<?php

/**
 * Custom validation class, accepts DTD child definitions
 *
 * @warning Currently this class is an all or nothing proposition, that is,
 *          it will only give a bool return value.
 */
class HTMLPurifier_ChildDef_Custom extends HTMLPurifier_ChildDef {
	/**
	 * @type string
	 */
	public $type = 'custom';
	
	/**
	 * @type bool
	 */
	public $allow_empty = false;
	
	/**
	 * Allowed child pattern as defined by the DTD.
	 * @type string
	 */
	public $dtd_regex;
	
	/**
	 * PCRE regex derived from $dtd_regex.
	 * @type string
	 */
	private $_pcre_regex;
	
	/**
	 *
	 * @param $dtd_regex Allowed
	 *        	child pattern from the DTD
	 */
	public function __construct($dtd_regex) {
		$this->dtd_regex = $dtd_regex;
		$this->_compileRegex ();
	}
	
	/**
	 * Compiles the PCRE regex from a DTD regex ($dtd_regex to $_pcre_regex)
	 */
	protected function _compileRegex() {
		$raw = str_replace ( ' ', '', $this->dtd_regex );
		if ($raw {0} != '(') {
			$raw = "($raw)";
		}
		$el = '[#a-zA-Z0-9_.-]+';
		$reg = $raw;
		
		// COMPLICATED! AND MIGHT BE BUGGY! I HAVE NO CLUE WHAT I'M
		// DOING! Seriously: if there's problems, please report them.
		
		// collect all elements into the $elements array
		preg_match_all ( "/$el/", $reg, $matches );
		foreach ( $matches [0] as $match ) {
			$this->elements [$match] = true;
		}
		
		// setup all elements as parentheticals with leading commas
		$reg = preg_replace ( "/$el/", '(,\\0)', $reg );
		
		// remove commas when they were not solicited
		$reg = preg_replace ( "/([^,(|]\(+),/", '\\1', $reg );
		
		// remove all non-paranthetical commas: they are handled by first regex
		$reg = preg_replace ( "/,\(/", '(', $reg );
		
		$this->_pcre_regex = $reg;
	}
	
	/**
	 *
	 * @param HTMLPurifier_Node[] $children        	
	 * @param HTMLPurifier_Config $config        	
	 * @param HTMLPurifier_Context $context        	
	 * @return bool
	 */
	public function validateChildren($children, $config, $context) {
		$list_of_children = '';
		$nesting = 0; // depth into the nest
		foreach ( $children as $node ) {
			if (! empty ( $node->is_whitespace )) {
				continue;
			}
			$list_of_children .= $node->name . ',';
		}
		// add leading comma to deal with stray comma declarations
		$list_of_children = ',' . rtrim ( $list_of_children, ',' );
		$okay = preg_match ( '/^,?' . $this->_pcre_regex . '$/', $list_of_children );
		return ( bool ) $okay;
	}
}

// vim: et sw=4 sts=4