message: Fix(Query): support single quotes string literals
diff: @@ -303,6 +303,36 @@ ResultSet::to_JSON()
  }
  }
  }
  + else if (ans_str[0] == '\'')
  + {
  + if (ans_str.find("'^^<") == string::npos)
  + {
  + if (ans_str.find("'@") != string::npos)
  + {
  + //for language string
  + ans_type = "literal";
  + string data_type = ans_str.substr(ans_str.rfind("@")+1, ans_str.length());
  + ans_str = ans_str.substr(1, ans_str.rfind('\'') - 1);
  + _buf << "\"" + this->var_name[j].substr(1) + "\": { ";
  + _buf << "\"type\": \"" + ans_type + "\", \"lang\": \"" + data_type + "\", \"value\": " + Util::node2string((string("\"") + ans_str + "\"").c_str()) + " }";
  + list_empty = false;
  + }
  + else
  + {
  + //no has type string
  + ans_type = "literal";
  + ans_str = ans_str.substr(1, ans_str.rfind('\'') - 1);
  + _buf << "\"" + this->var_name[j].substr(1) + "\": { ";
  + _buf << "\"type\": \"" + ans_type + "\", \"value\": " + Util::node2string((string("\"") + ans_str + "\"").c_str()) + " }";
  + list_empty = false;
  + }
  + }
  + else
  + {
  + _buf<<"\"error\":{\"errorMsg:\":\"the information is not complete!\"}";
  + list_empty=false;
  + }
  + }
  // else if (ans_str[0] == '"' && ans_str.find("\"^^<") == string::npos && ans_str[ans_str.length() - 1] != '>' )
  // {
  // ans_type = "literal";
  