/lib/leafo/lessphp/lessc.inc.php

Large files files are truncated, but you can click here to view the full file

<?php

/**
 * lessphp v0.3.5
 * http://leafo.net/lessphp
 *
 * LESS css compiler, adapted from http://lesscss.org
 *
 * Copyright 2012, Leaf Corcoran <leafot@gmail.com>
 * Licensed under MIT or GPLv3, see LICENSE
 */


/**
 * The less compiler and parser.
 *
 * Converting LESS to CSS is a two stage process. The incoming file is parsed
 * by `lessc_parser` into a tree, then compiled to CSS text by `lessc`. The
 * compile step has an implicit step called reduction, where values are brought
 * to their lowest form before being turned to text, eg. mathematical equations
 * are solved, and variables are dereferenced.
 *
 * The `lessc` class creates an intstance of the parser, feeds it LESS code, then
 * compiles the resulting tree to CSS
 *
 * The `lessc_parser` class is only concerned with parsing its input.
 *
 * The `lessc_formatter` classes are used to format the output of the CSS,
 * controlling things like whitespace and line-breaks.
 */
class lessc {
	static public $VERSION = "v0.3.5";
	static protected $TRUE = array("keyword", "true");
	static protected $FALSE = array("keyword", "false");

	protected $libFunctions = array();

	protected $indentLevel;

	protected $env = null;

	protected $allParsedFiles = array();

	public $vPrefix = '@'; // prefix of abstract properties
	public $mPrefix = '$'; // prefix of abstract blocks
	public $parentSelector = '&';

	// types that must be reduced before being compiled
	static protected $dtypes = array('expression', 'variable',
		'function', 'negative', 'list', 'lookup');

	public $importDisabled = false;
	public $importDir = '';

	public $compat = true; // lessjs compatibility mode, does nothing right now

	// set to the parser that generated the current line when compiling
	// so we know how to create error messages
	protected $sourceParser = null;
	protected $sourceLoc = null;

	// attempts to find the path of an import url, returns null for css files
	function findImport($url) {
		foreach ((array)$this->importDir as $dir) {
			$full = $dir.(substr($dir, -1) != '/' ? '/' : '').$url;
			if ($this->fileExists($file = $full.'.less') || $this->fileExists($file = $full)) {
				return $file;
			}
		}

		return null;
	}

	function fileExists($name) {
		return is_file($name);
	}

	static function compressList($items, $delim) {
		if (count($items) == 1) return $items[0];
		else return array('list', $delim, $items);
	}

	static function preg_quote($what) {
		return preg_quote($what, '/');
	}

	// just do a shallow property merge, seems to be what lessjs does
	function mergeBlock($target, $from) {
		$target = clone $target;
		$target->props = array_merge($target->props, $from->props);
		return $target;
	}

	// attempt to import $import into $parentBlock
	// $props is the property array that will given to $parentBlock at the end
	function mixImport($import, $parentBlock, &$props) {
		list(, $url, $media) = $import;

		if (empty($media) && substr_compare($url, '.css', -4, 4) !== 0) {
			if ($this->importDisabled) {
				$props[] = array('raw', '/* import disabled */');
				return true;
			}

			$realPath = $this->findImport($url);
			if (!is_null($realPath)) {
				$this->addParsedFile($realPath);

				$parser = new lessc_parser($this, $realPath);
				$root = $parser->parse(file_get_contents($realPath));
				$root->isRoot = false;
				$root->parent = $parentBlock;

				// handle all the imports in the new file
				$pi = pathinfo($realPath);
				$this->mixImports($root, $pi['dirname'].'/');

				// inject imported blocks into this block, local will overwrite import
				$parentBlock->children =
					array_merge($root->children,$parentBlock->children);

				// splice in the props
				foreach ($root->props as $prop) {
					// leave a reference to the file where it came from
					if (isset($prop[-1]) && !is_array($prop[-1])) {
						$prop[-1] = array($parser, $prop[-1]);
					}
					$props[] = $prop;
				}

				return true;
			}
		}

		// fallback to regular css import
		$props[] = array('raw', '@import url("'.$url.'")'.($media ? ' '.$media : '').';');
		return false;
	}

	// import all imports mentioned in the block
	function mixImports($block, $importDir = null) {
		$oldImport = $this->importDir;
		if (!is_null($importDir)) {
			$this->importDir = array_merge((array)$importDir, (array)$this->importDir);
		}

		$props = array();
		foreach ($block->props as $prop) {
			if ($prop[0] == 'import') {
				$this->mixImport($prop, $block, $props);
			} else {
				$props[] = $prop;
			}
		}
		$block->props = $props;
		$this->importDir = $oldImport;
	}

	/**
	 * Recursively compiles a block.
	 * @param $block the block
	 * @param $parentTags the tags of the block that contained this one
	 *
	 * A block is analogous to a CSS block in most cases. A single less document
	 * is encapsulated in a block when parsed, but it does not have parent tags
	 * so all of it's children appear on the root level when compiled.
	 *
	 * Blocks are made up of props and children.
	 *
	 * Props are property instructions, array tuples which describe an action
	 * to be taken, eg. write a property, set a variable, mixin a block.
	 *
	 * The children of a block are just all the blocks that are defined within.
	 *
	 * Compiling the block involves pushing a fresh environment on the stack,
	 * and iterating through the props, compiling each one.
	 *
	 * See lessc::compileProp()
	 *
	 */
	function compileBlock($block, $parent_tags = null) {
		if (!empty($block->no_multiply)) {
			$special_block = true;
			$tags = array();
		} else {
			$special_block = false;

			// evaluate expression tags
			$tags = null;
			if (is_array($block->tags)) {
				$tags = array();
				foreach ($block->tags as $tag) {
					if (is_array($tag)) {
						list(, $value) = $tag;
						$tags[] = $this->compileValue($this->reduce($value));
					} else {
						$tags[] = $tag;
					}
				}
			}

			$tags = $this->multiplyTags($parent_tags, $tags);
		}

		$env = $this->pushEnv();
		$env->nameDepth = array();

		$lines = array();
		$blocks = array();
		$this->mixImports($block);

		$idelta = $this->formatter->indentAmount($block);
		$this->indentLevel += $idelta;

		foreach ($this->sortProps($block->props) as $prop) {
			$this->compileProp($prop, $block, $tags, $lines, $blocks);
		}
		$this->indentLevel -= $idelta;

		$block->scope = $env;

		$this->pop();

		// override tags if it's a special block
		if (isset($block->media)) {
			$tags = $this->compileMedia($block);
		} elseif (isset($block->keyframes)) {
			$tags = $block->tags[0]." ".
				$this->compileValue($this->reduce($block->keyframes));
		} elseif ($special_block) { // font-face and the like
			$tags = $block->tags[0];
		}

		return $this->formatter->block($tags, $special_block, $lines,
			$blocks, $this->indentLevel);
	}

	function sortProps($props) {
		$out = array();
		foreach ($props as $prop) {
			if ($prop[0] == "assign") $out[] = $prop;
		}

		foreach ($props as $prop) {
			if ($prop[0] != "assign") $out[] = $prop;
		}

		return $out;
	}

	function expandParentSelectors(&$tag, $replace) {
		$parts = explode("$&$", $tag);
		$count = 0;
		foreach ($parts as &$part) {
			$part = str_replace($this->parentSelector, $replace, $part, $c);
			$count += $c;
		}
		$tag = implode($this->parentSelector, $parts);
		return $count;
	}

	// find the fully qualified tags for a block and its parent's tags
	function multiplyTags($parents, $current) {
		if ($parents == null) {
			if (is_array($current)) {
				// get rid of parent selectors and escapes in top level tag
				foreach ($current as &$tag) {
					$this->expandParentSelectors($tag, "");
				}
			}
			return $current;
		}

		$tags = array();
		foreach ($parents as $ptag) {
			foreach ($current as $tag) {
				$count = $this->expandParentSelectors($tag, $ptag);

				// don't prepend the parent tag if & was used
				if ($count > 0) {
					$tags[] = trim($tag);
				} else {
					$tags[] = trim($ptag . ' ' . $tag);
				}
			}
		}

		return $tags;
	}

	function eq($left, $right) {
		return $left == $right;
	}

	function patternMatch($block, $callingArgs) {
		// match the guards if it has them
		// any one of the groups must have all its guards pass for a match
		if (!empty($block->guards)) {
			$group_passed = false;
			foreach ($block->guards as $guard_group) {
				foreach ($guard_group as $guard) {
					$this->pushEnv();
					$this->zipSetArgs($block->args, $callingArgs);

					$negate = false;
					if ($guard[0] == "negate") {
						$guard = $guard[1];
						$negate = true;
					}

					$passed = $this->reduce($guard) == self::$TRUE;
					if ($negate) $passed = !$passed;

					$this->pop();

					if ($passed) {
						$group_passed = true;
					} else {
						$group_passed = false;
						break;
					}
				}

				if ($group_passed) break;
			}

			if (!$group_passed) {
				return false;
			}
		}

		$numCalling = count($callingArgs);

		if (empty($block->args)) {
			return $block->is_vararg || $numCalling == 0;
		}

		$i = -1; // no args
		// try to match by arity or by argument literal
		foreach ($block->args as $i => $arg) {
			switch ($arg[0]) {
			case "lit":
				if (empty($callingArgs[$i]) || !$this->eq($arg[1], $callingArgs[$i])) {
					return false;
				}
				break;
			case "arg":
				// no arg and no default value
				if (!isset($callingArgs[$i]) && !isset($arg[2])) {
					return false;
				}
				break;
			case "rest":
				$i--; // rest can be empty
				break 2;
			}
		}

		if ($block->is_vararg) {
			return true; // not having enough is handled above
		} else {
			$numMatched = $i + 1;
			// greater than becuase default values always match
			return $numMatched >= $numCalling;
		}
	}

	function patternMatchAll($blocks, $callingArgs) {
		$matches = null;
		foreach ($blocks as $block) {
			if ($this->patternMatch($block, $callingArgs)) {
				$matches[] = $block;
			}
		}

		return $matches;
	}

	// attempt to find blocks matched by path and args
	function findBlocks($search_in, $path, $args, $seen=array()) {
		if ($search_in == null) return null;
		if (isset($seen[$search_in->id])) return null;
		$seen[$search_in->id] = true;

		$name = $path[0];

		if (isset($search_in->children[$name])) {
			$blocks = $search_in->children[$name];
			if (count($path) == 1) {
				$matches = $this->patternMatchAll($blocks, $args);
				if (!empty($matches)) {
					// This will return all blocks that match in the closest
					// scope that has any matching block, like lessjs
					return $matches;
				}
			} else {
				return $this->findBlocks($blocks[0],
					array_slice($path, 1), $args, $seen);
			}
		}

		if ($search_in->parent === $search_in) return null;
		return $this->findBlocks($search_in->parent, $path, $args, $seen);
	}

	// sets all argument names in $args to either the default value
	// or the one passed in through $values
	function zipSetArgs($args, $values) {
		$i = 0;
		$assigned_values = array();
		foreach ($args as $a) {
			if ($a[0] == "arg") {
				if ($i < count($values) && !is_null($values[$i])) {
					$value = $values[$i];
				} elseif (isset($a[2])) {
					$value = $a[2];
				} else $value = null;

				$value = $this->reduce($value);
				$this->set($a[1], $value);
				$assigned_values[] = $value;
			}
			$i++;
		}

		// check for a rest
		$last = end($args);
		if ($last[0] == "rest") {
			$rest = array_slice($values, count($args) - 1);
			$this->set($last[1], $this->reduce(array("list", " ", $rest)));
		}

		$this->env->arguments = $assigned_values;
	}

	// compile a prop and update $lines or $blocks appropriately
	function compileProp($prop, $block, $tags, &$_lines, &$_blocks) {
		// set error position context
		if (isset($prop[-1])) {
			if (is_array($prop[-1])) {
				list($parser, $count) = $prop[-1];
				$this->sourceParser = $parser;
				$this->sourceLoc = $count;
			} else {
				$this->sourceParser = $this->parser;
				$this->sourceLoc = $prop[-1];
			}
		} else {
			$this->sourceLoc = -1;
		}

		switch ($prop[0]) {
		case 'assign':
			list(, $name, $value) = $prop;
			if ($name[0] == $this->vPrefix) {
				$this->set($name, $value);
			} else {
				$_lines[] = "$name:".
					$this->compileValue($this->reduce($value)).";";
			}
			break;
		case 'block':
			list(, $child) = $prop;
			$_blocks[] = $this->compileBlock($child, $tags);
			break;
		case 'mixin':
			list(, $path, $args, $suffix) = $prop;

			$args = array_map(array($this, "reduce"), (array)$args);
			$mixins = $this->findBlocks($block, $path, $args);
			if (is_null($mixins)) {
				// echo "failed to find block: ".implode(" > ", $path)."\n";
				break; // throw error here??
			}

			foreach ($mixins as $mixin) {
				$old_scope = null;
				if (isset($mixin->parent->scope)) {
					$old_scope = $this->env;
					$this->env = $mixin->parent->scope;
				}

				$have_args = false;
				if (isset($mixin->args)) {
					$have_args = true;
					$this->pushEnv();
					$this->zipSetArgs($mixin->args, $args);
				}

				$old_parent = $mixin->parent;
				if ($mixin != $block) $mixin->parent = $block;

				foreach ($this->sortProps($mixin->props) as $sub_prop) {
					if($suffix !== null) {
						$sub_prop[2] = array(
							'list', ' ',
							array($sub_prop[2], array('keyword', $suffix))
						);
					}

					$this->compileProp($sub_prop, $mixin, $tags, $_lines, $_blocks);
				}

				$mixin->parent = $old_parent;

				if ($have_args) $this->pop();

				if ($old_scope) {
					$this->env = $old_scope;
				}
			}

			break;
		case 'raw':
			$_lines[] = $prop[1];
			break;
		case 'charset':
			list(, $value) = $prop;
			$_lines[] = '@charset '.$this->compileValue($this->reduce($value)).';';
			break;
		default:
			$this->throwError("unknown op: {$prop[0]}\n");
		}
	}


	/**
	 * Compiles a primitive value into a CSS property value.
	 *
	 * Values in lessphp are typed by being wrapped in arrays, their format is
	 * typically:
	 *
	 *     array(type, contents [, additional_contents]*)
	 *
	 * The input is expected to be reduced. This function will not work on
	 * things like expressions and variables.
	 */
	function compileValue($value) {
		switch ($value[0]) {
		case 'list':
			// [1] - delimiter
			// [2] - array of values
			return implode($value[1], array_map(array($this, 'compileValue'), $value[2]));
		case 'raw_color';
		case 'keyword':
			// [1] - the keyword
		case 'number':
			// [1] - the number
			return $value[1];
		case 'escape':
		case 'string':
			// [1] - contents of string (includes quotes)

			// search for inline variables to replace
			$replace = array();
			if (preg_match_all('/'.self::preg_quote($this->vPrefix).'\{([\w-_][0-9\w-_]*)\}/', $value[1], $m)) {
				foreach ($m[1] as $name) {
					if (!isset($replace[$name]))
						$replace[$name] = $this->compileValue($this->reduce(array('variable', $this->vPrefix . $name)));
				}
			}

			foreach ($replace as $var=>$val) {
				if ($this->quoted($val)) {
					$val = substr($val, 1, -1);
				}
				$value[1] = str_replace($this->vPrefix. '{'.$var.'}', $val, $value[1]);
			}

			return $value[1];
		case 'color':
			// [1] - red component (either number for a %)
			// [2] - green component
			// [3] - blue component
			// [4] - optional alpha component
			list(, $r, $g, $b) = $value;
			$r = round($r);
			$g = round($g);
			$b = round($b);

			if (count($value) == 5 && $value[4] != 1) { // rgba
				return 'rgba('.$r.','.$g.','.$b.','.$value[4].')';
			}

			$h = sprintf("#%02x%02x%02x", $r, $g, $b);

			if (!empty($this->formatter->compress_colors)) {
				// Converting hex color to short notation (e.g. #003399 to #039) 
				if ($h[1] === $h[2] && $h[3] === $h[4] && $h[5] === $h[6]) {
					$h = '#' . $h[1] . $h[3] . $h[5];
				}
			}

			return $h;

		case 'function':
			// [1] - function name
			// [2] - some array value representing arguments, either ['string', value] or ['list', ',', values[]]

			// see if function evaluates to something else
			$value = $this->reduce($value);
			if ($value[0] == 'function') {
				return $value[1].'('.$this->compileValue($value[2]).')';
			}
			else return $this->compileValue($value);
		default: // assumed to be unit
			return $value[1].$value[0];
		}
	}

	function compileMedia($block) {
		$mediaParts = array();
		foreach ($block->media as $part) {
			if ($part[0] == "raw") {
				$mediaParts[] = $part[1];
			} elseif ($part[0] == "assign") {
				list(, $propName, $propVal) = $part;
				$mediaParts[] = "$propName: ".
					$this->compileValue($this->reduce($propVal));
			}
		}

		return "@media ".trim(implode($mediaParts));
	}

	function lib_isnumber($value) {
		return $this->toBool(is_numeric($value[1]) && $value[0] != "color");
	}

	function lib_isstring($value) {
		return $this->toBool($value[0] == "string");
	}

	function lib_iscolor($value) {
		return $this->toBool($this->coerceColor($value));
	}

	function lib_iskeyword($value) {
		return $this->toBool($value[0] == "keyword");
	}

	function lib_ispixel($value) {
		return $this->toBool($value[0] == "px");
	}

	function lib_ispercentage($value) {
		return $this->toBool($value[0] == "%");
	}

	function lib_isem($value) {
		return $this->toBool($value[0] == "em");
	}

	function lib_rgbahex($color) {
		$color = $this->coerceColor($color);
		if (is_null($color))
			$this->throwError("color expected for rgbahex");

		return sprintf("#%02x%02x%02x%02x",
			isset($color[4]) ? $color[4]*255 : 0,
			$color[1],$color[2], $color[3]);
	}

	function lib_argb($color){
            return $this->lib_rgbahex($color);
        }

	// utility func to unquote a string
	function lib_e($arg) {
		switch ($arg[0]) {
			case "list":
				$items = $arg[2];
				if (isset($items[0])) {
					return $this->lib_e($items[0]);
				}
				return "";
			case "string":
				$str = $this->compileValue($arg);
				return substr($str, 1, -1);
			default:
				return $this->compileValue($arg);
		}
	}

	function lib__sprintf($args) {
		if ($args[0] != "list") return $args;
		$values = $args[2];
		$source = $this->reduce(array_shift($values));
		if ($source[0] != "string") {
			return $source;
		}

		$str = $source[1];
		$i = 0;
		if (preg_match_all('/%[dsa]/', $str, $m)) {
			foreach ($m[0] as $match) {
				$val = isset($values[$i]) ? $this->reduce($values[$i]) : array('keyword', '');
				$i++;
				switch ($match[1]) {
				case "s":
					if ($val[0] == "string") {
						$rep = substr($val[1], 1, -1);
						break;
					}
				default:
					$rep = $this->compileValue($val);
				}
				$str = preg_replace('/'.self::preg_quote($match).'/', $rep, $str, 1);
			}
		}

		return array('string', $str);
	}

	function lib_floor($arg) {
		return array($arg[0], floor($arg[1]));
	}

	function lib_ceil($arg) {
		return array($arg[0], ceil($arg[1]));
	}

	function lib_round($arg) {
		return array($arg[0], round($arg[1]));
	}

	// is a string surrounded in quotes? returns the quoting char if true
	function quoted($s) {
		if (preg_match('/^("|\').*?\1$/', $s, $m))
			return $m[1];
		else return false;
	}

	/**
	 * Helper function to get arguments for color manipulation functions.
	 * takes a list that contains a color like thing and a percentage
	 */
	function colorArgs($args) {
		if ($args[0] != 'list' || count($args[2]) < 2) {
			return array(array('color', 0, 0, 0));
		}
		list($color, $delta) = $args[2];
		$color = $this->assertColor($color);
		$delta = floatval($delta[1]);

		return array($color, $delta);
	}

	function lib_darken($args) {
		list($color, $delta) = $this->colorArgs($args);

		$hsl = $this->toHSL($color);
		$hsl[3] = $this->clamp($hsl[3] - $delta, 100);
		return $this->toRGB($hsl);
	}

	function lib_lighten($args) {
		list($color, $delta) = $this->colorArgs($args);

		$hsl = $this->toHSL($color);
		$hsl[3] = $this->clamp($hsl[3] + $delta, 100);
		return $this->toRGB($hsl);
	}

	function lib_saturate($args) {
		list($color, $delta) = $this->colorArgs($args);

		$hsl = $this->toHSL($color);
		$hsl[2] = $this->clamp($hsl[2] + $delta, 100);
		return $this->toRGB($hsl);
	}

	function lib_desaturate($args) {
		list($color, $delta) = $this->colorArgs($args);

		$hsl = $this->toHSL($color);
		$hsl[2] = $this->clamp($hsl[2] - $delta, 100);
		return $this->toRGB($hsl);
	}

	function lib_spin($args) {
		list($color, $delta) = $this->colorArgs($args);

		$hsl = $this->toHSL($color);

		$hsl[1] = $hsl[1] + $delta % 360;
		if ($hsl[1] < 0) $hsl[1] += 360;

		return $this->toRGB($hsl);
	}

	function lib_fadeout($args) {
		list($color, $delta) = $this->colorArgs($args);
		$color[4] = $this->clamp((isset($color[4]) ? $color[4] : 1) - $delta/100);
		return $color;
	}

	function lib_fadein($args) {
		list($color, $delta) = $this->colorArgs($args);
		$color[4] = $this->clamp((isset($color[4]) ? $color[4] : 1) + $delta/100);
		return $color;
	}

	function lib_hue($color) {
		$hsl = $this->toHSL($this->assertColor($color));
		return round($hsl[1]);
	}

	function lib_saturation($color) {
		$hsl = $this->toHSL($this->assertColor($color));
		return round($hsl[2]);
	}

	function lib_lightness($color) {
		$hsl = $this->toHSL($this->assertColor($color));
		return round($hsl[3]);
	}

	// get the alpha of a color
	// defaults to 1 for non-colors or colors without an alpha
	function lib_alpha($color) {
		$color = $this->assertColor($color);
		return isset($color[4]) ? $color[4] : 1;
	}

	// set the alpha of the color
	function lib_fade($args) {
		list($color, $alpha) = $this->colorArgs($args);
		$color[4] = $this->clamp($alpha / 100.0);
		return $color;
	}

	function lib_percentage($number) {
		return array('%', $number[1]*100);
	}

	// mixes two colors by weight
	// mix(@color1, @color2, @weight);
	// http://sass-lang.com/docs/yardoc/Sass/Script/Functions.html#mix-instance_method
	function lib_mix($args) {
		if ($args[0] != "list" || count($args[2]) < 3)
			$this->throwError("mix expects (color1, color2, weight)");

		list($first, $second, $weight) = $args[2];
		$first = $this->assertColor($first);
		$second = $this->assertColor($second);

		$first_a = $this->lib_alpha($first);
		$second_a = $this->lib_alpha($second);
		$weight = $weight[1] / 100.0;

		$w = $weight * 2 - 1;
		$a = $first_a - $second_a;

		$w1 = (($w * $a == -1 ? $w : ($w + $a)/(1 + $w * $a)) + 1) / 2.0;
		$w2 = 1.0 - $w1;

		$new = array('color',
			$w1 * $first[1] + $w2 * $second[1],
			$w1 * $first[2] + $w2 * $second[2],
			$w1 * $first[3] + $w2 * $second[3],
		);

		if ($first_a != 1.0 || $second_a != 1.0) {
			$new[] = $first_a * $weight + $second_a * ($weight - 1);
		}

		return $this->fixColor($new);
	}

	function assertColor($value, $error = "expected color value") {
		$color = $this->coerceColor($value);
		if (is_null($color)) $this->throwError($error);
		return $color;
	}

	function toHSL($color) {
		if ($color[0] == 'hsl') return $color;

		$r = $color[1] / 255;
		$g = $color[2] / 255;
		$b = $color[3] / 255;

		$min = min($r, $g, $b);
		$max = max($r, $g, $b);

		$L = ($min + $max) / 2;
		if ($min == $max) {
			$S = $H = 0;
		} else {
			if ($L < 0.5)
				$S = ($max - $min)/($max + $min);
			else
				$S = ($max - $min)/(2.0 - $max - $min);

			if ($r == $max) $H = ($g - $b)/($max - $min);
			elseif ($g == $max) $H = 2.0 + ($b - $r)/($max - $min);
			elseif ($b == $max) $H = 4.0 + ($r - $g)/($max - $min);

		}

		$out = array('hsl',
			($H < 0 ? $H + 6 : $H)*60,
			$S*100,
			$L*100,
		);

		if (count($color) > 4) $out[] = $color[4]; // copy alpha
		return $out;
	}

	function toRGB_helper($comp, $temp1, $temp2) {
		if ($comp < 0) $comp += 1.0;
		elseif ($comp > 1) $comp -= 1.0;

		if (6 * $comp < 1) return $temp1 + ($temp2 - $temp1) * 6 * $comp;
		if (2 * $comp < 1) return $temp2;
		if (3 * $comp < 2) return $temp1 + ($temp2 - $temp1)*((2/3) - $comp) * 6;

		return $temp1;
	}

	/**
	 * Converts a hsl array into a color value in rgb.
	 * Expects H to be in range of 0 to 360, S and L in 0 to 100
	 */
	function toRGB($color) {
		if ($color == 'color') return $color;

		$H = $color[1] / 360;
		$S = $color[2] / 100;
		$L = $color[3] / 100;

		if ($S == 0) {
			$r = $g = $b = $L;
		} else {
			$temp2 = $L < 0.5 ?
				$L*(1.0 + $S) :
				$L + $S - $L * $S;

			$temp1 = 2.0 * $L - $temp2;

			$r = $this->toRGB_helper($H + 1/3, $temp1, $temp2);
			$g = $this->toRGB_helper($H, $temp1, $temp2);
			$b = $this->toRGB_helper($H - 1/3, $temp1, $temp2);
		}

		// $out = array('color', round($r*255), round($g*255), round($b*255));
		$out = array('color', $r*255, $g*255, $b*255);
		if (count($color) > 4) $out[] = $color[4]; // copy alpha
		return $out;
	}

	function clamp($v, $max = 1, $min = 0) {
		return min($max, max($min, $v));
	}

	/**
	 * Convert the rgb, rgba, hsl color literals of function type
	 * as returned by the parser into values of color type.
	 */
	function funcToColor($func) {
		$fname = $func[1];
		if ($func[2][0] != 'list') return false; // need a list of arguments
		$rawComponents = $func[2][2];

		if ($fname == 'hsl' || $fname == 'hsla') {
			$hsl = array('hsl');
			$i = 0;
			foreach ($rawComponents as $c) {
				$val = $this->reduce($c);
				$val = isset($val[1]) ? floatval($val[1]) : 0;

				if ($i == 0) $clamp = 360;
				elseif ($i < 4) $clamp = 100;
				else $clamp = 1;

				$hsl[] = $this->clamp($val, $clamp);
				$i++;
			}

			while (count($hsl) < 4) $hsl[] = 0;
			return $this->toRGB($hsl);

		} elseif ($fname == 'rgb' || $fname == 'rgba') {
			$components = array();
			$i = 1;
			foreach	($rawComponents as $c) {
				$c = $this->reduce($c);
				if ($i < 4) {
					if ($c[0] == '%') $components[] = 255 * ($c[1] / 100);
					else $components[] = floatval($c[1]);
				} elseif ($i == 4) {
					if ($c[0] == '%') $components[] = 1.0 * ($c[1] / 100);
					else $components[] = floatval($c[1]);
				} else break;

				$i++;
			}
			while (count($components) < 3) $components[] = 0;
			array_unshift($components, 'color');
			return $this->fixColor($components);
		}

		return false;
	}

	function toName($val) {
		switch($val[0]) {
		case "string":
			return substr($val[1], 1, -1);
		default:
			return $val[1];
		}
	}

	// reduce a delayed type to its final value
	// dereference variables and solve equations
	function reduce($var) {
		// this is done here for infinite loop checking
		if ($var[0] == "variable") {
			$key = is_array($var[1]) ?
				$this->vPrefix.$this->toName($this->reduce($var[1])) : $var[1];

			$seen =& $this->env->seenNames;

			if (!empty($seen[$key])) {
				$this->throwError("infinite loop detected: $key");
			}

			$seen[$key] = true;

			$out = $this->reduce($this->get($key));

			$seen[$key] = false;

			return $out;
		}

		while (in_array($var[0], self::$dtypes)) {
			if ($var[0] == 'list') {
				foreach ($var[2] as &$value) $value = $this->reduce($value);
				break;
			} elseif ($var[0] == 'expression') {
				$var = $this->evaluate($var[1], $var[2], $var[3]);
			} elseif ($var[0] == 'lookup') {
				// do accessor here....
				$var = array('number', 0);
			} elseif ($var[0] == 'function') {
				$color = $this->funcToColor($var);
				if ($color) $var = $color;
				else {
					list($_, $name, $args) = $var;
					if ($name == "%") $name = "_sprintf";
					$f = isset($this->libFunctions[$name]) ?
						$this->libFunctions[$name] : array($this, 'lib_'.$name);

					if (is_callable($f)) {
						if ($args[0] == 'list')
							$args = self::compressList($args[2], $args[1]);

						$var = call_user_func($f, $this->reduce($args), $this);

						// convert to a typed value if the result is a php primitive
						if (is_numeric($var)) $var = array('number', $var);
						elseif (!is_array($var)) $var = array('keyword', $var);
					} else {
						// plain function, reduce args
						$var[2] = $this->reduce($var[2]);
					}
				}
				break; // done reducing after a function
			} elseif ($var[0] == 'negative') {
				$value = $this->reduce($var[1]);
				if (is_numeric($value[1])) {
					$value[1] = -1*$value[1];
				}
				$var = $value;
			}
		}

		return $var;
	}

	// coerce a value for use in color operation
	function coerceColor($value) {
		switch($value[0]) {
			case 'color': return $value;
			case 'raw_color':
				$c = array("color", 0, 0, 0);
				$colorStr = substr($value[1], 1);
				$num = hexdec($colorStr);
				$width = strlen($colorStr) == 3 ? 16 : 256;

				for ($i = 3; $i > 0; $i--) { // 3 2 1
					$t = $num % $width;
					$num /= $width;

					$c[$i] = $t * (256/$width) + $t * floor(16/$width);
				}

				return $c;
			case 'keyword':
				$name = $value[1];
				if (isset(self::$cssColors[$name])) {
					list($r, $g, $b) = explode(',', self::$cssColors[$name]);
					return array('color', $r, $g, $b);
				}
				return null;
		}
	}

	function toBool($a) {
		if ($a) return self::$TRUE;
		else return self::$FALSE;
	}

	// evaluate an expression
	function evaluate($op, $left, $right) {
		$left = $this->reduce($left);
		$right = $this->reduce($right);

		if ($left_color = $this->coerceColor($left)) {
			$left = $left_color;
		}

		if ($right_color = $this->coerceColor($right)) {
			$right = $right_color;
		}

		if ($op == "and") {
			return $this->toBool($left == self::$TRUE && $right == self::$TRUE);
		}

		if ($op == "=") {
			return $this->toBool($this->eq($left, $right) );
		}

		if ($left[0] == 'color' && $right[0] == 'color') {
			$out = $this->op_color_color($op, $left, $right);
			return $out;
		}

		if ($left[0] == 'color') {
			return $this->op_color_number($op, $left, $right);
		}

		if ($right[0] == 'color') {
			return $this->op_number_color($op, $left, $right);
		}

		// concatenate strings
		if ($op == '+' && $left[0] == 'string') {
			$append = $this->compileValue($right);
			if ($this->quoted($append)) $append = substr($append, 1, -1);

			$lhs = $this->compileValue($left);
			if ($q = $this->quoted($lhs)) $lhs = substr($lhs, 1, -1);
			if (!$q) $q = '';

			return array('string', $q.$lhs.$append.$q);
		}

		if ($left[0] == 'keyword' || $right[0] == 'keyword' ||
			$left[0] == 'string' || $right[0] == 'string')
		{
			// look for negative op
			if ($op == '-') $right[1] = '-'.$right[1];
			return array('keyword', $this->compileValue($left) .' '. $this->compileValue($right));
		}

		// default to number operation
		return $this->op_number_number($op, $left, $right);
	}

	// make sure a color's components don't go out of bounds
	function fixColor($c) {
		foreach (range(1, 3) as $i) {
			if ($c[$i] < 0) $c[$i] = 0;
			if ($c[$i] > 255) $c[$i] = 255;
		}

		return $c;
	}

	function op_number_color($op, $lft, $rgt) {
		if ($op == '+' || $op = '*') {
			return $this->op_color_number($op, $rgt, $lft);
		}
	}

	function op_color_number($op, $lft, $rgt) {
		if ($rgt[0] == '%') $rgt[1] /= 100;

		return $this->op_color_color($op, $lft,
			array_fill(1, count($lft) - 1, $rgt[1]));
	}

	function op_color_color($op, $left, $right) {
		$out = array('color');
		$max = count($left) > count($right) ? count($left) : count($right);
		foreach (range(1, $max - 1) as $i) {
			$lval = isset($left[$i]) ? $left[$i] : 0;
			$rval = isset($right[$i]) ? $right[$i] : 0;
			switch ($op) {
			case '+':
				$out[] = $lval + $rval;
				break;
			case '-':
				$out[] = $lval - $rval;
				break;
			case '*':
				$out[] = $lval * $rval;
				break;
			case '%':
				$out[] = $lval % $rval;
				break;
			case '/':
				if ($rval == 0) $this->throwError("evaluate error: can't divide by zero");
				$out[] = $lval / $rval;
				break;
			default:
				$this->throwError('evaluate error: color op number failed on op '.$op);
			}
		}
		return $this->fixColor($out);
	}

	// operator on two numbers
	function op_number_number($op, $left, $right) {
		$type = is_null($left) ? "number" : $left[0];
		if ($type == "number") $type = $right[0];

		$value = 0;
		switch ($op) {
		case '+':
			$value = $left[1] + $right[1];
			break;
		case '*':
			$value = $left[1] * $right[1];
			break;
		case '-':
			$value = $left[1] - $right[1];
			break;
		case '%':
			$value = $left[1] % $right[1];
			break;
		case '/':
			if ($right[1] == 0) $this->throwError('parse error: divide by zero');
			$value = $left[1] / $right[1];
			break;
		case '<':
			return $this->toBool($left[1] < $right[1]);
		case '>':
			return $this->toBool($left[1] > $right[1]);
		case '>=':
			return $this->toBool($left[1] >= $right[1]);
		case '=<':
			return $this->toBool($left[1] <= $right[1]);
		default:
			$this->throwError('parse error: unknown number operator: '.$op);
		}

		return array($type, $value);
	}


	/* environment functions */

	// used for compiliation variable state
	function pushEnv() {
		$e = new stdclass;
		$e->parent = $this->env;

		$this->store = array();

		$this->env = $e;
		return $e;
	}

	// pop something off the stack
	function pop() {
		$old = $this->env;
		$this->env = $this->env->parent;
		return $old;
	}

	// set something in the current env
	function set($name, $value) {
		$this->env->store[$name] = $value;
	}


	// get the highest occurrence entry for a name
	function get($name) {
		$current = $this->env;

		$is_arguments = $name == $this->vPrefix . 'arguments';
		while ($current) {
			if ($is_arguments && isset($current->arguments)) {
				return array('list', ' ', $current->arguments);
			}

			if (isset($current->store[$name]))
				return $current->store[$name];
			else
				$current = $current->parent;
		}

		return null;
	}

	// create a child parser (for compiling an import)
	protected function createChild($fname) {
		$less = new lessc($fname);
		$less->importDir = array_merge((array)$less->importDir, (array)$this->importDir);
		$less->formatter = $this->formatter;
		$less->compat = $this->compat;
		return $less;
	}

	// inject array of unparsed strings into environment as variables
	protected function injectVariables($args) {
		$this->pushEnv();
		$parser = new lessc_parser($this, __METHOD__);
		foreach ($args as $name => $str_value) {
			if ($name{0} != '@') $name = '@'.$name;
			$parser->count = 0;
			$parser->buffer = (string)$str_value;
			if (!$parser->propertyValue($value)) {
				throw new Exception("failed to parse passed in variable $name: $str_value");
			}

			$this->set($name, $value);
		}
	}

	// parse and compile buffer
	function parse($str = null, $initialVariables = null) {
		if (is_array($str)) {
			$initialVariables = $str;
			$str = null;
		}

		$locale = setlocale(LC_NUMERIC, 0);
		setlocale(LC_NUMERIC, "C");

		$name = null;
		if (is_null($str)) {
			if (empty($this->fileName))
				throw new exception("nothing to parse");

			$name = $this->fileName;
			$str = file_get_contents($this->fileName);
		}

		$this->parser = new lessc_parser($this, $name);
		$root = $this->parser->parse($str);

		$this->formatter = $this->newFormatter();

		if ($initialVariables) $this->injectVariables($initialVariables);
		$this->indentLevel = -1;
		$out = $this->compileBlock($root);
		setlocale(LC_NUMERIC, $locale);
		return $out;
	}

	function setFormatter($name) {
		$this->formatterName = $name;
	}

	function newFormatter() {
		$className = "lessc_formatter";
		if (!empty($this->formatterName)) {
			if (!is_string($this->formatterName))
				return $this->formatterName;
			$className = "lessc_formatter_$this->formatterName";
		}

		return new $className;
	}

	/**
	 * Uses the current value of $this->count to show line and line number
	 */
	function throwError($msg = null) {
		if ($this->sourceLoc >= 0) {
			$this->sourceParser->throwError($msg, $this->sourceLoc);
		}
		throw new exception($msg);
	}

	/**
	 * Initialize any static state, can initialize parser for a file
	 * $opts isn't used yet
	 */
	function __construct($fname = null, $opts = null) {
		if ($fname) {
			if (!is_file($fname)) {
				throw new Exception('load error: failed to find '.$fname);
			}
			$pi = pathinfo($fname);

			$this->fileName = $fname;
			$this->importDir = $pi['dirname'].'/';
			$this->addParsedFile($fname);
		}
	}

	public function registerFunction($name, $func) {
		$this->libFunctions[$name] = $func;
	}

	public function unregisterFunction($name) {
		unset($this->libFunctions[$name]);
	}

	public function allParsedFiles() { return $this->allParsedFiles; }
	protected function addParsedFile($file) {
		$this->allParsedFiles[realpath($file)] = filemtime($file);
	}


	// compile file $in to file $out if $in is newer than $out
	// returns true when it compiles, false otherwise
	public static function ccompile($in, $out) {
		if (!is_file($out) || filemtime($in) > filemtime($out)) {
			$less = new lessc($in);
			file_put_contents($out, $less->parse());
			return true;
		}

		return false;
	}

	/**
	 * Execute lessphp on a .less file or a lessphp cache structure
	 *
	 * The lessphp cache structure contains information about a specific
	 * less file having been parsed. It can be used as a hint for future
	 * calls to determine whether or not a rebuild is required.
	 *
	 * The cache structure contains two important keys that may be used
	 * externally:
	 *
	 * compiled: The final compiled CSS
	 * updated: The time (in seconds) the CSS was last compiled
	 *
	 * The cache structure is a plain-ol' PHP associative array and can
	 * be serialized and unserialized without a hitch.
	 *
	 * @param mixed $in Input
	 * @param bool $force Force rebuild?
	 * @return array lessphp cache structure
	 */
	public static function cexecute($in, $force = false) {

		// assume no root
		$root = null;

		if (is_string($in)) {
			$root = $in;
		} elseif (is_array($in) and isset($in['root'])) {
			if ($force or ! isset($in['files'])) {
				// If we are forcing a recompile or if for some reason the
				// structure does not contain any file information we should
				// specify the root to trigger a rebuild.
				$root = $in['root'];
			} elseif (isset($in['files']) and is_array($in['files'])) {
				foreach ($in['files'] as $fname => $ftime ) {
					if (!file_exists($fname) or filemtime($fname) > $ftime) {
						// One of the files we knew about previously has changed
						// so we should look at our incoming root again.
						$root = $in['root'];
						break;
					}
				}
			}
		} else {
			// TODO: Throw an exception? We got neither a string nor something
			// that looks like a compatible lessphp cache structure.
			return null;
		}

		if ($root !== null) {
			// If we have a root value which means we should rebuild.
			$less = new lessc($root);
			$out = array();
			$out['root'] = $root;
			$out['compiled'] = $less->parse();
			$out['files'] = $less->allParsedFiles();
			$out['updated'] = time();
			return $out;
		} else {
			// No changes, pass back the structure
			// we were given initially.
			return $in;
		}

	}

	static protected $cssColors = array(
		'aliceblue' => '240,248,255',
		'antiquewhite' => '250,235,215',
		'aqua' => '0,255,255',
		'aquamarine' => '127,255,212',
		'azure' => '240,255,255',
		'beige' => '245,245,220',
		'bisque' => '255,228,196',
		'black' => '0,0,0',
		'blanchedalmond' => '255,235,205',
		'blue' => '0,0,255',
		'blueviolet' => '138,43,226',
		'brown' => '165,42,42',
		'burlywood' => '222,184,135',
		'cadetblue' => '95,158,160',
		'chartreuse' => '127,255,0',
		'chocolate' => '210,105,30',
		'coral' => '255,127,80',
		'cornflowerblue' => '100,149,237',
		'cornsilk' => '255,248,220',
		'crimson' => '220,20,60',
		'cyan' => '0,255,255',
		'darkblue' => '0,0,139',
		'darkcyan' => '0,139,139',
		'darkgoldenrod' => '184,134,11',
		'darkgray' => '169,169,169',
		'darkgreen' => '0,100,0',
		'darkgrey' => '169,169,169',
		'darkkhaki' => '189,183,107',
		'darkmagenta' => '139,0,139',
		'darkolivegreen' => '85,107,47',
		'darkorange' => '255,140,0',
		'darkorchid' => '153,50,204',
		'darkred' => '139,0,0',
		'darksalmon' => '233,150,122',
		'darkseagreen' => '143,188,143',
		'darkslateblue' => '72,61,139',
		'darkslategray' => '47,79,79',
		'darkslategrey' => '47,79,79',
		'darkturquoise' => '0,206,209',
		'darkviolet' => '148,0,211',
		'deeppink' => '255,20,147',
		'deepskyblue' => '0,191,255',
		'dimgray' => '105,105,105',
		'dimgrey' => '105,105,105',
		'dodgerblue' => '30,144,255',
		'firebrick' => '178,34,34',
		'floralwhite' => '255,250,240',
		'forestgreen' => '34,139,34',
		'fuchsia' => '255,0,255',
		'gainsboro' => '220,220,220',
		'ghostwhite' => '248,248,255',
		'gold' => '255,215,0',
		'goldenrod' => '218,165,32',
		'gray' => '128,128,128',
		'green' => '0,128,0',
		'greenyellow' => '173,255,47',
		'grey' => '128,128,128',
		'honeydew' => '240,255,240',
		'hotpink' => '255,105,180',
		'indianred' => '205,92,92',
		'indigo' => '75,0,130',
		'ivory' => '255,255,240',
		'khaki' => '240,230,140',
		'lavender' => '230,230,250',
		'lavenderblush' => '255,240,245',
		'lawngreen' => '124,252,0',
		'lemonchiffon' => '255,250,205',
		'lightblue' => '173,216,230',
		'lightcoral' => '240,128,128',
		'lightcyan' => '224,255,255',
		'lightgoldenrodyellow' => '250,250,210',
		'lightgray' => '211,211,211',
		'lightgreen' => '144,238,144',
		'lightgrey' => '211,211,211',
		'lightpink' => '255,182,193',
		'lightsalmon' => '255,160,122',
		'lightseagreen' => '32,178,170',
		'lightskyblue' => '135,206,250',
		'lightslategray' => '119,136,153',
		'lightslategrey' => '119,136,153',
		'lightsteelblue' => '176,196,222',
		'lightyellow' => '255,255,224',
		'lime' => '0,255,0',
		'limegreen' => '50,205,50',
		'linen' => '250,240,230',
		'magenta' => '255,0,255',
		'maroon' => '128,0,0',
		'mediumaquamarine' => '102,205,170',
		'mediumblue' => '0,0,205',
		'mediumorchid' => '186,85,211',
		'mediumpurple' => '147,112,219',
		'mediumseagreen' => '60,179,113',
		'mediumslateblue' => '123,104,238',
		'mediumspringgreen' => '0,250,154',
		'mediumturquoise' => '72,209,204',
		'mediumvioletred' => '199,21,133',
		'midnightblue' => '25,25,112',
		'mintcream' => '245,255,250',
		'mistyrose' => '255,228,225',
		'moccasin' => '255,228,181',
		'navajowhite' => '255,222,173',
		'navy' => '0,0,128',
		'oldlace' => '253,245,230',
		'olive' => '128,128,0',
		'olivedrab' => '107,142,35',
		'orange' => '255,165,0',
		'orangered' => '255,69,0',
		'orchid' => '218,112,214',
		'palegoldenrod' => '238,232,170',
		'palegreen' => '152,251,152',
		'paleturquoise' => '175,238,238',
		'palevioletred' => '219,112,147',
		'papayawhip' => '255,239,213',
		'peachpuff' => '255,218,185',
		'peru' => '205,133,63',
		'pink' => '255,192,203',
		'plum' => '221,160,221',
		'powderblue' => '176,224,230',
		'purple' => '128,0,128',
		'red' => '255,0,0',
		'rosybrown' => '188,143,143',
		'royalblue' => '65,105,225',
		'saddlebrown' => '139,69,19',
		'salmon' => '250,128,114',
		'sandybrown' => '244,164,96',
		'seagreen' => '46,139,87',
		'seashell' => '255,245,238',
		'sienna' => '160,82,45',
		'silver' => '192,192,192',
		'skyblue' => '135,206,235',
		'slateblue' => '106,90,205',
		'slategray' => '112,128,144',
		'slategrey' => '112,128,144',
		'snow' => '255,250,250',
		'springgreen' => '0,255,127',
		'steelblue' => '70,130,180',
		'tan' => '210,180,140',
		'teal' => '0,128,128',
		'thistle' => '216,191,216',
		'tomato' => '255,99,71',
		'turquoise' => '64,224,208',
		'violet' => '238,130,238',
		'wheat' => '245,222,179',
		'white' => '255,255,255',
		'whitesmoke' => '245,245,245',
		'yellow' => '255,255,0',
		'yellowgreen' => '154,205,50'
	);
}

// responsible for taking a string of LESS code and converting it into a
// syntax tree
class lessc_parser {
	static protected $nextBlockId = 0; // used to uniquely identify blocks

	static protected $precedence = array(
		'=<' => 0,
		'>=' => 0,
		'=' => 0,
		'<' => 0,
		'>' => 0,

		'+' => 1,
		'-' => 1,
		'*' => 2,
		'/' => 2,
		'%' => 2,
	);

	// regex string to match any of the operators
	static protected $operatorString;
	static protected $numberString;

	// these properties will supress division unless it's inside parenthases
	static protected $supressDivisionProps =
		array('/border-radius$/i', '/^font$/i');

	/**
	 * @link http://www.w3.org/TR/css3-values/
	 */
	static protected $units = array(
		'em', 'ex', 'px', 'gd', 'rem', 'vw', 'vh', 'vm', 'ch', // Relative length units
		'in', 'cm', 'mm', 'pt', 'pc', // Absolute length units
		'%', // Percentages
		'deg', 'grad', 'rad', 'turn', // Angles
		'ms', 's', // Times
		'Hz', 'kHz', //Frequencies
	);

	/**
	 * if we are in parens we can be more liberal with whitespace around
	 * operators because it must evaluate to a single value and thus is less
	 * ambiguous.
	 *
	 * Consider:
	 *     property1: 10 -5; // is two numbers, 10 and -5
	 *     property2: (10 -5); // should evaluate to 5
	 */
	protected $inParens = false;

	function __construct($lessc, $sourceName = null) {
		// reference to less needed for vPrefix, mPrefix, and parentSelector
		$this->lessc = $lessc;

		$this->sourceName = $sourceName; // name used for error messages

		if (!self::$operatorString) {
			self::$operatorString =
				'('.implode('|', array_map(array('lessc', 'preg_quote'),
					array_keys(self::$precedence))).')';
		}

		if (!self::$numberString) {
			self::$numberString =
				'(-?(?:\.[0-9]+|[0-9]+(?:\.[0-9]*)?))('.implode('|', self::$units).')?';
		}

	}

	function parse($buffer) {
		$this->count = 0;
		$this->line = 1;

		$this->env = null; // block stack
		$this->buffer = $this->removeComments($buffer);
		$this->pushBlock(null); // root

		// trim whitespace on head
		if (preg_match('/^\s+/', $this->buffer, $m)) {
			$this->line += substr_count($m[0], "\n");
			$this->buffer = ltrim($this->buffer);
		}

		// parse the entire file
		$lastCount = $this->count;
		while (false !== $this->parseChunk());

		if ($this->count != strlen($this->buffer))
			$this->throwError();

		// TODO report where the block was opened
		if (!is_null($this->env->parent))
			throw new exception('parse error: unclosed block');

		$this->env->isRoot = true;
		return $this->env;
	}

	/**
	 * Parse a single chunk off the head of the buffer and append it to the
	 * current parse environment.
	 * Returns false when the buffer is empty, or when there is an error.
	 *
	 * This function is called repeatedly until the entire document is
	 * parsed.
	 *
	 * This parser is most similar to a recursive descent parser. Single
	 * functions represent discrete grammatical rules for the language, and
	 * they are able to capture the text that represents those rules.
	 *
	 * Consider the function lessc::keyword(). (all parse functions are
	 * structured the same)
	 *
	 * The function takes a single reference argument. When calling the
	 * function it will attempt to match a keyword on the head of the buffer.
	 * If it is successful, it will place the keyword in the referenced
	 * argument, advance the position in the buffer, and return true. If it
	 * fails then it won't advance the buffer and it will return false.
	 *
	 * All of these parse functions are powered by lessc::match(), which behaves
	 * the same way, but takes a literal regular expression. Sometimes it is
	 * more convenient to use match instead of creating a new function.
	 *
	 * Because of the format of the functions, to parse an entire string of
	 * grammatical rules, you can chain them together using &&.
	 *
	 * But, if some of the rules in the chain succeed before one fails, then
	 * the buffer position will be left at an invalid state. In order to
	 * avoid this, lessc::seek() is used to remember and set buffer positions.
	 *
	 * Before parsing a chain, use $s = $this->seek() to remember the current
	 * position into $s. Then if a chain fails, use $this->seek($s) to
	 * go back where we started.
	 */
	protected function parseChunk() {
		if (empty($this->buffer)) return false;
		$s = $this->seek();

		// setting a property
		if ($this->keyword($key) && $this->assign() &&
			$this->propertyValue($value, $key) && $this->end())
		{
			$this->append(array('assign', $key, $value), $s);
			return true;
		} else {
			$this->seek($s);
		}

		// look for special css blocks
		if ($this->env->parent == null && $this->literal('@', false)) {
			$this->count--;

			// a font-face block
			if ($this->literal('@font-face') && $this->literal('{')) {
				$b = $this->pushSpecialBlock('@font-face');
				return true;
			} else {
				$this->seek($s);
			}

			// charset
			if ($this->literal('@charset') && $this->propertyValue($value) &&
				$this->end())
			{
				$this->append(array('charset', $value), $s);
				return true;
			} else {
				$this->seek($s);
			}


			// media
			if ($this->literal('@media') && $this->mediaTypes($types) &&
				$this->literal('{'))
			{
				$b = $this->pushSpecialBlock('@media');
				$b->media = $types;
				return true;
			} else {
				$this->seek($s);
			}

			// css animations
			if ($this->match('(@(-[a-z]+-)?keyframes)', $m) &&
				$this->propertyValue($value) && $this->literal('{'))
			{
				$b = $this->pushSpecialBlock(trim($m[0]));
				$b->keyframes = $value;
				return true;
			} else {
				$this->seek($s);
			}

			if ($this->literal("@page") &&
				($this->match('(:(left|right))', $m) || true) &&
				$this->literal("{"))
			{
				$name = "@page";
				if ($m) $name = $name . " " . $m[1];
				$this->pushSpecialBlock($name);
				return true;
			} else {
				$this->seek($s);
			}
		}

		if (isset($this->env->keyframes)) {
			if ($this->keyframeTags($ktags) && $this->literal('{')) {
				$this->pushSpecialBlock($ktags);
				return true;
			} else {
				$this->seek($s);
			}
		}

		// setting a variable
		if ($this->variable($var) && $this->assign() &&
			$this->propertyValue($value) && $this->end())
		{
			$this->append(array('assign', $var, $value), $s);
			return true;
		} else {
			$this->seek($s);
		}

		if ($this->import($url, $media)) {
			$this->append(array('import', $url, $media), $s);
			return true;

			// don't check .css files
			if (empty($media) && substr_compare($url, '.css', -4, 4) !== 0) {
				if ($this->importDisabled) {
					$this->append(array('raw', '/* import disabled */'));
				} else {
					$path = $this->findImport($url);
					if (!is_null($path)) {
						$this->append(array('import', $path), $s);
						return true;
					}
				}
			}

			$this->append(array('raw', '@import url("'.$url.'")'.
				($media ? ' '.$media : '').';'), $s);
			return true;
		}

		// opening parametric mixin
		if ($this->tag($tag, true) && $this->argumentDef($args, $is_vararg) &&
			($this->guards($guards) || true) &&
			$this->literal('{'))
		{
			$block = $this->pushBloc…