code: function getMatchRate(src, str) {
          if (typeof (src) === 'undefined' || typeof (str) === 'undefined') {
              return 0;
          }
  
          var maxLength = src.length > str.length ? src.length : str.length,
                  matchCnt = 0;
          if (maxLength === 0) {
              return 1;
          }
  
          for (var i = 0; i < maxLength; i++) {
              if (str.charAt(i) === src.charAt(i)) {
                  matchCnt++;
              }
          }
  
          if (matchCnt === 0) {
              return 0;
          }
  
          return matchCnt / maxLength;
      }
docs: Compare each character for ever line, and get ever line match rate.
  
  @param {type} src text for template.
  @param {type} str text for file.
  @returns {float} match rate.