<?php

/**
 * Definition that allows a set of elements, but disallows empty children.
 */
class HTMLPurifier_ChildDef_Required extends HTMLPurifier_ChildDef {
	/**
	 * Lookup table of allowed elements.
	 * @type array
	 */
	public $elements = array ();
	
	/**
	 * Whether or not the last passed node was all whitespace.
	 * @type bool
	 */
	protected $whitespace = false;
	
	/**
	 *
	 * @param array|string $elements
	 *        	List of allowed element names (lowercase).
	 */
	public function __construct($elements) {
		if (is_string ( $elements )) {
			$elements = str_replace ( ' ', '', $elements );
			$elements = explode ( '|', $elements );
		}
		$keys = array_keys ( $elements );
		if ($keys == array_keys ( $keys )) {
			$elements = array_flip ( $elements );
			foreach ( $elements as $i => $x ) {
				$elements [$i] = true;
				if (empty ( $i )) {
					unset ( $elements [$i] );
				} // remove blank
			}
		}
		$this->elements = $elements;
	}
	
	/**
	 * @type bool
	 */
	public $allow_empty = false;
	
	/**
	 * @type string
	 */
	public $type = 'required';
	
	/**
	 *
	 * @param array $children        	
	 * @param HTMLPurifier_Config $config        	
	 * @param HTMLPurifier_Context $context        	
	 * @return array
	 */
	public function validateChildren($children, $config, $context) {
		// Flag for subclasses
		$this->whitespace = false;
		
		// if there are no tokens, delete parent node
		if (empty ( $children )) {
			return false;
		}
		
		// the new set of children
		$result = array ();
		
		// whether or not parsed character data is allowed
		// this controls whether or not we silently drop a tag
		// or generate escaped HTML from it
		$pcdata_allowed = isset ( $this->elements ['#PCDATA'] );
		
		// a little sanity check to make sure it's not ALL whitespace
		$all_whitespace = true;
		
		$stack = array_reverse ( $children );
		while ( ! empty ( $stack ) ) {
			$node = array_pop ( $stack );
			if (! empty ( $node->is_whitespace )) {
				$result [] = $node;
				continue;
			}
			$all_whitespace = false; // phew, we're not talking about whitespace
			
			if (! isset ( $this->elements [$node->name] )) {
				// special case text
				// XXX One of these ought to be redundant or something
				if ($pcdata_allowed && $node instanceof HTMLPurifier_Node_Text) {
					$result [] = $node;
					continue;
				}
				// spill the child contents in
				// ToDo: Make configurable
				if ($node instanceof HTMLPurifier_Node_Element) {
					for($i = count ( $node->children ) - 1; $i >= 0; $i --) {
						$stack [] = $node->children [$i];
					}
					continue;
				}
				continue;
			}
			$result [] = $node;
		}
		if (empty ( $result )) {
			return false;
		}
		if ($all_whitespace) {
			$this->whitespace = true;
			return false;
		}
		return $result;
	}
}

// vim: et sw=4 sts=4