htmlpurifier/MarkupFragment.php

<?php

// MF = Markup Fragment
// all objects here are immutable

class MF {}

class MF_Tag extends MF
{
    var $name;
    function MF_Tag($name) {
        $this->name = strtolower($name);
    }
}

class MF_StartTag extends MF_Tag
{
    var $attributes = array();
    function MF_StartTag($type, $attributes = array()) {
        $this->MF_Tag($type);
        $this->attributes = $attributes;
    }
}

class MF_EmptyTag extends MF_StartTag {}
class MF_EndTag extends MF_Tag {}

class MF_Text extends MF
{
    var $name = '#PCDATA';
    var $data;
    function MF_Text($data) {
        $this->data = trim($data); // fairly certain trimming it's okay
    }
    function append($mf_text) {
        return new MF_Text($this->data . $mf_text->data);
    }
}

class MF_Comment extends MF
{
    var $data;
    function MF_Comment($data) {
        $this->data = $data;
    }
}

?>