update less.php to PHP 7.x compatible fork

36 files changed, 3913 insertions, 0 deletions

diff --git a/lib/less.php/Tree/Alpha.php b/lib/less.php/Tree/Alpha.php
new file mode 100644
index 0000000..935377d
--- /dev/null
+++ b/lib/less.php/Tree/Alpha.php
@@ -0,0 +1,51 @@
+<?php
+
+/**
+ * Alpha
+ *
+ * @package Less
+ * @subpackage tree
+ */
+class Less_Tree_Alpha extends Less_Tree{
+	public $value;
+	public $type = 'Alpha';
+
+	public function __construct($val){
+		$this->value = $val;
+	}
+
+	//function accept( $visitor ){
+	//	$this->value = $visitor->visit( $this->value );
+	//}
+
+	public function compile($env){
+
+		if( is_object($this->value) ){
+			$this->value = $this->value->compile($env);
+		}
+
+		return $this;
+	}
+
+    /**
+     * @see Less_Tree::genCSS
+     */
+	public function genCSS( $output ){
+
+		$output->add( "alpha(opacity=" );
+
+		if( is_string($this->value) ){
+			$output->add( $this->value );
+		}else{
+			$this->value->genCSS( $output);
+		}
+
+		$output->add( ')' );
+	}
+
+	public function toCSS(){
+		return "alpha(opacity=" . (is_string($this->value) ? $this->value : $this->value->toCSS()) . ")";
+	}
+
+
+}
\ No newline at end of file
diff --git a/lib/less.php/Tree/Anonymous.php b/lib/less.php/Tree/Anonymous.php
new file mode 100644
index 0000000..8889dc0
--- /dev/null
+++ b/lib/less.php/Tree/Anonymous.php
@@ -0,0 +1,58 @@
+<?php
+
+/**
+ * Anonymous
+ *
+ * @package Less
+ * @subpackage tree
+ */
+class Less_Tree_Anonymous extends Less_Tree{
+	public $value;
+	public $quote;
+	public $index;
+	public $mapLines;
+	public $currentFileInfo;
+	public $type = 'Anonymous';
+
+	/**
+	 * @param integer $index
+	 * @param boolean $mapLines
+	 */
+	public function __construct($value, $index = null, $currentFileInfo = null, $mapLines = null ){
+		$this->value = $value;
+		$this->index = $index;
+		$this->mapLines = $mapLines;
+		$this->currentFileInfo = $currentFileInfo;
+	}
+
+	public function compile(){
+		return new Less_Tree_Anonymous($this->value, $this->index, $this->currentFileInfo, $this->mapLines);
+	}
+
+    public function compare($x){
+		if( !is_object($x) ){
+			return -1;
+		}
+
+		$left = $this->toCSS();
+		$right = $x->toCSS();
+
+		if( $left === $right ){
+			return 0;
+		}
+
+		return $left < $right ? -1 : 1;
+	}
+
+    /**
+     * @see Less_Tree::genCSS
+     */
+	public function genCSS( $output ){
+		$output->add( $this->value, $this->currentFileInfo, $this->index, $this->mapLines );
+	}
+
+	public function toCSS(){
+		return $this->value;
+	}
+
+}
diff --git a/lib/less.php/Tree/Assignment.php b/lib/less.php/Tree/Assignment.php
new file mode 100644
index 0000000..2380006
--- /dev/null
+++ b/lib/less.php/Tree/Assignment.php
@@ -0,0 +1,39 @@
+<?php
+
+/**
+ * Assignment
+ *
+ * @package Less
+ * @subpackage tree
+ */
+class Less_Tree_Assignment extends Less_Tree{
+
+	public $key;
+	public $value;
+	public $type = 'Assignment';
+
+    public function __construct($key, $val) {
+		$this->key = $key;
+		$this->value = $val;
+	}
+
+    public function accept( $visitor ){
+		$this->value = $visitor->visitObj( $this->value );
+	}
+
+	public function compile($env) {
+		return new Less_Tree_Assignment( $this->key, $this->value->compile($env));
+	}
+
+    /**
+     * @see Less_Tree::genCSS
+     */
+	public function genCSS( $output ){
+		$output->add( $this->key . '=' );
+		$this->value->genCSS( $output );
+	}
+
+	public function toCss(){
+		return $this->key . '=' . $this->value->toCSS();
+	}
+}
diff --git a/lib/less.php/Tree/Attribute.php b/lib/less.php/Tree/Attribute.php
new file mode 100644
index 0000000..32b8900
--- /dev/null
+++ b/lib/less.php/Tree/Attribute.php
@@ -0,0 +1,54 @@
+<?php
+
+/**
+ * Attribute
+ *
+ * @package Less
+ * @subpackage tree
+ */
+class Less_Tree_Attribute extends Less_Tree{
+
+	public $key;
+	public $op;
+	public $value;
+	public $type = 'Attribute';
+
+    public function __construct($key, $op, $value){
+		$this->key = $key;
+		$this->op = $op;
+		$this->value = $value;
+	}
+
+    public function compile($env){
+
+		$key_obj = is_object($this->key);
+		$val_obj = is_object($this->value);
+
+		if( !$key_obj && !$val_obj ){
+			return $this;
+		}
+
+		return new Less_Tree_Attribute(
+			$key_obj ? $this->key->compile($env) : $this->key ,
+			$this->op,
+			$val_obj ? $this->value->compile($env) : $this->value);
+	}
+
+    /**
+     * @see Less_Tree::genCSS
+     */
+    public function genCSS( $output ){
+		$output->add( $this->toCSS() );
+	}
+
+    public function toCSS(){
+		$value = $this->key;
+
+		if( $this->op ){
+			$value .= $this->op;
+			$value .= (is_object($this->value) ? $this->value->toCSS() : $this->value);
+		}
+
+		return '[' . $value . ']';
+	}
+}
\ No newline at end of file
diff --git a/lib/less.php/Tree/Call.php b/lib/less.php/Tree/Call.php
new file mode 100644
index 0000000..3c3382d
--- /dev/null
+++ b/lib/less.php/Tree/Call.php
@@ -0,0 +1,121 @@
+<?php
+
+
+/**
+ * Call
+ *
+ * @package Less
+ * @subpackage tree
+ */
+class Less_Tree_Call extends Less_Tree{
+    public $value;
+
+    public $name;
+    public $args;
+    public $index;
+    public $currentFileInfo;
+    public $type = 'Call';
+
+	public function __construct($name, $args, $index, $currentFileInfo = null ){
+		$this->name = $name;
+		$this->args = $args;
+		$this->index = $index;
+		$this->currentFileInfo = $currentFileInfo;
+	}
+
+    public function accept( $visitor ){
+		$this->args = $visitor->visitArray( $this->args );
+	}
+
+    //
+    // When evaluating a function call,
+    // we either find the function in `tree.functions` [1],
+    // in which case we call it, passing the  evaluated arguments,
+    // or we simply print it out as it appeared originally [2].
+    //
+    // The *functions.js* file contains the built-in functions.
+    //
+    // The reason why we evaluate the arguments, is in the case where
+    // we try to pass a variable to a function, like: `saturate(@color)`.
+    // The function should receive the value, not the variable.
+    //
+    public function compile($env=null){
+		$args = array();
+		foreach($this->args as $a){
+			$args[] = $a->compile($env);
+		}
+
+		$nameLC = strtolower($this->name);
+		switch($nameLC){
+			case '%':
+			$nameLC = '_percent';
+			break;
+
+			case 'get-unit':
+			$nameLC = 'getunit';
+			break;
+
+			case 'data-uri':
+			$nameLC = 'datauri';
+			break;
+
+			case 'svg-gradient':
+			$nameLC = 'svggradient';
+			break;
+		}
+
+		$result = null;
+		if( $nameLC === 'default' ){
+			$result = Less_Tree_DefaultFunc::compile();
+
+		}else{
+
+			if( method_exists('Less_Functions',$nameLC) ){ // 1.
+				try {
+
+					$func = new Less_Functions($env, $this->currentFileInfo);
+					$result = call_user_func_array( array($func,$nameLC),$args);
+
+				} catch (Exception $e) {
+					throw new Less_Exception_Compiler('error evaluating function `' . $this->name . '` '.$e->getMessage().' index: '. $this->index);
+				}
+			} elseif( isset( $env->functions[$nameLC] ) && is_callable( $env->functions[$nameLC] ) ) {
+				try {
+					$result = call_user_func_array( $env->functions[$nameLC], $args );
+				} catch (Exception $e) {
+					throw new Less_Exception_Compiler('error evaluating function `' . $this->name . '` '.$e->getMessage().' index: '. $this->index);
+				}
+			}
+		}
+
+		if( $result !== null ){
+			return $result;
+		}
+
+
+		return new Less_Tree_Call( $this->name, $args, $this->index, $this->currentFileInfo );
+    }
+
+    /**
+     * @see Less_Tree::genCSS
+     */
+	public function genCSS( $output ){
+
+		$output->add( $this->name . '(', $this->currentFileInfo, $this->index );
+		$args_len = count($this->args);
+		for($i = 0; $i < $args_len; $i++ ){
+			$this->args[$i]->genCSS( $output );
+			if( $i + 1 < $args_len ){
+				$output->add( ', ' );
+			}
+		}
+
+		$output->add( ')' );
+	}
+
+
+    //public function toCSS(){
+    //    return $this->compile()->toCSS();
+    //}
+
+}
diff --git a/lib/less.php/Tree/Color.php b/lib/less.php/Tree/Color.php
new file mode 100644
index 0000000..77af07a
--- /dev/null
+++ b/lib/less.php/Tree/Color.php
@@ -0,0 +1,230 @@
+<?php
+
+/**
+ * Color
+ *
+ * @package Less
+ * @subpackage tree
+ */
+class Less_Tree_Color extends Less_Tree{
+	public $rgb;
+	public $alpha;
+	public $isTransparentKeyword;
+	public $type = 'Color';
+
+	public function __construct($rgb, $a = 1, $isTransparentKeyword = null ){
+
+		if( $isTransparentKeyword ){
+			$this->rgb = $rgb;
+			$this->alpha = $a;
+			$this->isTransparentKeyword = true;
+			return;
+		}
+
+		$this->rgb = array();
+		if( is_array($rgb) ){
+			$this->rgb = $rgb;
+		}else if( strlen($rgb) == 6 ){
+			foreach(str_split($rgb, 2) as $c){
+				$this->rgb[] = hexdec($c);
+			}
+		}else{
+			foreach(str_split($rgb, 1) as $c){
+				$this->rgb[] = hexdec($c.$c);
+			}
+		}
+		$this->alpha = is_numeric($a) ? $a : 1;
+	}
+
+	public function compile(){
+		return $this;
+	}
+
+	public function luma(){
+		$r = $this->rgb[0] / 255;
+		$g = $this->rgb[1] / 255;
+		$b = $this->rgb[2] / 255;
+
+		$r = ($r <= 0.03928) ? $r / 12.92 : pow((($r + 0.055) / 1.055), 2.4);
+		$g = ($g <= 0.03928) ? $g / 12.92 : pow((($g + 0.055) / 1.055), 2.4);
+		$b = ($b <= 0.03928) ? $b / 12.92 : pow((($b + 0.055) / 1.055), 2.4);
+
+		return 0.2126 * $r + 0.7152 * $g + 0.0722 * $b;
+	}
+
+	/**
+	 * @see Less_Tree::genCSS
+	 */
+	public function genCSS( $output ){
+		$output->add( $this->toCSS() );
+	}
+
+	public function toCSS( $doNotCompress = false ){
+		$compress = Less_Parser::$options['compress'] && !$doNotCompress;
+		$alpha = Less_Functions::fround( $this->alpha );
+
+
+		//
+		// If we have some transparency, the only way to represent it
+		// is via `rgba`. Otherwise, we use the hex representation,
+		// which has better compatibility with older browsers.
+		// Values are capped between `0` and `255`, rounded and zero-padded.
+		//
+		if( $alpha < 1 ){
+			if( ( $alpha === 0 || $alpha === 0.0 ) && isset($this->isTransparentKeyword) && $this->isTransparentKeyword ){
+				return 'transparent';
+			}
+
+			$values = array();
+			foreach($this->rgb as $c){
+				$values[] = Less_Functions::clamp( round($c), 255);
+			}
+			$values[] = $alpha;
+
+			$glue = ($compress ? ',' : ', ');
+			return "rgba(" . implode($glue, $values) . ")";
+		}else{
+
+			$color = $this->toRGB();
+
+			if( $compress ){
+
+				// Convert color to short format
+				if( $color[1] === $color[2] && $color[3] === $color[4] && $color[5] === $color[6]) {
+					$color = '#'.$color[1] . $color[3] . $color[5];
+				}
+			}
+
+			return $color;
+		}
+	}
+
+	//
+	// Operations have to be done per-channel, if not,
+	// channels will spill onto each other. Once we have
+	// our result, in the form of an integer triplet,
+	// we create a new Color node to hold the result.
+	//
+
+	/**
+	 * @param string $op
+	 */
+	public function operate( $op, $other) {
+		$rgb = array();
+		$alpha = $this->alpha * (1 - $other->alpha) + $other->alpha;
+		for ($c = 0; $c < 3; $c++) {
+			$rgb[$c] = Less_Functions::operate( $op, $this->rgb[$c], $other->rgb[$c]);
+		}
+		return new Less_Tree_Color($rgb, $alpha);
+	}
+
+	public function toRGB(){
+		return $this->toHex($this->rgb);
+	}
+
+	public function toHSL(){
+		$r = $this->rgb[0] / 255;
+		$g = $this->rgb[1] / 255;
+		$b = $this->rgb[2] / 255;
+		$a = $this->alpha;
+
+		$max = max($r, $g, $b);
+		$min = min($r, $g, $b);
+		$l = ($max + $min) / 2;
+		$d = $max - $min;
+
+		$h = $s = 0;
+		if( $max !== $min ){
+			$s = $l > 0.5 ? $d / (2 - $max - $min) : $d / ($max + $min);
+
+			switch ($max) {
+				case $r: $h = ($g - $b) / $d + ($g < $b ? 6 : 0); break;
+				case $g: $h = ($b - $r) / $d + 2;				 break;
+				case $b: $h = ($r - $g) / $d + 4;				 break;
+			}
+			$h /= 6;
+		}
+		return array('h' => $h * 360, 's' => $s, 'l' => $l, 'a' => $a );
+	}
+
+	//Adapted from http://mjijackson.com/2008/02/rgb-to-hsl-and-rgb-to-hsv-color-model-conversion-algorithms-in-javascript
+    public function toHSV() {
+		$r = $this->rgb[0] / 255;
+		$g = $this->rgb[1] / 255;
+		$b = $this->rgb[2] / 255;
+		$a = $this->alpha;
+
+		$max = max($r, $g, $b);
+		$min = min($r, $g, $b);
+
+		$v = $max;
+
+		$d = $max - $min;
+		if ($max === 0) {
+			$s = 0;
+		} else {
+			$s = $d / $max;
+		}
+
+		$h = 0;
+		if( $max !== $min ){
+			switch($max){
+				case $r: $h = ($g - $b) / $d + ($g < $b ? 6 : 0); break;
+				case $g: $h = ($b - $r) / $d + 2; break;
+				case $b: $h = ($r - $g) / $d + 4; break;
+			}
+			$h /= 6;
+		}
+		return array('h'=> $h * 360, 's'=> $s, 'v'=> $v, 'a' => $a );
+	}
+
+	public function toARGB(){
+		$argb = array_merge( (array) Less_Parser::round($this->alpha * 255), $this->rgb);
+		return $this->toHex( $argb );
+	}
+
+	public function compare($x){
+
+		if( !property_exists( $x, 'rgb' ) ){
+			return -1;
+		}
+
+
+		return ($x->rgb[0] === $this->rgb[0] &&
+			$x->rgb[1] === $this->rgb[1] &&
+			$x->rgb[2] === $this->rgb[2] &&
+			$x->alpha === $this->alpha) ? 0 : -1;
+	}
+
+    public function toHex( $v ){
+
+		$ret = '#';
+		foreach($v as $c){
+			$c = Less_Functions::clamp( Less_Parser::round($c), 255);
+			if( $c < 16 ){
+				$ret .= '0';
+			}
+			$ret .= dechex($c);
+		}
+
+		return $ret;
+	}
+
+
+	/**
+	 * @param string $keyword
+	 */
+	public static function fromKeyword( $keyword ){
+		$keyword = strtolower($keyword);
+
+		if( Less_Colors::hasOwnProperty($keyword) ){
+			// detect named color
+			return new Less_Tree_Color(substr(Less_Colors::color($keyword), 1));
+		}
+
+		if( $keyword === 'transparent' ){
+			return new Less_Tree_Color( array(0, 0, 0), 0, true);
+		}
+	}
+
+}
diff --git a/lib/less.php/Tree/Comment.php b/lib/less.php/Tree/Comment.php
new file mode 100644
index 0000000..7261284
--- /dev/null
+++ b/lib/less.php/Tree/Comment.php
@@ -0,0 +1,51 @@
+<?php
+
+/**
+ * Comment
+ *
+ * @package Less
+ * @subpackage tree
+ */
+class Less_Tree_Comment extends Less_Tree{
+
+	public $value;
+	public $silent;
+	public $isReferenced;
+	public $currentFileInfo;
+	public $type = 'Comment';
+
+	public function __construct($value, $silent, $index = null, $currentFileInfo = null ){
+		$this->value = $value;
+		$this->silent = !! $silent;
+		$this->currentFileInfo = $currentFileInfo;
+	}
+
+    /**
+     * @see Less_Tree::genCSS
+     */
+	public function genCSS( $output ){
+		//if( $this->debugInfo ){
+			//$output->add( tree.debugInfo($env, $this), $this->currentFileInfo, $this->index);
+		//}
+		$output->add( trim($this->value) );//TODO shouldn't need to trim, we shouldn't grab the \n
+	}
+
+	public function toCSS(){
+		return Less_Parser::$options['compress'] ? '' : $this->value;
+	}
+
+	public function isSilent(){
+		$isReference = ($this->currentFileInfo && isset($this->currentFileInfo['reference']) && (!isset($this->isReferenced) || !$this->isReferenced) );
+		$isCompressed = Less_Parser::$options['compress'] && !preg_match('/^\/\*!/', $this->value);
+		return $this->silent || $isReference || $isCompressed;
+	}
+
+	public function compile(){
+		return $this;
+	}
+
+	public function markReferenced(){
+		$this->isReferenced = true;
+	}
+
+}
diff --git a/lib/less.php/Tree/Condition.php b/lib/less.php/Tree/Condition.php
new file mode 100644
index 0000000..929d33b
--- /dev/null
+++ b/lib/less.php/Tree/Condition.php
@@ -0,0 +1,72 @@
+<?php
+
+/**
+ * Condition
+ *
+ * @package Less
+ * @subpackage tree
+ */
+class Less_Tree_Condition extends Less_Tree{
+
+	public $op;
+	public $lvalue;
+	public $rvalue;
+	public $index;
+	public $negate;
+	public $type = 'Condition';
+
+	public function __construct($op, $l, $r, $i = 0, $negate = false) {
+		$this->op = trim($op);
+		$this->lvalue = $l;
+		$this->rvalue = $r;
+		$this->index = $i;
+		$this->negate = $negate;
+	}
+
+	public function accept($visitor){
+		$this->lvalue = $visitor->visitObj( $this->lvalue );
+		$this->rvalue = $visitor->visitObj( $this->rvalue );
+	}
+
+    public function compile($env) {
+		$a = $this->lvalue->compile($env);
+		$b = $this->rvalue->compile($env);
+
+		switch( $this->op ){
+			case 'and':
+				$result = $a && $b;
+			break;
+
+			case 'or':
+				$result = $a || $b;
+			break;
+
+			default:
+				if( Less_Parser::is_method($a, 'compare') ){
+					$result = $a->compare($b);
+				}elseif( Less_Parser::is_method($b, 'compare') ){
+					$result = $b->compare($a);
+				}else{
+					throw new Less_Exception_Compiler('Unable to perform comparison', null, $this->index);
+				}
+
+				switch ($result) {
+					case -1:
+					$result = $this->op === '<' || $this->op === '=<' || $this->op === '<=';
+					break;
+
+					case  0:
+					$result = $this->op === '=' || $this->op === '>=' || $this->op === '=<' || $this->op === '<=';
+					break;
+
+					case  1:
+					$result = $this->op === '>' || $this->op === '>=';
+					break;
+				}
+			break;
+		}
+
+		return $this->negate ? !$result : $result;
+    }
+
+}
diff --git a/lib/less.php/Tree/DefaultFunc.php b/lib/less.php/Tree/DefaultFunc.php
new file mode 100644
index 0000000..c2dbf74
--- /dev/null
+++ b/lib/less.php/Tree/DefaultFunc.php
@@ -0,0 +1,34 @@
+<?php
+
+/**
+ * DefaultFunc
+ *
+ * @package Less
+ * @subpackage tree
+ */
+class Less_Tree_DefaultFunc{
+
+	static $error_;
+	static $value_;
+
+    public static function compile(){
+		if( self::$error_ ){
+			throw new Exception(self::$error_);
+		}
+		if( self::$value_ !== null ){
+			return self::$value_ ? new Less_Tree_Keyword('true') : new Less_Tree_Keyword('false');
+		}
+	}
+
+    public static function value( $v ){
+		self::$value_ = $v;
+	}
+
+    public static function error( $e ){
+		self::$error_ = $e;
+	}
+
+    public static function reset(){
+		self::$value_ = self::$error_ = null;
+	}
+}
\ No newline at end of file
diff --git a/lib/less.php/Tree/DetachedRuleset.php b/lib/less.php/Tree/DetachedRuleset.php
new file mode 100644
index 0000000..c887e40
--- /dev/null
+++ b/lib/less.php/Tree/DetachedRuleset.php
@@ -0,0 +1,40 @@
+<?php
+
+/**
+ * DetachedRuleset
+ *
+ * @package Less
+ * @subpackage tree
+ */
+class Less_Tree_DetachedRuleset extends Less_Tree{
+
+	public $ruleset;
+	public $frames;
+	public $type = 'DetachedRuleset';
+
+    public function __construct( $ruleset, $frames = null ){
+		$this->ruleset = $ruleset;
+		$this->frames = $frames;
+	}
+
+    public function accept($visitor) {
+		$this->ruleset = $visitor->visitObj($this->ruleset);
+	}
+
+    public function compile($env){
+		if( $this->frames ){
+			$frames = $this->frames;
+		}else{
+			$frames = $env->frames;
+		}
+		return new Less_Tree_DetachedRuleset($this->ruleset, $frames);
+	}
+
+    public function callEval($env) {
+		if( $this->frames ){
+			return $this->ruleset->compile( $env->copyEvalEnv( array_merge($this->frames,$env->frames) ) );
+		}
+		return $this->ruleset->compile( $env );
+	}
+}
+
diff --git a/lib/less.php/Tree/Dimension.php b/lib/less.php/Tree/Dimension.php
new file mode 100644
index 0000000..2bfb9d5
--- /dev/null
+++ b/lib/less.php/Tree/Dimension.php
@@ -0,0 +1,201 @@
+<?php
+
+/**
+ * Dimension
+ *
+ * @package Less
+ * @subpackage tree
+ */
+class Less_Tree_Dimension extends Less_Tree{
+
+	public $value;
+	public $unit;
+	public $type = 'Dimension';
+
+    public function __construct($value, $unit = null){
+        $this->value = floatval($value);
+
+		if( $unit && ($unit instanceof Less_Tree_Unit) ){
+			$this->unit = $unit;
+		}elseif( $unit ){
+			$this->unit = new Less_Tree_Unit( array($unit) );
+		}else{
+			$this->unit = new Less_Tree_Unit( );
+		}
+    }
+
+    public function accept( $visitor ){
+		$this->unit = $visitor->visitObj( $this->unit );
+	}
+
+    public function compile(){
+        return $this;
+    }
+
+    public function toColor() {
+        return new Less_Tree_Color(array($this->value, $this->value, $this->value));
+    }
+
+    /**
+     * @see Less_Tree::genCSS
+     */
+	public function genCSS( $output ){
+
+		if( Less_Parser::$options['strictUnits'] && !$this->unit->isSingular() ){
+			throw new Less_Exception_Compiler("Multiple units in dimension. Correct the units or use the unit function. Bad unit: ".$this->unit->toString());
+		}
+
+		$value = Less_Functions::fround( $this->value );
+		$strValue = (string)$value;
+
+		if( $value !== 0 && $value < 0.000001 && $value > -0.000001 ){
+			// would be output 1e-6 etc.
+			$strValue = number_format($strValue,10);
+			$strValue = preg_replace('/\.?0+$/','', $strValue);
+		}
+
+		if( Less_Parser::$options['compress'] ){
+			// Zero values doesn't need a unit
+			if( $value === 0 && $this->unit->isLength() ){
+				$output->add( $strValue );
+				return $strValue;
+			}
+
+			// Float values doesn't need a leading zero
+			if( $value > 0 && $value < 1 && $strValue[0] === '0' ){
+				$strValue = substr($strValue,1);
+			}
+		}
+
+		$output->add( $strValue );
+		$this->unit->genCSS( $output );
+	}
+
+    public function __toString(){
+        return $this->toCSS();
+    }
+
+    // In an operation between two Dimensions,
+    // we default to the first Dimension's unit,
+    // so `1px + 2em` will yield `3px`.
+
+    /**
+     * @param string $op
+     */
+    public function operate( $op, $other){
+
+		$value = Less_Functions::operate( $op, $this->value, $other->value);
+		$unit = clone $this->unit;
+
+		if( $op === '+' || $op === '-' ){
+
+			if( !$unit->numerator && !$unit->denominator ){
+				$unit->numerator = $other->unit->numerator;
+				$unit->denominator = $other->unit->denominator;
+			}elseif( !$other->unit->numerator && !$other->unit->denominator ){
+				// do nothing
+			}else{
+				$other = $other->convertTo( $this->unit->usedUnits());
+
+				if( Less_Parser::$options['strictUnits'] && $other->unit->toString() !== $unit->toCSS() ){
+					throw new Less_Exception_Compiler("Incompatible units. Change the units or use the unit function. Bad units: '" . $unit->toString() . "' and " . $other->unit->toString() . "'.");
+				}
+
+				$value = Less_Functions::operate( $op, $this->value, $other->value);
+			}
+		}elseif( $op === '*' ){
+			$unit->numerator = array_merge($unit->numerator, $other->unit->numerator);
+			$unit->denominator = array_merge($unit->denominator, $other->unit->denominator);
+			sort($unit->numerator);
+			sort($unit->denominator);
+			$unit->cancel();
+		}elseif( $op === '/' ){
+			$unit->numerator = array_merge($unit->numerator, $other->unit->denominator);
+			$unit->denominator = array_merge($unit->denominator, $other->unit->numerator);
+			sort($unit->numerator);
+			sort($unit->denominator);
+			$unit->cancel();
+		}
+		return new Less_Tree_Dimension( $value, $unit);
+    }
+
+	public function compare($other) {
+		if ($other instanceof Less_Tree_Dimension) {
+
+			if( $this->unit->isEmpty() || $other->unit->isEmpty() ){
+				$a = $this;
+				$b = $other;
+			} else {
+				$a = $this->unify();
+				$b = $other->unify();
+				if( $a->unit->compare($b->unit) !== 0 ){
+					return -1;
+				}
+			}
+			$aValue = $a->value;
+			$bValue = $b->value;
+
+			if ($bValue > $aValue) {
+				return -1;
+			} elseif ($bValue < $aValue) {
+				return 1;
+			} else {
+				return 0;
+			}
+		} else {
+			return -1;
+		}
+	}
+
+    public function unify() {
+		return $this->convertTo(array('length'=> 'px', 'duration'=> 's', 'angle' => 'rad' ));
+	}
+
+    public function convertTo($conversions) {
+		$value = $this->value;
+		$unit = clone $this->unit;
+
+		if( is_string($conversions) ){
+			$derivedConversions = array();
+			foreach( Less_Tree_UnitConversions::$groups as $i ){
+				if( isset(Less_Tree_UnitConversions::${$i}[$conversions]) ){
+					$derivedConversions = array( $i => $conversions);
+				}
+			}
+			$conversions = $derivedConversions;
+		}
+
+
+		foreach($conversions as $groupName => $targetUnit){
+			$group = Less_Tree_UnitConversions::${$groupName};
+
+			//numerator
+			foreach($unit->numerator as $i => $atomicUnit){
+				$atomicUnit = $unit->numerator[$i];
+				if( !isset($group[$atomicUnit]) ){
+					continue;
+				}
+
+				$value = $value * ($group[$atomicUnit] / $group[$targetUnit]);
+
+				$unit->numerator[$i] = $targetUnit;
+			}
+
+			//denominator
+			foreach($unit->denominator as $i => $atomicUnit){
+				$atomicUnit = $unit->denominator[$i];
+				if( !isset($group[$atomicUnit]) ){
+					continue;
+				}
+
+				$value = $value / ($group[$atomicUnit] / $group[$targetUnit]);
+
+				$unit->denominator[$i] = $targetUnit;
+			}
+		}
+
+		$unit->cancel();
+
+		return new Less_Tree_Dimension( $value, $unit);
+    }
+}
diff --git a/lib/less.php/Tree/Directive.php b/lib/less.php/Tree/Directive.php
new file mode 100644
index 0000000..04a1e46
--- /dev/null
+++ b/lib/less.php/Tree/Directive.php
@@ -0,0 +1,100 @@
+<?php
+
+/**
+ * Directive
+ *
+ * @package Less
+ * @subpackage tree
+ */
+class Less_Tree_Directive extends Less_Tree{
+
+	public $name;
+	public $value;
+	public $rules;
+	public $index;
+	public $isReferenced;
+	public $currentFileInfo;
+	public $debugInfo;
+	public $type = 'Directive';
+
+	public function __construct($name, $value = null, $rules, $index = null, $currentFileInfo = null, $debugInfo = null ){
+		$this->name = $name;
+		$this->value = $value;
+		if( $rules ){
+			$this->rules = $rules;
+			$this->rules->allowImports = true;
+		}
+
+		$this->index = $index;
+		$this->currentFileInfo = $currentFileInfo;
+		$this->debugInfo = $debugInfo;
+	}
+
+
+    public function accept( $visitor ){
+		if( $this->rules ){
+			$this->rules = $visitor->visitObj( $this->rules );
+		}
+		if( $this->value ){
+			$this->value = $visitor->visitObj( $this->value );
+		}
+	}
+
+
+    /**
+     * @see Less_Tree::genCSS
+     */
+    public function genCSS( $output ){
+		$value = $this->value;
+		$rules = $this->rules;
+		$output->add( $this->name, $this->currentFileInfo, $this->index );
+		if( $this->value ){
+			$output->add(' ');
+			$this->value->genCSS($output);
+		}
+		if( $this->rules ){
+			Less_Tree::outputRuleset( $output, array($this->rules));
+		} else {
+			$output->add(';');
+		}
+	}
+
+	public function compile($env){
+
+		$value = $this->value;
+		$rules = $this->rules;
+		if( $value ){
+			$value = $value->compile($env);
+		}
+
+		if( $rules ){
+			$rules = $rules->compile($env);
+			$rules->root = true;
+		}
+
+		return new Less_Tree_Directive( $this->name, $value, $rules, $this->index, $this->currentFileInfo, $this->debugInfo );
+	}
+
+
+	public function variable($name){
+		if( $this->rules ){
+			return $this->rules->variable($name);
+		}
+	}
+
+	public function find($selector){
+		if( $this->rules ){
+			return $this->rules->find($selector, $this);
+		}
+	}
+
+	//rulesets: function () { if (this.rules) return tree.Ruleset.prototype.rulesets.apply(this.rules); },
+
+	public function markReferenced(){
+		$this->isReferenced = true;
+		if( $this->rules ){
+			Less_Tree::ReferencedArray($this->rules->rules);
+		}
+	}
+
+}
diff --git a/lib/less.php/Tree/Element.php b/lib/less.php/Tree/Element.php
new file mode 100644
index 0000000..9cea5e4
--- /dev/null
+++ b/lib/less.php/Tree/Element.php
@@ -0,0 +1,75 @@
+<?php
+
+/**
+ * Element
+ *
+ * @package Less
+ * @subpackage tree
+ */
+class Less_Tree_Element extends Less_Tree{
+
+	public $combinator = '';
+	public $value = '';
+	public $index;
+	public $currentFileInfo;
+	public $type = 'Element';
+
+	public $value_is_object = false;
+
+	public function __construct($combinator, $value, $index = null, $currentFileInfo = null ){
+
+		$this->value = $value;
+		$this->value_is_object = is_object($value);
+
+		if( $combinator ){
+			$this->combinator = $combinator;
+		}
+
+		$this->index = $index;
+		$this->currentFileInfo = $currentFileInfo;
+	}
+
+    public function accept( $visitor ){
+		if( $this->value_is_object ){ //object or string
+			$this->value = $visitor->visitObj( $this->value );
+		}
+	}
+
+	public function compile($env){
+
+		if( Less_Environment::$mixin_stack ){
+			return new Less_Tree_Element($this->combinator, ($this->value_is_object ? $this->value->compile($env) : $this->value), $this->index, $this->currentFileInfo );
+		}
+
+		if( $this->value_is_object ){
+			$this->value = $this->value->compile($env);
+		}
+
+		return $this;
+	}
+
+    /**
+     * @see Less_Tree::genCSS
+     */
+	public function genCSS( $output ){
+		$output->add( $this->toCSS(), $this->currentFileInfo, $this->index );
+	}
+
+	public function toCSS(){
+
+		if( $this->value_is_object ){
+			$value = $this->value->toCSS();
+		}else{
+			$value = $this->value;
+		}
+
+
+		if( $value === '' && $this->combinator && $this->combinator === '&' ){
+			return '';
+		}
+
+
+		return Less_Environment::$_outputMap[$this->combinator] . $value;
+	}
+
+}
diff --git a/lib/less.php/Tree/Expression.php b/lib/less.php/Tree/Expression.php
new file mode 100644
index 0000000..d834354
--- /dev/null
+++ b/lib/less.php/Tree/Expression.php
@@ -0,0 +1,97 @@
+<?php
+
+/**
+ * Expression
+ *
+ * @package Less
+ * @subpackage tree
+ */
+class Less_Tree_Expression extends Less_Tree{
+
+	public $value = array();
+	public $parens = false;
+	public $parensInOp = false;
+	public $type = 'Expression';
+
+	public function __construct( $value, $parens = null ){
+		$this->value = $value;
+		$this->parens = $parens;
+	}
+
+    public function accept( $visitor ){
+		$this->value = $visitor->visitArray( $this->value );
+	}
+
+	public function compile($env) {
+
+		$doubleParen = false;
+
+		if( $this->parens && !$this->parensInOp ){
+			Less_Environment::$parensStack++;
+		}
+
+		$returnValue = null;
+		if( $this->value ){
+
+			$count = count($this->value);
+
+			if( $count > 1 ){
+
+				$ret = array();
+				foreach($this->value as $e){
+					$ret[] = $e->compile($env);
+				}
+				$returnValue = new Less_Tree_Expression($ret);
+
+			}else{
+
+				if( ($this->value[0] instanceof Less_Tree_Expression) && $this->value[0]->parens && !$this->value[0]->parensInOp ){
+					$doubleParen = true;
+				}
+
+				$returnValue = $this->value[0]->compile($env);
+			}
+
+		} else {
+			$returnValue = $this;
+		}
+
+		if( $this->parens ){
+			if( !$this->parensInOp ){
+				Less_Environment::$parensStack--;
+
+			}elseif( !Less_Environment::isMathOn() && !$doubleParen ){
+				$returnValue = new Less_Tree_Paren($returnValue);
+
+			}
+		}
+		return $returnValue;
+	}
+
+    /**
+     * @see Less_Tree::genCSS
+     */
+    public function genCSS( $output ){
+		$val_len = count($this->value);
+		for( $i = 0; $i < $val_len; $i++ ){
+			$this->value[$i]->genCSS( $output );
+			if( $i + 1 < $val_len ){
+				$output->add( ' ' );
+			}
+		}
+	}
+
+    public function throwAwayComments() {
+
+		if( is_array($this->value) ){
+			$new_value = array();
+			foreach($this->value as $v){
+				if( $v instanceof Less_Tree_Comment ){
+					continue;
+				}
+				$new_value[] = $v;
+			}
+			$this->value = $new_value;
+		}
+	}
+}
diff --git a/lib/less.php/Tree/Extend.php b/lib/less.php/Tree/Extend.php
new file mode 100644
index 0000000..8f21e93
--- /dev/null
+++ b/lib/less.php/Tree/Extend.php
@@ -0,0 +1,77 @@
+<?php
+
+/**
+ * Extend
+ *
+ * @package Less
+ * @subpackage tree
+ */
+class Less_Tree_Extend extends Less_Tree{
+
+	public $selector;
+	public $option;
+	public $index;
+	public $selfSelectors = array();
+	public $allowBefore;
+	public $allowAfter;
+	public $firstExtendOnThisSelectorPath;
+	public $type = 'Extend';
+	public $ruleset;
+
+
+	public $object_id;
+	public $parent_ids = array();
+
+	/**
+	 * @param integer $index
+	 */
+    public function __construct($selector, $option, $index){
+		static $i = 0;
+		$this->selector = $selector;
+		$this->option = $option;
+		$this->index = $index;
+
+		switch($option){
+			case "all":
+				$this->allowBefore = true;
+				$this->allowAfter = true;
+			break;
+			default:
+				$this->allowBefore = false;
+				$this->allowAfter = false;
+			break;
+		}
+
+		$this->object_id = $i++;
+		$this->parent_ids = array($this->object_id);
+	}
+
+    public function accept( $visitor ){
+		$this->selector = $visitor->visitObj( $this->selector );
+	}
+
+    public function compile( $env ){
+		Less_Parser::$has_extends = true;
+		$this->selector = $this->selector->compile($env);
+		return $this;
+		//return new Less_Tree_Extend( $this->selector->compile($env), $this->option, $this->index);
+	}
+
+    public function findSelfSelectors( $selectors ){
+		$selfElements = array();
+
+
+		for( $i = 0, $selectors_len = count($selectors); $i < $selectors_len; $i++ ){
+			$selectorElements = $selectors[$i]->elements;
+			// duplicate the logic in genCSS function inside the selector node.
+			// future TODO - move both logics into the selector joiner visitor
+			if( $i && $selectorElements && $selectorElements[0]->combinator === "") {
+				$selectorElements[0]->combinator = ' ';
+			}
+			$selfElements = array_merge( $selfElements, $selectors[$i]->elements );
+		}
+
+		$this->selfSelectors = array(new Less_Tree_Selector($selfElements));
+	}
+
+}
\ No newline at end of file
diff --git a/lib/less.php/Tree/Import.php b/lib/less.php/Tree/Import.php
new file mode 100644
index 0000000..4e14afe
--- /dev/null
+++ b/lib/less.php/Tree/Import.php
@@ -0,0 +1,304 @@
+<?php
+
+/**
+ * CSS @import node
+ *
+ * The general strategy here is that we don't want to wait
+ * for the parsing to be completed, before we start importing
+ * the file. That's because in the context of a browser,
+ * most of the time will be spent waiting for the server to respond.
+ *
+ * On creation, we push the import path to our import queue, though
+ * `import,push`, we also pass it a callback, which it'll call once
+ * the file has been fetched, and parsed.
+ *
+ * @package Less
+ * @subpackage tree
+ */
+class Less_Tree_Import extends Less_Tree{
+
+	public $options;
+	public $index;
+	public $path;
+	public $features;
+	public $currentFileInfo;
+	public $css;
+	public $skip;
+	public $root;
+	public $type = 'Import';
+
+    public function __construct($path, $features, $options, $index, $currentFileInfo = null ){
+		$this->options = $options;
+		$this->index = $index;
+		$this->path = $path;
+		$this->features = $features;
+		$this->currentFileInfo = $currentFileInfo;
+
+		if( is_array($options) ){
+			$this->options += array('inline'=>false);
+
+			if( isset($this->options['less']) || $this->options['inline'] ){
+				$this->css = !isset($this->options['less']) || !$this->options['less'] || $this->options['inline'];
+			} else {
+				$pathValue = $this->getPath();
+				if( $pathValue && preg_match('/css([\?;].*)?$/',$pathValue) ){
+					$this->css = true;
+				}
+			}
+		}
+	}
+
+//
+// The actual import node doesn't return anything, when converted to CSS.
+// The reason is that it's used at the evaluation stage, so that the rules
+// it imports can be treated like any other rules.
+//
+// In `eval`, we make sure all Import nodes get evaluated, recursively, so
+// we end up with a flat structure, which can easily be imported in the parent
+// ruleset.
+//
+
+    public function accept($visitor){
+
+		if( $this->features ){
+			$this->features = $visitor->visitObj($this->features);
+		}
+		$this->path = $visitor->visitObj($this->path);
+
+		if( !$this->options['inline'] && $this->root ){
+			$this->root = $visitor->visit($this->root);
+		}
+	}
+
+    /**
+     * @see Less_Tree::genCSS
+     */
+    public function genCSS( $output ){
+		if( $this->css ){
+
+			$output->add( '@import ', $this->currentFileInfo, $this->index );
+
+			$this->path->genCSS( $output );
+			if( $this->features ){
+				$output->add( ' ' );
+				$this->features->genCSS( $output );
+			}
+			$output->add( ';' );
+		}
+	}
+
+    public function toCSS(){
+		$features = $this->features ? ' ' . $this->features->toCSS() : '';
+
+		if ($this->css) {
+			return "@import " . $this->path->toCSS() . $features . ";\n";
+		} else {
+			return "";
+		}
+	}
+
+	/**
+	 * @return string
+	 */
+    public function getPath(){
+		if ($this->path instanceof Less_Tree_Quoted) {
+			$path = $this->path->value;
+			$path = ( isset($this->css) || preg_match('/(\.[a-z]*$)|([\?;].*)$/',$path)) ? $path : $path . '.less';
+		} else if ($this->path instanceof Less_Tree_URL) {
+			$path = $this->path->value->value;
+		}else{
+			return null;
+		}
+
+		//remove query string and fragment
+		return preg_replace('/[\?#][^\?]*$/','',$path);
+	}
+
+    public function compileForImport( $env ){
+		return new Less_Tree_Import( $this->path->compile($env), $this->features, $this->options, $this->index, $this->currentFileInfo);
+	}
+
+    public function compilePath($env) {
+		$path = $this->path->compile($env);
+		$rootpath = '';
+		if( $this->currentFileInfo && $this->currentFileInfo['rootpath'] ){
+			$rootpath = $this->currentFileInfo['rootpath'];
+		}
+
+
+		if( !($path instanceof Less_Tree_URL) ){
+			if( $rootpath ){
+				$pathValue = $path->value;
+				// Add the base path if the import is relative
+				if( $pathValue && Less_Environment::isPathRelative($pathValue) ){
+					$path->value = $this->currentFileInfo['uri_root'].$pathValue;
+				}
+			}
+			$path->value = Less_Environment::normalizePath($path->value);
+		}
+
+
+
+		return $path;
+	}
+
+    public function compile( $env ){
+
+		$evald = $this->compileForImport($env);
+
+		//get path & uri
+		$path_and_uri = null;
+		if( is_callable(Less_Parser::$options['import_callback']) ){
+			$path_and_uri = call_user_func(Less_Parser::$options['import_callback'],$evald);
+		}
+
+		if( !$path_and_uri ){
+			$path_and_uri = $evald->PathAndUri();
+		}
+
+		if( $path_and_uri ){
+			list($full_path, $uri) = $path_and_uri;
+		}else{
+			$full_path = $uri = $evald->getPath();
+		}
+
+
+		//import once
+		if( $evald->skip( $full_path, $env) ){
+			return array();
+		}
+
+		if( $this->options['inline'] ){
+			//todo needs to reference css file not import
+			//$contents = new Less_Tree_Anonymous($this->root, 0, array('filename'=>$this->importedFilename), true );
+
+			Less_Parser::AddParsedFile($full_path);
+			$contents = new Less_Tree_Anonymous( file_get_contents($full_path), 0, array(), true );
+
+			if( $this->features ){
+				return new Less_Tree_Media( array($contents), $this->features->value );
+			}
+
+			return array( $contents );
+		}
+
+		// optional (need to be before "CSS" to support optional CSS imports. CSS should be checked only if empty($this->currentFileInfo))
+		if( isset($this->options['optional']) && $this->options['optional'] && !file_exists($full_path) && (!$evald->css || !empty($this->currentFileInfo))) {
+			return array();
+		}
+
+
+		// css ?
+		if( $evald->css ){
+			$features = ( $evald->features ? $evald->features->compile($env) : null );
+			return new Less_Tree_Import( $this->compilePath( $env), $features, $this->options, $this->index);
+		}
+
+
+		return $this->ParseImport( $full_path, $uri, $env );
+	}
+
+
+	/**
+	 * Using the import directories, get the full absolute path and uri of the import
+	 *
+	 * @param Less_Tree_Import $evald
+	 */
+    public function PathAndUri(){
+
+		$evald_path = $this->getPath();
+
+		if( $evald_path ){
+
+			$import_dirs = array();
+
+			if( Less_Environment::isPathRelative($evald_path) ){
+				//if the path is relative, the file should be in the current directory
+				$import_dirs[ $this->currentFileInfo['currentDirectory'] ] = $this->currentFileInfo['uri_root'];
+
+			}else{
+				//otherwise, the file should be relative to the server root
+				$import_dirs[ $this->currentFileInfo['entryPath'] ] = $this->currentFileInfo['entryUri'];
+
+				//if the user supplied entryPath isn't the actual root
+				$import_dirs[ $_SERVER['DOCUMENT_ROOT'] ] = '';
+
+			}
+
+			// always look in user supplied import directories
+			$import_dirs = array_merge( $import_dirs, Less_Parser::$options['import_dirs'] );
+
+
+			foreach( $import_dirs as $rootpath => $rooturi){
+				if( is_callable($rooturi) ){
+					list($path, $uri) = call_user_func($rooturi, $evald_path);
+					if( is_string($path) ){
+						$full_path = $path;
+						return array( $full_path, $uri );
+					}
+				}elseif( !empty($rootpath) ){
+
+					$path = rtrim($rootpath,'/\\').'/'.ltrim($evald_path,'/\\');
+
+					if( file_exists($path) ){
+						$full_path = Less_Environment::normalizePath($path);
+						$uri = Less_Environment::normalizePath(dirname($rooturi.$evald_path));
+						return array( $full_path, $uri );
+					} elseif( file_exists($path.'.less') ){
+						$full_path = Less_Environment::normalizePath($path.'.less');
+						$uri = Less_Environment::normalizePath(dirname($rooturi.$evald_path.'.less'));
+						return array( $full_path, $uri );
+					}
+				}
+			}
+		}
+	}
+
+
+	/**
+	 * Parse the import url and return the rules
+	 *
+	 * @return Less_Tree_Media|array
+	 */
+    public function ParseImport( $full_path, $uri, $env ){
+
+		$import_env = clone $env;
+		if( (isset($this->options['reference']) && $this->options['reference']) || isset($this->currentFileInfo['reference']) ){
+			$import_env->currentFileInfo['reference'] = true;
+		}
+
+		if( (isset($this->options['multiple']) && $this->options['multiple']) ){
+			$import_env->importMultiple = true;
+		}
+
+		$parser = new Less_Parser($import_env);
+		$root = $parser->parseFile($full_path, $uri, true);
+
+
+		$ruleset = new Less_Tree_Ruleset(array(), $root->rules );
+		$ruleset->evalImports($import_env);
+
+		return $this->features ? new Less_Tree_Media($ruleset->rules, $this->features->value) : $ruleset->rules;
+	}
+
+
+	/**
+	 * Should the import be skipped?
+	 *
+	 * @return boolean|null
+	 */
+	private function Skip($path, $env){
+
+		$path = Less_Parser::AbsPath($path, true);
+
+		if( $path && Less_Parser::FileParsed($path) ){
+
+			if( isset($this->currentFileInfo['reference']) ){
+				return true;
+			}
+
+			return !isset($this->options['multiple']) && !$env->importMultiple;
+		}
+
+	}
+}
diff --git a/lib/less.php/Tree/Javascript.php b/lib/less.php/Tree/Javascript.php
new file mode 100644
index 0000000..1b03183
--- /dev/null
+++ b/lib/less.php/Tree/Javascript.php
@@ -0,0 +1,30 @@
+<?php
+
+/**
+ * Javascript
+ *
+ * @package Less
+ * @subpackage tree
+ */
+class Less_Tree_Javascript extends Less_Tree{
+
+	public $type = 'Javascript';
+	public $escaped;
+	public $expression;
+	public $index;
+
+	/**
+	 * @param boolean $index
+	 * @param boolean $escaped
+	 */
+	public function __construct($string, $index, $escaped){
+		$this->escaped = $escaped;
+		$this->expression = $string;
+		$this->index = $index;
+	}
+
+	public function compile(){
+		return new Less_Tree_Anonymous('/* Sorry, can not do JavaScript evaluation in PHP... :( */');
+	}
+
+}
diff --git a/lib/less.php/Tree/Keyword.php b/lib/less.php/Tree/Keyword.php
new file mode 100644
index 0000000..e1d98c4
--- /dev/null
+++ b/lib/less.php/Tree/Keyword.php
@@ -0,0 +1,44 @@
+<?php
+
+/**
+ * Keyword
+ *
+ * @package Less
+ * @subpackage tree
+ */
+class Less_Tree_Keyword extends Less_Tree{
+
+	public $value;
+	public $type = 'Keyword';
+
+	/**
+	 * @param string $value
+	 */
+	public function __construct($value){
+		$this->value = $value;
+	}
+
+	public function compile(){
+		return $this;
+	}
+
+    /**
+     * @see Less_Tree::genCSS
+     */
+	public function genCSS( $output ){
+
+		if( $this->value === '%') {
+			throw new Less_Exception_Compiler("Invalid % without number");
+		}
+
+		$output->add( $this->value );
+	}
+
+	public function compare($other) {
+		if ($other instanceof Less_Tree_Keyword) {
+			return $other->value === $this->value ? 0 : 1;
+		} else {
+			return -1;
+		}
+	}
+}
diff --git a/lib/less.php/Tree/Media.php b/lib/less.php/Tree/Media.php
new file mode 100644
index 0000000..f9ee9d4
--- /dev/null
+++ b/lib/less.php/Tree/Media.php
@@ -0,0 +1,179 @@
+<?php
+
+/**
+ * Media
+ *
+ * @package Less
+ * @subpackage tree
+ */
+class Less_Tree_Media extends Less_Tree{
+
+	public $features;
+	public $rules;
+	public $index;
+	public $currentFileInfo;
+	public $isReferenced;
+	public $type = 'Media';
+
+	public function __construct($value = array(), $features = array(), $index = null, $currentFileInfo = null ){
+
+		$this->index = $index;
+		$this->currentFileInfo = $currentFileInfo;
+
+		$selectors = $this->emptySelectors();
+
+		$this->features = new Less_Tree_Value($features);
+
+		$this->rules = array(new Less_Tree_Ruleset($selectors, $value));
+		$this->rules[0]->allowImports = true;
+	}
+
+    public function accept( $visitor ){
+		$this->features = $visitor->visitObj($this->features);
+		$this->rules = $visitor->visitArray($this->rules);
+	}
+
+    /**
+     * @see Less_Tree::genCSS
+     */
+    public function genCSS( $output ){
+
+		$output->add( '@media ', $this->currentFileInfo, $this->index );
+		$this->features->genCSS( $output );
+		Less_Tree::outputRuleset( $output, $this->rules);
+
+	}
+
+	public function compile($env) {
+
+		$media = new Less_Tree_Media(array(), array(), $this->index, $this->currentFileInfo );
+
+		$strictMathBypass = false;
+		if( Less_Parser::$options['strictMath'] === false) {
+			$strictMathBypass = true;
+			Less_Parser::$options['strictMath'] = true;
+		}
+
+		$media->features = $this->features->compile($env);
+
+		if( $strictMathBypass ){
+			Less_Parser::$options['strictMath'] = false;
+		}
+
+		$env->mediaPath[] = $media;
+		$env->mediaBlocks[] = $media;
+
+		array_unshift($env->frames, $this->rules[0]);
+		$media->rules = array($this->rules[0]->compile($env));
+		array_shift($env->frames);
+
+		array_pop($env->mediaPath);
+
+		return !$env->mediaPath ? $media->compileTop($env) : $media->compileNested($env);
+	}
+
+	public function variable($name) {
+		return $this->rules[0]->variable($name);
+	}
+
+	public function find($selector) {
+		return $this->rules[0]->find($selector, $this);
+	}
+
+	public function emptySelectors(){
+		$el = new Less_Tree_Element('','&', $this->index, $this->currentFileInfo );
+		$sels = array( new Less_Tree_Selector(array($el), array(), null, $this->index, $this->currentFileInfo) );
+		$sels[0]->mediaEmpty = true;
+        return $sels;
+	}
+
+	public function markReferenced(){
+		$this->rules[0]->markReferenced();
+		$this->isReferenced = true;
+		Less_Tree::ReferencedArray($this->rules[0]->rules);
+	}
+
+	// evaltop
+	public function compileTop($env) {
+		$result = $this;
+
+		if (count($env->mediaBlocks) > 1) {
+			$selectors = $this->emptySelectors();
+			$result = new Less_Tree_Ruleset($selectors, $env->mediaBlocks);
+			$result->multiMedia = true;
+		}
+
+		$env->mediaBlocks = array();
+		$env->mediaPath = array();
+
+		return $result;
+	}
+
+	public function compileNested($env) {
+		$path = array_merge($env->mediaPath, array($this));
+
+		// Extract the media-query conditions separated with `,` (OR).
+		foreach ($path as $key => $p) {
+			$value = $p->features instanceof Less_Tree_Value ? $p->features->value : $p->features;
+			$path[$key] = is_array($value) ? $value : array($value);
+		}
+
+		// Trace all permutations to generate the resulting media-query.
+		//
+		// (a, b and c) with nested (d, e) ->
+		//	a and d
+		//	a and e
+		//	b and c and d
+		//	b and c and e
+
+		$permuted = $this->permute($path);
+		$expressions = array();
+		foreach($permuted as $path){
+
+			for( $i=0, $len=count($path); $i < $len; $i++){
+				$path[$i] = Less_Parser::is_method($path[$i], 'toCSS') ? $path[$i] : new Less_Tree_Anonymous($path[$i]);
+			}
+
+			for( $i = count($path) - 1; $i > 0; $i-- ){
+				array_splice($path, $i, 0, array(new Less_Tree_Anonymous('and')));
+			}
+
+			$expressions[] = new Less_Tree_Expression($path);
+		}
+		$this->features = new Less_Tree_Value($expressions);
+
+
+
+		// Fake a tree-node that doesn't output anything.
+		return new Less_Tree_Ruleset(array(), array());
+	}
+
+	public function permute($arr) {
+		if (!$arr)
+			return array();
+
+		if (count($arr) == 1)
+			return $arr[0];
+
+		$result = array();
+		$rest = $this->permute(array_slice($arr, 1));
+		foreach ($rest as $r) {
+			foreach ($arr[0] as $a) {
+				$result[] = array_merge(
+					is_array($a) ? $a : array($a),
+					is_array($r) ? $r : array($r)
+				);
+			}
+		}
+
+		return $result;
+	}
+
+    public function bubbleSelectors($selectors) {
+
+		if( !$selectors) return;
+
+		$this->rules = array(new Less_Tree_Ruleset( $selectors, array($this->rules[0])));
+	}
+
+}
diff --git a/lib/less.php/Tree/Mixin/Call.php b/lib/less.php/Tree/Mixin/Call.php
new file mode 100644
index 0000000..04eb426
--- /dev/null
+++ b/lib/less.php/Tree/Mixin/Call.php
@@ -0,0 +1,202 @@
+<?php
+
+
+class Less_Tree_Mixin_Call extends Less_Tree{
+
+	public $selector;
+	public $arguments;
+	public $index;
+	public $currentFileInfo;
+
+	public $important;
+	public $type = 'MixinCall';
+
+	/**
+	 * less.js: tree.mixin.Call
+	 *
+	 */
+	public function __construct($elements, $args, $index, $currentFileInfo, $important = false){
+		$this->selector = new Less_Tree_Selector($elements);
+		$this->arguments = $args;
+		$this->index = $index;
+		$this->currentFileInfo = $currentFileInfo;
+		$this->important = $important;
+	}
+
+	//function accept($visitor){
+	//	$this->selector = $visitor->visit($this->selector);
+	//	$this->arguments = $visitor->visit($this->arguments);
+	//}
+
+
+	public function compile($env){
+
+		$rules = array();
+		$match = false;
+		$isOneFound = false;
+		$candidates = array();
+		$defaultUsed = false;
+		$conditionResult = array();
+
+		$args = array();
+		foreach($this->arguments as $a){
+			$args[] = array('name'=> $a['name'], 'value' => $a['value']->compile($env) );
+		}
+
+		foreach($env->frames as $frame){
+
+			$mixins = $frame->find($this->selector);
+
+			if( !$mixins ){
+				continue;
+			}
+
+			$isOneFound = true;
+			$defNone = 0;
+			$defTrue = 1;
+			$defFalse = 2;
+
+			// To make `default()` function independent of definition order we have two "subpasses" here.
+			// At first we evaluate each guard *twice* (with `default() == true` and `default() == false`),
+			// and build candidate list with corresponding flags. Then, when we know all possible matches,
+			// we make a final decision.
+
+			$mixins_len = count($mixins);
+			for( $m = 0; $m < $mixins_len; $m++ ){
+				$mixin = $mixins[$m];
+
+				if( $this->IsRecursive( $env, $mixin ) ){
+					continue;
+				}
+
+				if( $mixin->matchArgs($args, $env) ){
+
+					$candidate = array('mixin' => $mixin, 'group' => $defNone);
+
+					if( $mixin instanceof Less_Tree_Ruleset ){
+
+						for( $f = 0; $f < 2; $f++ ){
+							Less_Tree_DefaultFunc::value($f);
+							$conditionResult[$f] = $mixin->matchCondition( $args, $env);
+						}
+						if( $conditionResult[0] || $conditionResult[1] ){
+							if( $conditionResult[0] != $conditionResult[1] ){
+								$candidate['group'] = $conditionResult[1] ? $defTrue : $defFalse;
+							}
+
+							$candidates[] = $candidate;
+						}
+					}else{
+						$candidates[] = $candidate;
+					}
+
+					$match = true;
+				}
+			}
+
+			Less_Tree_DefaultFunc::reset();
+
+
+			$count = array(0, 0, 0);
+			for( $m = 0; $m < count($candidates); $m++ ){
+				$count[ $candidates[$m]['group'] ]++;
+			}
+
+			if( $count[$defNone] > 0 ){
+				$defaultResult = $defFalse;
+			} else {
+				$defaultResult = $defTrue;
+				if( ($count[$defTrue] + $count[$defFalse]) > 1 ){
+					throw new Exception( 'Ambiguous use of `default()` found when matching for `' . $this->format($args) . '`' );
+				}
+			}
+
+
+			$candidates_length = count($candidates);
+			$length_1 = ($candidates_length == 1);
+
+			for( $m = 0; $m < $candidates_length; $m++){
+				$candidate = $candidates[$m]['group'];
+				if( ($candidate === $defNone) || ($candidate === $defaultResult) ){
+					try{
+						$mixin = $candidates[$m]['mixin'];
+						if( !($mixin instanceof Less_Tree_Mixin_Definition) ){
+							$mixin = new Less_Tree_Mixin_Definition('', array(), $mixin->rules, null, false);
+							$mixin->originalRuleset = $mixins[$m]->originalRuleset;
+						}
+						$rules = array_merge($rules, $mixin->evalCall($env, $args, $this->important)->rules);
+					} catch (Exception $e) {
+						//throw new Less_Exception_Compiler($e->getMessage(), $e->index, null, $this->currentFileInfo['filename']);
+						throw new Less_Exception_Compiler($e->getMessage(), null, null, $this->currentFileInfo);
+					}
+				}
+			}
+
+			if( $match ){
+				if( !$this->currentFileInfo || !isset($this->currentFileInfo['reference']) || !$this->currentFileInfo['reference'] ){
+					Less_Tree::ReferencedArray($rules);
+				}
+
+				return $rules;
+			}
+		}
+
+		if( $isOneFound ){
+			throw new Less_Exception_Compiler('No matching definition was found for `'.$this->Format( $args ).'`', null, $this->index, $this->currentFileInfo);
+
+		}else{
+			throw new Less_Exception_Compiler(trim($this->selector->toCSS()) . " is undefined in ".$this->currentFileInfo['filename'], null, $this->index);
+		}
+
+	}
+
+	/**
+	 * Format the args for use in exception messages
+	 *
+	 */
+	private function Format($args){
+		$message = array();
+		if( $args ){
+			foreach($args as $a){
+				$argValue = '';
+				if( $a['name'] ){
+					$argValue .= $a['name'] . ':';
+				}
+				if( is_object($a['value']) ){
+					$argValue .= $a['value']->toCSS();
+				}else{
+					$argValue .= '???';
+				}
+				$message[] = $argValue;
+			}
+		}
+		return implode(', ',$message);
+	}
+
+
+	/**
+	 * Are we in a recursive mixin call?
+	 *
+	 * @return bool
+	 */
+	private function IsRecursive( $env, $mixin ){
+
+		foreach($env->frames as $recur_frame){
+			if( !($mixin instanceof Less_Tree_Mixin_Definition) ){
+
+				if( $mixin === $recur_frame ){
+					return true;
+				}
+
+				if( isset($recur_frame->originalRuleset) && $mixin->ruleset_id === $recur_frame->originalRuleset ){
+					return true;
+				}
+			}
+		}
+
+		return false;
+	}
+
+}
+
+
diff --git a/lib/less.php/Tree/Mixin/Definition.php b/lib/less.php/Tree/Mixin/Definition.php
new file mode 100644
index 0000000..b16d688
--- /dev/null
+++ b/lib/less.php/Tree/Mixin/Definition.php
@@ -0,0 +1,241 @@
+<?php
+
+class Less_Tree_Mixin_Definition extends Less_Tree_Ruleset{
+	public $name;
+	public $selectors;
+	public $params;
+	public $arity		= 0;
+	public $rules;
+	public $lookups		= array();
+	public $required	= 0;
+	public $frames		= array();
+	public $condition;
+	public $variadic;
+	public $type		= 'MixinDefinition';
+
+
+	// less.js : /lib/less/tree/mixin.js : tree.mixin.Definition
+	public function __construct($name, $params, $rules, $condition, $variadic = false, $frames = array() ){
+		$this->name = $name;
+		$this->selectors = array(new Less_Tree_Selector(array( new Less_Tree_Element(null, $name))));
+
+		$this->params = $params;
+		$this->condition = $condition;
+		$this->variadic = $variadic;
+		$this->rules = $rules;
+
+		if( $params ){
+			$this->arity = count($params);
+			foreach( $params as $p ){
+				if (! isset($p['name']) || ($p['name'] && !isset($p['value']))) {
+					$this->required++;
+				}
+			}
+		}
+
+		$this->frames = $frames;
+		$this->SetRulesetIndex();
+	}
+
+
+
+	//function accept( $visitor ){
+	//	$this->params = $visitor->visit($this->params);
+	//	$this->rules = $visitor->visit($this->rules);
+	//	$this->condition = $visitor->visit($this->condition);
+	//}
+
+
+	public function toCSS(){
+		return '';
+	}
+
+	// less.js : /lib/less/tree/mixin.js : tree.mixin.Definition.evalParams
+	public function compileParams($env, $mixinFrames, $args = array() , &$evaldArguments = array() ){
+		$frame = new Less_Tree_Ruleset(null, array());
+		$params = $this->params;
+		$mixinEnv = null;
+		$argsLength = 0;
+
+		if( $args ){
+			$argsLength = count($args);
+			for($i = 0; $i < $argsLength; $i++ ){
+				$arg = $args[$i];
+
+				if( $arg && $arg['name'] ){
+					$isNamedFound = false;
+
+					foreach($params as $j => $param){
+						if( !isset($evaldArguments[$j]) && $arg['name'] === $params[$j]['name']) {
+							$evaldArguments[$j] = $arg['value']->compile($env);
+							array_unshift($frame->rules, new Less_Tree_Rule( $arg['name'], $arg['value']->compile($env) ) );
+							$isNamedFound = true;
+							break;
+						}
+					}
+					if ($isNamedFound) {
+						array_splice($args, $i, 1);
+						$i--;
+						$argsLength--;
+						continue;
+					} else {
+						throw new Less_Exception_Compiler("Named argument for " . $this->name .' '.$args[$i]['name'] . ' not found');
+					}
+				}
+			}
+		}
+
+		$argIndex = 0;
+		foreach($params as $i => $param){
+
+			if ( isset($evaldArguments[$i]) ){ continue; }
+
+			$arg = null;
+			if( isset($args[$argIndex]) ){
+				$arg = $args[$argIndex];
+			}
+
+			if (isset($param['name']) && $param['name']) {
+
+				if( isset($param['variadic']) ){
+					$varargs = array();
+					for ($j = $argIndex; $j < $argsLength; $j++) {
+						$varargs[] = $args[$j]['value']->compile($env);
+					}
+					$expression = new Less_Tree_Expression($varargs);
+					array_unshift($frame->rules, new Less_Tree_Rule($param['name'], $expression->compile($env)));
+				}else{
+					$val = ($arg && $arg['value']) ? $arg['value'] : false;
+
+					if ($val) {
+						$val = $val->compile($env);
+					} else if ( isset($param['value']) ) {
+
+						if( !$mixinEnv ){
+							$mixinEnv = new Less_Environment();
+							$mixinEnv->frames = array_merge( array($frame), $mixinFrames);
+						}
+
+						$val = $param['value']->compile($mixinEnv);
+						$frame->resetCache();
+					} else {
+						throw new Less_Exception_Compiler("Wrong number of arguments for " . $this->name . " (" . $argsLength . ' for ' . $this->arity . ")");
+					}
+
+					array_unshift($frame->rules, new Less_Tree_Rule($param['name'], $val));
+					$evaldArguments[$i] = $val;
+				}
+			}
+
+			if ( isset($param['variadic']) && $args) {
+				for ($j = $argIndex; $j < $argsLength; $j++) {
+					$evaldArguments[$j] = $args[$j]['value']->compile($env);
+				}
+			}
+			$argIndex++;
+		}
+
+		ksort($evaldArguments);
+		$evaldArguments = array_values($evaldArguments);
+
+		return $frame;
+	}
+
+	public function compile($env) {
+		if( $this->frames ){
+			return new Less_Tree_Mixin_Definition($this->name, $this->params, $this->rules, $this->condition, $this->variadic, $this->frames );
+		}
+		return new Less_Tree_Mixin_Definition($this->name, $this->params, $this->rules, $this->condition, $this->variadic, $env->frames );
+	}
+
+	public function evalCall($env, $args = NULL, $important = NULL) {
+
+		Less_Environment::$mixin_stack++;
+
+		$_arguments = array();
+
+		if( $this->frames ){
+			$mixinFrames = array_merge($this->frames, $env->frames);
+		}else{
+			$mixinFrames = $env->frames;
+		}
+
+		$frame = $this->compileParams($env, $mixinFrames, $args, $_arguments);
+
+		$ex = new Less_Tree_Expression($_arguments);
+		array_unshift($frame->rules, new Less_Tree_Rule('@arguments', $ex->compile($env)));
+
+
+		$ruleset = new Less_Tree_Ruleset(null, $this->rules);
+		$ruleset->originalRuleset = $this->ruleset_id;
+
+
+		$ruleSetEnv = new Less_Environment();
+		$ruleSetEnv->frames = array_merge( array($this, $frame), $mixinFrames );
+		$ruleset = $ruleset->compile( $ruleSetEnv );
+
+		if( $important ){
+			$ruleset = $ruleset->makeImportant();
+		}
+
+		Less_Environment::$mixin_stack--;
+
+		return $ruleset;
+	}
+
+
+	public function matchCondition($args, $env) {
+
+		if( !$this->condition ){
+			return true;
+		}
+
+		// set array to prevent error on array_merge
+		if(!is_array($this->frames)) {
+             $this->frames = array();
+        }
+
+		$frame = $this->compileParams($env, array_merge($this->frames,$env->frames), $args );
+
+		$compile_env = new Less_Environment();
+		$compile_env->frames = array_merge(
+				array($frame)		// the parameter variables
+				, $this->frames		// the parent namespace/mixin frames
+				, $env->frames		// the current environment frames
+			);
+
+		$compile_env->functions = $env->functions;
+
+		return (bool)$this->condition->compile($compile_env);
+	}
+
+	public function matchArgs($args, $env = NULL){
+		$argsLength = count($args);
+
+		if( !$this->variadic ){
+			if( $argsLength < $this->required ){
+				return false;
+			}
+			if( $argsLength > count($this->params) ){
+				return false;
+			}
+		}else{
+			if( $argsLength < ($this->required - 1)){
+				return false;
+			}
+		}
+
+		$len = min($argsLength, $this->arity);
+
+		for( $i = 0; $i < $len; $i++ ){
+			if( !isset($this->params[$i]['name']) && !isset($this->params[$i]['variadic']) ){
+				if( $args[$i]['value']->compile($env)->toCSS() != $this->params[$i]['value']->compile($env)->toCSS() ){
+					return false;
+				}
+			}
+		}
+
+		return true;
+	}
+
+}
diff --git a/lib/less.php/Tree/NameValue.php b/lib/less.php/Tree/NameValue.php
new file mode 100644
index 0000000..31cbe03
--- /dev/null
+++ b/lib/less.php/Tree/NameValue.php
@@ -0,0 +1,51 @@
+<?php
+
+/**
+ * A simple css name-value pair
+ * ex: width:100px;
+ *
+ * In bootstrap, there are about 600-1,000 simple name-value pairs (depending on how forgiving the match is) -vs- 6,020 dynamic rules (Less_Tree_Rule)
+ * Using the name-value object can speed up bootstrap compilation slightly, but it breaks color keyword interpretation: color:red -> color:#FF0000;
+ *
+ * @package Less
+ * @subpackage tree
+ */
+class Less_Tree_NameValue extends Less_Tree{
+
+	public $name;
+	public $value;
+	public $index;
+	public $currentFileInfo;
+	public $type = 'NameValue';
+	public $important = '';
+
+	public function __construct($name, $value = null, $index = null, $currentFileInfo = null ){
+		$this->name = $name;
+		$this->value = $value;
+		$this->index = $index;
+		$this->currentFileInfo = $currentFileInfo;
+	}
+
+    public function genCSS( $output ){
+
+		$output->add(
+			$this->name
+			. Less_Environment::$_outputMap[': ']
+			. $this->value
+			. $this->important
+			. (((Less_Environment::$lastRule && Less_Parser::$options['compress'])) ? "" : ";")
+			, $this->currentFileInfo, $this->index);
+	}
+
+	public function compile ($env){
+		return $this;
+	}
+
+	public function makeImportant(){
+		$new = new Less_Tree_NameValue($this->name, $this->value, $this->index, $this->currentFileInfo);
+		$new->important = ' !important';
+		return $new;
+	}
+
+
+}
diff --git a/lib/less.php/Tree/Negative.php b/lib/less.php/Tree/Negative.php
new file mode 100644
index 0000000..507443e
--- /dev/null
+++ b/lib/less.php/Tree/Negative.php
@@ -0,0 +1,37 @@
+<?php
+
+/**
+ * Negative
+ *
+ * @package Less
+ * @subpackage tree
+ */
+class Less_Tree_Negative extends Less_Tree{
+
+	public $value;
+	public $type = 'Negative';
+
+    public function __construct($node){
+		$this->value = $node;
+	}
+
+	//function accept($visitor) {
+	//	$this->value = $visitor->visit($this->value);
+	//}
+
+    /**
+     * @see Less_Tree::genCSS
+     */
+    public function genCSS( $output ){
+		$output->add( '-' );
+		$this->value->genCSS( $output );
+	}
+
+    public function compile($env) {
+		if( Less_Environment::isMathOn() ){
+			$ret = new Less_Tree_Operation('*', array( new Less_Tree_Dimension(-1), $this->value ) );
+			return $ret->compile($env);
+		}
+		return new Less_Tree_Negative( $this->value->compile($env) );
+	}
+}
\ No newline at end of file
diff --git a/lib/less.php/Tree/Operation.php b/lib/less.php/Tree/Operation.php
new file mode 100644
index 0000000..e69e0da
--- /dev/null
+++ b/lib/less.php/Tree/Operation.php
@@ -0,0 +1,70 @@
+<?php
+
+/**
+ * Operation
+ *
+ * @package Less
+ * @subpackage tree
+ */
+class Less_Tree_Operation extends Less_Tree{
+
+	public $op;
+	public $operands;
+	public $isSpaced;
+	public $type = 'Operation';
+
+	/**
+	 * @param string $op
+	 */
+	public function __construct($op, $operands, $isSpaced = false){
+		$this->op = trim($op);
+		$this->operands = $operands;
+		$this->isSpaced = $isSpaced;
+	}
+
+    public function accept($visitor) {
+		$this->operands = $visitor->visitArray($this->operands);
+	}
+
+	public function compile($env){
+		$a = $this->operands[0]->compile($env);
+		$b = $this->operands[1]->compile($env);
+
+
+		if( Less_Environment::isMathOn() ){
+
+			if( $a instanceof Less_Tree_Dimension && $b instanceof Less_Tree_Color ){
+				$a = $a->toColor();
+
+			}elseif( $b instanceof Less_Tree_Dimension && $a instanceof Less_Tree_Color ){
+				$b = $b->toColor();
+
+			}
+
+			if( !method_exists($a,'operate') ){
+				throw new Less_Exception_Compiler("Operation on an invalid type");
+			}
+
+			return $a->operate( $this->op, $b);
+		}
+
+		return new Less_Tree_Operation($this->op, array($a, $b), $this->isSpaced );
+	}
+
+
+    /**
+     * @see Less_Tree::genCSS
+     */
+    public function genCSS( $output ){
+		$this->operands[0]->genCSS( $output );
+		if( $this->isSpaced ){
+			$output->add( " " );
+		}
+		$output->add( $this->op );
+		if( $this->isSpaced ){
+			$output->add( ' ' );
+		}
+		$this->operands[1]->genCSS( $output );
+	}
+
+}
diff --git a/lib/less.php/Tree/Paren.php b/lib/less.php/Tree/Paren.php
new file mode 100644
index 0000000..0186455
--- /dev/null
+++ b/lib/less.php/Tree/Paren.php
@@ -0,0 +1,35 @@
+<?php
+
+/**
+ * Paren
+ *
+ * @package Less
+ * @subpackage tree
+ */
+class Less_Tree_Paren extends Less_Tree{
+
+	public $value;
+	public $type = 'Paren';
+
+	public function __construct($value) {
+		$this->value = $value;
+	}
+
+    public function accept($visitor){
+		$this->value = $visitor->visitObj($this->value);
+	}
+
+    /**
+     * @see Less_Tree::genCSS
+     */
+    public function genCSS( $output ){
+		$output->add( '(' );
+		$this->value->genCSS( $output );
+		$output->add( ')' );
+	}
+
+	public function compile($env) {
+		return new Less_Tree_Paren($this->value->compile($env));
+	}
+
+}
diff --git a/lib/less.php/Tree/Quoted.php b/lib/less.php/Tree/Quoted.php
new file mode 100644
index 0000000..80063b5
--- /dev/null
+++ b/lib/less.php/Tree/Quoted.php
@@ -0,0 +1,81 @@
+<?php
+
+/**
+ * Quoted
+ *
+ * @package Less
+ * @subpackage tree
+ */
+class Less_Tree_Quoted extends Less_Tree{
+	public $escaped;
+	public $value;
+	public $quote;
+	public $index;
+	public $currentFileInfo;
+	public $type = 'Quoted';
+
+	/**
+	 * @param string $str
+	 */
+	public function __construct($str, $content = '', $escaped = false, $index = false, $currentFileInfo = null ){
+		$this->escaped = $escaped;
+		$this->value = $content;
+		if( $str ){
+			$this->quote = $str[0];
+		}
+		$this->index = $index;
+		$this->currentFileInfo = $currentFileInfo;
+	}
+
+    /**
+     * @see Less_Tree::genCSS
+     */
+    public function genCSS( $output ){
+		if( !$this->escaped ){
+			$output->add( $this->quote, $this->currentFileInfo, $this->index );
+        }
+        $output->add( $this->value );
+        if( !$this->escaped ){
+			$output->add( $this->quote );
+        }
+    }
+
+	public function compile($env){
+
+		$value = $this->value;
+		if( preg_match_all('/`([^`]+)`/', $this->value, $matches) ){
+			foreach($matches as $i => $match){
+				$js = new Less_Tree_JavaScript($matches[1], $this->index, true);
+				$js = $js->compile()->value;
+				$value = str_replace($matches[0][$i], $js, $value);
+			}
+		}
+
+		if( preg_match_all('/@\{([\w-]+)\}/',$value,$matches) ){
+			foreach($matches[1] as $i => $match){
+				$v = new Less_Tree_Variable('@' . $match, $this->index, $this->currentFileInfo );
+				$v = $v->compile($env);
+				$v = ($v instanceof Less_Tree_Quoted) ? $v->value : $v->toCSS();
+				$value = str_replace($matches[0][$i], $v, $value);
+			}
+		}
+
+		return new Less_Tree_Quoted($this->quote . $value . $this->quote, $value, $this->escaped, $this->index, $this->currentFileInfo);
+	}
+
+    public function compare($x) {
+
+		if( !Less_Parser::is_method($x, 'toCSS') ){
+			return -1;
+		}
+
+		$left = $this->toCSS();
+		$right = $x->toCSS();
+
+		if ($left === $right) {
+			return 0;
+		}
+
+		return $left < $right ? -1 : 1;
+	}
+}
diff --git a/lib/less.php/Tree/Rule.php b/lib/less.php/Tree/Rule.php
new file mode 100644
index 0000000..ee4a9e2
--- /dev/null
+++ b/lib/less.php/Tree/Rule.php
@@ -0,0 +1,115 @@
+<?php
+
+/**
+ * Rule
+ *
+ * @package Less
+ * @subpackage tree
+ */
+class Less_Tree_Rule extends Less_Tree{
+
+	public $name;
+	public $value;
+	public $important;
+	public $merge;
+	public $index;
+	public $inline;
+	public $variable;
+	public $currentFileInfo;
+	public $type = 'Rule';
+
+	/**
+	 * @param string $important
+	 */
+	public function __construct($name, $value = null, $important = null, $merge = null, $index = null, $currentFileInfo = null,  $inline = false){
+		$this->name = $name;
+		$this->value = ($value instanceof Less_Tree_Value || $value instanceof Less_Tree_Ruleset) ? $value : new Less_Tree_Value(array($value));
+		$this->important = $important ? ' ' . trim($important) : '';
+		$this->merge = $merge;
+		$this->index = $index;
+		$this->currentFileInfo = $currentFileInfo;
+		$this->inline = $inline;
+		$this->variable = ( is_string($name) && $name[0] === '@');
+	}
+
+    public function accept($visitor) {
+		$this->value = $visitor->visitObj( $this->value );
+	}
+
+    /**
+     * @see Less_Tree::genCSS
+     */
+    public function genCSS( $output ){
+
+		$output->add( $this->name . Less_Environment::$_outputMap[': '], $this->currentFileInfo, $this->index);
+		try{
+			$this->value->genCSS( $output);
+
+		}catch( Less_Exception_Parser $e ){
+			$e->index = $this->index;
+			$e->currentFile = $this->currentFileInfo;
+			throw $e;
+		}
+		$output->add( $this->important . (($this->inline || (Less_Environment::$lastRule && Less_Parser::$options['compress'])) ? "" : ";"), $this->currentFileInfo, $this->index);
+	}
+
+	public function compile ($env){
+
+		$name = $this->name;
+		if( is_array($name) ){
+			// expand 'primitive' name directly to get
+			// things faster (~10% for benchmark.less):
+			if( count($name) === 1 && $name[0] instanceof Less_Tree_Keyword ){
+				$name = $name[0]->value;
+			}else{
+				$name = $this->CompileName($env,$name);
+			}
+		}
+
+		$strictMathBypass = Less_Parser::$options['strictMath'];
+		if( $name === "font" && !Less_Parser::$options['strictMath'] ){
+			Less_Parser::$options['strictMath'] = true;
+		}
+
+		try {
+			$evaldValue = $this->value->compile($env);
+
+			if( !$this->variable && $evaldValue->type === "DetachedRuleset") {
+				throw new Less_Exception_Compiler("Rulesets cannot be evaluated on a property.", null, $this->index, $this->currentFileInfo);
+			}
+
+			if( Less_Environment::$mixin_stack ){
+				$return = new Less_Tree_Rule($name, $evaldValue, $this->important, $this->merge, $this->index, $this->currentFileInfo, $this->inline);
+			}else{
+				$this->name = $name;
+				$this->value = $evaldValue;
+				$return = $this;
+			}
+
+		}catch( Less_Exception_Parser $e ){
+			if( !is_numeric($e->index) ){
+				$e->index = $this->index;
+				$e->currentFile = $this->currentFileInfo;
+			}
+			throw $e;
+		}
+
+		Less_Parser::$options['strictMath'] = $strictMathBypass;
+
+		return $return;
+	}
+
+
+    public function CompileName( $env, $name ){
+		$output = new Less_Output();
+		foreach($name as $n){
+			$n->compile($env)->genCSS($output);
+		}
+		return $output->toString();
+	}
+
+    public function makeImportant(){
+		return new Less_Tree_Rule($this->name, $this->value, '!important', $this->merge, $this->index, $this->currentFileInfo, $this->inline);
+	}
+
+}
diff --git a/lib/less.php/Tree/Ruleset.php b/lib/less.php/Tree/Ruleset.php
new file mode 100644
index 0000000..bdf9fec
--- /dev/null
+++ b/lib/less.php/Tree/Ruleset.php
@@ -0,0 +1,643 @@
+<?php
+
+/**
+ * Ruleset
+ *
+ * @package Less
+ * @subpackage tree
+ */
+class Less_Tree_Ruleset extends Less_Tree{
+
+	protected $lookups;
+	public $_variables;
+	public $_rulesets;
+
+	public $strictImports;
+
+	public $selectors;
+	public $rules;
+	public $root;
+	public $allowImports;
+	public $paths;
+	public $firstRoot;
+	public $type = 'Ruleset';
+	public $multiMedia;
+	public $allExtends;
+
+	public $ruleset_id;
+	public $originalRuleset;
+
+	public $first_oelements;
+
+	public function SetRulesetIndex(){
+		$this->ruleset_id = Less_Parser::$next_id++;
+		$this->originalRuleset = $this->ruleset_id;
+
+		if( $this->selectors ){
+			foreach($this->selectors as $sel){
+				if( $sel->_oelements ){
+					$this->first_oelements[$sel->_oelements[0]] = true;
+				}
+			}
+		}
+	}
+
+	public function __construct($selectors, $rules, $strictImports = null){
+		$this->selectors = $selectors;
+		$this->rules = $rules;
+		$this->lookups = array();
+		$this->strictImports = $strictImports;
+		$this->SetRulesetIndex();
+	}
+
+	public function accept( $visitor ){
+		if( $this->paths ){
+			$paths_len = count($this->paths);
+			for($i = 0,$paths_len; $i < $paths_len; $i++ ){
+				$this->paths[$i] = $visitor->visitArray($this->paths[$i]);
+			}
+		}elseif( $this->selectors ){
+			$this->selectors = $visitor->visitArray($this->selectors);
+		}
+
+		if( $this->rules ){
+			$this->rules = $visitor->visitArray($this->rules);
+		}
+	}
+
+	public function compile($env){
+
+		$ruleset = $this->PrepareRuleset($env);
+
+
+		// Store the frames around mixin definitions,
+		// so they can be evaluated like closures when the time comes.
+		$rsRuleCnt = count($ruleset->rules);
+		for( $i = 0; $i < $rsRuleCnt; $i++ ){
+			if( $ruleset->rules[$i] instanceof Less_Tree_Mixin_Definition || $ruleset->rules[$i] instanceof Less_Tree_DetachedRuleset ){
+				$ruleset->rules[$i] = $ruleset->rules[$i]->compile($env);
+			}
+		}
+
+		$mediaBlockCount = 0;
+		if( $env instanceof Less_Environment ){
+			$mediaBlockCount = count($env->mediaBlocks);
+		}
+
+		// Evaluate mixin calls.
+		$this->EvalMixinCalls( $ruleset, $env, $rsRuleCnt );
+
+
+		// Evaluate everything else
+		for( $i=0; $i<$rsRuleCnt; $i++ ){
+			if(! ($ruleset->rules[$i] instanceof Less_Tree_Mixin_Definition || $ruleset->rules[$i] instanceof Less_Tree_DetachedRuleset) ){
+				$ruleset->rules[$i] = $ruleset->rules[$i]->compile($env);
+			}
+		}
+
+        // Evaluate everything else
+		for( $i=0; $i<$rsRuleCnt; $i++ ){
+			$rule = $ruleset->rules[$i];
+
+            // for rulesets, check if it is a css guard and can be removed
+			if( $rule instanceof Less_Tree_Ruleset && $rule->selectors && count($rule->selectors) === 1 ){
+
+                // check if it can be folded in (e.g. & where)
+				if( $rule->selectors[0]->isJustParentSelector() ){
+					array_splice($ruleset->rules,$i--,1);
+					$rsRuleCnt--;
+
+					for($j = 0; $j < count($rule->rules); $j++ ){
+						$subRule = $rule->rules[$j];
+						if( !($subRule instanceof Less_Tree_Rule) || !$subRule->variable ){
+							array_splice($ruleset->rules, ++$i, 0, array($subRule));
+							$rsRuleCnt++;
+						}
+					}
+
+                }
+            }
+        }
+
+
+		// Pop the stack
+		$env->shiftFrame();
+
+		if ($mediaBlockCount) {
+			$len = count($env->mediaBlocks);
+			for($i = $mediaBlockCount; $i < $len; $i++ ){
+				$env->mediaBlocks[$i]->bubbleSelectors($ruleset->selectors);
+			}
+		}
+
+		return $ruleset;
+	}
+
+	/**
+	 * Compile Less_Tree_Mixin_Call objects
+	 *
+	 * @param Less_Tree_Ruleset $ruleset
+	 * @param integer $rsRuleCnt
+	 */
+	private function EvalMixinCalls( $ruleset, $env, &$rsRuleCnt ){
+		for($i=0; $i < $rsRuleCnt; $i++){
+			$rule = $ruleset->rules[$i];
+
+			if( $rule instanceof Less_Tree_Mixin_Call ){
+				$rule = $rule->compile($env);
+
+				$temp = array();
+				foreach($rule as $r){
+					if( ($r instanceof Less_Tree_Rule) && $r->variable ){
+						// do not pollute the scope if the variable is
+						// already there. consider returning false here
+						// but we need a way to "return" variable from mixins
+						if( !$ruleset->variable($r->name) ){
+							$temp[] = $r;
+						}
+					}else{
+						$temp[] = $r;
+					}
+				}
+				$temp_count = count($temp)-1;
+				array_splice($ruleset->rules, $i, 1, $temp);
+				$rsRuleCnt += $temp_count;
+				$i += $temp_count;
+				$ruleset->resetCache();
+
+			}elseif( $rule instanceof Less_Tree_RulesetCall ){
+
+				$rule = $rule->compile($env);
+				$rules = array();
+				foreach($rule->rules as $r){
+					if( ($r instanceof Less_Tree_Rule) && $r->variable ){
+						continue;
+					}
+					$rules[] = $r;
+				}
+
+				array_splice($ruleset->rules, $i, 1, $rules);
+				$temp_count = count($rules);
+				$rsRuleCnt += $temp_count - 1;
+				$i += $temp_count-1;
+				$ruleset->resetCache();
+			}
+
+		}
+	}
+
+
+	/**
+	 * Compile the selectors and create a new ruleset object for the compile() method
+	 *
+	 */
+	private function PrepareRuleset($env){
+
+		$hasOnePassingSelector = false;
+		$selectors = array();
+		if( $this->selectors ){
+			Less_Tree_DefaultFunc::error("it is currently only allowed in parametric mixin guards,");
+
+			foreach($this->selectors as $s){
+				$selector = $s->compile($env);
+				$selectors[] = $selector;
+				if( $selector->evaldCondition ){
+					$hasOnePassingSelector = true;
+				}
+			}
+
+			Less_Tree_DefaultFunc::reset();
+		} else {
+			$hasOnePassingSelector = true;
+		}
+
+		if( $this->rules && $hasOnePassingSelector ){
+			$rules = $this->rules;
+		}else{
+			$rules = array();
+		}
+
+		$ruleset = new Less_Tree_Ruleset($selectors, $rules, $this->strictImports);
+
+		$ruleset->originalRuleset = $this->ruleset_id;
+
+		$ruleset->root = $this->root;
+		$ruleset->firstRoot = $this->firstRoot;
+		$ruleset->allowImports = $this->allowImports;
+
+
+		// push the current ruleset to the frames stack
+		$env->unshiftFrame($ruleset);
+
+
+		// Evaluate imports
+		if( $ruleset->root || $ruleset->allowImports || !$ruleset->strictImports ){
+			$ruleset->evalImports($env);
+		}
+
+		return $ruleset;
+	}
+
+	function evalImports($env) {
+
+		$rules_len = count($this->rules);
+		for($i=0; $i < $rules_len; $i++){
+			$rule = $this->rules[$i];
+
+			if( $rule instanceof Less_Tree_Import ){
+				$rules = $rule->compile($env);
+				if( is_array($rules) ){
+					array_splice($this->rules, $i, 1, $rules);
+					$temp_count = count($rules)-1;
+					$i += $temp_count;
+					$rules_len += $temp_count;
+				}else{
+					array_splice($this->rules, $i, 1, array($rules));
+				}
+
+				$this->resetCache();
+			}
+		}
+	}
+
+	function makeImportant(){
+
+		$important_rules = array();
+		foreach($this->rules as $rule){
+			if( $rule instanceof Less_Tree_Rule || $rule instanceof Less_Tree_Ruleset || $rule instanceof Less_Tree_NameValue ){
+				$important_rules[] = $rule->makeImportant();
+			}else{
+				$important_rules[] = $rule;
+			}
+		}
+
+		return new Less_Tree_Ruleset($this->selectors, $important_rules, $this->strictImports );
+	}
+
+	public function matchArgs($args){
+		return !$args;
+	}
+
+	// lets you call a css selector with a guard
+	public function matchCondition( $args, $env ){
+		$lastSelector = end($this->selectors);
+
+		if( !$lastSelector->evaldCondition ){
+			return false;
+		}
+		if( $lastSelector->condition && !$lastSelector->condition->compile( $env->copyEvalEnv( $env->frames ) ) ){
+			return false;
+		}
+		return true;
+	}
+
+	function resetCache(){
+		$this->_rulesets = null;
+		$this->_variables = null;
+		$this->lookups = array();
+	}
+
+	public function variables(){
+		$this->_variables = array();
+		foreach( $this->rules as $r){
+			if ($r instanceof Less_Tree_Rule && $r->variable === true) {
+				$this->_variables[$r->name] = $r;
+			}
+		}
+	}
+
+	public function variable($name){
+
+		if( is_null($this->_variables) ){
+			$this->variables();
+		}
+		return isset($this->_variables[$name]) ? $this->_variables[$name] : null;
+	}
+
+	public function find( $selector, $self = null ){
+
+		$key = implode(' ',$selector->_oelements);
+
+		if( !isset($this->lookups[$key]) ){
+
+			if( !$self ){
+				$self = $this->ruleset_id;
+			}
+
+			$this->lookups[$key] = array();
+
+			$first_oelement = $selector->_oelements[0];
+
+			foreach($this->rules as $rule){
+				if( $rule instanceof Less_Tree_Ruleset && $rule->ruleset_id != $self ){
+
+					if( isset($rule->first_oelements[$first_oelement]) ){
+
+						foreach( $rule->selectors as $ruleSelector ){
+							$match = $selector->match($ruleSelector);
+							if( $match ){
+								if( $selector->elements_len > $match ){
+									$this->lookups[$key] = array_merge($this->lookups[$key], $rule->find( new Less_Tree_Selector(array_slice($selector->elements, $match)), $self));
+								} else {
+									$this->lookups[$key][] = $rule;
+								}
+								break;
+							}
+						}
+					}
+				}
+			}
+		}
+
+		return $this->lookups[$key];
+	}
+
+
+	/**
+	 * @see Less_Tree::genCSS
+	 */
+	public function genCSS( $output ){
+
+		if( !$this->root ){
+			Less_Environment::$tabLevel++;
+		}
+
+		$tabRuleStr = $tabSetStr = '';
+		if( !Less_Parser::$options['compress'] ){
+			if( Less_Environment::$tabLevel ){
+				$tabRuleStr = "\n".str_repeat( Less_Parser::$options['indentation'] , Less_Environment::$tabLevel );
+				$tabSetStr = "\n".str_repeat( Less_Parser::$options['indentation'] , Less_Environment::$tabLevel-1 );
+			}else{
+				$tabSetStr = $tabRuleStr = "\n";
+			}
+		}
+
+
+		$ruleNodes = array();
+		$rulesetNodes = array();
+		foreach($this->rules as $rule){
+
+			$class = get_class($rule);
+			if( ($class === 'Less_Tree_Media') || ($class === 'Less_Tree_Directive') || ($this->root && $class === 'Less_Tree_Comment') || ($class === 'Less_Tree_Ruleset' && $rule->rules) ){
+				$rulesetNodes[] = $rule;
+			}else{
+				$ruleNodes[] = $rule;
+			}
+		}
+
+		// If this is the root node, we don't render
+		// a selector, or {}.
+		if( !$this->root ){
+
+			/*
+			debugInfo = tree.debugInfo(env, this, tabSetStr);
+
+			if (debugInfo) {
+				output.add(debugInfo);
+				output.add(tabSetStr);
+			}
+			*/
+
+			$paths_len = count($this->paths);
+			for( $i = 0; $i < $paths_len; $i++ ){
+				$path = $this->paths[$i];
+				$firstSelector = true;
+
+				foreach($path as $p){
+					$p->genCSS( $output, $firstSelector );
+					$firstSelector = false;
+				}
+
+				if( $i + 1 < $paths_len ){
+					$output->add( ',' . $tabSetStr );
+				}
+			}
+
+			$output->add( (Less_Parser::$options['compress'] ? '{' : " {") . $tabRuleStr );
+		}
+
+		// Compile rules and rulesets
+		$ruleNodes_len = count($ruleNodes);
+		$rulesetNodes_len = count($rulesetNodes);
+		for( $i = 0; $i < $ruleNodes_len; $i++ ){
+			$rule = $ruleNodes[$i];
+
+			// @page{ directive ends up with root elements inside it, a mix of rules and rulesets
+			// In this instance we do not know whether it is the last property
+			if( $i + 1 === $ruleNodes_len && (!$this->root || $rulesetNodes_len === 0 || $this->firstRoot ) ){
+				Less_Environment::$lastRule = true;
+			}
+
+			$rule->genCSS( $output );
+
+			if( !Less_Environment::$lastRule ){
+				$output->add( $tabRuleStr );
+			}else{
+				Less_Environment::$lastRule = false;
+			}
+		}
+
+		if( !$this->root ){
+			$output->add( $tabSetStr . '}' );
+			Less_Environment::$tabLevel--;
+		}
+
+		$firstRuleset = true;
+		$space = ($this->root ? $tabRuleStr : $tabSetStr);
+		for( $i = 0; $i < $rulesetNodes_len; $i++ ){
+
+			if( $ruleNodes_len && $firstRuleset ){
+				$output->add( $space );
+			}elseif( !$firstRuleset ){
+				$output->add( $space );
+			}
+			$firstRuleset = false;
+			$rulesetNodes[$i]->genCSS( $output);
+		}
+
+		if( !Less_Parser::$options['compress'] && $this->firstRoot ){
+			$output->add( "\n" );
+		}
+
+	}
+
+
+	function markReferenced(){
+		if( !$this->selectors ){
+			return;
+		}
+		foreach($this->selectors as $selector){
+			$selector->markReferenced();
+		}
+	}
+
+	public function joinSelectors( $context, $selectors ){
+		$paths = array();
+		if( is_array($selectors) ){
+			foreach($selectors as $selector) {
+				$this->joinSelector( $paths, $context, $selector);
+			}
+		}
+		return $paths;
+	}
+
+	public function joinSelector( &$paths, $context, $selector){
+
+		$hasParentSelector = false;
+
+		foreach($selector->elements as $el) {
+			if( $el->value === '&') {
+				$hasParentSelector = true;
+			}
+		}
+
+		if( !$hasParentSelector ){
+			if( $context ){
+				foreach($context as $context_el){
+					$paths[] = array_merge($context_el, array($selector) );
+				}
+			}else {
+				$paths[] = array($selector);
+			}
+			return;
+		}
+
+
+		// The paths are [[Selector]]
+		// The first list is a list of comma separated selectors
+		// The inner list is a list of inheritance separated selectors
+		// e.g.
+		// .a, .b {
+		//   .c {
+		//   }
+		// }
+		// == [[.a] [.c]] [[.b] [.c]]
+		//
+
+		// the elements from the current selector so far
+		$currentElements = array();
+		// the current list of new selectors to add to the path.
+		// We will build it up. We initiate it with one empty selector as we "multiply" the new selectors
+		// by the parents
+		$newSelectors = array(array());
+
+
+		foreach( $selector->elements as $el){
+
+			// non parent reference elements just get added
+			if( $el->value !== '&' ){
+				$currentElements[] = $el;
+			} else {
+				// the new list of selectors to add
+				$selectorsMultiplied = array();
+
+				// merge the current list of non parent selector elements
+				// on to the current list of selectors to add
+				if( $currentElements ){
+					$this->mergeElementsOnToSelectors( $currentElements, $newSelectors);
+				}
+
+				// loop through our current selectors
+				foreach($newSelectors as $sel){
+
+					// if we don't have any parent paths, the & might be in a mixin so that it can be used
+					// whether there are parents or not
+					if( !$context ){
+						// the combinator used on el should now be applied to the next element instead so that
+						// it is not lost
+						if( $sel ){
+							$sel[0]->elements = array_slice($sel[0]->elements,0);
+							$sel[0]->elements[] = new Less_Tree_Element($el->combinator, '', $el->index, $el->currentFileInfo );
+						}
+						$selectorsMultiplied[] = $sel;
+					}else {
+
+						// and the parent selectors
+						foreach($context as $parentSel){
+							// We need to put the current selectors
+							// then join the last selector's elements on to the parents selectors
+
+							// our new selector path
+							$newSelectorPath = array();
+							// selectors from the parent after the join
+							$afterParentJoin = array();
+							$newJoinedSelectorEmpty = true;
+
+							//construct the joined selector - if & is the first thing this will be empty,
+							// if not newJoinedSelector will be the last set of elements in the selector
+							if( $sel ){
+								$newSelectorPath = $sel;
+								$lastSelector = array_pop($newSelectorPath);
+								$newJoinedSelector = $selector->createDerived( array_slice($lastSelector->elements,0) );
+								$newJoinedSelectorEmpty = false;
+							}
+							else {
+								$newJoinedSelector = $selector->createDerived(array());
+							}
+
+							//put together the parent selectors after the join
+							if ( count($parentSel) > 1) {
+								$afterParentJoin = array_merge($afterParentJoin, array_slice($parentSel,1) );
+							}
+
+							if ( $parentSel ){
+								$newJoinedSelectorEmpty = false;
+
+								// join the elements so far with the first part of the parent
+								$newJoinedSelector->elements[] = new Less_Tree_Element( $el->combinator, $parentSel[0]->elements[0]->value, $el->index, $el->currentFileInfo);
+
+								$newJoinedSelector->elements = array_merge( $newJoinedSelector->elements, array_slice($parentSel[0]->elements, 1) );
+							}
+
+							if (!$newJoinedSelectorEmpty) {
+								// now add the joined selector
+								$newSelectorPath[] = $newJoinedSelector;
+							}
+
+							// and the rest of the parent
+							$newSelectorPath = array_merge($newSelectorPath, $afterParentJoin);
+
+							// add that to our new set of selectors
+							$selectorsMultiplied[] = $newSelectorPath;
+						}
+					}
+				}
+
+				// our new selectors has been multiplied, so reset the state
+				$newSelectors = $selectorsMultiplied;
+				$currentElements = array();
+			}
+		}
+
+		// if we have any elements left over (e.g. .a& .b == .b)
+		// add them on to all the current selectors
+		if( $currentElements ){
+			$this->mergeElementsOnToSelectors($currentElements, $newSelectors);
+		}
+		foreach( $newSelectors as $new_sel){
+			if( $new_sel ){
+				$paths[] = $new_sel;
+			}
+		}
+	}
+
+	function mergeElementsOnToSelectors( $elements, &$selectors){
+
+		if( !$selectors ){
+			$selectors[] = array( new Less_Tree_Selector($elements) );
+			return;
+		}
+
+
+		foreach( $selectors as &$sel){
+
+			// if the previous thing in sel is a parent this needs to join on to it
+			if( $sel ){
+				$last = count($sel)-1;
+				$sel[$last] = $sel[$last]->createDerived( array_merge($sel[$last]->elements, $elements) );
+			}else{
+				$sel[] = new Less_Tree_Selector( $elements );
+			}
+		}
+	}
+}
diff --git a/lib/less.php/Tree/RulesetCall.php b/lib/less.php/Tree/RulesetCall.php
new file mode 100644
index 0000000..ed4c723
--- /dev/null
+++ b/lib/less.php/Tree/RulesetCall.php
@@ -0,0 +1,26 @@
+<?php
+
+/**
+ * RulesetCall
+ *
+ * @package Less
+ * @subpackage tree
+ */
+class Less_Tree_RulesetCall extends Less_Tree{
+
+	public $variable;
+	public $type = "RulesetCall";
+
+    public function __construct($variable){
+		$this->variable = $variable;
+	}
+
+    public function accept($visitor) {}
+
+    public function compile( $env ){
+		$variable = new Less_Tree_Variable($this->variable);
+		$detachedRuleset = $variable->compile($env);
+		return $detachedRuleset->callEval($env);
+	}
+}
+
diff --git a/lib/less.php/Tree/Selector.php b/lib/less.php/Tree/Selector.php
new file mode 100644
index 0000000..6b9dae6
--- /dev/null
+++ b/lib/less.php/Tree/Selector.php
@@ -0,0 +1,168 @@
+<?php
+
+/**
+ * Selector
+ *
+ * @package Less
+ * @subpackage tree
+ */
+class Less_Tree_Selector extends Less_Tree{
+
+	public $elements;
+	public $condition;
+	public $extendList = array();
+	public $_css;
+	public $index;
+	public $evaldCondition = false;
+	public $type = 'Selector';
+	public $currentFileInfo = array();
+	public $isReferenced;
+	public $mediaEmpty;
+
+	public $elements_len = 0;
+
+	public $_oelements;
+	public $_oelements_len;
+	public $cacheable = true;
+
+	/**
+	 * @param boolean $isReferenced
+	 */
+	public function __construct( $elements, $extendList = array() , $condition = null, $index=null, $currentFileInfo=null, $isReferenced=null ){
+
+		$this->elements = $elements;
+		$this->elements_len = count($elements);
+		$this->extendList = $extendList;
+		$this->condition = $condition;
+		if( $currentFileInfo ){
+			$this->currentFileInfo = $currentFileInfo;
+		}
+		$this->isReferenced = $isReferenced;
+		if( !$condition ){
+			$this->evaldCondition = true;
+		}
+
+		$this->CacheElements();
+	}
+
+    public function accept($visitor) {
+		$this->elements = $visitor->visitArray($this->elements);
+		$this->extendList = $visitor->visitArray($this->extendList);
+		if( $this->condition ){
+			$this->condition = $visitor->visitObj($this->condition);
+		}
+
+		if( $visitor instanceof Less_Visitor_extendFinder ){
+			$this->CacheElements();
+		}
+	}
+
+    public function createDerived( $elements, $extendList = null, $evaldCondition = null ){
+		$newSelector = new Less_Tree_Selector( $elements, ($extendList ? $extendList : $this->extendList), null, $this->index, $this->currentFileInfo, $this->isReferenced);
+		$newSelector->evaldCondition = $evaldCondition ? $evaldCondition : $this->evaldCondition;
+		return $newSelector;
+	}
+
+
+	public function match( $other ){
+
+		if( !$other->_oelements || ($this->elements_len < $other->_oelements_len) ){
+			return 0;
+		}
+
+		for( $i = 0; $i < $other->_oelements_len; $i++ ){
+			if( $this->elements[$i]->value !== $other->_oelements[$i]) {
+				return 0;
+			}
+		}
+
+		return $other->_oelements_len; // return number of matched elements
+	}
+
+
+	public function CacheElements(){
+
+		$this->_oelements = array();
+		$css = '';
+
+		foreach($this->elements as $v){
+
+			$css .= $v->combinator;
+			if( !$v->value_is_object ){
+				$css .= $v->value;
+				continue;
+			}
+
+			if( !property_exists($v->value,'value') || !is_string($v->value->value) ){
+				$this->cacheable = false;
+				return;
+			}
+			$css .= $v->value->value;
+		}
+
+		$this->_oelements_len = preg_match_all('/[,&#\.\w-](?:[\w-]|(?:\\\\.))*/', $css, $matches);
+		if( $this->_oelements_len ){
+			$this->_oelements = $matches[0];
+
+			if( $this->_oelements[0] === '&' ){
+				array_shift($this->_oelements);
+				$this->_oelements_len--;
+			}
+		}
+	}
+
+	public function isJustParentSelector(){
+		return !$this->mediaEmpty &&
+			count($this->elements) === 1 &&
+			$this->elements[0]->value === '&' &&
+			($this->elements[0]->combinator === ' ' || $this->elements[0]->combinator === '');
+	}
+
+	public function compile($env) {
+
+		$elements = array();
+		foreach($this->elements as $el){
+			$elements[] = $el->compile($env);
+		}
+
+		$extendList = array();
+		foreach($this->extendList as $el){
+			$extendList[] = $el->compile($el);
+		}
+
+		$evaldCondition = false;
+		if( $this->condition ){
+			$evaldCondition = $this->condition->compile($env);
+		}
+
+		return $this->createDerived( $elements, $extendList, $evaldCondition );
+	}
+
+
+	/**
+	 * @see Less_Tree::genCSS
+	 */
+    public function genCSS( $output, $firstSelector = true ){
+
+		if( !$firstSelector && $this->elements[0]->combinator === "" ){
+			$output->add(' ', $this->currentFileInfo, $this->index);
+		}
+
+		foreach($this->elements as $element){
+			$element->genCSS( $output );
+		}
+	}
+
+    public function markReferenced(){
+		$this->isReferenced = true;
+	}
+
+    public function getIsReferenced(){
+		return !isset($this->currentFileInfo['reference']) || !$this->currentFileInfo['reference'] || $this->isReferenced;
+	}
+
+    public function getIsOutput(){
+		return $this->evaldCondition;
+	}
+
+}
diff --git a/lib/less.php/Tree/UnicodeDescriptor.php b/lib/less.php/Tree/UnicodeDescriptor.php
new file mode 100644
index 0000000..8c4707e
--- /dev/null
+++ b/lib/less.php/Tree/UnicodeDescriptor.php
@@ -0,0 +1,29 @@
+<?php
+
+/**
+ * UnicodeDescriptor
+ *
+ * @package Less
+ * @subpackage tree
+ */
+class Less_Tree_UnicodeDescriptor extends Less_Tree{
+
+	public $value;
+	public $type = 'UnicodeDescriptor';
+
+	public function __construct($value){
+		$this->value = $value;
+	}
+
+    /**
+     * @see Less_Tree::genCSS
+     */
+	public function genCSS( $output ){
+		$output->add( $this->value );
+	}
+
+	public function compile(){
+		return $this;
+	}
+}
+
diff --git a/lib/less.php/Tree/Unit.php b/lib/less.php/Tree/Unit.php
new file mode 100644
index 0000000..e13b100
--- /dev/null
+++ b/lib/less.php/Tree/Unit.php
@@ -0,0 +1,147 @@
+<?php
+
+/**
+ * Unit
+ *
+ * @package Less
+ * @subpackage tree
+ */
+class Less_Tree_Unit extends Less_Tree{
+
+	var $numerator = array();
+	var $denominator = array();
+	public $backupUnit;
+	public $type = 'Unit';
+
+    public function __construct($numerator = array(), $denominator = array(), $backupUnit = null ){
+		$this->numerator = $numerator;
+		$this->denominator = $denominator;
+		$this->backupUnit = $backupUnit;
+	}
+
+    public function __clone(){
+	}
+
+    /**
+     * @see Less_Tree::genCSS
+     */
+    public function genCSS( $output ){
+
+		if( $this->numerator ){
+			$output->add( $this->numerator[0] );
+		}elseif( $this->denominator ){
+			$output->add( $this->denominator[0] );
+		}elseif( !Less_Parser::$options['strictUnits'] && $this->backupUnit ){
+			$output->add( $this->backupUnit );
+			return ;
+		}
+	}
+
+    public function toString(){
+		$returnStr = implode('*',$this->numerator);
+		foreach($this->denominator as $d){
+			$returnStr .= '/'.$d;
+		}
+		return $returnStr;
+	}
+
+    public function __toString(){
+		return $this->toString();
+	}
+
+
+	/**
+	 * @param Less_Tree_Unit $other
+	 */
+    public function compare($other) {
+		return $this->is( $other->toString() ) ? 0 : -1;
+	}
+
+    public function is($unitString){
+		return $this->toString() === $unitString;
+	}
+
+    public function isLength(){
+		$css = $this->toCSS();
+		return !!preg_match('/px|em|%|in|cm|mm|pc|pt|ex/',$css);
+	}
+
+    public function isAngle() {
+		return isset( Less_Tree_UnitConversions::$angle[$this->toCSS()] );
+	}
+
+    public function isEmpty(){
+		return !$this->numerator && !$this->denominator;
+	}
+
+    public function isSingular() {
+		return count($this->numerator) <= 1 && !$this->denominator;
+	}
+
+
+    public function usedUnits(){
+		$result = array();
+
+		foreach(Less_Tree_UnitConversions::$groups as $groupName){
+			$group = Less_Tree_UnitConversions::${$groupName};
+
+			foreach($this->numerator as $atomicUnit){
+				if( isset($group[$atomicUnit]) && !isset($result[$groupName]) ){
+					$result[$groupName] = $atomicUnit;
+				}
+			}
+
+			foreach($this->denominator as $atomicUnit){
+				if( isset($group[$atomicUnit]) && !isset($result[$groupName]) ){
+					$result[$groupName] = $atomicUnit;
+				}
+			}
+		}
+
+		return $result;
+	}
+
+    public function cancel(){
+		$counter = array();
+		$backup = null;
+
+		foreach($this->numerator as $atomicUnit){
+			if( !$backup ){
+				$backup = $atomicUnit;
+			}
+			$counter[$atomicUnit] = ( isset($counter[$atomicUnit]) ? $counter[$atomicUnit] : 0) + 1;
+		}
+
+		foreach($this->denominator as $atomicUnit){
+			if( !$backup ){
+				$backup = $atomicUnit;
+			}
+			$counter[$atomicUnit] = ( isset($counter[$atomicUnit]) ? $counter[$atomicUnit] : 0) - 1;
+		}
+
+		$this->numerator = array();
+		$this->denominator = array();
+
+		foreach($counter as $atomicUnit => $count){
+			if( $count > 0 ){
+				for( $i = 0; $i < $count; $i++ ){
+					$this->numerator[] = $atomicUnit;
+				}
+			}elseif( $count < 0 ){
+				for( $i = 0; $i < -$count; $i++ ){
+					$this->denominator[] = $atomicUnit;
+				}
+			}
+		}
+
+		if( !$this->numerator && !$this->denominator && $backup ){
+			$this->backupUnit = $backup;
+		}
+
+		sort($this->numerator);
+		sort($this->denominator);
+	}
+
+
+}
+
diff --git a/lib/less.php/Tree/UnitConversions.php b/lib/less.php/Tree/UnitConversions.php
new file mode 100644
index 0000000..c86b290
--- /dev/null
+++ b/lib/less.php/Tree/UnitConversions.php
@@ -0,0 +1,35 @@
+<?php
+
+/**
+ * UnitConversions
+ *
+ * @package Less
+ * @subpackage tree
+ */
+class Less_Tree_UnitConversions{
+
+	public static $groups = array('length','duration','angle');
+
+	public static $length = array(
+		'm'=> 1,
+		'cm'=> 0.01,
+		'mm'=> 0.001,
+		'in'=> 0.0254,
+		'px'=> 0.000264583, // 0.0254 / 96,
+		'pt'=> 0.000352778, // 0.0254 / 72,
+		'pc'=> 0.004233333, // 0.0254 / 72 * 12
+		);
+
+	public static $duration = array(
+		's'=> 1,
+		'ms'=> 0.001
+		);
+
+	public static $angle = array(
+		'rad' => 0.1591549430919,	// 1/(2*M_PI),
+		'deg' => 0.002777778, 		// 1/360,
+		'grad'=> 0.0025,			// 1/400,
+		'turn'=> 1
+		);
+
+}
\ No newline at end of file
diff --git a/lib/less.php/Tree/Url.php b/lib/less.php/Tree/Url.php
new file mode 100644
index 0000000..ef9c3c6
--- /dev/null
+++ b/lib/less.php/Tree/Url.php
@@ -0,0 +1,76 @@
+<?php
+
+/**
+ * Url
+ *
+ * @package Less
+ * @subpackage tree
+ */
+class Less_Tree_Url extends Less_Tree{
+
+	public $attrs;
+	public $value;
+	public $currentFileInfo;
+	public $isEvald;
+	public $type = 'Url';
+
+	public function __construct($value, $currentFileInfo = null, $isEvald = null){
+		$this->value = $value;
+		$this->currentFileInfo = $currentFileInfo;
+		$this->isEvald = $isEvald;
+	}
+
+    public function accept( $visitor ){
+		$this->value = $visitor->visitObj($this->value);
+	}
+
+    /**
+     * @see Less_Tree::genCSS
+     */
+    public function genCSS( $output ){
+		$output->add( 'url(' );
+		$this->value->genCSS( $output );
+		$output->add( ')' );
+	}
+
+	/**
+	 * @param Less_Functions $ctx
+	 */
+	public function compile($ctx){
+		$val = $this->value->compile($ctx);
+
+		if( !$this->isEvald ){
+			// Add the base path if the URL is relative
+			if( Less_Parser::$options['relativeUrls']
+				&& $this->currentFileInfo
+				&& is_string($val->value)
+				&& Less_Environment::isPathRelative($val->value)
+			){
+				$rootpath = $this->currentFileInfo['uri_root'];
+				if ( !$val->quote ){
+					$rootpath = preg_replace('/[\(\)\'"\s]/', '\\$1', $rootpath );
+				}
+				$val->value = $rootpath . $val->value;
+			}
+
+			$val->value = Less_Environment::normalizePath( $val->value);
+		}
+
+		// Add cache buster if enabled
+		if( Less_Parser::$options['urlArgs'] ){
+			if( !preg_match('/^\s*data:/',$val->value) ){
+				$delimiter = strpos($val->value,'?') === false ? '?' : '&';
+				$urlArgs = $delimiter . Less_Parser::$options['urlArgs'];
+				$hash_pos = strpos($val->value,'#');
+				if( $hash_pos !== false ){
+					$val->value = substr_replace($val->value,$urlArgs, $hash_pos, 0);
+				} else {
+					$val->value .= $urlArgs;
+				}
+			}
+		}
+
+		return new Less_Tree_URL($val, $this->currentFileInfo, true);
+	}
+
+}
diff --git a/lib/less.php/Tree/Value.php b/lib/less.php/Tree/Value.php
new file mode 100644
index 0000000..9f077bc
--- /dev/null
+++ b/lib/less.php/Tree/Value.php
@@ -0,0 +1,48 @@
+<?php
+
+/**
+ * Value
+ *
+ * @package Less
+ * @subpackage tree
+ */
+class Less_Tree_Value extends Less_Tree{
+
+	public $type = 'Value';
+	public $value;
+
+	public function __construct($value){
+		$this->value = $value;
+	}
+
+    public function accept($visitor) {
+		$this->value = $visitor->visitArray($this->value);
+	}
+
+	public function compile($env){
+
+		$ret = array();
+		$i = 0;
+		foreach($this->value as $i => $v){
+			$ret[] = $v->compile($env);
+		}
+		if( $i > 0 ){
+			return new Less_Tree_Value($ret);
+		}
+		return $ret[0];
+	}
+
+    /**
+     * @see Less_Tree::genCSS
+     */
+	function genCSS( $output ){
+		$len = count($this->value);
+		for($i = 0; $i < $len; $i++ ){
+			$this->value[$i]->genCSS( $output );
+			if( $i+1 < $len ){
+				$output->add( Less_Environment::$_outputMap[','] );
+			}
+		}
+	}
+
+}
diff --git a/lib/less.php/Tree/Variable.php b/lib/less.php/Tree/Variable.php
new file mode 100644
index 0000000..cc0182c
--- /dev/null
+++ b/lib/less.php/Tree/Variable.php
@@ -0,0 +1,52 @@
+<?php
+
+/**
+ * Variable
+ *
+ * @package Less
+ * @subpackage tree
+ */
+class Less_Tree_Variable extends Less_Tree{
+
+	public $name;
+	public $index;
+	public $currentFileInfo;
+	public $evaluating = false;
+	public $type = 'Variable';
+
+    /**
+     * @param string $name
+     */
+    public function __construct($name, $index = null, $currentFileInfo = null) {
+        $this->name = $name;
+        $this->index = $index;
+		$this->currentFileInfo = $currentFileInfo;
+    }
+
+	public function compile($env) {
+
+		if( $this->name[1] === '@' ){
+			$v = new Less_Tree_Variable(substr($this->name, 1), $this->index + 1, $this->currentFileInfo);
+			$name = '@' . $v->compile($env)->value;
+		}else{
+			$name = $this->name;
+		}
+
+		if ($this->evaluating) {
+			throw new Less_Exception_Compiler("Recursive variable definition for " . $name, null, $this->index, $this->currentFileInfo);
+		}
+
+		$this->evaluating = true;
+
+		foreach($env->frames as $frame){
+			if( $v = $frame->variable($name) ){
+				$r = $v->value->compile($env);
+				$this->evaluating = false;
+				return $r;
+			}
+		}
+
+		throw new Less_Exception_Compiler("variable " . $name . " is undefined in file ".$this->currentFileInfo["filename"], null, $this->index, $this->currentFileInfo);
+	}
+
+}