<?php
/**
 * Class Minify_CommentPreserver 
 * @package Minify
 */

/**
 * Process a string in pieces preserving C-style comments that begin with "/*!"
 * 
 * @package Minify
 * @author Stephen Clay <steve@mrclay.org>
 */
class Minify_CommentPreserver {
 
 /**
 * String to be prepended to each preserved comment
 *
 * @var string
 */
 public static $prepend = "\n";
 
 /**
 * String to be appended to each preserved comment
 *
 * @var string
 */
 public static $append = "\n";
 
 /**
 * Process a string outside of C-style comments that begin with "/*!"
 *
 * On each non-empty string outside these comments, the given processor 
 * function will be called. The comments will be surrounded by 
 * Minify_CommentPreserver::$preprend and Minify_CommentPreserver::$append.
 * 
 * @param string $content
 * @param callback $processor function
 * @param array $args array of extra arguments to pass to the processor 
 * function (default = array())
 * @return string
 */
 public static function process($content, $processor, $args = array())
 {
 $ret = '';
 while (true) {
 list($beforeComment, $comment, $afterComment) = self::_nextComment($content);
 if ('' !== $beforeComment) {
 $callArgs = $args;
 array_unshift($callArgs, $beforeComment);
 $ret .= call_user_func_array($processor, $callArgs); 
 }
 if (false === $comment) {
 break;
 }
 $ret .= $comment;
 $content = $afterComment;
 }
 return $ret;
 }
 
 /**
 * Extract comments that YUI Compressor preserves.
 * 
 * @param string $in input
 * 
 * @return array 3 elements are returned. If a YUI comment is found, the
 * 2nd element is the comment and the 1st and 3rd are the surrounding
 * strings. If no comment is found, the entire string is returned as the 
 * 1st element and the other two are false.
 */
 private static function _nextComment($in)
 {
 if (
 false === ($start = strpos($in, '/*!'))
 || false === ($end = strpos($in, '*/', $start + 3))
 ) {
 return array($in, false, false);
 }
 $ret = array(
 substr($in, 0, $start)
 ,self::$prepend . '/*!' . substr($in, $start + 3, $end - $start - 1) . self::$append
 );
 $endChars = (strlen($in) - $end - 2);
 $ret[] = (0 === $endChars)
 ? ''
 : substr($in, -$endChars);
 return $ret;
 }
}