the method name is always case sensitive.
	 *
	 * @abstract
	 * @return array Returns an array of items. Each key => value pair is one of three forms:
	 *  - template name (no key)
	 *  - template name => method name
	 *  - template name => array(), where the array can contain these key => value pairs
	 *     - "method" => method name
	 *     - "casting" => casting class to use (i.e., Varchar, HTMLFragment, etc)
	 */
	public static function get_template_iterator_variables();

	/**
	 * Set the current iterator properties - where we are on the iterator.
	 *
	 * This is called by SSViewer prior to calling any of the variables exposed to the template (that is, as returned
	 * from a call to get_template_iterator_variables)
	 *
	 * @abstract
	 * @param int $pos position in iterator
	 * @param int $totalItems total number of items
	 */
	public function iteratorProperties($pos, $totalItems);
}