text: var EscapeStore = require('./escape-store');
  var QuoteScanner = require('./quote-scanner');
  
  module.exports = function Comments(context, keepSpecialComments, keepBreaks, lineBreak) {
    var comments = new EscapeStore('COMMENT');
  
    return {
      // Strip special comments (/*! ... */) by replacing them by a special marker
      // for further restoring. Plain comments are removed. It's done by scanning data using
      // String#indexOf scanning instead of regexps to speed up the process.
      escape: function(data) {
        var tempData = [];
        var nextStart = 0;
        var nextEnd = 0;
        var cursor = 0;
        var isQuotedAt = (function () {
          var quoteMap = [];
          new QuoteScanner(data).each(function (quotedString, _, startsAt) {
            quoteMap.push([startsAt, startsAt + quotedString.length]);
          });
  
          return function (position) {
            for (var i = 0, l = quoteMap.length; i < l; i++) {
              if (quoteMap[i][0] < position && quoteMap[i][1] > position)
                return true;
            }
  
            return false;
          };
        })();
  
        for (; nextEnd < data.length;) {
          nextStart = data.indexOf('/*', cursor);
          if (nextStart == -1)
            break;
          if (isQuotedAt(nextStart)) {
            tempData.push(data.substring(cursor, nextStart + 2));
            cursor = nextStart + 2;
            continue;
          }
  
          nextEnd = data.indexOf('*/', nextStart + 2);
          if (nextEnd == -1) {
            context.warnings.push('Broken comment: \'' + data.substring(nextStart) + '\'.');
            nextEnd = data.length - 2;
          }
  
          tempData.push(data.substring(cursor, nextStart));
          if (data[nextStart + 2] == '!') {
            // in case of special comments, replace them with a placeholder
            var comment = data.substring(nextStart, nextEnd + 2);
            var placeholder = comments.store(comment);
            tempData.push(placeholder);
          }
          cursor = nextEnd + 2;
        }
  
        return tempData.length > 0 ?
          tempData.join('') + data.substring(cursor, data.length) :
          data;
      },
  
      restore: function(data) {
        var restored = 0;
        var breakSuffix = keepBreaks ? lineBreak : '';
  
        return data.replace(new RegExp(comments.placeholderPattern + '(' + lineBreak + '| )?', 'g'), function(match, placeholder) {
          restored++;
  
          switch (keepSpecialComments) {
            case '*':
              return comments.restore(placeholder) + breakSuffix;
            case 1:
            case '1':
              return restored == 1 ?
                comments.restore(placeholder) + breakSuffix :
                '';
            case 0:
            case '0':
              return '';
          }
        });
      }
    };
  };
  