<?php

/**
 * Defines allowed child nodes and validates nodes against it.
 */
abstract class HTMLPurifier_ChildDef {
	/**
	 * Type of child definition, usually right-most part of class name lowercase.
	 * Used occasionally in terms of context.
	 * @type string
	 */
	public $type;
	
	/**
	 * Indicates whether or not an empty array of children is okay.
	 *
	 * This is necessary for redundant checking when changes affecting
	 * a child node may cause a parent node to now be disallowed.
	 * @type bool
	 */
	public $allow_empty;
	
	/**
	 * Lookup array of all elements that this definition could possibly allow.
	 * @type array
	 */
	public $elements = array ();
	
	/**
	 * Get lookup of tag names that should not close this element automatically.
	 * All other elements will do so.
	 * 
	 * @param HTMLPurifier_Config $config
	 *        	HTMLPurifier_Config object
	 * @return array
	 */
	public function getAllowedElements($config) {
		return $this->elements;
	}
	
	/**
	 * Validates nodes according to definition and returns modification.
	 *
	 * @param HTMLPurifier_Node[] $children
	 *        	Array of HTMLPurifier_Node
	 * @param HTMLPurifier_Config $config
	 *        	HTMLPurifier_Config object
	 * @param HTMLPurifier_Context $context
	 *        	HTMLPurifier_Context object
	 * @return bool|array true to leave nodes as is, false to remove parent node, array of replacement children
	 */
	abstract public function validateChildren($children, $config, $context);
}

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