rapidjson/example/messagereader/messagereader.cpp at master · Tencent/rapidjson · GitHub

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// Reading a message JSON with Reader (SAX-style API).
// The JSON should be an object with key-string pairs.

#include"rapidjson/reader.h"
#include"rapidjson/error/en.h"
#include<iostream>
#include<string>
#include<map>

usingnamespacestd;
usingnamespacerapidjson;

typedef map<string, string> MessageMap;

#if defined(__GNUC__)
RAPIDJSON_DIAG_PUSH
RAPIDJSON_DIAG_OFF(effc++)
#endif

#ifdef __clang__
RAPIDJSON_DIAG_PUSH
RAPIDJSON_DIAG_OFF(switch-enum)
#endif

structMessageHandler
 : public BaseReaderHandler<UTF8<>, MessageHandler> {
MessageHandler() : messages_(), state_(kExpectObjectStart), name_() {}

boolStartObject() {
switch (state_) {
casekExpectObjectStart:
 state_ = kExpectNameOrObjectEnd;
returntrue;
default:
returnfalse;
 }
 }

boolString(constchar* str, SizeType length, bool) {
switch (state_) {
casekExpectNameOrObjectEnd:
 name_ = string(str, length);
 state_ = kExpectValue;
returntrue;
casekExpectValue:
 messages_.insert(MessageMap::value_type(name_, string(str, length)));
 state_ = kExpectNameOrObjectEnd;
returntrue;
default:
returnfalse;
 }
 }

boolEndObject(SizeType) { return state_ == kExpectNameOrObjectEnd; }

boolDefault() { returnfalse; } // All other events are invalid.

 MessageMap messages_;
enum State {
kExpectObjectStart,
kExpectNameOrObjectEnd,
kExpectValue
 }state_;
 std::string name_;
};

#if defined(__GNUC__)
RAPIDJSON_DIAG_POP
#endif

#ifdef __clang__
RAPIDJSON_DIAG_POP
#endif

staticvoidParseMessages(constchar* json, MessageMap& messages) {
 Reader reader;
 MessageHandler handler;
 StringStream ss(json);
if (reader.Parse(ss, handler))
 messages.swap(handler.messages_); // Only change it if success.
else {
 ParseErrorCode e = reader.GetParseErrorCode();
size_t o = reader.GetErrorOffset();
 cout << "Error: " << GetParseError_En(e) << endl;;
 cout << " at offset " << o << " near '" << string(json).substr(o, 10) << "...'" << endl;
 }
}

intmain() {
 MessageMap messages;

constchar* json1 = "{ \"greeting\" : \"Hello!\", \"farewell\" : \"bye-bye!\" }";
 cout << json1 << endl;
ParseMessages(json1, messages);

for (MessageMap::const_iterator itr = messages.begin(); itr != messages.end(); ++itr)
 cout << itr->first << ": " << itr->second << endl;

 cout << endl << "Parse a JSON with invalid schema." << endl;
constchar* json2 = "{ \"greeting\" : \"Hello!\", \"farewell\" : \"bye-bye!\", \"foo\" : {} }";
 cout << json2 << endl;
ParseMessages(json2, messages);

return0;
}