<?php

/**
 * lessphp v0.4.0
 * 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 three stage process. The incoming file is parsed
 * by `lessc_parser` into a syntax tree, then it is compiled into another tree
 * representing the CSS structure by `lessc`. The CSS tree is fed into a
 * formatter, like `lessc_formatter` which then outputs CSS as a string.
 *
 * During the first compile, all values are *reduced*, which means that their
 * types are brought to the lowest form before being dump as strings. This
 * handles math equations, variable dereferences, and the like.
 *
 * The `parse` function of `lessc` is the entry point.
 *
 * In summary:
 *
 * The `lessc` class creates an intstance of the parser, feeds it LESS code,
 * then transforms the resulting tree to a CSS tree. This class also holds the
 * evaluation context, such as all available mixins and variables at any given
 * time.
 *
 * The `lessc_parser` class is only concerned with parsing its input.
 *
 * The `lessc_formatter` takes a CSS tree, and dumps it to a formatted string,
 * handling things like indentation.
 */
class lessc {
	static public $VERSION = "v0.4.0";
	static protected $TRUE = array( "keyword", "true" );
	static protected $FALSE = array( "keyword", "false" );

	protected $libFunctions = array();
	protected $registeredVars = array();
	protected $preserveComments = false;

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

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

	protected $numberPrecision = null;

	protected $allParsedFiles = array();

	// 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;

	static public $defaultValue = array( "keyword", "" );

	static protected $nextImportId = 0; // uniquely identify imports

	// attempts to find the path of an import url, returns null for css files
	protected 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;
	}

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

	static public function compressList( $items, $delim ) {
		if ( !isset( $items[1] ) && isset( $items[0] ) ) {
			return $items[0];
		} else {
			return array( 'list', $delim, $items );
		}
	}

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

	protected function tryImport( $importPath, $parentBlock, $out ) {
		if ( $importPath[0] == "function" && $importPath[1] == "url" ) {
			$importPath = $this->flattenList( $importPath[2] );
		}

		$str = $this->coerceString( $importPath );
		if ( $str === null ) {
			return false;
		}

		$url = $this->compileValue( $this->lib_e( $str ) );

		// don't import if it ends in css
		if ( substr_compare( $url, '.css', -4, 4 ) === 0 ) {
			return false;
		}

		$realPath = $this->findImport( $url );

		if ( $realPath === null ) {
			return false;
		}

		if ( $this->importDisabled ) {
			return array( false, "/* import disabled */" );
		}

		if ( isset( $this->allParsedFiles[realpath( $realPath )] ) ) {
			return array( false, null );
		}

		$this->addParsedFile( $realPath );
		$parser = $this->makeParser( $realPath );
		$root = $parser->parse( file_get_contents( $realPath ) );

		// set the parents of all the block props
		foreach ( $root->props as $prop ) {
			if ( $prop[0] == "block" ) {
				$prop[1]->parent = $parentBlock;
			}
		}

		// copy mixins into scope, set their parents
		// bring blocks from import into current block
		// TODO: need to mark the source parser	these came from this file
		foreach ( $root->children as $childName => $child ) {
			if ( isset( $parentBlock->children[ $childName ] ) ) {
				$parentBlock->children[ $childName ] = array_merge(
					$parentBlock->children[ $childName ],
					$child 
				);
			} else {
				$parentBlock->children[ $childName ] = $child;
			}
		}

		$pi = pathinfo( $realPath );
		$dir = $pi["dirname"];

		list( $top, $bottom ) = $this->sortProps( $root->props, true );
		$this->compileImportedProps( $top, $parentBlock, $out, $parser, $dir );

		return array( true, $bottom, $parser, $dir );
	}

	protected function compileImportedProps( $props, $block, $out, $sourceParser, $importDir ) {
		$oldSourceParser = $this->sourceParser;

		$oldImport = $this->importDir;

		// TODO: this is because the importDir api is stupid
		$this->importDir = (array) $this->importDir;
		array_unshift( $this->importDir, $importDir );

		foreach ( $props as $prop ) {
			$this->compileProp( $prop, $block, $out );
		}

		$this->importDir = $oldImport;
		$this->sourceParser = $oldSourceParser;
	}

	/**
	 * Recursively compiles a block.
	 *
	 * 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.
	 * This is used to look up mixins when performing a mixin.
	 *
	 * Compiling the block involves pushing a fresh environment on the stack,
	 * and iterating through the props, compiling each one.
	 *
	 * See lessc::compileProp()
	 *
	 */
	protected function compileBlock( $block ) {
		switch ( $block->type ) {
			case "root":
				$this->compileRoot( $block );
				break;
			case null:
				$this->compileCSSBlock( $block );
				break;
			case "media":
				$this->compileMedia( $block );
				break;
			case "directive":
				$name = "@" . $block->name;
				if ( !empty( $block->value ) ) {
					$name .= " " . $this->compileValue( $this->reduce( $block->value ) );
				}
	
				$this->compileNestedBlock( $block, array( $name ) );
				break;
			default:
				$this->throwError( "unknown block type: $block->type\n" );
		}
	}

	protected function compileCSSBlock( $block ) {
		$env = $this->pushEnv();

		$selectors = $this->compileSelectors( $block->tags );
		$env->selectors = $this->multiplySelectors( $selectors );
		$out = $this->makeOutputBlock( null, $env->selectors );

		$this->scope->children[] = $out;
		$this->compileProps( $block, $out );

		$block->scope = $env; // mixins carry scope with them!
		$this->popEnv();
	}

	protected function compileMedia( $media ) {
		$env = $this->pushEnv( $media );
		$parentScope = $this->mediaParent( $this->scope );

		$query = $this->compileMediaQuery( $this->multiplyMedia( $env ) );

		$this->scope = $this->makeOutputBlock( $media->type, array( $query ) );
		$parentScope->children[] = $this->scope;

		$this->compileProps( $media, $this->scope );

		if ( count( $this->scope->lines ) > 0 ) {
			$orphanSelelectors = $this->findClosestSelectors();
			if ( !is_null( $orphanSelelectors ) ) {
				$orphan = $this->makeOutputBlock( null, $orphanSelelectors );
				$orphan->lines = $this->scope->lines;
				array_unshift( $this->scope->children, $orphan );
				$this->scope->lines = array();
			}
		}

		$this->scope = $this->scope->parent;
		$this->popEnv();
	}

	protected function mediaParent( $scope ) {
		while ( !empty( $scope->parent ) ) {
			if ( !empty( $scope->type ) && $scope->type != "media" ) {
				break;
			}
			$scope = $scope->parent;
		}

		return $scope;
	}

	protected function compileNestedBlock( $block, $selectors ) {
		$this->pushEnv( $block );
		$this->scope = $this->makeOutputBlock( $block->type, $selectors );
		$this->scope->parent->children[] = $this->scope;

		$this->compileProps( $block, $this->scope );

		$this->scope = $this->scope->parent;
		$this->popEnv();
	}

	protected function compileRoot( $root ) {
		$this->pushEnv();
		$this->scope = $this->makeOutputBlock( $root->type );
		$this->compileProps( $root, $this->scope );
		$this->popEnv();
	}

	protected function compileProps( $block, $out ) {
		foreach ( $this->sortProps( $block->props ) as $prop ) {
			$this->compileProp( $prop, $block, $out );
		}

		$out->lines = array_values( array_unique( $out->lines ) );
	}

	protected function sortProps( $props, $split = false ) {
		$vars = array();
		$imports = array();
		$other = array();

		foreach ( $props as $prop ) {
			switch ( $prop[0] ) {
				case "assign":
					if ( isset( $prop[1][0] ) && $prop[1][0] == $this->vPrefix ) {
						$vars[] = $prop;
					} else {
						$other[] = $prop;
					}
					break;
				case "import":
					$id = self::$nextImportId++;
					$prop[] = $id;
					$imports[] = $prop;
					$other[] = array( "import_mixin", $id );
					break;
				default:
					$other[] = $prop;
			}
		}

		if ( $split ) {
			return array( array_merge( $vars, $imports ), $other );
		} else {
			return array_merge( $vars, $imports, $other );
		}
	}

	protected function compileMediaQuery( $queries ) {
		$compiledQueries = array();
		foreach ( $queries as $query ) {
			$parts = array();
			foreach ( $query as $q ) {
				switch ( $q[0] ) {
					case "mediaType":
						$parts[] = implode( " ", array_slice( $q, 1 ) );
						break;
					case "mediaExp":
						if ( isset( $q[2] ) ) {
							$parts[] = "($q[1]: " .
								$this->compileValue( $this->reduce( $q[2] ) ) . ")";
						} else {
							$parts[] = "($q[1])";
						}
						break;
					case "variable":
						$parts[] = $this->compileValue( $this->reduce( $q ) );
						break;
				}
			}

			if ( count( $parts ) > 0 ) {
				$compiledQueries[] = implode( " and ", $parts );
			}
		}

		$out = "@media";
		if ( !empty( $parts ) ) {
			$out .= " " . implode( $this->formatter->selectorSeparator, $compiledQueries );
		}
		return $out;
	}

	protected function multiplyMedia( $env, $childQueries = null ) {
		if ( is_null( $env ) || !empty( $env->block->type ) && $env->block->type != "media" ) {
			return $childQueries;
		}

		// plain old block, skip
		if ( empty( $env->block->type ) ) {
			return $this->multiplyMedia( $env->parent, $childQueries );
		}

		$out = array();
		$queries = $env->block->queries;
		if ( is_null( $childQueries ) ) {
			$out = $queries;
		} else {
			foreach ( $queries as $parent ) {
				foreach ( $childQueries as $child ) {
					$out[] = array_merge( $parent, $child );
				}
			}
		}

		return $this->multiplyMedia( $env->parent, $out );
	}

	protected 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;
	}

	protected function findClosestSelectors() {
		$env = $this->env;
		$selectors = null;
		while ( $env !== null ) {
			if ( isset( $env->selectors ) ) {
				$selectors = $env->selectors;
				break;
			}
			$env = $env->parent;
		}

		return $selectors;
	}


	// multiply $selectors against the nearest selectors in env
	protected function multiplySelectors( $selectors ) {
		// find parent selectors

		$parentSelectors = $this->findClosestSelectors();
		if ( is_null( $parentSelectors ) ) {
			// kill parent reference in top level selector
			foreach ( $selectors as &$s ) {
				$this->expandParentSelectors( $s, "" );
			}

			return $selectors;
		}

		$out = array();
		foreach ( $parentSelectors as $parent ) {
			foreach ( $selectors as $child ) {
				$count = $this->expandParentSelectors( $child, $parent );

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

		return $out;
	}

	// reduces selector expressions
	protected function compileSelectors( $selectors ) {
		$out = array();

		foreach ( $selectors as $s ) {
			if ( is_array( $s ) ) {
				list( , $value ) = $s;
				$out[] = trim( $this->compileValue( $this->reduce( $value ) ) );
			} else {
				$out[] = $s;
			}
		}

		return $out;
	}

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

	protected function patternMatch( $block, $orderedArgs, $keywordArgs ) {
		// 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 ) ) {
			$groupPassed = false;
			foreach ( $block->guards as $guardGroup ) {
				foreach ( $guardGroup as $guard ) {
					$this->pushEnv();
					$this->zipSetArgs( $block->args, $orderedArgs, $keywordArgs );

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

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

					$this->popEnv();

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

				if ( $groupPassed ) {
					break;
				}
			}

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

		if ( empty( $block->args ) ) {
			return $block->isVararg || empty( $orderedArgs ) && empty( $keywordArgs );
		}

		$remainingArgs = $block->args;
		if ( $keywordArgs ) {
			$remainingArgs = array();
			foreach ( $block->args as $arg ) {
				if ( $arg[0] == "arg" && isset( $keywordArgs[ $arg[1] ] ) ) {
					continue;
				}

				$remainingArgs[] = $arg;
			}
		}

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

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

	protected function patternMatchAll( $blocks, $orderedArgs, $keywordArgs, $skip = array() ) {
		$matches = null;
		foreach ( $blocks as $block ) {
			// skip seen blocks that don't have arguments
			if ( isset( $skip[ $block->id ] ) && !isset( $block->args ) ) {
				continue;
			}

			if ( $this->patternMatch( $block, $orderedArgs, $keywordArgs ) ) {
				$matches[] = $block;
			}
		}

		return $matches;
	}

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

		$name = $path[0];

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

					if ( !is_null( $subMatches ) ) {
						foreach ( $subMatches as $sm ) {
							$matches[] = $sm;
						}
					}
				}

				return count( $matches ) > 0 ? $matches : null;
			}
		}
		if ( $searchIn->parent === $searchIn ) {
			return null;
		}
		return $this->findBlocks( $searchIn->parent, $path, $orderedArgs, $keywordArgs, $seen );
	}

	// sets all argument names in $args to either the default value
	// or the one passed in through $values
	protected function zipSetArgs( $args, $orderedValues, $keywordValues ) {
		$assignedValues = array();

		$i = 0;
		foreach ( $args as $a ) {
			if ( $a[0] == "arg" ) {
				if ( isset( $keywordValues[ $a[1] ] ) ) {
					// has keyword arg
					$value = $keywordValues[ $a[1] ];
				} elseif ( isset( $orderedValues[ $i ] ) ) {
					// has ordered arg
					$value = $orderedValues[ $i ];
					$i++;
				} elseif ( isset( $a[2] ) ) {
					// has default value
					$value = $a[2];
				} else {
					$this->throwError( "Failed to assign arg " . $a[1] );
					$value = null; // :(
				}

				$value = $this->reduce( $value );
				$this->set( $a[1], $value );
				$assignedValues[] = $value;
			} else {
				// a lit
				$i++;
			}
		}

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

		// wow is this the only true use of PHP's + operator for arrays?
		$this->env->arguments = $assignedValues + $orderedValues;
	}

	// compile a prop and update $lines or $blocks appropriately
	protected function compileProp( $prop, $block, $out ) {
		// set error position context
		$this->sourceLoc = isset( $prop[-1] ) ? $prop[-1] : -1;

		switch ( $prop[0] ) {
			case 'assign':
				list( , $name, $value ) = $prop;
				if ( $name[0] == $this->vPrefix ) {
					$this->set( $name, $value );
				} else {
					$out->lines[] = $this->formatter->property( $name,
							$this->compileValue( $this->reduce( $value ) ) );
				}
				break;
			case 'block':
				list( , $child ) = $prop;
				$this->compileBlock( $child );
				break;
			case 'mixin':
				list( , $path, $args, $suffix ) = $prop;
	
				$orderedArgs = array();
				$keywordArgs = array();
				foreach ( (array )$args as $arg ) {
					$argval = null;
					switch ( $arg[0] ) {
						case "arg":
							if ( !isset( $arg[2] ) ) {
								$orderedArgs[] = $this->reduce( array( "variable", $arg[1] ) );
							} else {
								$keywordArgs[ $arg[1] ] = $this->reduce( $arg[2] );
							}
							break;
		
						case "lit":
							$orderedArgs[] = $this->reduce( $arg[1] );
							break;
						default:
							$this->throwError( "Unknown arg type: " . $arg[0] );
					}
				}
	
				$mixins = $this->findBlocks( $block, $path, $orderedArgs, $keywordArgs );
	
				if ( $mixins === null ) {
					// fwrite( STDERR, "failed to find block: " . implode( " > ", $path ) . "\n" );
					break; // throw error here??
				}
	
				foreach ( $mixins as $mixin ) {
					if ( $mixin === $block && !$orderedArgs ) {
						continue;
					}
	
					$haveScope = false;
					if ( isset( $mixin->parent->scope ) ) {
						$haveScope = true;
						$mixinParentEnv = $this->pushEnv();
						$mixinParentEnv->storeParent = $mixin->parent->scope;
					}
	
					$haveArgs = false;
					if ( isset( $mixin->args ) ) {
						$haveArgs = true;
						$this->pushEnv();
						$this->zipSetArgs( $mixin->args, $orderedArgs, $keywordArgs );
					}
	
					$oldParent = $mixin->parent;
					if ( $mixin != $block ) {
						$mixin->parent = $block;
					}
	
					foreach ( $this->sortProps( $mixin->props ) as $subProp ) {
						if ( $suffix !== null &&
							$subProp[0] == "assign" &&
							is_string( $subProp[1] ) &&
							$subProp[1]{0} != $this->vPrefix ) {
							$subProp[2] = array(
								'list', ' ',
								array( $subProp[2], array( 'keyword', $suffix ) )
							);
						}

						$this->compileProp( $subProp, $mixin, $out );
					}
	
					$mixin->parent = $oldParent;

					if ( $haveArgs ) {
						$this->popEnv();
					}
					if ( $haveScope ) {
						$this->popEnv();
					}
				}
				break;
			case 'raw':
				$out->lines[] = $prop[1];
				break;
			case "directive":
				list( , $name, $value ) = $prop;
				$out->lines[] = "@$name " . $this->compileValue( $this->reduce( $value ) ) . ';';
				break;
			case "comment":
				$out->lines[] = $prop[1];
				break;
			case "import";
				list( , $importPath, $importId ) = $prop;
				$importPath = $this->reduce( $importPath );
	
				if ( !isset( $this->env->imports ) ) {
					$this->env->imports = array();
				}
	
				$result = $this->tryImport( $importPath, $block, $out );
	
				$this->env->imports[ $importId ] = $result === false ?
					array( false, "@import " . $this->compileValue( $importPath ) . ";" ) :
					$result;
				break;
			case "import_mixin":
				list( , $importId ) = $prop;
				$import = $this->env->imports[ $importId ];
				if ( $import[0] === false ) {
					if ( isset( $import[1] ) ) {
						$out->lines[] = $import[1];
					}
				} else {
					list( , $bottom, $parser, $importDir ) = $import;
					$this->compileImportedProps( $bottom, $block, $out, $parser, $importDir );
				}
				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.
	 */
	protected 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':
				if ( !empty( $this->formatter->compressColors ) ) {
					return $this->compileValue( $this->coerceColor( $value ) );
				}
				return $value[1];
			case 'keyword':
				// [1] - the keyword
				return $value[1];
			case 'number':
				list( , $num, $unit ) = $value;
				// [1] - the number
				// [2] - the unit
				if ( $this->numberPrecision !== null ) {
					$num = round( $num, $this->numberPrecision );
				}
				return $num . $unit;
			case 'string':
				// [1] - contents of string (includes quotes)
				list( , $delim, $content ) = $value;
				foreach ( $content as &$part ) {
					if ( is_array( $part ) ) {
						$part = $this->compileValue( $part );
					}
				}
				return $delim . implode( $content ) . $delim;
			case 'color':
				// [1] - red component (either number or 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->compressColors ) ) {
					// 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':
				list( , $name, $args ) = $value;
				return $name . '(' . $this->compileValue( $args ) . ')';
			default: // assumed to be unit
				$this->throwError( "unknown value type: $value[0]" );
		}
	}

	protected function lib_pow( $args ) {
		list( $base, $exp ) = $this->assertArgs( $args, 2, "pow" );
		return pow( $this->assertNumber( $base ), $this->assertNumber( $exp ) );
	}

	protected function lib_pi() {
		return pi();
	}

	protected function lib_mod( $args ) {
		list( $a, $b ) = $this->assertArgs( $args, 2, "mod" );
		return $this->assertNumber( $a ) % $this->assertNumber( $b );
	}

	protected function lib_tan( $num ) {
		return tan( $this->assertNumber( $num ) );
	}

	protected function lib_sin( $num ) {
		return sin( $this->assertNumber( $num ) );
	}

	protected function lib_cos( $num ) {
		return cos( $this->assertNumber( $num ) );
	}

	protected function lib_atan( $num ) {
		$num = atan( $this->assertNumber( $num ) );
		return array( "number", $num, "rad" );
	}

	protected function lib_asin( $num ) {
		$num = asin( $this->assertNumber( $num ) );
		return array( "number", $num, "rad" );
	}

	protected function lib_acos( $num ) {
		$num = acos( $this->assertNumber( $num ) );
		return array( "number", $num, "rad" );
	}

	protected function lib_sqrt( $num ) {
		return sqrt( $this->assertNumber( $num ) );
	}

	protected function lib_extract( $value ) {
		list( $list, $idx ) = $this->assertArgs( $value, 2, "extract" );
		$idx = $this->assertNumber( $idx );
		// 1 indexed
		if ( $list[0] == "list" && isset( $list[2][ $idx - 1 ] ) ) {
			return $list[2][ $idx - 1 ];
		}
	}

	protected function lib_isnumber( $value ) {
		return $this->toBool( $value[0] == "number" );
	}

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

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

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

	protected function lib_ispixel( $value ) {
		return $this->toBool( $value[0] == "number" && $value[2] == "px" );
	}

	protected function lib_ispercentage( $value ) {
		return $this->toBool( $value[0] == "number" && $value[2] == "%" );
	}

	protected function lib_isem( $value ) {
		return $this->toBool( $value[0] == "number" && $value[2] == "em" );
	}

	protected function lib_isrem( $value ) {
		return $this->toBool( $value[0] == "number" && $value[2] == "rem" );
	}

	protected 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 : 255,
			$color[1], $color[2], $color[3] );
	}

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

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

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

		$i = 0;
		if ( preg_match_all( '/%[dsa]/', $template, $m ) ) {
			foreach ( $m[0] as $match ) {
				$val = isset( $values[ $i ] ) ?
					$this->reduce( $values[ $i ] ) : array( 'keyword', '' );

				// lessjs compat, renders fully expanded color, not raw color
				if ( $color = $this->coerceColor( $val ) ) {
					$val = $color;
				}

				$i++;
				$rep = $this->compileValue( $this->lib_e( $val ) );
				$template = preg_replace( '/' . self::preg_quote( $match ) . '/',
					$rep, $template, 1 );
			}
		}

		$d = $string[0] == "string" ? $string[1] : '"';
		return array( "string", $d, array( $template ) );
	}

	protected function lib_floor( $arg ) {
		$value = $this->assertNumber( $arg );
		return array( "number", floor( $value ), $arg[2] );
	}

	protected function lib_ceil( $arg ) {
		$value = $this->assertNumber( $arg );
		return array( "number", ceil( $value ), $arg[2] );
	}

	protected function lib_round( $arg ) {
		$value = $this->assertNumber( $arg );
		return array( "number", round( $value ), $arg[2] );
	}

	protected function lib_unit( $arg ) {
		if ( $arg[0] == "list" ) {
			list( $number, $newUnit ) = $arg[2];
			return array( "number", $this->assertNumber( $number ),
				$this->compileValue( $this->lib_e( $newUnit ) ) );
		} else {
			return array( "number", $this->assertNumber( $arg ), "" );
		}
	}

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

		return array( $color, $delta );
	}

	protected 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 );
	}

	protected 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 );
	}

	protected 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 );
	}

	protected 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 );
	}

	protected 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 );
	}

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

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

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

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

	protected 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
	protected function lib_alpha( $value ) {
		if ( !is_null( $color = $this->coerceColor( $value ) ) ) {
			return isset( $color[4] ) ? $color[4] : 1;
		}
	}

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

	protected function lib_percentage( $arg ) {
		$num = $this->assertNumber( $arg );
		return array( "number", $num * 100, "%" );
	}

	// mixes two colors by weight
	// mix(@color1, @color2, [@weight: 50%]);
	// http://sass-lang.com/docs/yardoc/Sass/Script/Functions.html#mix-instance_method
	protected function lib_mix( $args ) {
		if ( $args[0] != "list" || count( $args[2] ) < 2 ) {
			$this->throwError( "mix expects (color1, color2, weight )" );
		}

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

		$first_a = $this->lib_alpha( $first );
		$second_a = $this->lib_alpha( $second );

		if ( isset( $args[2][2] ) ) {
			$weight = $args[2][2][1] / 100.0;
		} else {
			$weight = 0.5;
		}

		$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 );
	}

	protected function lib_contrast( $args ) {
		if ( $args[0] != 'list' || count( $args[2] ) < 3 ) {
			return array( array( 'color', 0, 0, 0 ), 0 );
		}

		list( $inputColor, $darkColor, $lightColor ) = $args[2];

		$inputColor = $this->assertColor( $inputColor );
		$darkColor = $this->assertColor( $darkColor );
		$lightColor = $this->assertColor( $lightColor );
		$hsl = $this->toHSL( $inputColor );

		if ( $hsl[3] > 50 ) {
			return $darkColor;
		}

		return $lightColor;
	}

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

	protected function assertNumber( $value, $error = "expecting number" ) {
		if ( $value[0] == "number" ) {
			return $value[1];
		}
		$this->throwError( $error );
	}

	protected function assertArgs( $value, $expectedArgs, $name="" ) {
		if ( $expectedArgs == 1 ) {
			return $value;
		} else {
			if ( $value[0] !== "list" || $value[1] != "," ) {
				$this->throwError( "expecting list" );
			}
			$values = $value[2];
			$numValues = count( $values );
			if ( $expectedArgs != $numValues ) {
				if ( $name ) {
					$name = $name . ": ";
				}

				$this->throwError( "${name}expecting $expectedArgs arguments, got $numValues" );
			}

			return $values;
		}
	}

	protected 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;
	}

	protected 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
	 */
	protected function toRGB( $color ) {
		if ( $color[0] == '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;
	}

	protected 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.
	 */
	protected 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 < 3 ) {
					$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] == "number" && $c[2] == "%" ) {
						$components[] = 255 * ( $c[1] / 100 );
					} else {
						$components[] = floatval( $c[1] );
					}
				} elseif ( $i == 4 ) {
					if ( $c[0] == "number" && $c[2] == "%" ) {
						$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;
	}

	protected function reduce( $value, $forExpression = false ) {
		switch ( $value[0] ) {
			case "interpolate":
				$reduced = $this->reduce( $value[1] );
				$var = $this->compileValue( $reduced );
				$res = $this->reduce( array( "variable", $this->vPrefix . $var ) );
	
				if ( $res[0] == "raw_color" ) {
					$res = $this->coerceColor( $res );
				}
	
				if ( empty( $value[2] ) ) {
					$res = $this->lib_e( $res );
				}
	
				return $res;
			case "variable":
				$key = $value[1];
				if ( is_array( $key ) ) {
					$key = $this->reduce( $key );
					$key = $this->vPrefix . $this->compileValue( $this->lib_e( $key ) );
				}
	
				$seen =& $this->env->seenNames;
	
				if ( !empty( $seen[ $key ] ) ) {
					$this->throwError( "infinite loop detected: $key" );
				}
	
				$seen[ $key ] = true;
				$out = $this->reduce( $this->get( $key, self::$defaultValue ) );
				$seen[ $key ] = false;
				return $out;
			case "list":
				foreach ( $value[2] as &$item ) {
					$item = $this->reduce( $item, $forExpression );
				}
				return $value;
			case "expression":
				return $this->evaluate( $value );
			case "string":
				foreach ( $value[2] as &$part ) {
					if ( is_array( $part ) ) {
						$strip = $part[0] == "variable";
						$part = $this->reduce( $part );
						if ( $strip ) {
							$part = $this->lib_e( $part );
						}
					}
				}
				return $value;
			case "escape":
				list( ,$inner ) = $value;
				return $this->lib_e( $this->reduce( $inner ) );
			case "function":
				$color = $this->funcToColor( $value );
				if ( $color ) {
					return $color;
				}
	
				list( , $name, $args ) = $value;
				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] );
					}
	
					$ret = call_user_func( $f, $this->reduce( $args, true ), $this );
	
					if ( is_null( $ret ) ) {
						return array( "string", "", array(
							$name, "(", $args, ")"
						) );
					}
	
					// convert to a typed value if the result is a php primitive
					if ( is_numeric( $ret ) ) {
						$ret = array( 'number', $ret, "" );
					} elseif ( !is_array( $ret ) ) {
						$ret = array( 'keyword', $ret );
					}
	
					return $ret;
				}
	
				// plain function, reduce args
				$value[2] = $this->reduce( $value[2] );
				return $value;
			case "unary":
				list( , $op, $exp ) = $value;
				$exp = $this->reduce( $exp );
	
				if ( $exp[0] == "number" ) {
					switch ( $op ) {
						case "+":
							return $exp;
						case "-":
							$exp[1] *= -1;
							return $exp;
						}
				}
				return array( "string", "", array( $op, $exp ) );
		}

		if ( $forExpression ) {
			switch ( $value[0] ) {
				case "keyword":
					if ( $color = $this->coerceColor( $value ) ) {
						return $color;
					}
					break;
				case "raw_color":
					return $this->coerceColor( $value );
			}
		}

		return $value;
	}


	// coerce a value for use in color operation
	protected 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 ] ) ) {
					$rgba = explode( ',', self::$cssColors[ $name ] );

					if( isset( $rgba[3] ) ) {
						return array( 'color', $rgba[0], $rgba[1], $rgba[2], $rgba[3] );
					}

					return array( 'color', $rgba[0], $rgba[1], $rgba[2] );
				}
				return null;
		}
	}

	// make something string like into a string
	protected function coerceString( $value ) {
		switch ( $value[0] ) {
			case "string":
				return $value;
			case "keyword":
				return array( "string", "", array( $value[1] ) );
		}
		return null;
	}

	// turn list of length 1 into value type
	protected function flattenList( $value ) {
		if ( $value[0] == "list" && count( $value[2] ) == 1 ) {
			return $this->flattenList( $value[2][0] );
		}
		return $value;
	}

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

	// evaluate an expression
	protected function evaluate( $exp ) {
		list( , $op, $left, $right, $whiteBefore, $whiteAfter ) = $exp;

		$left = $this->reduce( $left, true );
		$right = $this->reduce( $right, true );

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

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

		$ltype = $left[0];
		$rtype = $right[0];

		// operators that work on all types
		if ( $op == "and" ) {
			return $this->toBool( $left == self::$TRUE && $right == self::$TRUE );
		}

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

		if ( $op == "+" && !is_null( $str = $this->stringConcatenate( $left, $right ) ) ) {
			return $str;
		}

		// type based operators
		$fname = "op_${ltype}_${rtype}";
		if ( is_callable( array( $this, $fname ) ) ) {
			$out = $this->$fname( $op, $left, $right );
			if ( !is_null( $out ) ) {
				return $out;
			}
		}

		// make the expression look it did before being parsed
		$paddedOp = $op;
		if ( $whiteBefore ) {
			$paddedOp = " " . $paddedOp;
		}
		if ( $whiteAfter ) {
			$paddedOp .= " ";
		}

		return array( "string", "", array( $left, $paddedOp, $right ) );
	}

	protected function stringConcatenate( $left, $right ) {
		if ( $strLeft = $this->coerceString( $left ) ) {
			if ( $right[0] == "string" ) {
				$right[1] = "";
			}
			$strLeft[2][] = $right;
			return $strLeft;
		}

		if ( $strRight = $this->coerceString( $right ) ) {
			array_unshift( $strRight[2], $left );
			return $strRight;
		}
	}


	// make sure a color's components don't go out of bounds
	protected 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;
	}

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

	protected 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] ) );
	}

	protected 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 );
	}

	function lib_red( $color ) {
		$color = $this->coerceColor( $color );
		if ( is_null( $color ) ) {
			$this->throwError( 'color expected for red()' );
		}

		return $color[1];
	}

	function lib_green( $color ) {
		$color = $this->coerceColor( $color );
		if ( is_null( $color ) ) {
			$this->throwError( 'color expected for green()' );
		}

		return $color[2];
	}

	function lib_blue( $color ) {
		$color = $this->coerceColor( $color );
		if ( is_null( $color ) ) {
			$this->throwError( 'color expected for blue()' );
		}

		return $color[3];
	}


	// operator on two numbers
	protected function op_number_number( $op, $left, $right ) {
		$unit = empty( $left[2] ) ? $right[2] : $left[2];

		$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( "number", $value, $unit );
	}


	/* environment functions */

	protected function makeOutputBlock( $type, $selectors = null ) {
		$b = new stdclass;
		$b->lines = array();
		$b->children = array();
		$b->selectors = $selectors;
		$b->type = $type;
		$b->parent = $this->scope;
		return $b;
	}

	// the state of execution
	protected function pushEnv( $block = null ) {
		$e = new stdclass;
		$e->parent = $this->env;
		$e->store = array();
		$e->block = $block;

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

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

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


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

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

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

		return $default;
	}

	// 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 => $strValue ) {
			if ( $name{0} != '@' ) {
				$name = '@' . $name;
			}
			$parser->count = 0;
			$parser->buffer = (string) $strValue;
			if ( !$parser->propertyValue( $value ) ) {
				throw new Exception( "failed to parse passed in variable $name: $strValue" );
			}

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

	/**
	 * Initialize any static state, can initialize parser for a file
	 * $opts isn't used yet
	 */
	public function __construct( $fname = null ) {
		if ( $fname !== null ) {
			// used for deprecated parse method
			$this->_parseFile = $fname;
		}
	}

	public function compile( $string, $name = null ) {
		$locale = setlocale( LC_NUMERIC, 0 );
		setlocale( LC_NUMERIC, "C" );

		$this->parser = $this->makeParser( $name );
		$root = $this->parser->parse( $string );

		$this->env = null;
		$this->scope = null;

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

		if ( !empty( $this->registeredVars ) ) {
			$this->injectVariables( $this->registeredVars );
		}

		$this->sourceParser = $this->parser; // used for error messages
		$this->compileBlock( $root );

		ob_start();
		$this->formatter->block( $this->scope );
		$out = ob_get_clean();
		setlocale( LC_NUMERIC, $locale );
		return $out;
	}

	public function compileFile( $fname, $outFname = null ) {
		if ( !is_readable( $fname ) ) {
			throw new Exception( 'load error: failed to find ' . $fname );
		}

		$pi = pathinfo( $fname );

		$oldImport = $this->importDir;

		$this->importDir = (array) $this->importDir;
		$this->importDir[] = $pi['dirname'] . '/';

		$this->addParsedFile( $fname );

		$out = $this->compile( file_get_contents( $fname ), $fname );

		$this->importDir = $oldImport;

		if ( $outFname !== null ) {
			return file_put_contents( $outFname, $out );
		}

		return $out;
	}

	// compile only if changed input has changed or output doesn't exist
	public function checkedCompile( $in, $out ) {
		if ( !is_file( $out ) || filemtime( $in ) > filemtime( $out ) ) {
			$this->compileFile( $in, $out );
			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 function cachedCompile( $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.
			$out = array();
			$out['root'] = $root;
			$out['compiled'] = $this->compileFile( $root );
			$out['files'] = $this->allParsedFiles();
			$out['updated'] = time();
			return $out;
		} else {
			// No changes, pass back the structure
			// we were given initially.
			return $in;
		}

	}

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

		$oldVars = $this->registeredVars;
		if ( $initialVariables !== null ) {
			$this->setVariables( $initialVariables );
		}

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

			$out = $this->compileFile( $this->_parseFile );
		} else {
			$out = $this->compile( $str );
		}

		$this->registeredVars = $oldVars;
		return $out;
	}

	protected function makeParser( $name ) {
		$parser = new lessc_parser( $this, $name );
		$parser->writeComments = $this->preserveComments;

		return $parser;
	}

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

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

		return new $className;
	}

	public function setPreserveComments( $preserve ) {
		$this->preserveComments = $preserve;
	}

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

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

	public function setVariables( $variables ) {
		$this->registeredVars = array_merge( $this->registeredVars, $variables );
	}

	public function unsetVariable( $name ) {
		unset( $this->registeredVars[ $name ] );
	}

	public function setImportDir( $dirs ) {
		$this->importDir = (array) $dirs;
	}

	public function addImportDir( $dir ) {
		$this->importDir = (array) $this->importDir;
		$this->importDir[] = $dir;
	}

	public function allParsedFiles() {
		return $this->allParsedFiles;
	}

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

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

	// 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, $less = null ) {
		if ( $less === null ) {
			$less = new self;
		}
		return $less->checkedCompile( $in, $out );
	}

	public static function cexecute( $in, $force = false, $less = null ) {
		if ( $less === null ) {
			$less = new self;
		}
		return $less->cachedCompile( $in, $force );
	}

	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',
		'transparent' => '0,0,0,0',
		'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,
	);

	static protected $whitePattern;
	static protected $commentMulti;

	static protected $commentSingle = "//";
	static protected $commentMultiLeft = "/*";
	static protected $commentMultiRight = "*/";

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

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

	protected $blockDirectives = array( "font-face", "keyframes", "page", "-moz-document", "viewport", "-moz-viewport", "-o-viewport", "-ms-viewport" );
	protected $lineDirectives = array( "charset" );

	/**
	 * 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;

	// caches preg escaped literals
	static protected $literalCache = array();

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

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

		$this->writeComments = false;

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

			$commentSingle = lessc::preg_quote( self::$commentSingle );
			$commentMultiLeft = lessc::preg_quote( self::$commentMultiLeft );
			$commentMultiRight = lessc::preg_quote( self::$commentMultiRight );

			self::$commentMulti = $commentMultiLeft . '.*?' . $commentMultiRight;
			self::$whitePattern = '/' . $commentSingle . '[^\n]*\s*|(' . self::$commentMulti . ')\s*|\s+/Ais';
		}
	}

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

		$this->env = null; // block stack
		$this->buffer = $this->writeComments ? $buffer : $this->removeComments( $buffer );
		$this->pushSpecialBlock( "root" );
		$this->eatWhiteDefault = true;
		$this->seenComments = array();

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

		// 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' );
		}

		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->literal( '@', false ) ) {
			$this->count--;

			// media
			if ( $this->literal( '@media' ) ) {
				if ( ( $this->mediaQueryList( $mediaQueries ) || true ) && $this->literal( '{' ) ) {
					$media = $this->pushSpecialBlock( "media" );
					$media->queries = is_null( $mediaQueries ) ? array() : $mediaQueries;
					return true;
				} else {
					$this->seek( $s );
					return false;
				}
			}

			if ( $this->literal( "@", false ) && $this->keyword( $dirName ) ) {
				if ( $this->isDirective( $dirName, $this->blockDirectives ) ) {
					if ( ( $this->openString( "{", $dirValue, null, array( ";" ) ) || true ) &&
						$this->literal( "{" ) ) {
						$dir = $this->pushSpecialBlock( "directive" );
						$dir->name = $dirName;
						if ( isset( $dirValue ) ) {
							$dir->value = $dirValue;
						}
						return true;
					}
				} elseif ( $this->isDirective( $dirName, $this->lineDirectives ) ) {
					if ( $this->propertyValue( $dirValue ) && $this->end() ) {
						$this->append( array( "directive", $dirName, $dirValue ) );
						return true;
					}
				}
			}

			$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( $importValue ) ) {
			$this->append( $importValue, $s );
			return true;
		}

		// opening parametric mixin
		if ( $this->tag( $tag, true ) && $this->argumentDef( $args, $isVararg ) && ( $this->guards( $guards ) || true ) && $this->literal( '{' ) ) {
			$block = $this->pushBlock( $this->fixTags( array( $tag ) ) );
			$block->args = $args;
			$block->isVararg = $isVararg;
			if ( !empty( $guards ) ) {
				$block->guards = $guards;
			}
			return true;
		} else {
			$this->seek( $s );
		}

		// opening a simple block
		if ( $this->tags( $tags ) && $this->literal( '{' ) ) {
			$tags = $this->fixTags( $tags );
			$this->pushBlock( $tags );
			return true;
		} else {
			$this->seek( $s );
		}

		// closing a block
		if ( $this->literal( '}', false ) ) {
			try {
				$block = $this->pop();
			} catch ( exception $e ) {
				$this->seek( $s );
				$this->throwError( $e->getMessage() );
			}

			$hidden = false;
			if ( is_null( $block->type ) ) {
				$hidden = true;
				if ( !isset( $block->args ) ) {
					foreach ( $block->tags as $tag ) {
						if ( !is_string( $tag ) || $tag{0} != $this->lessc->mPrefix ) {
							$hidden = false;
							break;
						}
					}
				}

				foreach ( $block->tags as $tag ) {
					if ( is_string( $tag ) ) {
						$this->env->children[ $tag ][] = $block;
					}
				}
			}

			if ( !$hidden ) {
				$this->append( array( 'block', $block ), $s );
			}

			// this is done here so comments aren't bundled into he block that
			// was just closed
			$this->whitespace();
			return true;
		}

		// mixin
		if ( $this->mixinTags( $tags ) && ( $this->argumentDef( $argv, $isVararg ) || true ) && ( $this->keyword( $suffix ) || true ) && $this->end() ) {
			$tags = $this->fixTags( $tags );
			$this->append( array( 'mixin', $tags, $argv, $suffix ), $s );
			return true;
		} else {
			$this->seek( $s );
		}

		// spare ;
		if ( $this->literal( ';' ) ) {
			return true;
		}

		return false; // got nothing, throw error
	}

	protected function isDirective( $dirname, $directives ) {
		// TODO: cache pattern in parser
		$pattern = implode( "|",
			array_map( array( "lessc", "preg_quote" ), $directives ) );
		$pattern = '/^(-[a-z-]+-)?(' . $pattern . ')$/i';

		return preg_match( $pattern, $dirname );
	}

	protected function fixTags( $tags ) {
		// move @ tags out of variable namespace
		foreach ( $tags as &$tag ) {
			if ( $tag{0} == $this->lessc->vPrefix ) {
				$tag[0] = $this->lessc->mPrefix;
			}
		}
		return $tags;
	}

	// a list of expressions
	protected function expressionList( &$exps ) {
		$values = array();

		while ( $this->expression( $exp ) ) {
			$values[] = $exp;
		}

		if ( count( $values ) == 0 ) {
			return false;
		}

		$exps = lessc::compressList( $values, ' ' );
		return true;
	}

	/**
	 * Attempt to consume an expression.
	 * @link http://en.wikipedia.org/wiki/Operator-precedence_parser#Pseudo-code
	 */
	protected function expression( &$out ) {
		if ( $this->value( $lhs ) ) {
			$out = $this->expHelper( $lhs, 0 );

			// look for / shorthand
			if ( !empty( $this->env->supressedDivision ) ) {
				unset( $this->env->supressedDivision );
				$s = $this->seek();
				if ( $this->literal( "/" ) && $this->value( $rhs ) ) {
					$out = array( "list", "",
						array( $out, array( "keyword", "/" ), $rhs ) );
				} else {
					$this->seek( $s );
				}
			}

			return true;
		}
		return false;
	}

	/**
	 * recursively parse infix equation with $lhs at precedence $minP
	 */
	protected function expHelper( $lhs, $minP ) {
		$this->inExp = true;
		$ss = $this->seek();

		while ( true ) {
			$whiteBefore = isset( $this->buffer[ $this->count - 1 ] ) &&
				ctype_space( $this->buffer[ $this->count - 1 ] );

			// If there is whitespace before the operator, then we require
			// whitespace after the operator for it to be an expression
			$needWhite = $whiteBefore && !$this->inParens;

			if ( $this->match( self::$operatorString . ( $needWhite ? '\s' : '' ), $m ) && self::$precedence[ $m[1] ] >= $minP ) {
				if ( !$this->inParens && isset( $this->env->currentProperty ) && $m[1] == "/" && empty( $this->env->supressedDivision ) ) {
					foreach ( self::$supressDivisionProps as $pattern ) {
						if ( preg_match( $pattern, $this->env->currentProperty ) ) {
							$this->env->supressedDivision = true;
							break 2;
						}
					}
				}


				$whiteAfter = isset( $this->buffer[ $this->count - 1 ] ) &&
					ctype_space( $this->buffer[ $this->count - 1 ] );

				if ( !$this->value( $rhs ) ) {
					break;
				}

				// peek for next operator to see what to do with rhs
				if ( $this->peek( self::$operatorString, $next ) && self::$precedence[ $next[1] ] > self::$precedence[ $m[1] ] ) {
					$rhs = $this->expHelper( $rhs, self::$precedence[ $next[1] ] );
				}

				$lhs = array( 'expression', $m[1], $lhs, $rhs, $whiteBefore, $whiteAfter );
				$ss = $this->seek();

				continue;
			}

			break;
		}

		$this->seek( $ss );

		return $lhs;
	}

	// consume a list of values for a property
	public function propertyValue( &$value, $keyName = null ) {
		$values = array();

		if ( $keyName !== null ) {
			$this->env->currentProperty = $keyName;
		}

		$s = null;
		while ( $this->expressionList( $v ) ) {
			$values[] = $v;
			$s = $this->seek();
			if ( !$this->literal( ',' ) ) {
				break;
			}
		}

		if ( $s ) {
			$this->seek( $s );
		}

		if ( $keyName !== null ) {
			unset( $this->env->currentProperty );
		}

		if ( count( $values ) == 0 ) {
			return false;
		}

		$value = lessc::compressList( $values, ', ' );
		return true;
	}

	protected function parenValue( &$out ) {
		$s = $this->seek();

		// speed shortcut
		if ( isset( $this->buffer[ $this->count ] ) && $this->buffer[ $this->count ] != "(" ) {
			return false;
		}

		$inParens = $this->inParens;
		if ( $this->literal( "(" ) &&
			( $this->inParens = true ) && $this->expression( $exp ) &&
			$this->literal( ")" ) )
		{
			$out = $exp;
			$this->inParens = $inParens;
			return true;
		} else {
			$this->inParens = $inParens;
			$this->seek( $s );
		}

		return false;
	}

	// a single value
	protected function value( &$value ) {
		$s = $this->seek();

		// speed shortcut
		if ( isset( $this->buffer[ $this->count ] ) && $this->buffer[ $this->count ] == "-" ) {
			// negation
			if ( $this->literal( "-", false ) &&
				( ( $this->variable( $inner ) && $inner = array( "variable", $inner ) ) ||
				$this->unit( $inner ) ||
				$this->parenValue( $inner ) ) )
			{
				$value = array( "unary", "-", $inner );
				return true;
			} else {
				$this->seek( $s );
			}
		}

		if ( $this->parenValue( $value ) ) {
			return true;
		}
		if ( $this->unit( $value ) ) {
			return true;
		}
		if ( $this->color( $value ) ) {
			return true;
		}
		if ( $this->func( $value ) ) {
			return true;
		}
		if ( $this->string( $value ) ) {
			return true;
		}
		if ( $this->keyword( $word ) ) {
			$value = array( 'keyword', $word );
			return true;
		}

		// try a variable
		if ( $this->variable( $var ) ) {
			$value = array( 'variable', $var );
			return true;
		}

		// unquote string (should this work on any type?
		if ( $this->literal( "~" ) && $this->string( $str ) ) {
			$value = array( "escape", $str );
			return true;
		} else {
			$this->seek( $s );
		}

		// css hack: \0
		if ( $this->literal( '\\' ) && $this->match( '([0-9]+)', $m ) ) {
			$value = array( 'keyword', '\\' . $m[1] );
			return true;
		} else {
			$this->seek( $s );
		}

		return false;
	}

	// an import statement
	protected function import( &$out ) {
		$s = $this->seek();
		if ( !$this->literal( '@import' ) ) {
			return false;
		}

		// @import "something.css" media;
		// @import url("something.css") media;
		// @import url(something.css) media;

		if ( $this->propertyValue( $value ) ) {
			$out = array( "import", $value );
			return true;
		}
	}

	protected function mediaQueryList( &$out ) {
		if ( $this->genericList( $list, "mediaQuery", ",", false ) ) {
			$out = $list[2];
			return true;
		}
		return false;
	}

	protected function mediaQuery( &$out ) {
		$s = $this->seek();

		$expressions = null;
		$parts = array();

		if ( ( $this->literal( "only" ) && ( $only = true ) || $this->literal( "not" ) && ( $not = true ) || true ) && $this->keyword( $mediaType ) ) {
			$prop = array( "mediaType" );
			if ( isset( $only ) ) {
				$prop[] = "only";
			}
			if ( isset( $not ) ) {
				$prop[] = "not";
			}
			$prop[] = $mediaType;
			$parts[] = $prop;
		} else {
			$this->seek( $s );
		}


		if ( !empty( $mediaType ) && !$this->literal( "and" ) ) {
			// ~
		} else {
			$this->genericList( $expressions, "mediaExpression", "and", false );
			if ( is_array( $expressions ) ) {
				$parts = array_merge( $parts, $expressions[2] );
			}
		}

		if ( count( $parts ) == 0 ) {
			$this->seek( $s );
			return false;
		}

		$out = $parts;
		return true;
	}

	protected function mediaExpression( &$out ) {
		$s = $this->seek();
		$value = null;
		if ( $this->literal( "(" ) &&
			$this->keyword( $feature ) &&
			( $this->literal( ":" ) && $this->expression( $value ) || true ) &&
			$this->literal( ")" ) )
		{
			$out = array( "mediaExp", $feature );
			if ( $value ) {
				$out[] = $value;
			}
			return true;
		} elseif ( $this->variable( $variable ) ) {
			$out = array( 'variable', $variable );
			return true;
		}

		$this->seek( $s );
		return false;
	}

	// an unbounded string stopped by $end
	protected function openString( $end, &$out, $nestingOpen = null, $rejectStrs = null ) {
		$oldWhite = $this->eatWhiteDefault;
		$this->eatWhiteDefault = false;

		$stop = array( "'", '"', "@{", $end );
		$stop = array_map( array( "lessc", "preg_quote" ), $stop );
		// $stop[] = self::$commentMulti;

		if ( !is_null( $rejectStrs ) ) {
			$stop = array_merge( $stop, $rejectStrs );
		}

		$patt = '(.*?)(' . implode("|", $stop ) . ')';

		$nestingLevel = 0;

		$content = array();
		while ( $this->match( $patt, $m, false ) ) {
			if ( !empty( $m[1] ) ) {
				$content[] = $m[1];
				if ( $nestingOpen ) {
					$nestingLevel += substr_count( $m[1], $nestingOpen );
				}
			}

			$tok = $m[2];

			$this->count-= strlen( $tok );
			if ( $tok == $end ) {
				if ( $nestingLevel == 0 ) {
					break;
				} else {
					$nestingLevel--;
				}
			}

			if ( ( $tok == "'" || $tok == '"' ) && $this->string( $str ) ) {
				$content[] = $str;
				continue;
			}

			if ( $tok == "@{" && $this->interpolation( $inter ) ) {
				$content[] = $inter;
				continue;
			}

			if ( !empty( $rejectStrs ) && in_array( $tok, $rejectStrs ) ) {
				break;
			}

			$content[] = $tok;
			$this->count += strlen( $tok );
		}

		$this->eatWhiteDefault = $oldWhite;

		if ( count( $content ) == 0 ) {
			return false;
		}

		// trim the end
		if ( is_string( end( $content ) ) ) {
			$content[count( $content ) - 1] = rtrim( end( $content ) );
		}

		$out = array( "string", "", $content );
		return true;
	}

	protected function string( &$out ) {
		$s = $this->seek();
		if ( $this->literal( '"', false ) ) {
			$delim = '"';
		} elseif ( $this->literal( "'", false ) ) {
			$delim = "'";
		} else {
			return false;
		}

		$content = array();

		// look for either ending delim , escape, or string interpolation
		$patt = '([^\n]*?)(@\{|\\\\|' .
			lessc::preg_quote( $delim ) . ')';

		$oldWhite = $this->eatWhiteDefault;
		$this->eatWhiteDefault = false;

		while ( $this->match( $patt, $m, false ) ) {
			$content[] = $m[1];
			if ( $m[2] == "@{" ) {
				$this->count -= strlen( $m[2] );
				if ( $this->interpolation( $inter, false ) ) {
					$content[] = $inter;
				} else {
					$this->count += strlen( $m[2] );
					$content[] = "@{"; // ignore it
				}
			} elseif ( $m[2] == '\\' ) {
				$content[] = $m[2];
				if ( $this->literal( $delim, false ) ) {
					$content[] = $delim;
				}
			} else {
				$this->count -= strlen( $delim );
				break; // delim
			}
		}

		$this->eatWhiteDefault = $oldWhite;

		if ( $this->literal( $delim ) ) {
			$out = array( "string", $delim, $content );
			return true;
		}

		$this->seek( $s );
		return false;
	}

	protected function interpolation( &$out ) {
		$oldWhite = $this->eatWhiteDefault;
		$this->eatWhiteDefault = true;

		$s = $this->seek();
		if ( $this->literal( "@{" ) &&
			$this->openString( "}", $interp, null, array( "'", '"', ";" ) ) &&
			$this->literal( "}", false ) )
		{
			$out = array( "interpolate", $interp );
			$this->eatWhiteDefault = $oldWhite;
			if ( $this->eatWhiteDefault ) {
				$this->whitespace();
			}
			return true;
		}

		$this->eatWhiteDefault = $oldWhite;
		$this->seek( $s );
		return false;
	}

	protected function unit( &$unit ) {
		// speed shortcut
		if ( isset( $this->buffer[ $this->count ] ) ) {
			$char = $this->buffer[ $this->count ];
			if ( !ctype_digit( $char ) && $char != "." ) {
				return false;
			}
		}

		if ( $this->match( '([0-9]+(?:\.[0-9]*)?|\.[0-9]+)([%a-zA-Z]+)?', $m ) ) {
			$unit = array( "number", $m[1], empty( $m[2] ) ? "" : $m[2] );
			return true;
		}
		return false;
	}

	// a # color
	protected function color( &$out ) {
		if ( $this->match( '(#(?:[0-9a-f]{8}|[0-9a-f]{6}|[0-9a-f]{3}))', $m ) ) {
			if ( strlen( $m[1] ) > 7 ) {
				$out = array( "string", "", array( $m[1] ) );
			} else {
				$out = array( "raw_color", $m[1] );
			}
			return true;
		}

		return false;
	}

	// consume an argument definition list surrounded by ()
	// each argument is a variable name with optional value
	// or at the end a ... or a variable named followed by ...
	// arguments are separated by , unless a ; is in the list, then ; is the
	// delimiter.
	protected function argumentDef( &$args, &$isVararg ) {
		$s = $this->seek();
		if ( !$this->literal( '(' ) ) {
			return false;
		}

		$values = array();
		$delim = ",";
		$method = "expressionList";

		$isVararg = false;
		while ( true ) {
			if ( $this->literal( "..." ) ) {
				$isVararg = true;
				break;
			}

			if ( $this->$method( $value ) ) {
				if ( $value[0] == "variable" ) {
					$arg = array( "arg", $value[1] );
					$ss = $this->seek();

					if ( $this->assign() && $this->$method( $rhs ) ) {
						$arg[] = $rhs;
					} else {
						$this->seek( $ss );
						if ( $this->literal( "..." ) ) {
							$arg[0] = "rest";
							$isVararg = true;
						}
					}

					$values[] = $arg;
					if ( $isVararg ) {
						break;
					}
					continue;
				} else {
					$values[] = array( "lit", $value );
				}
			}


			if ( !$this->literal( $delim ) ) {
				if ( $delim == "," && $this->literal( ";" ) ) {
					// found new delim, convert existing args
					$delim = ";";
					$method = "propertyValue";

					// transform arg list
					if ( isset( $values[1] ) ) { // 2 items
						$newList = array();
						foreach ( $values as $i => $arg ) {
							switch( $arg[0] ) {
								case "arg":
									if ( $i ) {
										$this->throwError( "Cannot mix ; and , as delimiter types" );
									}
									$newList[] = $arg[2];
									break;
								case "lit":
									$newList[] = $arg[1];
									break;
								case "rest":
									$this->throwError( "Unexpected rest before semicolon" );
							}
						}

						$newList = array( "list", ", ", $newList );

						switch ( $values[0][0] ) {
							case "arg":
								$newArg = array( "arg", $values[0][1], $newList );
								break;
							case "lit":
								$newArg = array( "lit", $newList );
								break;
						}

					} elseif ( $values ) { // 1 item
						$newArg = $values[0];
					}

					if ( $newArg ) {
						$values = array( $newArg );
					}
				} else {
					break;
				}
			}
		}

		if ( !$this->literal( ')' ) ) {
			$this->seek( $s );
			return false;
		}

		$args = $values;

		return true;
	}

	// consume a list of tags
	// this accepts a hanging delimiter
	protected function tags( &$tags, $simple = false, $delim = ',' ) {
		$tags = array();
		while ( $this->tag( $tt, $simple ) ) {
			$tags[] = $tt;
			if ( !$this->literal( $delim ) ) {
				break;
			}
		}
		if ( count( $tags ) == 0 ) {
			return false;
		}

		return true;
	}

	// list of tags of specifying mixin path
	// optionally separated by > (lazy, accepts extra >)
	protected function mixinTags( &$tags ) {
		$s = $this->seek();
		$tags = array();
		while ( $this->tag( $tt, true ) ) {
			$tags[] = $tt;
			$this->literal( ">" );
		}

		if ( count( $tags ) == 0 ) {
			return false;
		}

		return true;
	}

	// a bracketed value (contained within in a tag definition)
	protected function tagBracket( &$parts, &$hasExpression ) {
		// speed shortcut
		if ( isset( $this->buffer[ $this->count ] ) && $this->buffer[ $this->count ] != "[" ) {
			return false;
		}

		$s = $this->seek();

		$hasInterpolation = false;

		if ( $this->literal( "[", false ) ) {
			$attrParts = array( "[" );
			// keyword, string, operator
			while ( true ) {
				if ( $this->literal( "]", false ) ) {
					$this->count--;
					break; // get out early
				}

				if ( $this->match( '\s+', $m ) ) {
					$attrParts[] = " ";
					continue;
				}
				if ( $this->string( $str ) ) {
					// escape parent selector, (yuck)
					foreach ( $str[2] as &$chunk ) {
						$chunk = str_replace( $this->lessc->parentSelector, "$&$", $chunk );
					}

					$attrParts[] = $str;
					$hasInterpolation = true;
					continue;
				}

				if ( $this->keyword( $word ) ) {
					$attrParts[] = $word;
					continue;
				}

				if ( $this->interpolation( $inter, false ) ) {
					$attrParts[] = $inter;
					$hasInterpolation = true;
					continue;
				}

				// operator, handles attr namespace too
				if ( $this->match( '[|-~\$\*\^=]+', $m ) ) {
					$attrParts[] = $m[0];
					continue;
				}

				break;
			}

			if ( $this->literal( "]", false ) ) {
				$attrParts[] = "]";
				foreach ( $attrParts as $part ) {
					$parts[] = $part;
				}
				$hasExpression = $hasExpression || $hasInterpolation;
				return true;
			}
			$this->seek( $s );
		}

		$this->seek( $s );
		return false;
	}

	// a space separated list of selectors
	protected function tag( &$tag, $simple = false ) {
		if ( $simple ) {
			$chars = '^@,:;{}\][>\(\) "\'';
		} else {
			$chars = '^@,;{}["\'';
		}

		$s = $this->seek();

		$hasExpression = false;
		$parts = array();
		while ( $this->tagBracket( $parts, $hasExpression ) );

		$oldWhite = $this->eatWhiteDefault;
		$this->eatWhiteDefault = false;

		while ( true ) {
			if ( $this->match( '([' . $chars.'0-9][' . $chars . ']*)', $m ) ) {
				$parts[] = $m[1];
				if ( $simple ) {
					break;
				}

				while ( $this->tagBracket( $parts, $hasExpression ) );
				continue;
			}

			if ( isset( $this->buffer[ $this->count ] ) && $this->buffer[ $this->count ] == "@" ) {
				if ( $this->interpolation( $interp ) ) {
					$hasExpression = true;
					$interp[2] = true; // don't unescape
					$parts[] = $interp;
					continue;
				}

				if ( $this->literal( "@" ) ) {
					$parts[] = "@";
					continue;
				}
			}

			if ( $this->unit( $unit ) ) { // for keyframes
				$parts[] = $unit[1];
				$parts[] = $unit[2];
				continue;
			}

			break;
		}

		$this->eatWhiteDefault = $oldWhite;
		if ( !$parts ) {
			$this->seek( $s );
			return false;
		}

		if ( $hasExpression ) {
			$tag = array( "exp", array( "string", "", $parts ) );
		} else {
			$tag = trim( implode( $parts ) );
		}

		$this->whitespace();
		return true;
	}

	// a css function
	protected function func( &$func ) {
		$s = $this->seek();

		if ( $this->match( '(%|[\w\-_][\w\-_:\.]+|[\w_])', $m ) && $this->literal( '(' ) ) {
			$fname = $m[1];

			$sPreArgs = $this->seek();

			$args = array();
			while ( true ) {
				$ss = $this->seek();
				// this ugly nonsense is for ie filter properties
				if ( $this->keyword( $name ) && $this->literal( '=' ) && $this->expressionList( $value ) ) {
					$args[] = array( "string", "", array( $name, "=", $value ) );
				} else {
					$this->seek( $ss );
					if ( $this->expressionList( $value ) ) {
						$args[] = $value;
					}
				}

				if ( !$this->literal( ',' ) ) {
					break;
				}
			}
			$args = array( 'list', ',', $args );

			if ( $this->literal( ')' ) ) {
				$func = array( 'function', $fname, $args );
				return true;
			} elseif ( $fname == 'url' ) {
				// couldn't parse and in url? treat as string
				$this->seek( $sPreArgs );
				if ( $this->openString( ")", $string ) && $this->literal( ")" ) ) {
					$func = array( 'function', $fname, $string );
					return true;
				}
			}
		}

		$this->seek( $s );
		return false;
	}

	// consume a less variable
	protected function variable( &$name ) {
		$s = $this->seek();
		if ( $this->literal( $this->lessc->vPrefix, false ) &&
			( $this->variable( $sub ) || $this->keyword( $name ) ) )
		{
			if ( !empty( $sub ) ) {
				$name = array( 'variable', $sub );
			} else {
				$name = $this->lessc->vPrefix . $name;
			}
			return true;
		}

		$name = null;
		$this->seek( $s );
		return false;
	}

	/**
	 * Consume an assignment operator
	 * Can optionally take a name that will be set to the current property name
	 */
	protected function assign( $name = null ) {
		if ( $name ) {
			$this->currentProperty = $name;
		}
		return $this->literal( ':' ) || $this->literal( '=' );
	}

	// consume a keyword
	protected function keyword( &$word ) {
		if ( $this->match( '([\w_\-\*!"][\w\-_"]*)', $m ) ) {
			$word = $m[1];
			return true;
		}
		return false;
	}

	// consume an end of statement delimiter
	protected function end() {
		if ( $this->literal( ';' ) ) {
			return true;
		} elseif ( $this->count == strlen( $this->buffer ) || $this->buffer[ $this->count ] == '}' ) {
			// if there is end of file or a closing block next then we don't need a ;
			return true;
		}
		return false;
	}

	protected function guards( &$guards ) {
		$s = $this->seek();

		if ( !$this->literal( "when" ) ) {
			$this->seek( $s );
			return false;
		}

		$guards = array();

		while ( $this->guardGroup( $g ) ) {
			$guards[] = $g;
			if ( !$this->literal( "," ) ) {
				break;
			}
		}

		if ( count( $guards ) == 0 ) {
			$guards = null;
			$this->seek( $s );
			return false;
		}

		return true;
	}

	// a bunch of guards that are and'd together
	// TODO rename to guardGroup
	protected function guardGroup( &$guardGroup ) {
		$s = $this->seek();
		$guardGroup = array();
		while ( $this->guard( $guard ) ) {
			$guardGroup[] = $guard;
			if ( !$this->literal( "and" ) ) {
				break;
			}
		}

		if ( count( $guardGroup ) == 0 ) {
			$guardGroup = null;
			$this->seek( $s );
			return false;
		}

		return true;
	}

	protected function guard( &$guard ) {
		$s = $this->seek();
		$negate = $this->literal( "not" );

		if ( $this->literal( "(" ) && $this->expression( $exp ) && $this->literal( ")" ) ) {
			$guard = $exp;
			if ( $negate ) {
				$guard = array( "negate", $guard );
			}
			return true;
		}

		$this->seek( $s );
		return false;
	}

	/* raw parsing functions */

	protected function literal( $what, $eatWhitespace = null ) {
		if ( $eatWhitespace === null ) {
			$eatWhitespace = $this->eatWhiteDefault;
		}

		// shortcut on single letter
		if ( !isset( $what[1] ) && isset( $this->buffer[ $this->count ] ) ) {
			if ( $this->buffer[ $this->count ] == $what ) {
				if ( !$eatWhitespace ) {
					$this->count++;
					return true;
				}
				// goes below...
			} else {
				return false;
			}
		}

		if ( !isset( self::$literalCache[ $what ] ) ) {
			self::$literalCache[ $what ] = lessc::preg_quote( $what );
		}

		return $this->match( self::$literalCache[ $what ], $m, $eatWhitespace );
	}

	protected function genericList( &$out, $parseItem, $delim="", $flatten = true ) {
		$s = $this->seek();
		$items = array();
		while ( $this->$parseItem( $value ) ) {
			$items[] = $value;
			if ( $delim ) {
				if ( !$this->literal( $delim ) ) {
					break;
				}
			}
		}

		if ( count( $items ) == 0 ) {
			$this->seek( $s );
			return false;
		}

		if ( $flatten && count( $items ) == 1 ) {
			$out = $items[0];
		} else {
			$out = array( "list", $delim, $items );
		}

		return true;
	}


	// advance counter to next occurrence of $what
	// $until - don't include $what in advance
	// $allowNewline, if string, will be used as valid char set
	protected function to( $what, &$out, $until = false, $allowNewline = false ) {
		if ( is_string( $allowNewline ) ) {
			$validChars = $allowNewline;
		} else {
			$validChars = $allowNewline ? "." : "[^\n]";
		}
		if ( !$this->match( '(' . $validChars.'*?)' . lessc::preg_quote( $what ), $m, !$until ) ) {
			return false;
		}
		if ( $until ) {
			$this->count -= strlen( $what ); // give back $what
		}
		$out = $m[1];
		return true;
	}

	// try to match something on head of buffer
	protected function match( $regex, &$out, $eatWhitespace = null ) {
		if ( $eatWhitespace === null ) {
			$eatWhitespace = $this->eatWhiteDefault;
		}

		$r = '/' . $regex . ( $eatWhitespace && !$this->writeComments ? '\s*' : '' ) . '/Ais';
		if ( preg_match( $r, $this->buffer, $out, null, $this->count ) ) {
			$this->count += strlen( $out[0] );
			if ( $eatWhitespace && $this->writeComments ) {
				$this->whitespace();
			}
			return true;
		}
		return false;
	}

	// match some whitespace
	protected function whitespace() {
		if ( $this->writeComments ) {
			$gotWhite = false;
			while ( preg_match( self::$whitePattern, $this->buffer, $m, null, $this->count ) ) {
				if ( isset( $m[1] ) && empty( $this->commentsSeen[ $this->count ] ) ) {
					$this->append( array( "comment", $m[1] ) );
					$this->commentsSeen[ $this->count ] = true;
				}
				$this->count += strlen( $m[0] );
				$gotWhite = true;
			}
			return $gotWhite;
		} else {
			$this->match( "", $m );
			return strlen( $m[0] ) > 0;
		}
	}

	// match something without consuming it
	protected function peek( $regex, &$out = null, $from = null ) {
		if ( is_null( $from ) ) {
			$from = $this->count;
		}
		$r = '/' . $regex . '/Ais';
		$result = preg_match( $r, $this->buffer, $out, null, $from );

		return $result;
	}

	// seek to a spot in the buffer or return where we are on no argument
	protected function seek( $where = null ) {
		if ( $where === null ) {
			return $this->count;
		} else {
			$this->count = $where;
		}
		return true;
	}

	/* misc functions */

	public function throwError( $msg = "parse error", $count = null ) {
		$count = is_null( $count ) ? $this->count : $count;

		$line = $this->line +
			substr_count( substr( $this->buffer, 0, $count ), "\n" );

		if ( !empty( $this->sourceName ) ) {
			$loc = "$this->sourceName on line $line";
		} else {
			$loc = "line: $line";
		}

		// TODO this depends on $this->count
		if ( $this->peek( "(.*?)(\n|$)", $m, $count ) ) {
			throw new exception( "$msg: failed at `$m[1]` $loc" );
		} else {
			throw new exception( "$msg: $loc" );
		}
	}

	protected function pushBlock( $selectors = null, $type = null ) {
		$b = new stdclass;
		$b->parent = $this->env;

		$b->type = $type;
		$b->id = self::$nextBlockId++;

		$b->isVararg = false; // TODO: kill me from here
		$b->tags = $selectors;

		$b->props = array();
		$b->children = array();

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

	// push a block that doesn't multiply tags
	protected function pushSpecialBlock( $type ) {
		return $this->pushBlock( null, $type );
	}

	// append a property to the current block
	protected function append( $prop, $pos = null ) {
		if ( $pos !== null ) {
			$prop[-1] = $pos;
		}
		$this->env->props[] = $prop;
	}

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

	// remove comments from $text
	// todo: make it work for all functions, not just url
	protected function removeComments( $text ) {
		$look = array(
			'url(', '//', '/*', '"', "'"
		);

		$out = '';
		$min = null;
		while ( true ) {
			// find the next item
			foreach ( $look as $token ) {
				$pos = strpos( $text, $token );
				if ( $pos !== false ) {
					if ( !isset( $min ) || $pos < $min[1] ) {
						$min = array( $token, $pos );
					}
				}
			}

			if ( is_null( $min ) ) {
				break;
			}

			$count = $min[1];
			$skip = 0;
			$newlines = 0;
			switch ( $min[0] ) {
				case 'url(':
					if ( preg_match( '/url\(.*?\)/', $text, $m, 0, $count ) ) {
						$count += strlen( $m[0] ) - strlen( $min[0] );
					}
					break;
				case '"':
				case "'":
					if ( preg_match( '/' . $min[0] . '.*?(?<!\\\\)' . $min[0] . '/', $text, $m, 0, $count ) ) {
						$count += strlen( $m[0] ) - 1;
					}
					break;
				case '//':
					$skip = strpos( $text, "\n", $count );
					if ( $skip === false ) {
						$skip = strlen( $text ) - $count;
					} else {
						$skip -= $count;
					}
					break;
				case '/*':
					if ( preg_match( '/\/\*.*?\*\//s', $text, $m, 0, $count ) ) {
						$skip = strlen( $m[0] );
						$newlines = substr_count( $m[0], "\n" );
					}
					break;
			}

			if ( $skip == 0 ) {
				$count += strlen( $min[0] );
			}

			$out .= substr( $text, 0, $count ) . str_repeat( "\n", $newlines );
			$text = substr( $text, $count + $skip );

			$min = null;
		}

		return $out . $text;
	}

}

class lessc_formatter_classic {
	public $indentChar = " ";

	public $break = "\n";
	public $open = " {";
	public $close = "}";
	public $selectorSeparator = ", ";
	public $assignSeparator = ":";

	public $openSingle = " { ";
	public $closeSingle = " }";

	public $disableSingle = false;
	public $breakSelectors = false;

	public $compressColors = false;

	public function __construct() {
		$this->indentLevel = 0;
	}

	public function indentStr( $n = 0 ) {
		return str_repeat( $this->indentChar, max( $this->indentLevel + $n, 0 ) );
	}

	public function property( $name, $value ) {
		return $name . $this->assignSeparator . $value . ";";
	}

	protected function isEmpty( $block ) {
		if ( empty( $block->lines ) ) {
			foreach ( $block->children as $child ) {
				if ( !$this->isEmpty( $child ) ) {
					return false;
				}
			}

			return true;
		}
		return false;
	}

	public function block( $block ) {
		if ( $this->isEmpty( $block ) ) {
			return;
		}

		$inner = $pre = $this->indentStr();

		$isSingle = !$this->disableSingle &&
			is_null( $block->type ) && count( $block->lines ) == 1;

		if ( !empty( $block->selectors ) ) {
			$this->indentLevel++;

			if ( $this->breakSelectors ) {
				$selectorSeparator = $this->selectorSeparator . $this->break . $pre;
			} else {
				$selectorSeparator = $this->selectorSeparator;
			}

			echo $pre .
				implode( $selectorSeparator, $block->selectors );
			if ( $isSingle ) {
				echo $this->openSingle;
				$inner = "";
			} else {
				echo $this->open . $this->break;
				$inner = $this->indentStr();
			}

		}

		if ( !empty( $block->lines ) ) {
			$glue = $this->break . $inner;
			echo $inner . implode( $glue, $block->lines );
			if ( !$isSingle && !empty( $block->children ) ) {
				echo $this->break;
			}
		}

		foreach ( $block->children as $child ) {
			$this->block( $child );
		}

		if ( !empty( $block->selectors ) ) {
			if ( !$isSingle && empty( $block->children ) ) {
				echo $this->break;
			}

			if ( $isSingle ) {
				echo $this->closeSingle . $this->break;
			} else {
				echo $pre . $this->close . $this->break;
			}

			$this->indentLevel--;
		}
	}
}

class lessc_formatter_compressed extends lessc_formatter_classic {
	public $disableSingle = true;
	public $open = "{";
	public $selectorSeparator = ",";
	public $assignSeparator = ":";
	public $break = "";
	public $compressColors = true;

	public function indentStr( $n = 0 ) {
		return "";
	}
}

class lessc_formatter_lessjs extends lessc_formatter_classic {
	public $disableSingle = true;
	public $breakSelectors = true;
	public $assignSeparator = ": ";
	public $selectorSeparator = ",";
}


