htmlpurifier/library/HTMLPurifier/ChildDef.php

<?php

// HTMLPurifier_ChildDef and inheritance have three types of output:
// true = leave nodes as is
// false = delete parent node and all children
// array(...) = replace children nodes with these

// this is the hardest one to implement. We'll use fancy regexp tricks
// right now, we only expect it to return TRUE or FALSE (it won't attempt
// to fix the tree)

// we may end up writing custom code for each HTML case
// in order to make it self correcting

class HTMLPurifier_ChildDef
{
    var $type;
    var $allow_empty;
    function validateChildren($tokens_of_children) {
        trigger_error('Call to abstract function', E_USER_ERROR);
    }
}

class HTMLPurifier_ChildDef_Custom extends HTMLPurifier_ChildDef
{
    var $type = 'custom';
    var $allow_empty = false;
    var $dtd_regex;
    var $_pcre_regex;
    function HTMLPurifier_ChildDef_Custom($dtd_regex) {
        $this->dtd_regex = $dtd_regex;
        $this->_compileRegex();
    }
    function _compileRegex() {
        $raw = str_replace(' ', '', $this->dtd_regex);
        if ($raw{0} != '(') {
            $raw = "($raw)";
        }
        $reg = str_replace(',', ',?', $raw);
        $reg = preg_replace('/([#a-zA-Z0-9_.-]+)/', '(,?\\0)', $reg);
        $this->_pcre_regex = $reg;
    }
    function validateChildren($tokens_of_children) {
        $list_of_children = '';
        $nesting = 0; // depth into the nest
        foreach ($tokens_of_children as $token) {
            if (!empty($token->is_whitespace)) continue;
            
            $is_child = ($nesting == 0); // direct
            
            if ($token->type == 'start') {
                $nesting++;
            } elseif ($token->type == 'end') {
                $nesting--;
            }
            
            if ($is_child) {
                $list_of_children .= $token->name . ',';
            }
        }
        $list_of_children = rtrim($list_of_children, ',');
        
        $okay =
            preg_match(
                '/^'.$this->_pcre_regex.'$/',
                $list_of_children
            );
        
        return (bool) $okay;
    }
}

class HTMLPurifier_ChildDef_Required extends HTMLPurifier_ChildDef
{
    var $elements = array();
    function HTMLPurifier_ChildDef_Required($elements) {
        if (is_string($elements)) {
            $elements = str_replace(' ', '', $elements);
            $elements = explode('|', $elements);
        }
        $elements = array_flip($elements);
        foreach ($elements as $i => $x) $elements[$i] = true;
        $this->elements = $elements;
        $this->gen = new HTMLPurifier_Generator();
    }
    var $allow_empty = false;
    var $type = 'required';
    function validateChildren($tokens_of_children) {
        // if there are no tokens, delete parent node
        if (empty($tokens_of_children)) return false;
        
        // the new set of children
        $result = array();
        
        // current depth into the nest
        $nesting = 0;
        
        // whether or not we're deleting a node
        $is_deleting = false;
        
        // 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;
        
        foreach ($tokens_of_children as $token) {
            if (!empty($token->is_whitespace)) {
                $result[] = $token;
                continue;
            }
            $all_whitespace = false; // phew, we're not talking about whitespace
            
            $is_child = ($nesting == 0);
            
            if ($token->type == 'start') {
                $nesting++;
            } elseif ($token->type == 'end') {
                $nesting--;
            }
            
            if ($is_child) {
                $is_deleting = false;
                if (!isset($this->elements[$token->name])) {
                    $is_deleting = true;
                    if ($pcdata_allowed) {
                        $result[] = new HTMLPurifier_Token_Text(
                            $this->gen->generateFromToken($token)
                        );
                    }
                    continue;
                }
            }
            if (!$is_deleting) {
                $result[] = $token;
            } elseif ($pcdata_allowed) {
                $result[] =
                    new HTMLPurifier_Token_Text(
                        $this->gen->generateFromToken( $token )
                    );
            } else {
                // drop silently
            }
        }
        if (empty($result)) return false;
        if ($all_whitespace) return false;
        if ($tokens_of_children == $result) return true;
        return $result;
    }
}

// only altered behavior is that it returns an empty array
// instead of a false (to delete the node)
class HTMLPurifier_ChildDef_Optional extends HTMLPurifier_ChildDef_Required
{
    var $allow_empty = true;
    var $type = 'optional';
    function validateChildren($tokens_of_children) {
        $result = parent::validateChildren($tokens_of_children);
        if ($result === false) return array();
        return $result;
    }
}

// placeholder
class HTMLPurifier_ChildDef_Empty extends HTMLPurifier_ChildDef
{
    var $allow_empty = true;
    var $type = 'empty';
    function HTMLPurifier_ChildDef_Empty() {}
    function validateChildren() {
        return false;
    }
}

class HTMLPurifier_ChildDef_Chameleon extends HTMLPurifier_ChildDef
{
    
    var $inline;
    var $block;
    
    function HTMLPurifier_ChildDef_Chameleon($inline, $block) {
        $this->inline = new HTMLPurifier_ChildDef_Optional($inline);
        $this->block  = new HTMLPurifier_ChildDef_Optional($block);
    }
    
    function validateChildren($tokens_of_children, $context) {
        switch ($context) {
            case 'unknown':
            case 'inline':
                $result = $this->inline->validateChildren($tokens_of_children);
                break;
            case 'block':
                $result = $this->block->validateChildren($tokens_of_children);
                break;
            default:
                trigger_error('Invalid context', E_USER_ERROR);
                return false;
        }
        return $result;
    }
}

?>