lessc.class.php

<?php
class Lessc {
  public static $VERSION = "v0.5.0";

  public static $TRUE = array("keyword", "true");
  public static $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;

  protected static $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);
  }

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

  public static 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;
  }

  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 = $this->deduplicate($out->lines);
  }

  protected function deduplicate($lines) {
    $unique = array();
    $comments = array();

    foreach ($lines as $line) {
      if (strpos($line, '/*') === 0) {
        $comments[] = $line;
        continue;
      }
      if (!in_array($line, $unique)) {
        $unique[] = $line;
      }
      array_splice($unique, array_search($line, $unique), 0, $comments);
      $comments = array();
    }
    return array_merge($unique, $comments);
  }

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

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

    if ($split) {
      return array(array_merge($imports, $vars), $other);
    } else {
      return array_merge($imports, $vars, $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 because 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) {
          $this->throwError("{$prop[1][0]} is undefined");
        }

        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");
    }
  }


  public 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);
  }

  protected function lib_data_uri($value) {
    $mime = ($value[0] === 'list') ? $value[2][0][2] : null;
    $url = ($value[0] === 'list') ? $value[2][1][2][0] : $value[2][0];

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

    if ($fullpath && ($fsize = filesize($fullpath)) !== false) {
      // IE8 can't handle data uris larger than 32KB
      if ($fsize / 1024 < 32) {
        if (is_null($mime)) {
          if (class_exists('finfo')) { // php 5.3+
            $finfo = new finfo(FILEINFO_MIME);
            $mime = explode('; ', $finfo->file($fullpath));
            $mime = $mime[0];
          } elseif (function_exists('mime_content_type')) { // PHP 5.2
            $mime = mime_content_type($fullpath);
          }
        }

        if (!is_null($mime)) // fallback if the mime type is still unknown
          $url = sprintf('data:%s;base64,%s', $mime, base64_encode(file_get_contents($fullpath)));
      }
    }

    return 'url("'.$url.'")';
  }

  // 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]);
        }
        $this->throwError("unrecognised input");
        return null;
      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;
    $m = array();
    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($arg) {
    if ($arg[0] != "list") {
      $value = $this->assertNumber($arg);
      return array("number", round($value), $arg[2]);
    } else {
      $value = $this->assertNumber($arg[2][0]);
      $precision = $this->assertNumber($arg[2][1]);
      return array("number", round($value, $precision), $arg[2][0][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), "");
    }
  }

  public 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, "%");
  }

  protected function lib_tint($args) {
    $white = ['color', 255, 255, 255];
    if ($args[0] == 'color') {
      return $this->lib_mix(['list', ',', [$white, $args]]);
    } elseif ($args[0] == "list" && count($args[2]) == 2) {
      return $this->lib_mix([$args[0], $args[1], [$white, $args[2][0], $args[2][1]]]);
    } else {
      $this->throwError("tint expects (color, weight)");
    }
  }

  protected function lib_shade($args) {
    $black = ['color', 0, 0, 0];
    if ($args[0] == 'color') {
      return $this->lib_mix(['list', ',', [$black, $args]]);
    } elseif ($args[0] == "list" && count($args[2]) == 2) {
      return $this->lib_mix([$args[0], $args[1], [$black, $args[2][0], $args[2][1]]]);
    } else {
      $this->throwError("shade expects (color, weight)");
    }
  }

  // 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) {
    $darkColor  = array('color', 0, 0, 0);
    $lightColor = array('color', 255, 255, 255);
    $threshold  = 0.43;

    if ($args[0] == 'list') {
      $inputColor = (isset($args[2][0])) ? $this->assertColor($args[2][0]) : $lightColor;
      $darkColor  = (isset($args[2][1])) ? $this->assertColor($args[2][1]) : $darkColor;
      $lightColor = (isset($args[2][2])) ? $this->assertColor($args[2][2]) : $lightColor;
      $threshold  = (isset($args[2][3])) ? $this->assertNumber($args[2][3]) : $threshold;
    }
    else {
      $inputColor = $this->assertColor($args);
    }

    $inputColor = $this->coerceColor($inputColor);
    $darkColor  = $this->coerceColor($darkColor);
    $lightColor = $this->coerceColor($lightColor);

    //Figure out which is actually light and dark!
    if ($this->toLuma($darkColor) > $this->toLuma($lightColor)) {
      $t = $lightColor;
      $lightColor = $darkColor;
      $darkColor  = $t;
    }

    $inputColor_alpha = $this->lib_alpha($inputColor);
    if (($this->toLuma($inputColor) * $inputColor_alpha) < $threshold) {
      return $lightColor;
    }
    return $darkColor;
  }

  private function toLuma($color) {
    list(, $r, $g, $b) = $this->coerceColor($color);

    $r = $r / 255;
    $g = $g / 255;
    $b = $b / 255;

    $r = ($r <= 0.03928) ? $r / 12.92 : pow((($r + 0.055) / 1.055), 2.4);
    $g = ($g <= 0.03928) ? $g / 12.92 : pow((($g + 0.055) / 1.055), 2.4);
    $b = ($b <= 0.03928) ? $b / 12.92 : pow((($b + 0.055) / 1.055), 2.4);

    return (0.2126 * $r) + (0.7152 * $g) + (0.0722 * $b);
  }

  protected function lib_luma($color) {
    return array("number", round($this->toLuma($color) * 100, 8), "%");
  }


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

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

  public 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) {
      // copy alpha
      $out[] = $color[4];
    }
    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;
  }

  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) {
      // copy alpha
      $out[] = $color[4];
    }
    return $out;
  }

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

  protected function funcToColor($func) {
    $fname = $func[1];
    if ($func[2][0] != 'list') {
      // need a list of arguments
      return false;
    }
    $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));
        $seen[$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_'.str_replace('-', '_', $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;
  }

  public function toBool($a) {
    return $a ? self::$TRUE : 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);
  }

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

    return $color[1];
  }

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

    return $color[2];
  }

  public 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) {
    $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];
      }

      $current = isset($current->storeParent) ?
      $current->storeParent : $current->parent;
    }

    $this->throwError("variable $name is undefined");
  }

  // 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);
    }
  }

  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;
  }

  public function cachedCompile($in, $force = false) {
    // assume no root
    $root = null;

    if (is_string($in)) {
      $root = $in;
    } elseif (is_array($in) && isset($in['root'])) {
      if ($force || !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']) && is_array($in['files'])) {
        foreach ($in['files'] as $fname => $ftime) {
          if (!file_exists($fname) || 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;
  }

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

  public 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);
  }

  protected static $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 {
  protected static $nextBlockId = 0; // used to uniquely identify blocks

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

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

  protected static $whitePattern;
  protected static $commentMulti;

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

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

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

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

  protected $inParens = false;

  // caches preg escaped literals
  protected static $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
      while (false !== $this->parseChunk());

      if ($this->count != strlen($this->buffer))
      {
        $this->throwError('parse error count '.$this->count.' != len buffer '.strlen($this->buffer));
      }

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

      return $this->env;
    }

    protected function parseChunk() {
      if (empty($this->buffer)) return false;
      $s = $this->seek();

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

      // 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('{', false)) {
              $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;
    }

    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;
    }

    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(&$out) {
      if (!$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)) {
              $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) {
      $tags = array();
      while ($this->tag($tt, true)) {
        $tags[] = $tt;
        $this->literal(">");
      }

      if (!$tags) {
        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)) {
            $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;
    }

    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 ($this->literal(';', false)) {
        return true;
      } elseif ($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($this->seenComments[$this->count])) {
            $this->append(array("comment", $m[1]));
            $this->seenComments[$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 = ",";
}