icingaweb2/library/vendor/dompdf/include/frame.cls.php

1192 lines
28 KiB
PHP

<?php
/**
* @package dompdf
* @link http://dompdf.github.com/
* @author Benj Carson <benjcarson@digitaljunkies.ca>
* @license http://www.gnu.org/copyleft/lesser.html GNU Lesser General Public License
*/
/**
* The main Frame class
*
* This class represents a single HTML element. This class stores
* positioning information as well as containing block location and
* dimensions. Style information for the element is stored in a {@link
* Style} object. Tree structure is maintained via the parent & children
* links.
*
* @access protected
* @package dompdf
*/
class Frame {
/**
* The DOMElement or DOMText object this frame represents
*
* @var DOMElement|DOMText
*/
protected $_node;
/**
* Unique identifier for this frame. Used to reference this frame
* via the node.
*
* @var string
*/
protected $_id;
/**
* Unique id counter
*/
static /*protected*/ $ID_COUNTER = 0;
/**
* This frame's calculated style
*
* @var Style
*/
protected $_style;
/**
* This frame's original style. Needed for cases where frames are
* split across pages.
*
* @var Style
*/
protected $_original_style;
/**
* This frame's parent in the document tree.
*
* @var Frame
*/
protected $_parent;
/**
* This frame's children
*
* @var Frame[]
*/
protected $_frame_list;
/**
* This frame's first child. All children are handled as a
* doubly-linked list.
*
* @var Frame
*/
protected $_first_child;
/**
* This frame's last child.
*
* @var Frame
*/
protected $_last_child;
/**
* This frame's previous sibling in the document tree.
*
* @var Frame
*/
protected $_prev_sibling;
/**
* This frame's next sibling in the document tree.
*
* @var Frame
*/
protected $_next_sibling;
/**
* This frame's containing block (used in layout): array(x, y, w, h)
*
* @var float[]
*/
protected $_containing_block;
/**
* Position on the page of the top-left corner of the margin box of
* this frame: array(x,y)
*
* @var float[]
*/
protected $_position;
/**
* Absolute opacity of this frame
*
* @var float
*/
protected $_opacity;
/**
* This frame's decorator
*
* @var Frame_Decorator
*/
protected $_decorator;
/**
* This frame's containing line box
*
* @var Line_Box
*/
protected $_containing_line;
protected $_is_cache = array();
/**
* Tells wether the frame was already pushed to the next page
*
* @var bool
*/
public $_already_pushed = false;
public $_float_next_line = false;
/**
* Tells wether the frame was split
*
* @var bool
*/
public $_splitted;
static $_ws_state = self::WS_SPACE;
const WS_TEXT = 1;
const WS_SPACE = 2;
/**
* Class destructor
*/
function __destruct() {
clear_object($this);
}
/**
* Class constructor
*
* @param DOMNode $node the DOMNode this frame represents
*/
function __construct(DOMNode $node) {
$this->_node = $node;
$this->_parent = null;
$this->_first_child = null;
$this->_last_child = null;
$this->_prev_sibling = $this->_next_sibling = null;
$this->_style = null;
$this->_original_style = null;
$this->_containing_block = array(
"x" => null,
"y" => null,
"w" => null,
"h" => null,
);
$this->_containing_block[0] =& $this->_containing_block["x"];
$this->_containing_block[1] =& $this->_containing_block["y"];
$this->_containing_block[2] =& $this->_containing_block["w"];
$this->_containing_block[3] =& $this->_containing_block["h"];
$this->_position = array(
"x" => null,
"y" => null,
);
$this->_position[0] =& $this->_position["x"];
$this->_position[1] =& $this->_position["y"];
$this->_opacity = 1.0;
$this->_decorator = null;
$this->set_id( self::$ID_COUNTER++ );
}
// WIP : preprocessing to remove all the unused whitespace
protected function ws_trim(){
if ( $this->ws_keep() ) {
return;
}
switch(self::$_ws_state) {
case self::WS_SPACE:
$node = $this->_node;
if ( $node->nodeName === "#text" ) {
$node->nodeValue = preg_replace("/[ \t\r\n\f]+/u", " ", $node->nodeValue);
// starts with a whitespace
if ( isset($node->nodeValue[0]) && $node->nodeValue[0] === " " ) {
$node->nodeValue = ltrim($node->nodeValue);
}
// if not empty
if ( $node->nodeValue !== "" ) {
// change the current state (text)
self::$_ws_state = self::WS_TEXT;
// ends with a whitespace
if ( preg_match("/[ \t\r\n\f]+$/u", $node->nodeValue) ) {
$node->nodeValue = ltrim($node->nodeValue);
}
}
}
break;
case self::WS_TEXT:
}
}
protected function ws_keep(){
$whitespace = $this->get_style()->white_space;
return in_array($whitespace, array("pre", "pre-wrap", "pre-line"));
}
protected function ws_is_text(){
$node = $this->get_node();
if ($node->nodeName === "img") {
return true;
}
if ( !$this->is_in_flow() ) {
return false;
}
if ($this->is_text_node()) {
return trim($node->nodeValue) !== "";
}
return true;
}
/**
* "Destructor": forcibly free all references held by this frame
*
* @param bool $recursive if true, call dispose on all children
*/
function dispose($recursive = false) {
if ( $recursive ) {
while ( $child = $this->_first_child ) {
$child->dispose(true);
}
}
// Remove this frame from the tree
if ( $this->_prev_sibling ) {
$this->_prev_sibling->_next_sibling = $this->_next_sibling;
}
if ( $this->_next_sibling ) {
$this->_next_sibling->_prev_sibling = $this->_prev_sibling;
}
if ( $this->_parent && $this->_parent->_first_child === $this ) {
$this->_parent->_first_child = $this->_next_sibling;
}
if ( $this->_parent && $this->_parent->_last_child === $this ) {
$this->_parent->_last_child = $this->_prev_sibling;
}
if ( $this->_parent ) {
$this->_parent->get_node()->removeChild($this->_node);
}
$this->_style->dispose();
$this->_style = null;
unset($this->_style);
$this->_original_style->dispose();
$this->_original_style = null;
unset($this->_original_style);
}
// Re-initialize the frame
function reset() {
$this->_position["x"] = null;
$this->_position["y"] = null;
$this->_containing_block["x"] = null;
$this->_containing_block["y"] = null;
$this->_containing_block["w"] = null;
$this->_containing_block["h"] = null;
$this->_style = null;
unset($this->_style);
$this->_style = clone $this->_original_style;
}
//........................................................................
/**
* @return DOMElement|DOMText
*/
function get_node() {
return $this->_node;
}
/**
* @return string
*/
function get_id() {
return $this->_id;
}
/**
* @return Style
*/
function get_style() {
return $this->_style;
}
/**
* @return Style
*/
function get_original_style() {
return $this->_original_style;
}
/**
* @return Frame
*/
function get_parent() {
return $this->_parent;
}
/**
* @return Frame_Decorator
*/
function get_decorator() {
return $this->_decorator;
}
/**
* @return Frame
*/
function get_first_child() {
return $this->_first_child;
}
/**
* @return Frame
*/
function get_last_child() {
return $this->_last_child;
}
/**
* @return Frame
*/
function get_prev_sibling() {
return $this->_prev_sibling;
}
/**
* @return Frame
*/
function get_next_sibling() {
return $this->_next_sibling;
}
/**
* @return FrameList|Frame[]
*/
function get_children() {
if ( isset($this->_frame_list) ) {
return $this->_frame_list;
}
$this->_frame_list = new FrameList($this);
return $this->_frame_list;
}
// Layout property accessors
/**
* Containing block dimensions
*
* @param $i string The key of the wanted containing block's dimension (x, y, x, h)
*
* @return float[]|float
*/
function get_containing_block($i = null) {
if ( isset($i) ) {
return $this->_containing_block[$i];
}
return $this->_containing_block;
}
/**
* Block position
*
* @param $i string The key of the wanted position value (x, y)
*
* @return array|float
*/
function get_position($i = null) {
if ( isset($i) ) {
return $this->_position[$i];
}
return $this->_position;
}
//........................................................................
/**
* Return the height of the margin box of the frame, in pt. Meaningless
* unless the height has been calculated properly.
*
* @return float
*/
function get_margin_height() {
$style = $this->_style;
return $style->length_in_pt(array(
$style->height,
$style->margin_top,
$style->margin_bottom,
$style->border_top_width,
$style->border_bottom_width,
$style->padding_top,
$style->padding_bottom
), $this->_containing_block["h"]);
}
/**
* Return the width of the margin box of the frame, in pt. Meaningless
* unless the width has been calculated properly.
*
* @return float
*/
function get_margin_width() {
$style = $this->_style;
return $style->length_in_pt(array(
$style->width,
$style->margin_left,
$style->margin_right,
$style->border_left_width,
$style->border_right_width,
$style->padding_left,
$style->padding_right
), $this->_containing_block["w"]);
}
function get_break_margins(){
$style = $this->_style;
return $style->length_in_pt(array(
//$style->height,
$style->margin_top,
$style->margin_bottom,
$style->border_top_width,
$style->border_bottom_width,
$style->padding_top,
$style->padding_bottom
), $this->_containing_block["h"]);
}
/**
* Return the padding box (x,y,w,h) of the frame
*
* @return array
*/
function get_padding_box() {
$style = $this->_style;
$cb = $this->_containing_block;
$x = $this->_position["x"] +
$style->length_in_pt(array($style->margin_left,
$style->border_left_width),
$cb["w"]);
$y = $this->_position["y"] +
$style->length_in_pt(array($style->margin_top,
$style->border_top_width),
$cb["h"]);
$w = $style->length_in_pt(array($style->padding_left,
$style->width,
$style->padding_right),
$cb["w"]);
$h = $style->length_in_pt(array($style->padding_top,
$style->height,
$style->padding_bottom),
$cb["h"]);
return array(0 => $x, "x" => $x,
1 => $y, "y" => $y,
2 => $w, "w" => $w,
3 => $h, "h" => $h);
}
/**
* Return the border box of the frame
*
* @return array
*/
function get_border_box() {
$style = $this->_style;
$cb = $this->_containing_block;
$x = $this->_position["x"] + $style->length_in_pt($style->margin_left, $cb["w"]);
$y = $this->_position["y"] + $style->length_in_pt($style->margin_top, $cb["h"]);
$w = $style->length_in_pt(array($style->border_left_width,
$style->padding_left,
$style->width,
$style->padding_right,
$style->border_right_width),
$cb["w"]);
$h = $style->length_in_pt(array($style->border_top_width,
$style->padding_top,
$style->height,
$style->padding_bottom,
$style->border_bottom_width),
$cb["h"]);
return array(0 => $x, "x" => $x,
1 => $y, "y" => $y,
2 => $w, "w" => $w,
3 => $h, "h" => $h);
}
function get_opacity($opacity = null) {
if ( $opacity !== null ) {
$this->set_opacity($opacity);
}
return $this->_opacity;
}
/**
* @return Line_Box
*/
function &get_containing_line() {
return $this->_containing_line;
}
//........................................................................
// Set methods
function set_id($id) {
$this->_id = $id;
// We can only set attributes of DOMElement objects (nodeType == 1).
// Since these are the only objects that we can assign CSS rules to,
// this shortcoming is okay.
if ( $this->_node->nodeType == XML_ELEMENT_NODE ) {
$this->_node->setAttribute("frame_id", $id);
}
}
function set_style(Style $style) {
if ( is_null($this->_style) ) {
$this->_original_style = clone $style;
}
//$style->set_frame($this);
$this->_style = $style;
}
function set_decorator(Frame_Decorator $decorator) {
$this->_decorator = $decorator;
}
function set_containing_block($x = null, $y = null, $w = null, $h = null) {
if ( is_array($x) ){
foreach($x as $key => $val){
$$key = $val;
}
}
if (is_numeric($x)) {
$this->_containing_block["x"] = $x;
}
if (is_numeric($y)) {
$this->_containing_block["y"] = $y;
}
if (is_numeric($w)) {
$this->_containing_block["w"] = $w;
}
if (is_numeric($h)) {
$this->_containing_block["h"] = $h;
}
}
function set_position($x = null, $y = null) {
if ( is_array($x) ) {
list($x, $y) = array($x["x"], $x["y"]);
}
if ( is_numeric($x) ) {
$this->_position["x"] = $x;
}
if ( is_numeric($y) ) {
$this->_position["y"] = $y;
}
}
function set_opacity($opacity) {
$parent = $this->get_parent();
$base_opacity = (($parent && $parent->_opacity !== null) ? $parent->_opacity : 1.0);
$this->_opacity = $base_opacity * $opacity;
}
function set_containing_line(Line_Box $line) {
$this->_containing_line = $line;
}
//........................................................................
/**
* Tells if the frame is a text node
* @return bool
*/
function is_text_node() {
if ( isset($this->_is_cache["text_node"]) ) {
return $this->_is_cache["text_node"];
}
return $this->_is_cache["text_node"] = ($this->get_node()->nodeName === "#text");
}
function is_positionned() {
if ( isset($this->_is_cache["positionned"]) ) {
return $this->_is_cache["positionned"];
}
$position = $this->get_style()->position;
return $this->_is_cache["positionned"] = in_array($position, Style::$POSITIONNED_TYPES);
}
function is_absolute() {
if ( isset($this->_is_cache["absolute"]) ) {
return $this->_is_cache["absolute"];
}
$position = $this->get_style()->position;
return $this->_is_cache["absolute"] = ($position === "absolute" || $position === "fixed");
}
function is_block() {
if ( isset($this->_is_cache["block"]) ) {
return $this->_is_cache["block"];
}
return $this->_is_cache["block"] = in_array($this->get_style()->display, Style::$BLOCK_TYPES);
}
function is_in_flow() {
if ( isset($this->_is_cache["in_flow"]) ) {
return $this->_is_cache["in_flow"];
}
$enable_css_float = $this->get_style()->get_stylesheet()->get_dompdf()->get_option("enable_css_float");
return $this->_is_cache["in_flow"] = !($enable_css_float && $this->get_style()->float !== "none" || $this->is_absolute());
}
function is_pre(){
if ( isset($this->_is_cache["pre"]) ) {
return $this->_is_cache["pre"];
}
$white_space = $this->get_style()->white_space;
return $this->_is_cache["pre"] = in_array($white_space, array("pre", "pre-wrap"));
}
function is_table(){
if ( isset($this->_is_cache["table"]) ) {
return $this->_is_cache["table"];
}
$display = $this->get_style()->display;
return $this->_is_cache["table"] = in_array($display, Style::$TABLE_TYPES);
}
/**
* Inserts a new child at the beginning of the Frame
*
* @param $child Frame The new Frame to insert
* @param $update_node boolean Whether or not to update the DOM
*/
function prepend_child(Frame $child, $update_node = true) {
if ( $update_node ) {
$this->_node->insertBefore($child->_node, $this->_first_child ? $this->_first_child->_node : null);
}
// Remove the child from its parent
if ( $child->_parent ) {
$child->_parent->remove_child($child, false);
}
$child->_parent = $this;
$child->_prev_sibling = null;
// Handle the first child
if ( !$this->_first_child ) {
$this->_first_child = $child;
$this->_last_child = $child;
$child->_next_sibling = null;
}
else {
$this->_first_child->_prev_sibling = $child;
$child->_next_sibling = $this->_first_child;
$this->_first_child = $child;
}
}
/**
* Inserts a new child at the end of the Frame
*
* @param $child Frame The new Frame to insert
* @param $update_node boolean Whether or not to update the DOM
*/
function append_child(Frame $child, $update_node = true) {
if ( $update_node ) {
$this->_node->appendChild($child->_node);
}
// Remove the child from its parent
if ( $child->_parent ) {
$child->_parent->remove_child($child, false);
}
$child->_parent = $this;
$child->_next_sibling = null;
// Handle the first child
if ( !$this->_last_child ) {
$this->_first_child = $child;
$this->_last_child = $child;
$child->_prev_sibling = null;
}
else {
$this->_last_child->_next_sibling = $child;
$child->_prev_sibling = $this->_last_child;
$this->_last_child = $child;
}
}
/**
* Inserts a new child immediately before the specified frame
*
* @param $new_child Frame The new Frame to insert
* @param $ref Frame The Frame after the new Frame
* @param $update_node boolean Whether or not to update the DOM
*
* @throws DOMPDF_Exception
*/
function insert_child_before(Frame $new_child, Frame $ref, $update_node = true) {
if ( $ref === $this->_first_child ) {
$this->prepend_child($new_child, $update_node);
return;
}
if ( is_null($ref) ) {
$this->append_child($new_child, $update_node);
return;
}
if ( $ref->_parent !== $this ) {
throw new DOMPDF_Exception("Reference child is not a child of this node.");
}
// Update the node
if ( $update_node ) {
$this->_node->insertBefore($new_child->_node, $ref->_node);
}
// Remove the child from its parent
if ( $new_child->_parent ) {
$new_child->_parent->remove_child($new_child, false);
}
$new_child->_parent = $this;
$new_child->_next_sibling = $ref;
$new_child->_prev_sibling = $ref->_prev_sibling;
if ( $ref->_prev_sibling ) {
$ref->_prev_sibling->_next_sibling = $new_child;
}
$ref->_prev_sibling = $new_child;
}
/**
* Inserts a new child immediately after the specified frame
*
* @param $new_child Frame The new Frame to insert
* @param $ref Frame The Frame before the new Frame
* @param $update_node boolean Whether or not to update the DOM
*
* @throws DOMPDF_Exception
*/
function insert_child_after(Frame $new_child, Frame $ref, $update_node = true) {
if ( $ref === $this->_last_child ) {
$this->append_child($new_child, $update_node);
return;
}
if ( is_null($ref) ) {
$this->prepend_child($new_child, $update_node);
return;
}
if ( $ref->_parent !== $this ) {
throw new DOMPDF_Exception("Reference child is not a child of this node.");
}
// Update the node
if ( $update_node ) {
if ( $ref->_next_sibling ) {
$next_node = $ref->_next_sibling->_node;
$this->_node->insertBefore($new_child->_node, $next_node);
}
else {
$new_child->_node = $this->_node->appendChild($new_child->_node);
}
}
// Remove the child from its parent
if ( $new_child->_parent ) {
$new_child->_parent->remove_child($new_child, false);
}
$new_child->_parent = $this;
$new_child->_prev_sibling = $ref;
$new_child->_next_sibling = $ref->_next_sibling;
if ( $ref->_next_sibling ) {
$ref->_next_sibling->_prev_sibling = $new_child;
}
$ref->_next_sibling = $new_child;
}
/**
* Remove a child frame
*
* @param Frame $child
* @param boolean $update_node Whether or not to remove the DOM node
*
* @throws DOMPDF_Exception
* @return Frame The removed child frame
*/
function remove_child(Frame $child, $update_node = true) {
if ( $child->_parent !== $this ) {
throw new DOMPDF_Exception("Child not found in this frame");
}
if ( $update_node ) {
$this->_node->removeChild($child->_node);
}
if ( $child === $this->_first_child ) {
$this->_first_child = $child->_next_sibling;
}
if ( $child === $this->_last_child ) {
$this->_last_child = $child->_prev_sibling;
}
if ( $child->_prev_sibling ) {
$child->_prev_sibling->_next_sibling = $child->_next_sibling;
}
if ( $child->_next_sibling ) {
$child->_next_sibling->_prev_sibling = $child->_prev_sibling;
}
$child->_next_sibling = null;
$child->_prev_sibling = null;
$child->_parent = null;
return $child;
}
//........................................................................
// Debugging function:
function __toString() {
// Skip empty text frames
// if ( $this->is_text_node() &&
// preg_replace("/\s/", "", $this->_node->data) === "" )
// return "";
$str = "<b>" . $this->_node->nodeName . ":</b><br/>";
//$str .= spl_object_hash($this->_node) . "<br/>";
$str .= "Id: " .$this->get_id() . "<br/>";
$str .= "Class: " .get_class($this) . "<br/>";
if ( $this->is_text_node() ) {
$tmp = htmlspecialchars($this->_node->nodeValue);
$str .= "<pre>'" . mb_substr($tmp,0,70) .
(mb_strlen($tmp) > 70 ? "..." : "") . "'</pre>";
}
elseif ( $css_class = $this->_node->getAttribute("class") ) {
$str .= "CSS class: '$css_class'<br/>";
}
if ( $this->_parent ) {
$str .= "\nParent:" . $this->_parent->_node->nodeName .
" (" . spl_object_hash($this->_parent->_node) . ") " .
"<br/>";
}
if ( $this->_prev_sibling ) {
$str .= "Prev: " . $this->_prev_sibling->_node->nodeName .
" (" . spl_object_hash($this->_prev_sibling->_node) . ") " .
"<br/>";
}
if ( $this->_next_sibling ) {
$str .= "Next: " . $this->_next_sibling->_node->nodeName .
" (" . spl_object_hash($this->_next_sibling->_node) . ") " .
"<br/>";
}
$d = $this->get_decorator();
while ($d && $d != $d->get_decorator()) {
$str .= "Decorator: " . get_class($d) . "<br/>";
$d = $d->get_decorator();
}
$str .= "Position: " . pre_r($this->_position, true);
$str .= "\nContaining block: " . pre_r($this->_containing_block, true);
$str .= "\nMargin width: " . pre_r($this->get_margin_width(), true);
$str .= "\nMargin height: " . pre_r($this->get_margin_height(), true);
$str .= "\nStyle: <pre>". $this->_style->__toString() . "</pre>";
if ( $this->_decorator instanceof Block_Frame_Decorator ) {
$str .= "Lines:<pre>";
foreach ($this->_decorator->get_line_boxes() as $line) {
foreach ($line->get_frames() as $frame) {
if ($frame instanceof Text_Frame_Decorator) {
$str .= "\ntext: ";
$str .= "'". htmlspecialchars($frame->get_text()) ."'";
}
else {
$str .= "\nBlock: " . $frame->get_node()->nodeName . " (" . spl_object_hash($frame->get_node()) . ")";
}
}
$str .=
"\ny => " . $line->y . "\n" .
"w => " . $line->w . "\n" .
"h => " . $line->h . "\n" .
"left => " . $line->left . "\n" .
"right => " . $line->right . "\n";
}
$str .= "</pre>";
}
$str .= "\n";
if ( php_sapi_name() === "cli" ) {
$str = strip_tags(str_replace(array("<br/>","<b>","</b>"),
array("\n","",""),
$str));
}
return $str;
}
}
//------------------------------------------------------------------------
/**
* Linked-list IteratorAggregate
*
* @access private
* @package dompdf
*/
class FrameList implements IteratorAggregate {
protected $_frame;
function __construct($frame) { $this->_frame = $frame; }
function getIterator() { return new FrameListIterator($this->_frame); }
}
/**
* Linked-list Iterator
*
* Returns children in order and allows for list to change during iteration,
* provided the changes occur to or after the current element
*
* @access private
* @package dompdf
*/
class FrameListIterator implements Iterator {
/**
* @var Frame
*/
protected $_parent;
/**
* @var Frame
*/
protected $_cur;
/**
* @var int
*/
protected $_num;
function __construct(Frame $frame) {
$this->_parent = $frame;
$this->_cur = $frame->get_first_child();
$this->_num = 0;
}
function rewind() {
$this->_cur = $this->_parent->get_first_child();
$this->_num = 0;
}
/**
* @return bool
*/
function valid() {
return isset($this->_cur);// && ($this->_cur->get_prev_sibling() === $this->_prev);
}
function key() { return $this->_num; }
/**
* @return Frame
*/
function current() { return $this->_cur; }
/**
* @return Frame
*/
function next() {
$ret = $this->_cur;
if ( !$ret ) {
return null;
}
$this->_cur = $this->_cur->get_next_sibling();
$this->_num++;
return $ret;
}
}
//------------------------------------------------------------------------
/**
* Pre-order IteratorAggregate
*
* @access private
* @package dompdf
*/
class FrameTreeList implements IteratorAggregate {
/**
* @var Frame
*/
protected $_root;
function __construct(Frame $root) { $this->_root = $root; }
/**
* @return FrameTreeIterator
*/
function getIterator() { return new FrameTreeIterator($this->_root); }
}
/**
* Pre-order Iterator
*
* Returns frames in preorder traversal order (parent then children)
*
* @access private
* @package dompdf
*/
class FrameTreeIterator implements Iterator {
/**
* @var Frame
*/
protected $_root;
protected $_stack = array();
/**
* @var int
*/
protected $_num;
function __construct(Frame $root) {
$this->_stack[] = $this->_root = $root;
$this->_num = 0;
}
function rewind() {
$this->_stack = array($this->_root);
$this->_num = 0;
}
/**
* @return bool
*/
function valid() {
return count($this->_stack) > 0;
}
/**
* @return int
*/
function key() {
return $this->_num;
}
/**
* @return Frame
*/
function current() {
return end($this->_stack);
}
/**
* @return Frame
*/
function next() {
$b = end($this->_stack);
// Pop last element
unset($this->_stack[ key($this->_stack) ]);
$this->_num++;
// Push all children onto the stack in reverse order
if ( $c = $b->get_last_child() ) {
$this->_stack[] = $c;
while ( $c = $c->get_prev_sibling() ) {
$this->_stack[] = $c;
}
}
return $b;
}
}