code: function getConverter(content) {
      var rbr = /\r\n|\r|\n/mg;
      var steps = [0], m;
  
      while((m = rbr.exec(content))) {
          steps.push(m.index + m[0].length);
      }
  
      return function(line, column) {
          if (steps.length < line) {
              return -1;
          }
  
          return steps[line-1] + column;
      };
  }
docs: 生成转换坐标为位置的函数。