ceph/src/rapidjson/example/messagereader/messagereader.cpp

   1 // Reading a message JSON with Reader (SAX-style API).
   2 // The JSON should be an object with key-string pairs.
   3
   4 #include "rapidjson/reader.h"
   5 #include "rapidjson/error/en.h"
   6 #include <iostream>
   7 #include <string>
   8 #include <map>
   9
  10 using namespace std;
  11 using namespace rapidjson;
  12
  13 typedef map<string, string> MessageMap;
  14
  15 #if defined(__GNUC__)
  16 RAPIDJSON_DIAG_PUSH
  17 RAPIDJSON_DIAG_OFF(effc++)
  18 #endif
  19
  20 #ifdef __clang__
  21 RAPIDJSON_DIAG_PUSH
  22 RAPIDJSON_DIAG_OFF(switch-enum)
  23 #endif
  24
  25 struct MessageHandler
  26     : public BaseReaderHandler<UTF8<>, MessageHandler> {
  27     MessageHandler() : messages_(), state_(kExpectObjectStart), name_() {}
  28
  29     bool StartObject() {
  30         switch (state_) {
  31         case kExpectObjectStart:
  32             state_ = kExpectNameOrObjectEnd;
  33             return true;
  34         default:
  35             return false;
  36         }
  37     }
  38
  39     bool String(const char* str, SizeType length, bool) {
  40         switch (state_) {
  41         case kExpectNameOrObjectEnd:
  42             name_ = string(str, length);
  43             state_ = kExpectValue;
  44             return true;
  45         case kExpectValue:
  46             messages_.insert(MessageMap::value_type(name_, string(str, length)));
  47             state_ = kExpectNameOrObjectEnd;
  48             return true;
  49         default:
  50             return false;
  51         }
  52     }
  53
  54     bool EndObject(SizeType) { return state_ == kExpectNameOrObjectEnd; }
  55
  56     bool Default() { return false; } // All other events are invalid.
  57
  58     MessageMap messages_;
  59     enum State {
  60         kExpectObjectStart,
  61         kExpectNameOrObjectEnd,
  62         kExpectValue
  63     }state_;
  64     std::string name_;
  65 };
  66
  67 #if defined(__GNUC__)
  68 RAPIDJSON_DIAG_POP
  69 #endif
  70
  71 #ifdef __clang__
  72 RAPIDJSON_DIAG_POP
  73 #endif
  74
  75 static void ParseMessages(const char* json, MessageMap& messages) {
  76     Reader reader;
  77     MessageHandler handler;
  78     StringStream ss(json);
  79     if (reader.Parse(ss, handler))
  80         messages.swap(handler.messages_);   // Only change it if success.
  81     else {
  82         ParseErrorCode e = reader.GetParseErrorCode();
  83         size_t o = reader.GetErrorOffset();
  84         cout << "Error: " << GetParseError_En(e) << endl;;
  85         cout << " at offset " << o << " near '" << string(json).substr(o, 10) << "...'" << endl;
  86     }
  87 }
  88
  89 int main() {
  90     MessageMap messages;
  91
  92     const char* json1 = "{ \"greeting\" : \"Hello!\", \"farewell\" : \"bye-bye!\" }";
  93     cout << json1 << endl;
  94     ParseMessages(json1, messages);
  95
  96     for (MessageMap::const_iterator itr = messages.begin(); itr != messages.end(); ++itr)
  97         cout << itr->first << ": " << itr->second << endl;
  98
  99     cout << endl << "Parse a JSON with invalid schema." << endl;
 100     const char* json2 = "{ \"greeting\" : \"Hello!\", \"farewell\" : \"bye-bye!\", \"foo\" : {} }";
 101     cout << json2 << endl;
 102     ParseMessages(json2, messages);
 103
 104     return 0;
 105 }