Fix File

• /home/sportsfe.../httpdocs/wp-conte.../plugins/smart-sl.../Nextend/Framewor.../Asset/Css/Less

• File: LessCompiler.php

• Content:

<?php

namespace Nextend\Framework\Asset\Css\Less;

use Exception;
use Nextend\Framework\Asset\Css\Less\Formatter\Classic;
use Nextend\Framework\Asset\Css\Less\Formatter\Compressed;
use Nextend\Framework\Asset\Css\Less\Formatter\Debug;
use Nextend\Framework\Filesystem\Filesystem;
use stdClass;

/**
 * The less compiler and parser.
 *
 * Converting LESS to CSS is a three stage process. The incoming file is parsed
 * by `lessc_parser` into a syntax tree, then it is compiled into another tree
 * representing the CSS structure by `lessc`. The CSS tree is fed into a
 * formatter, like `lessc_formatter` which then outputs CSS as a string.
 *
 * During the first compile, all values are *reduced*, which means that their
 * types are brought to the lowest form before being dump as strings. This
 * handles math equations, variable dereferences, and the like.
 *
 * The `parse` function of `lessc` is the entry point.
 *
 * In summary:
 *
 * The `lessc` class creates an intstance of the parser, feeds it LESS code,
 * then transforms the resulting tree to a CSS tree. This class also holds the
 * evaluation context, such as all available mixins and variables at any given
 * time.
 *
 * The `lessc_parser` class is only concerned with parsing its input.
 *
 * The `lessc_formatter` takes a CSS tree, and dumps it to a formatted string,
 * handling things like indentation.
 */
#[\AllowDynamicProperties]
class LessCompiler {

static public $VERSION = "v0.3.8";
    static protected $TRUE = array(
        "keyword",
        "true"
    );
    static protected $FALSE = array(
        "keyword",
        "false"
    );

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

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

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

protected $numberPrecision = null;

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

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

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

// attempts to find the path of an import url, returns null for css files
    protected function findImport($url) {
        foreach ((array)$this->importDir as $dir) {
            $full = $dir . (substr($dir, -1) != '/' ? '/' : '') . $url;
            if ($this->fileExists($file = $full . '.n2less') || $this->fileExists($file = $full)) {
                return $file;
            }
        }

return null;
    }

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

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

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

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

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

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

if (isset($this->registeredVars[$url])) {
            $url = $this->registeredVars[$url];
        }

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

$realPath = $this->findImport($url);
        if ($realPath === null) return false;

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

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

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

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

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

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

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

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

$oldImport = $this->importDir;

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

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

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

/**
     * Recursively compiles a block.
     *
     * A block is analogous to a CSS block in most cases. A single LESS document
     * is encapsulated in a block when parsed, but it does not have parent tags
     * so all of it's children appear on the root level when compiled.
     *
     * Blocks are made up of props and children.
     *
     * Props are property instructions, array tuples which describe an action
     * to be taken, eg. write a property, set a variable, mixin a block.
     *
     * The children of a block are just all the blocks that are defined within.
     * This is used to look up mixins when performing a mixin.
     *
     * Compiling the block involves pushing a fresh environment on the stack,
     * and iterating through the props, compiling each one.
     *
     * See lessc::compileProp()
     *
     */
    protected function compileBlock($block) {
        switch ($block->type) {
            case "root":
                $this->compileRoot($block);
                break;
            case null:
                $this->compileCSSBlock($block);
                break;
            case "media":
                $this->compileMedia($block);
                break;
            case "directive":
                $name = "@" . $block->name;
                if (!empty($block->value)) {
                    $name .= " " . $this->compileValue($this->reduce($block->value));
                }

$this->compileNestedBlock($block, array($name));
                break;
            default:
                $this->throwError("unknown block type: $block->type\n");
        }
    }

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

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

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

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

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

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

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

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

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

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

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

return $scope;
    }

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

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

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

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

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

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

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

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

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

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

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

return $out;
    }

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

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

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

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

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

return $count;
    }

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

return $selectors;
    }

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

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

return $selectors;
        }

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

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

return $out;
    }

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

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

return $out;
    }

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

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

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

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

$this->popEnv();

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

if ($groupPassed) break;
            }

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

$numCalling = count($callingArgs);

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

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

if ($block->isVararg) {
            return true; // not having enough is handled above
        } else {
            $numMatched = $i + 1;

// greater than becuase default values always match
            return $numMatched >= $numCalling;
        }
    }

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

return $matches;
    }

// attempt to find blocks matched by path and args
    protected function findBlocks($searchIn, $path, $args, $seen = array()) {
        if ($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, $args);
                if (!empty($matches)) {
                    // This will return all blocks that match in the closest
                    // scope that has any matching block, like lessjs
                    return $matches;
                }
            } else {
                $matches = array();
                foreach ($blocks as $subBlock) {
                    $subMatches = $this->findBlocks($subBlock, array_slice($path, 1), $args, $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, $args, $seen);
    }

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

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

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

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

// 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;

$args   = array_map(array(
                    $this,
                    "reduce"
                ), (array)$args);
                $mixins = $this->findBlocks($block, $path, $args);

if ($mixins === null) {
                    // fwrite(STDERR,"failed to find block: ".implode(" > ", $path)."\n");
                    break; // throw error here??
                }

foreach ($mixins as $mixin) {
                    $haveScope = false;
                    if (isset($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, $args);
                    }

$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) {
                    $out->lines[] = $import[1];
                } else {
                    list(, $bottom, $parser, $importDir) = $import;
                    $this->compileImportedProps($bottom, $block, $out, $parser, $importDir);
                }

break;
            default:
                $this->throwError("unknown op: {$prop[0]}\n");
        }
    }

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

return $value[1];
            case 'keyword':
                // [1] - the keyword
                return $value[1];
            case 'number':
                list(, $num, $unit) = $value;
                // [1] - the number
                // [2] - the unit
                if ($this->numberPrecision !== null) {
                    $num = round($num, $this->numberPrecision);
                }

return $num . $unit;
            case 'string':
                // [1] - contents of string (includes quotes)
                list(, $delim, $content) = $value;
                foreach ($content as &$part) {
                    if (is_array($part)) {
                        $part = $this->compileValue($part);
                    }
                }

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

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

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

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

return $h;

case 'function':
                list(, $name, $args) = $value;

return $name . '(' . $this->compileValue($args) . ')';
            default: // assumed to be unit
                $this->throwError("unknown value type: $value[0]");
        }
    }

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

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

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

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

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

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

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

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

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

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

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

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

return self::$defaultValue;
            case "string":
                $arg[1] = "";

return $arg;
            case "keyword":
                return $arg;
            default:
                return array(
                    "keyword",
                    $this->compileValue($arg)
                );
        }
    }

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

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

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

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

$d = $string[0] == "string" ? $string[1] : '"';

return array(
            "string",
            $d,
            array($template)
        );
    }

protected function lib_floor($arg) {
        $value = $this->assertNumber($arg);

return array(
            "number",
            floor($value),
            $arg[2]
        );
    }

protected function lib_ceil($arg) {
        $value = $this->assertNumber($arg);

return array(
            "number",
            ceil($value),
            $arg[2]
        );
    }

protected function lib_round($arg) {
        $value = $this->assertNumber($arg);

return array(
            "number",
            round($value),
            $arg[2]
        );
    }

protected function lib_unit($arg) {
        if ($arg[0] == "list") {
            list($number, $newUnit) = $arg[2];

return array(
                "number",
                $this->assertNumber($number),
                $this->compileValue($this->lib_e($newUnit))
            );
        } else {
            return array(
                "number",
                $this->assertNumber($arg),
                ""
            );
        }
    }

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

return array(
            $color,
            $delta
        );
    }

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

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