CSSMin.inc in Advanced CSS/JS Aggregation 8.2

File

advagg_css_minify/yui/CSSMin.inc

<?php

// @codingStandardsIgnoreFile
// @ignore comment_docblock_file:file
// @ignore style_curly_braces:file
// @ignore style_string_spacing:file
// @ignore style_else_spacing:file
// @ignore comment_comment_docblock_missing:file
// @ignore comment_comment_eg:file
// @ignore production_code:file
// @ignore druplart_unary:file
// @ignore style_uppercase_constants:file
// @ignore comment_comment_space:file
// @ignore druplart_conditional_assignment:file
// @ignore style_paren_spacing:file
// @ignore :file

/*!
 * cssmin.php v2.4.8-4
 * Author: Tubal Martin - http://tubalmartin.me/
 * Repo: https://github.com/tubalmartin/YUI-CSS-compressor-PHP-port
 *
 * This is a PHP port of the CSS minification tool distributed with YUICompressor,
 * itself a port of the cssmin utility by Isaac Schlueter - http://foohack.com/
 * Permission is hereby granted to use the PHP version under the same
 * conditions as the YUICompressor.
 */

/*!
 * YUI Compressor
 * http://developer.yahoo.com/yui/compressor/
 * Author: Julien Lecomte - http://www.julienlecomte.net/
 * Copyright (c) 2013 Yahoo! Inc. All rights reserved.
 * The copyrights embodied in the content of this file are licensed
 * by Yahoo! Inc. under the BSD (revised) open source license.
 */
class CSSmin {
  const NL = '___YUICSSMIN_PRESERVED_NL___';
  const TOKEN = '___YUICSSMIN_PRESERVED_TOKEN_';
  const COMMENT = '___YUICSSMIN_PRESERVE_CANDIDATE_COMMENT_';
  const CLASSCOLON = '___YUICSSMIN_PSEUDOCLASSCOLON___';
  const QUERY_FRACTION = '___YUICSSMIN_QUERY_FRACTION___';
  private $comments;
  private $preserved_tokens;
  private $memory_limit;
  private $max_execution_time;
  private $pcre_backtrack_limit;
  private $pcre_recursion_limit;
  private $raise_php_limits;

  /**
   * @param bool|int $raise_php_limits
   * If true, PHP settings will be raised if needed
   */
  public function __construct($raise_php_limits = TRUE) {

    // Set suggested PHP limits
    $this->memory_limit = 128 * 1048576;

    // 128MB in bytes
    $this->max_execution_time = 60;

    // 1 min
    $this->pcre_backtrack_limit = 1000 * 1000;
    $this->pcre_recursion_limit = 500 * 1000;
    $this->raise_php_limits = (bool) $raise_php_limits;
  }

  /**
   * Minify a string of CSS
   * @param string $css
   * @param int|bool $linebreak_pos
   * @return string
   */
  public function run($css = '', $linebreak_pos = FALSE) {
    if (empty($css)) {
      return '';
    }
    if ($this->raise_php_limits) {
      $this
        ->do_raise_php_limits();
    }
    $this->comments = array();
    $this->preserved_tokens = array();
    $start_index = 0;
    $length = strlen($css);
    $css = $this
      ->extract_data_urls($css);

    // collect all comment blocks...
    while (($start_index = $this
      ->index_of($css, '/*', $start_index)) >= 0) {
      $end_index = $this
        ->index_of($css, '*/', $start_index + 2);
      if ($end_index < 0) {
        $end_index = $length;
      }
      $comment_found = $this
        ->str_slice($css, $start_index + 2, $end_index);
      $this->comments[] = $comment_found;
      $comment_preserve_string = self::COMMENT . (count($this->comments) - 1) . '___';
      $css = $this
        ->str_slice($css, 0, $start_index + 2) . $comment_preserve_string . $this
        ->str_slice($css, $end_index);

      // Set correct start_index: Fixes issue #2528130
      $start_index = $end_index + 2 + strlen($comment_preserve_string) - strlen($comment_found);
    }

    // preserve strings so their content doesn't get accidentally minified
    $css = preg_replace_callback('/(?:"(?:[^\\\\"]|\\\\.|\\\\)*")|' . "(?:'(?:[^\\\\']|\\\\.|\\\\)*')/S", array(
      $this,
      'replace_string',
    ), $css);

    // Let's divide css code in chunks of 5.000 chars aprox.
    // Reason: PHP's PCRE functions like preg_replace have a "backtrack limit"
    // of 100.000 chars by default (php < 5.3.7) so if we're dealing with really
    // long strings and a (sub)pattern matches a number of chars greater than
    // the backtrack limit number (i.e. /(.*)/s) PCRE functions may fail silently
    // returning NULL and $css would be empty.
    $charset = '';
    $charset_regexp = '/(@charset)( [^;]+;)/i';
    $css_chunks = array();
    $css_chunk_length = 5000;

    // aprox size, not exact
    $start_index = 0;
    $i = $css_chunk_length;

    // save initial iterations
    $l = strlen($css);

    // if the number of characters is 5000 or less, do not chunk
    if ($l <= $css_chunk_length) {
      $css_chunks[] = $css;
    }
    else {

      // chunk css code securely
      while ($i < $l) {
        $i += 50;

        // save iterations
        if ($l - $start_index <= $css_chunk_length || $i >= $l) {
          $css_chunks[] = $this
            ->str_slice($css, $start_index);
          break;
        }
        if ($css[$i - 1] === '}' && $i - $start_index > $css_chunk_length) {

          // If there are two ending curly braces }} separated or not by spaces,
          // join them in the same chunk (i.e. @media blocks)
          $next_chunk = substr($css, $i);
          if (preg_match('/^\\s*\\}/', $next_chunk)) {
            $i = $i + $this
              ->index_of($next_chunk, '}') + 1;
          }
          $css_chunks[] = $this
            ->str_slice($css, $start_index, $i);
          $start_index = $i;
        }
      }
    }

    // Minify each chunk
    for ($i = 0, $n = count($css_chunks); $i < $n; $i++) {
      $css_chunks[$i] = $this
        ->minify($css_chunks[$i], $linebreak_pos);

      // Keep the first @charset at-rule found
      if (empty($charset) && preg_match($charset_regexp, $css_chunks[$i], $matches)) {
        $charset = strtolower($matches[1]) . $matches[2];
      }

      // Delete all @charset at-rules
      $css_chunks[$i] = preg_replace($charset_regexp, '', $css_chunks[$i]);
    }

    // Update the first chunk and push the charset to the top of the file.
    $css_chunks[0] = $charset . $css_chunks[0];
    return implode('', $css_chunks);
  }

  /**
   * Sets the memory limit for this script
   * @param int|string $limit
   */
  public function set_memory_limit($limit) {
    $this->memory_limit = $this
      ->normalize_int($limit);
  }

  /**
   * Sets the maximum execution time for this script
   * @param int|string $seconds
   */
  public function set_max_execution_time($seconds) {
    $this->max_execution_time = (int) $seconds;
  }

  /**
   * Sets the PCRE backtrack limit for this script
   * @param int $limit
   */
  public function set_pcre_backtrack_limit($limit) {
    $this->pcre_backtrack_limit = (int) $limit;
  }

  /**
   * Sets the PCRE recursion limit for this script
   * @param int $limit
   */
  public function set_pcre_recursion_limit($limit) {
    $this->pcre_recursion_limit = (int) $limit;
  }

  /**
   * Try to configure PHP to use at least the suggested minimum settings
   */
  private function do_raise_php_limits() {
    $php_limits = array(
      'memory_limit' => $this->memory_limit,
      'max_execution_time' => $this->max_execution_time,
      'pcre.backtrack_limit' => $this->pcre_backtrack_limit,
      'pcre.recursion_limit' => $this->pcre_recursion_limit,
    );

    // If current settings are higher respect them.
    foreach ($php_limits as $name => $suggested) {
      $current = $this
        ->normalize_int(ini_get($name));

      // memory_limit exception: allow -1 for "no memory limit".
      if ($current > -1 && ($suggested == -1 || $current < $suggested)) {
        ini_set($name, $suggested);
      }
    }
  }

  /**
   * Does bulk of the minification
   * @param string $css
   * @param int|bool $linebreak_pos
   * @return string
   */
  private function minify($css, $linebreak_pos) {

    // strings are safe, now wrestle the comments
    for ($i = 0, $max = count($this->comments); $i < $max; $i++) {
      $token = $this->comments[$i];
      $placeholder = '/' . self::COMMENT . $i . '___/';

      // ! in the first position of the comment means preserve
      // so push to the preserved tokens keeping the !
      if (substr($token, 0, 1) === '!') {
        $this->preserved_tokens[] = $token;
        $token_tring = self::TOKEN . (count($this->preserved_tokens) - 1) . '___';
        $css = preg_replace($placeholder, $token_tring, $css, 1);

        // Preserve new lines for /*! important comments
        $css = preg_replace('/\\s*[\\n\\r\\f]+\\s*(\\/\\*' . $token_tring . ')/S', self::NL . '$1', $css);
        $css = preg_replace('/(' . $token_tring . '\\*\\/)\\s*[\\n\\r\\f]+\\s*/', '$1' . self::NL, $css);
        continue;
      }

      // \ in the last position looks like hack for Mac/IE5
      // shorten that to /*\*/ and the next one to /**/
      if (substr($token, strlen($token) - 1, 1) === '\\') {
        $this->preserved_tokens[] = '\\';
        $css = preg_replace($placeholder, self::TOKEN . (count($this->preserved_tokens) - 1) . '___', $css, 1);
        $i = $i + 1;

        // attn: advancing the loop
        $this->preserved_tokens[] = '';
        $css = preg_replace('/' . self::COMMENT . $i . '___/', self::TOKEN . (count($this->preserved_tokens) - 1) . '___', $css, 1);
        continue;
      }

      // keep empty comments after child selectors (IE7 hack)
      // e.g. html >/**/ body
      if (strlen($token) === 0) {
        $start_index = $this
          ->index_of($css, $this
          ->str_slice($placeholder, 1, -1));
        if ($start_index > 2) {
          if (substr($css, $start_index - 3, 1) === '>') {
            $this->preserved_tokens[] = '';
            $css = preg_replace($placeholder, self::TOKEN . (count($this->preserved_tokens) - 1) . '___', $css, 1);
          }
        }
      }

      // in all other cases kill the comment
      $css = preg_replace('/\\/\\*' . $this
        ->str_slice($placeholder, 1, -1) . '\\*\\//', '', $css, 1);
    }

    // Normalize all whitespace strings to single spaces. Easier to work with that way.
    $css = preg_replace('/\\s+/', ' ', $css);

    // Fix IE7 issue on matrix filters which browser accept whitespaces between Matrix parameters
    $css = preg_replace_callback('/\\s*filter\\:\\s*progid:DXImageTransform\\.Microsoft\\.Matrix\\(([^\\)]+)\\)/', array(
      $this,
      'preserve_old_IE_specific_matrix_definition',
    ), $css);

    // Shorten & preserve calculations calc(...) since spaces are important
    $css = preg_replace_callback('/calc(\\(((?:[^\\(\\)]+|(?1))*)\\))/i', array(
      $this,
      'replace_calc',
    ), $css);

    // Replace positive sign from numbers preceded by : or a white-space before the leading space is removed
    // +1.2em to 1.2em, +.8px to .8px, +2% to 2%
    $css = preg_replace('/((?<!\\\\)\\:|\\s)\\+(\\.?\\d+)/S', '$1$2', $css);

    // Remove leading zeros from integer and float numbers preceded by : or a white-space
    // 000.6 to .6, -0.8 to -.8, 0050 to 50, -01.05 to -1.05
    $css = preg_replace('/((?<!\\\\)\\:|\\s)(\\-?)0+(\\.?\\d+)/S', '$1$2$3', $css);

    // Remove trailing zeros from float numbers preceded by : or a white-space
    // -6.0100em to -6.01em, .0100 to .01, 1.200px to 1.2px
    $css = preg_replace('/((?<!\\\\)\\:|\\s)(\\-?)(\\d?\\.\\d+?)0+([^\\d])/S', '$1$2$3$4', $css);

    // Remove trailing .0 -> -9.0 to -9
    $css = preg_replace('/((?<!\\\\)\\:|\\s)(\\-?\\d+)\\.0([^\\d])/S', '$1$2$3', $css);

    // Replace 0 length numbers with 0
    $css = preg_replace('/((?<!\\\\)\\:|\\s)\\-?\\.?0+([^\\d])/S', '${1}0$2', $css);

    // Remove the spaces before the things that should not have spaces before them.
    // But, be careful not to turn "p :link {...}" into "p:link{...}"
    // Swap out any pseudo-class colons with the token, and then swap back.
    $css = preg_replace_callback('/(?:^|\\})[^\\{]*\\s+\\:/', array(
      $this,
      'replace_colon',
    ), $css);

    // Remove spaces before the things that should not have spaces before them.
    $css = preg_replace('/\\s+([\\!\\{\\}\\;\\:\\>\\+\\(\\)\\]\\~\\=,])/', '$1', $css);

    // Restore spaces for !important
    $css = preg_replace('/\\!important/i', ' !important', $css);

    // bring back the colon
    $css = preg_replace('/' . self::CLASSCOLON . '/', ':', $css);

    // retain space for special IE6 cases
    $css = preg_replace_callback('/\\:first\\-(line|letter)(\\{|,)/i', array(
      $this,
      'lowercase_pseudo_first',
    ), $css);

    // no space after the end of a preserved comment
    $css = preg_replace('/\\*\\/ /', '*/', $css);

    // lowercase some popular @directives
    $css = preg_replace_callback('/@(font-face|import|(?:-(?:atsc|khtml|moz|ms|o|wap|webkit)-)?keyframe|media|page|namespace)/i', array(
      $this,
      'lowercase_directives',
    ), $css);

    // lowercase some more common pseudo-elements
    $css = preg_replace_callback('/:(active|after|before|checked|disabled|empty|enabled|first-(?:child|of-type)|focus|hover|last-(?:child|of-type)|link|only-(?:child|of-type)|root|:selection|target|visited)/i', array(
      $this,
      'lowercase_pseudo_elements',
    ), $css);

    // lowercase some more common functions
    $css = preg_replace_callback('/:(lang|not|nth-child|nth-last-child|nth-last-of-type|nth-of-type|(?:-(?:moz|webkit)-)?any)\\(/i', array(
      $this,
      'lowercase_common_functions',
    ), $css);

    // lower case some common function that can be values
    // NOTE: rgb() isn't useful as we replace with #hex later, as well as and() is already done for us
    $css = preg_replace_callback('/([:,\\( ]\\s*)(attr|color-stop|from|rgba|to|url|(?:-(?:atsc|khtml|moz|ms|o|wap|webkit)-)?(?:calc|max|min|(?:repeating-)?(?:linear|radial)-gradient)|-webkit-gradient)/iS', array(
      $this,
      'lowercase_common_functions_values',
    ), $css);

    // Put the space back in some cases, to support stuff like
    // @media screen and (-webkit-min-device-pixel-ratio:0){
    $css = preg_replace('/\\band\\(/i', 'and (', $css);

    // Remove the spaces after the things that should not have spaces after them.
    $css = preg_replace('/([\\!\\{\\}\\:;\\>\\+\\(\\[\\~\\=,])\\s+/S', '$1', $css);

    // remove unnecessary semicolons
    $css = preg_replace('/;+\\}/', '}', $css);

    // Fix for issue: #2528146
    // Restore semicolon if the last property is prefixed with a `*` (lte IE7 hack)
    // to avoid issues on Symbian S60 3.x browsers.
    $css = preg_replace('/(\\*[a-z0-9\\-]+\\s*\\:[^;\\}]+)(\\})/', '$1;$2', $css);

    // Replace 0 <length> and 0 <percentage> values with 0.
    // <length> data type: https://developer.mozilla.org/en-US/docs/Web/CSS/length
    // <percentage> data type: https://developer.mozilla.org/en-US/docs/Web/CSS/percentage
    $css = preg_replace('/([^\\\\]\\:|\\s)0(?:em|ex|ch|rem|vw|vh|vm|vmin|cm|mm|in|px|pt|pc|%)/iS', '${1}0', $css);

    // 0% step in a keyframe? restore the % unit
    $css = preg_replace_callback('/(@[a-z\\-]*?keyframes[^\\{]+\\{)(.*?)(\\}\\})/iS', array(
      $this,
      'replace_keyframe_zero',
    ), $css);

    // Replace 0 0; or 0 0 0; or 0 0 0 0; with 0.
    $css = preg_replace('/\\:0(?: 0){1,3}(;|\\}| \\!)/', ':0$1', $css);

    // Fix for issue: #2528142
    // Replace text-shadow:0; with text-shadow:0 0 0;
    $css = preg_replace('/(text-shadow\\:0)(;|\\}| \\!)/i', '$1 0 0$2', $css);

    // Replace background-position:0; with background-position:0 0;
    // same for transform-origin
    // Changing -webkit-mask-position: 0 0 to just a single 0 will result in the second parameter defaulting to 50% (center)
    $css = preg_replace('/(background|background\\-position|webkit\\-mask\\-position|(?:webkit|moz|o|ms|)\\-?transform\\-origin)\\:0(;|\\}| \\!)/iS', '$1:0 0$2', $css);

    // Shorten colors from rgb(51,102,153) to #336699, rgb(100%,0%,0%) to #ff0000 (sRGB color space)
    // Shorten colors from hsl(0, 100%, 50%) to #ff0000 (sRGB color space)
    // This makes it more likely that it'll get further compressed in the next step.
    $css = preg_replace_callback('/rgb\\s*\\(\\s*([0-9,\\s\\-\\.\\%]+)\\s*\\)(.{1})/i', array(
      $this,
      'rgb_to_hex',
    ), $css);
    $css = preg_replace_callback('/hsl\\s*\\(\\s*([0-9,\\s\\-\\.\\%]+)\\s*\\)(.{1})/i', array(
      $this,
      'hsl_to_hex',
    ), $css);

    // Shorten colors from #AABBCC to #ABC or short color name.
    $css = $this
      ->compress_hex_colors($css);

    // border: none to border:0, outline: none to outline:0
    $css = preg_replace('/(border\\-?(?:top|right|bottom|left|)|outline)\\:none(;|\\}| \\!)/iS', '$1:0$2', $css);

    // shorter opacity IE filter
    $css = preg_replace('/progid\\:DXImageTransform\\.Microsoft\\.Alpha\\(Opacity\\=/i', 'alpha(opacity=', $css);

    // Find a fraction that is used for Opera's -o-device-pixel-ratio query
    // Add token to add the "\" back in later
    $css = preg_replace('/\\(([a-z\\-]+):([0-9]+)\\/([0-9]+)\\)/i', '($1:$2' . self::QUERY_FRACTION . '$3)', $css);

    // Remove empty rules.
    $css = preg_replace('/[^\\};\\{\\/]+\\{\\}/S', '', $css);

    // Add "/" back to fix Opera -o-device-pixel-ratio query
    $css = preg_replace('/' . self::QUERY_FRACTION . '/', '/', $css);

    // Replace multiple semi-colons in a row by a single one
    // See SF bug #1980989
    $css = preg_replace('/;;+/', ';', $css);

    // Restore new lines for /*! important comments
    $css = preg_replace('/' . self::NL . '/', "\n", $css);

    // Lowercase all uppercase properties
    $css = preg_replace_callback('/(\\{|\\;)([A-Z\\-]+)(\\:)/', array(
      $this,
      'lowercase_properties',
    ), $css);

    // Some source control tools don't like it when files containing lines longer
    // than, say 8000 characters, are checked in. The linebreak option is used in
    // that case to split long lines after a specific column.
    if ($linebreak_pos !== FALSE && (int) $linebreak_pos >= 0) {
      $linebreak_pos = (int) $linebreak_pos;
      $start_index = $i = 0;
      while ($i < strlen($css)) {
        $i++;
        if ($css[$i - 1] === '}' && $i - $start_index > $linebreak_pos) {
          $css = $this
            ->str_slice($css, 0, $i) . "\n" . $this
            ->str_slice($css, $i);
          $start_index = $i;
        }
      }
    }

    // restore preserved comments and strings in reverse order
    for ($i = count($this->preserved_tokens) - 1; $i >= 0; $i--) {
      $css = preg_replace('/' . self::TOKEN . $i . '___/', $this->preserved_tokens[$i], $css, 1);
    }

    // Trim the final string (for any leading or trailing white spaces)
    return trim($css);
  }

  /**
   * Utility method to replace all data urls with tokens before we start
   * compressing, to avoid performance issues running some of the subsequent
   * regexes against large strings chunks.
   *
   * @param string $css
   * @return string
   */
  private function extract_data_urls($css) {

    // Leave data urls alone to increase parse performance.
    $max_index = strlen($css) - 1;
    $append_index = $index = $last_index = $offset = 0;
    $sb = array();
    $pattern = '/url\\(\\s*(["\']?)data\\:/i';

    // Since we need to account for non-base64 data urls, we need to handle
    // ' and ) being part of the data string. Hence switching to indexOf,
    // to determine whether or not we have matching string terminators and
    // handling sb appends directly, instead of using matcher.append* methods.
    while (preg_match($pattern, $css, $m, 0, $offset)) {
      $index = $this
        ->index_of($css, $m[0], $offset);
      $last_index = $index + strlen($m[0]);
      $start_index = $index + 4;

      // "url(".length()
      $end_index = $last_index - 1;
      $terminator = $m[1];

      // ', " or empty (not quoted)
      $found_terminator = FALSE;
      if (strlen($terminator) === 0) {
        $terminator = ')';
      }
      while ($found_terminator === FALSE && $end_index + 1 <= $max_index) {
        $end_index = $this
          ->index_of($css, $terminator, $end_index + 1);

        // endIndex == 0 doesn't really apply here
        if ($end_index > 0 && substr($css, $end_index - 1, 1) !== '\\') {
          $found_terminator = TRUE;
          if (')' != $terminator) {
            $end_index = $this
              ->index_of($css, ')', $end_index);
          }
        }
      }

      // Enough searching, start moving stuff over to the buffer
      $sb[] = $this
        ->str_slice($css, $append_index, $index);
      if ($found_terminator) {
        $token = $this
          ->str_slice($css, $start_index, $end_index);
        $token = preg_replace('/\\s+/', '', $token);
        $this->preserved_tokens[] = $token;
        $preserver = 'url(' . self::TOKEN . (count($this->preserved_tokens) - 1) . '___)';
        $sb[] = $preserver;
        $append_index = $end_index + 1;
      }
      else {

        // No end terminator found, re-add the whole match. Should we throw/warn here?
        $sb[] = $this
          ->str_slice($css, $index, $last_index);
        $append_index = $last_index;
      }
      $offset = $last_index;
    }
    $sb[] = $this
      ->str_slice($css, $append_index);
    return implode('', $sb);
  }

  /**
   * Utility method to compress hex color values of the form #AABBCC to #ABC or short color name.
   *
   * DOES NOT compress CSS ID selectors which match the above pattern (which would break things).
   * e.g. #AddressForm { ... }
   *
   * DOES NOT compress IE filters, which have hex color values (which would break things).
   * e.g. filter: chroma(color="#FFFFFF");
   *
   * DOES NOT compress invalid hex values.
   * e.g. background-color: #aabbccdd
   *
   * @param string $css
   * @return string
   */
  private function compress_hex_colors($css) {

    // Look for hex colors inside { ... } (to avoid IDs) and which don't have a =, or a " in front of them (to avoid filters)
    $pattern = '/(\\=\\s*?["\']?)?#([0-9a-f])([0-9a-f])([0-9a-f])([0-9a-f])([0-9a-f])([0-9a-f])(\\}|[^0-9a-f{][^{]*?\\})/iS';
    $_index = $index = $last_index = $offset = 0;
    $sb = array();

    // See: http://ajaxmin.codeplex.com/wikipage?title=CSS%20Colors
    $short_safe = array(
      '#808080' => 'gray',
      '#008000' => 'green',
      '#800000' => 'maroon',
      '#000080' => 'navy',
      '#808000' => 'olive',
      '#ffa500' => 'orange',
      '#800080' => 'purple',
      '#c0c0c0' => 'silver',
      '#008080' => 'teal',
      '#f00' => 'red',
    );
    while (preg_match($pattern, $css, $m, 0, $offset)) {
      $index = $this
        ->index_of($css, $m[0], $offset);
      $last_index = $index + strlen($m[0]);
      $is_filter = $m[1] !== null && $m[1] !== '';
      $sb[] = $this
        ->str_slice($css, $_index, $index);
      if ($is_filter) {

        // Restore, maintain case, otherwise filter will break
        $sb[] = $m[1] . '#' . $m[2] . $m[3] . $m[4] . $m[5] . $m[6] . $m[7];
      }
      else {
        if (strtolower($m[2]) == strtolower($m[3]) && strtolower($m[4]) == strtolower($m[5]) && strtolower($m[6]) == strtolower($m[7])) {

          // Compress.
          $hex = '#' . strtolower($m[3] . $m[5] . $m[7]);
        }
        else {

          // Non compressible color, restore but lower case.
          $hex = '#' . strtolower($m[2] . $m[3] . $m[4] . $m[5] . $m[6] . $m[7]);
        }

        // replace Hex colors to short safe color names
        $sb[] = array_key_exists($hex, $short_safe) ? $short_safe[$hex] : $hex;
      }
      $_index = $offset = $last_index - strlen($m[8]);
    }
    $sb[] = $this
      ->str_slice($css, $_index);
    return implode('', $sb);
  }

  /* CALLBACKS
   * ---------------------------------------------------------------------------------------------
   */
  private function replace_string($matches) {
    $match = $matches[0];
    $quote = substr($match, 0, 1);

    // Must use addcslashes in PHP to avoid parsing of backslashes
    $match = addcslashes($this
      ->str_slice($match, 1, -1), '\\');

    // maybe the string contains a comment-like substring?
    // one, maybe more? put'em back then
    if (($pos = $this
      ->index_of($match, self::COMMENT)) >= 0) {
      for ($i = 0, $max = count($this->comments); $i < $max; $i++) {
        $match = preg_replace('/' . self::COMMENT . $i . '___/', $this->comments[$i], $match, 1);
      }
    }

    // minify alpha opacity in filter strings
    $match = preg_replace('/progid\\:DXImageTransform\\.Microsoft\\.Alpha\\(Opacity\\=/i', 'alpha(opacity=', $match);
    $this->preserved_tokens[] = $match;
    return $quote . self::TOKEN . (count($this->preserved_tokens) - 1) . '___' . $quote;
  }
  private function replace_colon($matches) {
    return preg_replace('/\\:/', self::CLASSCOLON, $matches[0]);
  }
  private function replace_calc($matches) {
    $this->preserved_tokens[] = trim(preg_replace('/\\s*([\\*\\/\\(\\),])\\s*/', '$1', $matches[2]));
    return 'calc(' . self::TOKEN . (count($this->preserved_tokens) - 1) . '___' . ')';
  }
  private function preserve_old_IE_specific_matrix_definition($matches) {
    $this->preserved_tokens[] = $matches[1];
    return 'filter:progid:DXImageTransform.Microsoft.Matrix(' . self::TOKEN . (count($this->preserved_tokens) - 1) . '___' . ')';
  }
  private function replace_keyframe_zero($matches) {
    return $matches[1] . preg_replace('/0(\\{|,[^\\)\\{]+\\{)/', '0%$1', $matches[2]) . $matches[3];
  }
  private function rgb_to_hex($matches) {

    // Support for percentage values rgb(100%, 0%, 45%);
    if ($this
      ->index_of($matches[1], '%') >= 0) {
      $rgbcolors = explode(',', str_replace('%', '', $matches[1]));
      for ($i = 0; $i < count($rgbcolors); $i++) {
        $rgbcolors[$i] = $this
          ->round_number(floatval($rgbcolors[$i]) * 2.55);
      }
    }
    else {
      $rgbcolors = explode(',', $matches[1]);
    }

    // Values outside the sRGB color space should be clipped (0-255)
    for ($i = 0; $i < count($rgbcolors); $i++) {
      $rgbcolors[$i] = $this
        ->clamp_number(intval($rgbcolors[$i], 10), 0, 255);
      $rgbcolors[$i] = sprintf("%02x", $rgbcolors[$i]);
    }

    // Fix for issue #2528093
    if (!preg_match('/[\\s\\,\\);\\}]/', $matches[2])) {
      $matches[2] = ' ' . $matches[2];
    }
    return '#' . implode('', $rgbcolors) . $matches[2];
  }
  private function hsl_to_hex($matches) {
    $values = explode(',', str_replace('%', '', $matches[1]));
    $h = floatval($values[0]);
    $s = floatval($values[1]);
    $l = floatval($values[2]);

    // Wrap and clamp, then fraction!
    $h = ($h % 360 + 360) % 360 / 360;
    $s = $this
      ->clamp_number($s, 0, 100) / 100;
    $l = $this
      ->clamp_number($l, 0, 100) / 100;
    if ($s == 0) {
      $r = $g = $b = $this
        ->round_number(255 * $l);
    }
    else {
      $v2 = $l < 0.5 ? $l * (1 + $s) : $l + $s - $s * $l;
      $v1 = 2 * $l - $v2;
      $r = $this
        ->round_number(255 * $this
        ->hue_to_rgb($v1, $v2, $h + 1 / 3));
      $g = $this
        ->round_number(255 * $this
        ->hue_to_rgb($v1, $v2, $h));
      $b = $this
        ->round_number(255 * $this
        ->hue_to_rgb($v1, $v2, $h - 1 / 3));
    }
    return $this
      ->rgb_to_hex(array(
      '',
      $r . ',' . $g . ',' . $b,
      $matches[2],
    ));
  }
  private function lowercase_pseudo_first($matches) {
    return ':first-' . strtolower($matches[1]) . ' ' . $matches[2];
  }
  private function lowercase_directives($matches) {
    return '@' . strtolower($matches[1]);
  }
  private function lowercase_pseudo_elements($matches) {
    return ':' . strtolower($matches[1]);
  }
  private function lowercase_common_functions($matches) {
    return ':' . strtolower($matches[1]) . '(';
  }
  private function lowercase_common_functions_values($matches) {
    return $matches[1] . strtolower($matches[2]);
  }
  private function lowercase_properties($matches) {
    return $matches[1] . strtolower($matches[2]) . $matches[3];
  }

  /* HELPERS
   * ---------------------------------------------------------------------------------------------
   */
  private function hue_to_rgb($v1, $v2, $vh) {
    $vh = $vh < 0 ? $vh + 1 : ($vh > 1 ? $vh - 1 : $vh);
    if ($vh * 6 < 1) {
      return $v1 + ($v2 - $v1) * 6 * $vh;
    }
    if ($vh * 2 < 1) {
      return $v2;
    }
    if ($vh * 3 < 2) {
      return $v1 + ($v2 - $v1) * (2 / 3 - $vh) * 6;
    }
    return $v1;
  }
  private function round_number($n) {
    return intval(floor(floatval($n) + 0.5), 10);
  }
  private function clamp_number($n, $min, $max) {
    return min(max($n, $min), $max);
  }

  /**
   * PHP port of Javascript's "indexOf" function for strings only
   * Author: Tubal Martin http://blog.margenn.com
   *
   * @param string $haystack
   * @param string $needle
   * @param int    $offset index (optional)
   * @return int
   */
  private function index_of($haystack, $needle, $offset = 0) {
    $index = strpos($haystack, $needle, $offset);
    return $index !== FALSE ? $index : -1;
  }

  /**
   * PHP port of Javascript's "slice" function for strings only
   * Author: Tubal Martin http://blog.margenn.com
   * Tests: http://margenn.com/tubal/str_slice/
   *
   * @param string   $str
   * @param int      $start index
   * @param int|bool $end index (optional)
   * @return string
   */
  private function str_slice($str, $start = 0, $end = FALSE) {
    if ($end !== FALSE && ($start < 0 || $end <= 0)) {
      $max = strlen($str);
      if ($start < 0) {
        if (($start = $max + $start) < 0) {
          return '';
        }
      }
      if ($end < 0) {
        if (($end = $max + $end) < 0) {
          return '';
        }
      }
      if ($end <= $start) {
        return '';
      }
    }
    $slice = $end === FALSE ? substr($str, $start) : substr($str, $start, $end - $start);
    return $slice === FALSE ? '' : $slice;
  }

  /**
   * Convert strings like "64M" or "30" to int values
   * @param mixed $size
   * @return int
   */
  private function normalize_int($size) {
    if (is_string($size)) {
      switch (substr($size, -1)) {
        case 'M':
        case 'm':
          return (int) $size * 1048576;
        case 'K':
        case 'k':
          return (int) $size * 1024;
        case 'G':
        case 'g':
          return (int) $size * 1073741824;
      }
    }
    return (int) $size;
  }

}

Classes

Name	Description
CSSmin